I learned about the importance of polarity when I was young. I received a ghetto blaster for xmas and I was shocked that AM radio sounded so much better than FM. AM was in mono and only came from the left speaker but FM being stereo came from both. My natural curiosity got the better of me and I opened it up 2 days after getting it. My mother was furious. I had no idea what I was doing or should be looking for but I knew the difference between positive and negative and colour coding. I saw the left speaker was wired white to + and black to - which seemed normal to me. But the right speaker was wired white to - and black to + which seemed wrong. I had already been soldering for a few years so I desoldered the wires from the right speaker, switched them and soldered them again. I put it on FM and was amazed at how good it sounded. My mother was so happy that it worked but still never gave me any credit for fixing/improving my gift. For years she would say "Do you remember that xmas you took apart your radio?" and I would always ask her if she remembered that not only did I put it back together but that it was better than when I had taken it apart. Never got any credit for that.
@@PauldeVries I still regularly take things apart. Often only to see what's inside. I've gotten a LOT better at putting them back together again as well. lol But yes, 99% of the time I will try and fix it. I'm cheap and would much rather spend a couple of bucks on parts and a little bit of time instead of tossing it out and replacing it. That's one thing my grandparents taught me: Repair it until it can't be repaired any longer and then salvage whatever parts you can and repurpose what can't be salvaged.
Pretty sure she would have given you credit if someone had thought her how and why to do it. Don't think she intentionally held back on giving you credit. But yeah man, sometimes those unimportant moments for adults can become lifelong memories for kids.
Years ago, I found I had accidentally wired one of my two subwoofers in reverse (in my mobile DJ rig). When I saw how I had screwed it up, I laughed so hard! I had been struggling for several months with my system - asking myself, "Why can I hear the base coming out of each sub when I stand right in front of it but when I move to the center of the dance floor, I don't hear or feel it?" No amount of EQing or compression made any difference. When I saw I had the cable to one sub wired backwards (positive to negative and negative to positive), man oh man, I was relieved. I still laugh today thinking about it.
I worked on a recording system that sounded perfectly fine but when you tried to record you got nothing. Someone wired one of the inputs backwards so the mono signals from the mic were being cancelled.... The tech who installed it couldn't figure it out for 2 weeks.
Haha that's a good laugh. I mean in the sense that we've all made simple mistakes but genuinely bothered us. Then we happen to stumble upon the solution like it felt sorry for us lmao
At live events you'll often see arrays or fills aimed backstage and wired out of phase. This cancels the sound from monitors and main PA. While the crowd is getting blasted. The crew backstage can speak normally and often don't need ear pro while working. They do the same thing to create "dead zones" in large clubs - areas like the lounge or the bar. Those speakers over the bar that don't appear to be on are actually doing a big job. Theme parks even use phase cancellation to kill mechanical noise.
Fun fact: I once installed a dual subwoofer setup in my Nissan 100NX (yes it's been a while) .. After installation I played some subwoofer test music and was disapointed by the lack of bass from the subwoofers. I didn't understand, I had two subwoofers and still heard almost nothing. It was at this point I thought about polarity and I changed the phase setting (on one of the amplifiers). It was at this moment I learned that I should not have done that while the system was running a subwoofer bass test on 80% volume. The moment I flipped that switch I was scared to death, the system was playing so load suddenly. Learned some lessons that day!
My college roommate blew out his rear glass because he was trying a test and realized a wire came loose or something. Suddenly bbbrrrrrrrtttttt and he was covered in little glass cubes.
Very simply, when one speaker is out of phase (wired backwards) in a stereo system, they cancel each other out. Mainly heard in the lower frequencies, but also affecting image and sound staging.
It's heard in all frequencies that are pannes with an identical signal to both speakers. It's the same as a common mode interference supressor in a balanced signal chain. There is usually just one bass and bass drums are usually not panned so that is why they dissapear more than other instruments, has nothing to do with them being low frequency though.
I once played at a psytrance party where one of two subs was wired incorrectly, resulting in the bass literally disappearing right in the middle of the dance floor. 😂 Since is was open air, you hadn't even echoes from walls. Super weird.
@@NeovanGoth The person that made those speaker cables really messed up. Should never happen in a PA system since the speaker cabler are hard wired unless there is a phaze switch somewhere in the system.
I heard about phase back in the 70's. I don't recall being able to hear a difference, but I didn't have speakers that reproduced heavy bass. I've always tried to wire correctly anyway.
If you have two stereo speakers wired with opposite polarity (a.k.a half a cycle out of phase), you get an interesting effect because the signals cancel each other out in a fringe pattern which generally makes it feel like the sound is coming from around or behind you, because it will bounce off the room walls before it reaches your ears. This effect is used in legend of zelda ocarina of time for the sound of the townspeople in the castle town courtyard, and in the movie twelve monkeys for the mystery voice he hears in his head Flipping the polarity of one of the channels in a pop song can also work as a useful hack to get something approximating an instrumental version of the track, because generally the vocal is dead centre but the backing is not so the vocal gets cancelled out
my science teacher did this in school with speakers out of phase and made us walk around the room, the volume changed depending on where you were in the room because of the phase cancellation
But that messes with the "dubbing" The effect is still in play when recorded, and requires micro editing in the DAW where cancelations occur in track adding... Someone once suggested changing the waveform, but it's still the inverse frequency loss to deal with.
I seem to recall an old CD player stereo my sister got for Christmas had this as a feature? (I think it was intended as a Karaoke mode?) I don't remember much other then it was weird to child me for the vocals to just all the sudden disappear like the vocals were on some different audio channel getting disabled.
You have a gift, dude. I spent decades in the professional audio industry having been born into it with my father coming before me. And you have generated over one and a half million hits to this video sharing something I've known since I was in grade school. This isn't me criticizing you, it's me applauding you. To be able to do this, it's a gift. Things I took for granted surprise me often. I had inherited a half dozen JBL Professional transformers. So common in our shop were these, I literally thought they were garbage For giggles, put one up for sale on ebay years ago. They started stabbing each other to obtain it. Ended up getting $200 for something I almost threw away and had five more of. Just one example of a pleasant surprise. You should do a video on impedance matching. Reversing the polarity of speaker isn't something that commonly happens with polarity marked on the speakers or speakers with wiring included having these wires color coated. You are correct in stating it does and does not matter if reversed. As a professional, it absolutely matters. Nothing would scream amatuer louder than having screwed up the obvious. Doesn't matter in typical two speaker stereo systems much because two independent channels, etc. But impedance matching of speakers to amplifiers is not well known at all. Yet is simple and straight forward. And very important. The common person is typically power output motivated when it comes to amplifiers and sound systems. Yet, they are ignorant to what they are referring to because all they know is what salesman tell them. Salesman are always motivated by making bigger, better, and more sales. Usually equally as ignorant as the end user. So, more, more, more and bragging rights for power output rules the world. Which makes any video you would offer on proper impedance matching that much more relevant to the common consumer of audio amplification and sound reproduction equipment. You're a good presenter. Don't know your background in audio. You may be another TH-cam creator who presents him or herself as expert, but the we and us they often use to make them look like a great big rolling railroad is non existent. I can hear them justifying the terms used by saying they were referring to their wife/husband or baby children. Can't blame anyone for trying. Impedance matching is necessary to get all the wattage you thought you really needed when you bought that big power amp or stereo system that put out all that advertised power to actually be used. If the output rating of an amp is 4 ohms for example. Let's clarify at 4 ohms per channel, to get the 100 advertised watts of power per channel you paid for, you need to match the input impedance of the speakers to it. 4 ohm amplifier output to 4 ohm speaker input means all 100 watts of power is available. Impedance mismatches will still make the amplifier's power output available, but in lesser percentages than advertised. Same example of amplifier with 8 ohm speaker. The mismatch is a factor of two or half. The 100 watts would not be available and only half this, 50 watts, would be. It's always a reduction in advertised power not an increase. So another speaker, listed as having a 2 ohm impedance input connected to the same 100 watt, 4 ohm rated amplifier output, would also produce half the 100 watts of power available and 50 watts of power tops. Start mixing multiple speakers per channel and that's another complexity all together but on the same level. Since impedance is basically the resistance measurement of an ac device, it increases and decreases in rating same as resistance does. Put two 8 ohm speakers in parallel, and the amplifier does not see 8 ohms but 4 ohms. Put the same speakers in series, now the amplifier sees 16 ohms. In this scenario, on a 100 watt power amplifier with a 4 ohm output, the most you'll see from that 100 watts of power you have is 25 watts being 4 is one forth of 16. Always lose power from mismatches, never gain. Sorry to lecture. I'm old and too much to do, nothing I really want to. Thanks.
We used a battery to figure out the polarity of the speakers;when trouble shooting a previous installation. A dead give away is solid bass when turned to one channel or the other, but when balanced no bass out of either indicates inverted polarity on one or more speakers depending upon setup. Our shop used to troubleshoot a lot of other shops work. Motor noise used to be a huge issue for some shops.
On a side note, the term phase and polarity are often used to describe the same thing but are actually different. Polarity inversion (flip or swap)is what is described in this video and is a 180 degree phase inversion. It is possible to have phase discrepancies that are not a full 180 degrees.
Also, polarity is a reversal of a physical or electrical connection that results in a 180° phase shift. Many issues can create phase shift. Polarity reversal is just one that has a singular shift.
You can but they will be different at all frequencies. Simply having one speaker further away from your ears than another will give you a phase change - could be partial or the full 180 depending on frequency.
It's actually fun to experiment with out of phase speakers and placement. If they are directly facing each other with the listener in between, you get a push-pull effect that's pretty cool. It depends on the spacing and frequencies as well.
@@jnawk83 You do not get silence, only damped bass and the higher frequencies is pretty much unaffected but with weird / cool sound effects of "sound phasing".
It can result in a kind of "fake stereo" effect. When I was a kid I got a kick out of doing that. Even better was setting up an AM radio and FM radio on the same station (here in NZ at the time we had stations that broadcasted on both) for whatever reason there was a significant time difference between the two, causing a fairly extreme slapback echo effect. It was a trip.
You should take a pair of those linear transducers and have them agitate a shallow pool of ~dyed water. In theory, we should be able to see how the delay required to propagate the signals through the media affect constructive and destructive interference at different frequencies, distances, polarities, etc.
Installing a stroboscope illuminating the water at the same frequency as the waves, will also make it so that the waves appear stationary, so the differences can be pictured better
@@rojirrim7298 I think showing the agitation of the water would be better. Otherwise, when you have a spot with looks like it hasn't moved is that because it cancels or because it just isn't moving at that point. Alternatively, the stroboscope slightly off frequency, so you can see the waves moving and interacting.
When you listen to the initial hit of a kick drum there is a definite change of sound and feel with a single speaker wired with reverse polarity. Especially with a PA sub system that covers the 25Hz range. If everything is wired correctly you should feel the air hitting your chest. If the sub polarity is reversed then the kick drum completely loses it's impact. This because the first positive peak of the sine wave is the largest and sound pressure waves in compression have better projection than ratification of sound waves.
Absolutely correct. I was going to post similar comment. If that would be no difference at all then drummer can put his kick pedal in front of bass drum and play that way. But nobody ever played such way in a music history for obvious reason. You need LF sound kick to propagate toward audience. However I agree that it would be no difference in mid and high freq ranges.
Thank you for this. I learned about out of phase speakers in the late 70’s when I took audio engineering classes. It’s hard to explain to the layman. You did it perfectly. You could also add that it’s similar to the way noise canceling headphones work.
Coincidentally last week I was installing an home theater in my room (the old style one, not a sound bar) and I was wondering why the speakers had polarity and I was very afraid of inverting wires. Now everything is very clear. Thanks for the video!
Nice, a real home theater! I hope you enjoy your build. I just got a pair of TAD 1601c, some altec 288c, and gauss 1502 drivers /horns. My wife vehemently refused to let them near the living room, so down to the Home Theater they went! The kids love it
Having some education in electronics and a half century experience with home stereo, I can't say I learned from the video. But oh how I enjoyed seeing it explained so well. This young man has a gift for explanation.
I like that it was explained without assuming every member of the audience already knew the basics. People often skip the basics, and those are so important in building a good foundational knowledge. I agree. He did a great job, and his voice is calm and soothing. He makes good eye contact, and speaks without ums and ahs.
Yeah you are right bro, all people can broadcast information however what make difference is the Way of delivering that information. This respectful Guy touched the top of perfection in his explanation.
This just happened to of popped up on my TH-cam. I spent many years in the automotive stereo industry, starting out very young. I could never hear the difference AS long as everything was wired the same. But wire one speaker wrong in a stereo system and you most assuredly can and will hear it. That was almost 40 years when I started, and nothing much has changed. Very important to get it right and right the first time. Nothing worse than having that person coming back because you got it wrong.
Great vid. Last year I had one of my main speakers wired out of polarity. I had a mate over (who works in audio) to tune my subs. He listened for about 10secs and said 'I think your wiring is out of polarity' and of course it was. When I corrected it the only noticeable difference was the imaging, the sound quality was the same but the voice was no longer smeared, it was positioned. Always learning, thanks!
Back in the mid 1970's I worked installing PA systems in a grocery store chain, the system was a 70 volt system that was used to play mono background music when it was not being use for announcements. The speakers were mounted in the ceiling of the stores and to keep the speakers from canceling one another out we had to space the speaker properly to take in account the delay of the audio from each of the speakers and we had to switch the polarity of each of the speakers because of that delay to keep them in phase with one another. This was to minimize the locations in the shopping aisle that presented cancellation zones. It worked very good.
Yes. But you guys make me think about something here but not here. We don't have it. Let me imagine this for a moment or so .. Can't we have a button on our so, advanced remote that we can flip polarity around?
You have to do the math between the ohms of the speakers and series and parallel loads on the amp. You just can't hook them all up in parallel like most people would. Thankfully those days of problems are loin behind me. Uh I meant long behind me. Same thing I guess, oh well.
@@TimpBizkit You are correct that music is all different frequencies, but when you reverse the polarity of one speaker you are reversing or changing the phase of all of the frequencies to that speaker in relation to the other speakers by 180 degrees, so *_PHASE MATTERS._*
I noticed a difference in sound decades ago on my Dad's stereo. Maybe it's not noticeable on headphones, but if the speakers are far enough apart, the inverted wiring caused it to sound very hollow.
It is taught in certain math and physics classes, but there is little practical application for most people, except installing speakers, or getting a job that uses math or physics
Wave addition (or cancellation if one signal is reversed) has a very practical application in noise canceling headphones and earbuds. A microphone picks up the ambient noise, which is then reversed and added to the music being played by the speakers in the headphones, the reversed noise cancels out the ambient noise and you hear just the music.
I don’t think it was mentioned in the video, so I just wanted to add that the common naming when speakers are wired the same is “in phase” and when they are wired with different polarities is “out of phase”. There are some interesting acoustic characteristics when speakers are wired out of phase in a home listening environment where the sound seems to appear diffuse and almost like it’s “floating around your head” with no distinct source. There are some fun examples elsewhere on TH-cam where you can listen to in-phase and out-of-phase white noise that demonstrate this.
What you describe results because vocals and other instruments that are intended to be front and center experience more interference than those panned more to one side or another because they are essentially equal in each speaker. This causes more cancellation of anything in the center.
Im not 100% sure I am correct, but i heard somewhere over the years that some high end speaker manufacturers using a lot of X-over points design speaker cabs with the low bass drivers intentionaly wired 180 degrees out of phase to take advantage of this phenomenon and give the low end a wider sound stage
@@Angellus502 Interesting idea, however, I wonder about this. Bass frequencies are extremely problematic when out of phase between multiple speakers. I would expect dissonant artifacts that would be anything but audiophile, from such a setup. I don't know the specific acoustic properties, but in the concert PA world, it's fairly common now to physically reverse several of the subwoofer boxes, but not to create phase artifacts. It's done to acoustically cancel bass frequencies behind the subwoofes. It's the speaker equivalent to phase ports on the back of directional microphone capsules. The steers the bass towards the audience and away from the stage where it can be problematic vibrating the performers, their gear, and the microphones on amplifiers and other instruments.
The inverse wiring can be tailored to a room. If you hold dinner parties and want background music, but not so that it overcomes conversation, then put your stereo speakers behind the furniture, but wire one backwards. The people seated can hear the music, but the people standing cannot (or significantly reduced). Also, putting a microphone in your car, and playing the inverse wave back over the speakers will soften the road noise. Great video.
6:14 Fun fact: This is actually how noise cancelation works on headphones, microphones take the sound, and play an inverted version of it in the same ms (some may have a delay if it is a lower end headset)
It's possible to isolate the voice in all songs that have a similar instrumental version by inverting one of the two audio files. It doesn't work perfectly because of audio compression and sometimes the original song includes more or less sounds than the instrumental. But with a bit of luck you can get pretty good results.
Playing the difference between channels (left minus right) usually cancels out the lead vocal and the bass because the lead vocal and bass are usually mixed dead-center. You get some of the instruments and some of the harmony vocals. It can be mildly amazing. Try it on Olivia Newton-John tunes (she's almost a choir). "Saturday in the Park" by Chicago some surprises that cancellation brings to the front.
@@quaztron It all depends on the mixing. Many recordings, to save money or because the engineers have tin ears, record the vocals or guitar solos or bass monaurally, and then pan them to the center of the mix. With a single monaural source it's relatively easy to inject a 180º opposite and thus cancel out the original. With true stereo recordings, not so easy.
I saw a perfect example of this in application - there’s a documentary on making of Metallica’s Black Album where the sound engineers had James Hetfield sing in a booth with two monitors wired in opposite phase so that the mic would only pick up his voice. He was having trouble wearing headphones for some reason. It was truly mind blowing how this worked.
Actually if you wire your headphones backwards and out of phase with the earth's magnetic field, it causes and aluminum foil hat to grow right out of your head between the hairs, this is fed from the years and years of using underarm deodorants and taking excessive jabs (those "j's" especially as hey go right to the brain which is in close proximity) to the "hat" growing area! Napoleon Hill was experimenting with this, you can tell from his pictures, even tho b&w.... you can see the tell tale peak starting to grow - this is probably WHY his book *"Stink and Grow Rich" was transcribed to cassettes later on :P (*Written after "Think" due to people who avoided the deodorants to stop "hat growth")
The "audiophiles" as they call themselves are also incredibly toxic. Ask any questions and you'll get smugly talked down to for not knowing. Disagree with them and you'll get the most vile insults. Stay far away from them.
@@PunakiviAddikti Not only will you get ridiculed for not knowing, but you'll be buried under a mountain of wildly inaccurate or downright wrong information right after.
Back when I was building and tuning subwoofer enclosures, and learned all about proper tuning for clipping avoidance, I accidentally mis-wired the internals of one enclosure. (Lousy blue/blue stripe wiring convention!) Anyway, had it all nicely tuned for max wattage at 60hz and I could hear "bass" but it was like weirdly quiet. No boom. No SPL compression on my chest. Yeah. . .a quick recheck of everything, discovering my mistake, fixing it, and retry almost left my ears bleeding. 😂 First hand experience in cancelling sound waves! Thanks for the vid too! Excellent scientific description of my "oops!"
i "hear" the difference in the snare, but honestly i think it's more about feeling it. the pressure difference in a speaker pushing the note vs pulling the note into existence. sound waves are just a transfer of energy from one object to your eardrum. under normal conditions, the eardrum is pushed first, then pulled by the sound made by the speaker, where as with inverted phase the eardrum is being pulled first, then pushed by the soundwave produced by the speaker, and i think that subtle difference is what people are noticing.
A snare is usually tuned to ~ 170 hz so that initial "pull" is only 0.0029 seconds (2.9 milliseconds) long before there is a "push" and the cycle repeats.
@@hughobyrne2588 No, a fan does not produce a waveform (unless you have a rotary subwoofer). A speaker does not blow air like a fan. The only time you feel air move is when you have a vented sub where air starts to move relatively fast or a horn speaker playing bass at loud volume. But since sound is a waveform, there is no front or back per se, it varies like AC varies in electric grid. Doesn't matter which way you put the plug in.
Many, many years ago (like 1970s), I installed 2 speakers in my car's front doors for my Pioneer Super Tuner stereo system. Somewhere, I saw an article about adding a 3rd speaker and mounting it on the rear deck of the car. I took a positive lead from the left and right channels and connected them to the 3rd speaker. Whether or not or was good for the electronics, I don't know, but it made for an interesting effect since the only sound coming from the 3rd speaker was the difference between the 2 channels. Like sounds were filtered out.
this was pseudo quadrophonic sound system developed by a bloke called Hafler. i have had my stereo setup like this using 2 speakers for the rear wired in series but opposite polarity since the seventy's.
What a flashback! I had a 1970 Mustang Mach 1 with a Pioneer Supertuner hooked up to a Pioneer 100W amp. 2 bookshelf speakers with 8 in woofers seatbelted in the back seat, each with about 30 feet of wire. When we were hanging out at the park, speakers spread apart and awesome tunes!
i was taught this about 30yrs ago from some sound engineers for both studio and live situations. there's also been several articles in guitar magazine about this because especially important to the life of your gear and what's going to go on record. the last interview i read about this was from one of the sound engineers who worked on crew for Jimmy Hendrix on tour. it is as follows: when you wires your speakers backwards your cones hit in reverse. the initial blast from the speaker, i.e. that first vibration should always be the cone pushing outwards to deliver that first hit. when you wire them backwards the cones take a breath instead. i.e. pull in instead of pushing forward. that's going to affect the sound quality and volume of your session and speakers. if you got several amps going and one is in reverse, your phase is going to be messed up. it won't be something crazy like a full cancellation but your signals won't be balanced. over time, if the speakers are wired in reverse, the initial hit from your speakers will lead to damage from always sucking in at first instead of blowing outwards.
That last bit is wrong. The coil and therefore cone excursion is held in an equilibrium and the availability of excursions in and out are the same therefore there is not any damage to the speaker that sucks in first. It does that hundreds or thousands of times, a second anyway.
@@jamesm90 I wonder if damping circuits are expecting specific phase on the initial signal and could that have something to do with whether or not the damping is effective on the first impulse? I suppose this would be most of the concern for powerful low and very low end signals like sub-bass since now we're concerned with these things down to 5 CPSand such
There is one case in which connecting stereo speakers in reverse polarity is a GOOD thing. The best imaging and sound stage is acquired by placing a twin set of tweeters and midrange drivers on the outside of your main speakers and wiring them to the opposite channel in reverse polarity to cancel crosstalk. That's how the Polk Audio SDA's work.
To some people this video may be useless if I read the comments but let me tell you, not so long ago I've bought a very expensive home entertainment system with pretty decent sound. I had a get together with some buddies and wanted to show off my new set so I disconnected the complete system to play it outside and had a little help from one of my oh so helpful buddies. Eventually everything was connected and when it was time to play, I could only hear the mids and treble but the base was virtually non existing. With two subwoofers connected I looked like a total fool. When doing fault finding we quickly realised that the guy who connected the subs did the wrong way around, not following the colour code. So yes, very important to take note of and this is a very good video for the younger generation starting their sound journey. 💯👌
Years ago when speakers didn't give polarity we used to put them face to face about a half inch apart and reverse the wires on one. Which ever way sounded better is the way you would leave it. We called it putting them in the same phase.
This is true that there should be no audible difference when your DAC, amp, and speaker are all operating linearly. However, in practice there are nonlinearities and biases in all these systems. I would imagine it would be easier to A/B test polarity inversion on cheaper systems or at very high sound pressure levels.
Subwoofers can sound different if wired 180 degrees out, depending on the frequency and distance to the listener. This is why powered subs and often sub amplifiers have a "0/180" phase switch. This just reverses the direction of the subs. You may perceive more bass in one or the other settings.
That is a question I have pondered for years. I appreciate how clearly you explain a subject in such a concise and orderly fashion. My autistic brain totally gets it.
Actually, engineer here, speaker does not have positive and negative terminals. As you said it is just a coil, which is an inductor wound to a circle. Some electronic components and machines does have polarity because it is important where does the current flow and in which direction. That is why you must put DC voltage in correct polarity on input. But as you connect coil to an AC power source you can imagine it not just changing the ammount of current/voltage but also its polarity (sine wave). That means it does not matter which way you plug it in. What were you talking about in video (the speaker muting while "reversed") is phase shift. You phase shifted the signal on one speaker so when the signal on number one is in top + section, the signal on second one is in top - section and then they indeed disturb each other.
So what your saying is if I know which way to wire it before hand like if I mark one red and one black and call it forward for up and reverse for down then we will know hownto connected the speaker just in case they make a mistake like in the factory and forget that hey don't wire that speaker backwards because the customer won't know the difference but don't tell them it's a dc speaker. Sounds good 👍 where did you go to school?
Its not phase, as phase is time related. It is polarity, because regardless of frequency which is derivative of time, the output of the driver is inverted.
Rubbish. Then why if the pos and neg are reversed does the woofer suck inwards instead of moving outwards? That's right, due to polarity. Try on an old speaker with a 9v battery and you'll see.
A little car audio story.. I was testing two subwoofers. I place one in the trunk and one on the back seat. They were sounding loud higher than 50hz but weak below 50Hz. ( Had them wired inverted) Then when inverted the polarity (back to normal), they did the opposite, they sounded weak higher than 50Hz but louder under 50Hz. With that said, speaker placement is crucial thus all frequencies travel at different wavelengths as well as the environment they are placed in. I was kind of in "awe" when I heard the high frequencies sound louder when there were out of phase at the position they were in. But mind you the bass frequencies were creating nodes and other issues when inverted. So keeping them in phase is always the best idea UNLESS you are doing some weird experiment like I did.
This honestly makes me feel better about repurposing speakers without clear labels on the wiring to a new receiver. They say the positive usually has dashes or text. Well, I had dashes on one wire and text on the other. Took my chances with dashes on positive, and made sure to keep it consistent.
I paused the video to write what will happen when you attach a speaker to a battery. The cone will either go forward or backward and stay there, as long as it is connected to the battery or until the battery goes dead.. if you do not know which terminal is positive, this is a way to find out, with a battery terminal marked positive connected to a speaker terminal, the wiring that makes the cone come forward away from the magnet is the identifying telltale sign. Which ever terminal you have connected to the battery when the speaker cone moves forward, Then the terminal on the speaker that you have the positive wire from the battery connected to is the positive wire on the speaker.. Being in rock bands through the 70s 80s and 90s, I have fried my share of speakers and a few amplifiers
This is something i love about beeing an electrician and make 3-Phase electronics and meassuring sine waves so intersting. At the End of it all, it makes Motors turn.
An old trick for interesting "Surround sound" is to connect a third speaker to the positive output of the left and right amplifier outputs and put it behind you... this third speaker only produces the difference signal (out of phase or otherwise), and adds a lot of "depth" to the image produced by the main stereo pair. If you add a speaker-level "L-Pad" in series with the third speaker, you can dial in a lower volume setting. We used to do this with a single speaker and a modern car stereo rig installed on 60's cars that had a single speaker mounted high up in the middle of the dashboard or back seat cushion, and a pair of door speakers in the front. We would connect the rear speaker to the rear amp outputs and use the front-to-rear fader to control the amount of "surround" output.
I did this experiment a few years ago and found that if you connect all speakers the wrong way, that is all negative are connected to positive and all positive to negative, the system plays excellent. Once one speaker is connected differently, the cancellation starts.
Thank you, yes. I'm currently (November 2024) in the process of upgrading my car stereo (2002 Saturn) with an aftermarket SONY head unit. I'm paying careful attention to get positive and negative wires hooked up correctly to the speakers. When I'm finished, I'll put in my "test CD" of sounds released by DENON years ago (including IN PHASE and OUT OF PHASE sounds). I'm sure I'll notice the difference.
When I worked on cars as a Auto Electrician in late 80’s. So many cars had owner installed stereo’s with no regard to polarity! I could hear the dullness and fixed many.
while we're talking about speaker wiring, on the back of a brian eno album, he describes how he takes a wire connected to the positive (or it can be the negative ) of each speaker and connects it to a third speaker. it results in getting a signal that is the difference between the 2 channels. this might be how cheap surround sound amplifiers work. anyway, ive tried it. it works. for those of you who dont know, brian eno was an original member of roxy music.
Apropos of near nothing, way back afore most of you were born, AR LST was a happening speaker. It was said to be able to handle the output of the Crown DC-300 and SAE amplifiers. They did a multi speaker test using a steady tone to see which speaker could handle how much power. The LST's voicecoil lit up like a lightbulb at 8w and smoked at 12w... but today we have 200 watt speakers - progress!
Waaaay back in the mid 70s we had a stereo console with turntable that wasn't working. I was 14 and I started messing around with the player and all that. Just tinkering I got my hands on Quadrophenia. I had heard it was supposed to be in quadrophonic. Somehow by playing with the speakers and crappy old equalizer, I managed to isolate the whole drum track to Love Reign O'er Me; albeit, I could still hear echoes of vocals and other instruments. It was so good, that before the final drumming piece, I could hear one of the band members either sniffle or cough. I'll have to try it again with my gold cd I have of that album.
There is a fascinating explanation within this video (starting at 5:02) of constructive/destructive interference in wave patterns using sound waves instead of the typical light waves. Well done.
When you wire one bass driver normally and the other one inversed, you can use isobaric push-pull coupling to make them behave like one with double the stiffness. You either mount them cone-to-cone inside a cube-shaped box with a bass reflex tube for an opening, or you can use a big short tube as your bass box and put the speakers on both end facing outwards.
Very clear sir,,I didn't knew that,except that when speakers wire is reverse,the sounds not centered and separated to properly polarized speakers,,that's why polarity is very important in wiring speakers..
As a cinema technician, this is something we have to address carefully. Surrounds on the walls can cancel each other out (note, the word is can, not will, since there is rarely identical audio being output), and also have a habit of decreasing the preceived output of the already lower (than the stage speakers) 82dB (at reference level, sound calibration for stage speakers is 85dB). Also, although we always test and correct reverse polarity, there are those who argue that as long as every speaker is either out of phase or all speakers are in phase, it's fine. I don't agree, but there are some.
Wow, you had some expert opinions here! When I was young I was told how important it was to get your speakers wired up correctly, that was the whole thing about stereo! Then I studied more secrets of life... let me tell you one... Remember the "snail house" that is your inner ear? It allows higher frequencies to travel deeper and tiggle the little hairs on the sensitive cells more. -They have no idea about synchronisation-. They feel when certain frequencies are present, and they make us feel happy when they can jiggle a little with their friends, that's why we really love chords. But they have no idea when any of the jiggling starts. So please....
This principle is used in the music industry. Where events are regulated with maximum DBc Levels. Usually 80-100m behind the stage. We turn the subwoofers 180 degrees facing backwards and let them play out of phase. This results in lower dbs in the back and a little boost in the front. Works great if you want to go loud but not get fined.
Simple explanation: its an electromagnet aka the coil will change it's magnetic field to fight against/with the magnets current. When you wire it backwards it will still create a simmilar frequency due to it still moving up and down at the same rate. You will still want to wire it correctly just in case you have several speakers fighting each other. Hope this helped!
For a single frequency of sound, when two speakers are separated in space, there are positions in the room where the sound waves constructively interfere (such as the point exactly between them) and places where they destructively interfere (such as a point between them that is a bit closer to one speaker than the other (the "bit" being exactly one quarter of a wavelength). If you plot out these points of constructive and destructive interference, you get lines of constructive and destructive interference that are separated by distances in the range of 1/4 of the wavelength. Even when the speakers are wired "correctly", you STILL get spots that have destructive interference, but where the spots are depends on the frequency/wavelength of the sound. Flipping the polarity of one of the speakers should just move the various quiet and loud spots around the room. If one speaker is flipped, the position half-way between the speakers is one of those destructive interference spots. Importantly, this spot has destructive interference for EVERY frequency of sound. Middle C is around 256 Hz, so about 78 cm of wavelength, with higher frequencies having shorter wavelengths. For the very low frequency sounds (60Hz has a wavelength of around 5.3 metres (18.3 feet), the destructive interference zone would be a large part of the room. Thus you probably would be unable to notice a reversed polarity speaker for any of the high frequencies, but could for the lowest frequencies. Thus, if you have mismatched polarity on your pair of speakers in two corners of the room - the centre line of the room will be quiet for all frequencies, and for the lowest frequencies, the quiet area will extend well beyond this centre line. For higher frequencies, even a little distance from the room's centre line, all other places in the room will sound pretty much the same as if the speakers were "properly" hooked up.
I learned in the 1960's that wiring stereo speakers at opposite polarity diminishes the bass output of the woofer speakers. Because when one speaker is pushing air, the other speaker is pulling air. This cancels the bass sonic energy that gives music it's punch. My old tube stereo amplifier had a polarity switch that would switch the polarity of one of the speakers. I could really notice the difference!
While teaching physics I did a little experiment involving these waves. Take a simple minded tone generator and using a relatively low (ie slow) wave put it through both speakers. and you will find that the wave cancels in certain locations in the room. Of course this problem is nearly undetectable with actualy music since actual is changing all the time.
Just to clear some things up here. If the driver is wired to move outwards at DC, this does not mean that it moves outwards for a positive voltage across the entire frequency range. Below its fundamental resonance frequency, it does move outwards for a positive voltage (assuming one polarity of the two choices). However, then it moves INWARDS for a positive voltage at higher frequencies well above it fundamental frequency. This is typically also what you want, because the inwards movement will result in a positive pressure when the driver is loaded with a free-field-ish condition, which a room pretty much is at higher frequencies (excluding at lot of details here). This goes against most acoustical engineer's intution, but the theory as well as simulations will reveal this. So the battery test is merely a proxy for what is actually going in the frequency range of interest; the pass-band of the driver.
If you're standing perfectly in the middle between two speakers, then even perfectly opposite waves will not cancel each other out perfectly because they won't reach your ears at the same time. In fact, they may even add up constructively! For example, take an A note at 880Hz: since sound travels at 343m/s, the wavelength is 343/880 = 0.39m. And your ears are about 0.20m apart, which is almost exactly half a wavelength. So opposite waves will actually add up constructively around your ears! Of course, if you just move 0.2m towards one speaker, the waves will now cancel out. So the polarity really doesn't matter much when we're talking about these "normal" frequencies. However, if you consider a very low pitch sound, say at 20Hz, and do the same math, then you will find that its wavelength is over 17 meters. So no matter where you are in the room, the waves will cancel out. This explains why the problem is mostly noticeable for low pitch sounds. It also depends on your position relative to the speakers. If you walk far away from both speakers, remaining at an equal distance from both, then the sound waves will take approximately the same time to reach your left and right ear from both speakers, and the problem may become noticeable, even at higher frequencies.
in fact this was the topic of my Master study in Physics. I discovered that the non-linearity of our hearing system can make polarity differences audible. This was the case with headphones and in the anechoic room with signals with distinct higher harmonics. In a "normal" room, the reflections mess up the phases of a the frequency components (Fourier) and there is no more interference with the auditory distortion products. Therefore, in a normal room you cannot hear the effect of polarity.
The best argument I have heard for monaural polarity is regarding long excursions for bass drums. the theory is that a bass kick needs to go outwards because that is where the speaker cove is strongest and most efficiently moves air for that single pulse. it does make sense. Well, it makes more sense than anything else I have heard.
Whether or not there's an audible difference will depend on the driver and/or enclosure. The signal is identical, but if the driver performs differently when pushing out vs pushing in, for dynamic audio (basically anything except a tone generator) it will color the sound differently. Like the snare hit example, the largest amplitude is in the 1st movement. If the cone is not equally flexible in both directions, and more flexible in the direction of 1st motion, that period will be louder than when the signal changes direction electrically (i.e. moves under the line). So, if you have good ears, and you have good drivers and enclosures and yet you can hear a difference when reversing the wires that's actually an indication that your drivers or enclosures aren't good as they do not perform equally in both directions of cone movement. With good equipment, good ears will be just as oblivious to this kind of phase change as bad ears.
Years ago, when Dick Smith made electronics kits, I remember building one and reading his words (paraphrasing) "No matter what anyone tells you, speakers are not polarized". While this is technically true, it's a terrible splinter to put into a young mind as it implies the +/- designations are completely meaningless, which is only the case while you're working with a single, directly connected driver.
Wiring the speakers opposite will give you a wider perception of the sound , THX did a kinda similar thing in the rear channels but instead of reversing one signal they have both sides constantly phase-shifting
I like to hook the plus wire to the minus terminal on both speakers, and the minus wire to the plus terminal on both of the used speakers I bought. That way all of the electrons that have piled up in the speaker boxes over time can drain back out so the speakers won't start sounded muffled. You might say I'm just a troublemaker, but all of the best audiophiles know to switch their speaker leads back and forth every month. It's like rotating a car's tires. My buddy told me I'd blow up my speakers by reversing the leads, but he's no audiophile, so I guess I showed him. Hah! Now I'm saving up for an $800 low-oxygen, Litz-wire AC power cord. I hear they are the best! All the audiophiles say so!
Great video, really enjoyed the explanation! It made me think, though - some people seem to believe that wiring speakers backwards doesn't make much of a difference, while others claim it drastically affects sound quality. I’m not sure where I stand, but it’s definitely an intriguing debate. What do u think?
Thank you for a simple and understandable demenstration . I've always been very careful when hooking up my speakers correctly . Just never knew how important the audio results would be ...........DGR
As long as everything is wired backwards it doesn't matter, it's all relative. For instance wiring a subwoofer backwards can cause issues at the crossover frequency but can sometimes actually do the opposite and fix those issues, this helps if you don't have a variable phase knob and you can only invert polarity
To conduct a proper phase cancellation test, you should ensure that both the normal phase and the inverted phase signals are on the same channel. Additionally, when you switch your stereo system to mono mode and position the speakers to face each other, it’s crucial to set one speaker to be out of phase to optimize the response. Experimenting with phase inversion on a mixing console’s inputs can lead to nearly complete signal cancellation. However, attempting to achieve 100% cancellation with speakers is challenging due to off-axis coloration. It’s also a common error to tamper with the phasing between two channels, such as the left and right, on a loudspeaker system. This is because these channels often do not carry identical signals.
since its just the polarity/direction of the coil, it mean up will be down & vice versa ... wich can either just sound "off" or breaks the speaker! but overall its not THAT much of a difference, because the soundwave will still be "up/down" wich for our ear equals "down/up"
As a Retired Disc Jock, I have seen and heard a reversed speaker under heavy Audio Load give out what is called "Baffling." This occurs when the backside of the Coil recoils against the rear of the Magnet Enclosure Housing. This can also result in structural deformity of the said Coil. MJ. in B'dos.😢
This is related to how you can detect subtle differences in different versions of an audio recording: You reverse the polarity of one and layer it on top of the other and look at what's left over.
I think the hearing of the snare differently does happen but only when the speakers are a distance away from your ears. With your headphones on, they are right next to each other thus any air pressure difference is directly picked up. With speakers a distance away, however, the following effect gets more pronounced - how blowing (outward movements) go forward strongly like a laser and sucking (inward movements) suck from all around. This is why your speaker playing a sine wave can actually blow a net force of air forward and blow out a candle -- and means that the initial spike of the snare will be stronger if it starts in the positive and you are a distance from your speakers - as the air pressure will travel further if the cone moves outwards
Just stumbled across this video. I've always heard about this and always made sure to wire correctly, but now I feel like I need to experiment and actually listen to this cancelling effect.
Reverse emplifying is used by headphones to silence environmental noise. It reverses the phase of environmental noise by 180⁰ and cancel it out. It's as well used by expensive cars to cancel out noises from outside and car vibrations.
I remember installing speakers in my one car well over 30 years ago and was wondering when I centered the balance that I lost almost all bass response in my 6 x 9 speakers. I flipped the polarity of one after tracking my wires down and it was correct then and sounded way better. Although I'm usually very careful about wiring, somehow that one got past me. That was a phenomenal system.
Hello! You seem to know about audio equipment and some of it's untold features. So I think you're just the right person to ask. From the very first days back then when I got my PC and speakers with mini-jack plug I can remember I've noticed strange yet COOLEST effect which I want to be described at last by some professional like you. It really helps distinguish electric guitar from the whole set of instruments which was great from because I just started to dive into rock music. The effect can be achieved like this: you take mini-jack plug into your device (PC audio card, MP3 player, CD player). Open some rock music (for example, a "Weeds" cover played by Pro-Pain). Now hold the plug and start pulling it out very slowly. At some narrow point you will notice that an electric guitar sound is what you can clearly hear at the moment - other sounds alongside with the vocalist are somewhere at the deep background. What is it? How it works? Why is it that only the electric guitar remains audible? And why does this remind karaoke option of a cheap Realtek audiocard? Thanks in advance!
A super-simple way to check polarity of (moveable) speakers with a stereo amplifier, is to just point both speakers towards each other (less than 100mm between them is good). If incorrectly phased (wired polarity) the sound will not diminish very much. If correctly phased, the sound will be very noticeably attenuated.
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I learned about the importance of polarity when I was young. I received a ghetto blaster for xmas and I was shocked that AM radio sounded so much better than FM. AM was in mono and only came from the left speaker but FM being stereo came from both. My natural curiosity got the better of me and I opened it up 2 days after getting it. My mother was furious. I had no idea what I was doing or should be looking for but I knew the difference between positive and negative and colour coding. I saw the left speaker was wired white to + and black to - which seemed normal to me. But the right speaker was wired white to - and black to + which seemed wrong. I had already been soldering for a few years so I desoldered the wires from the right speaker, switched them and soldered them again. I put it on FM and was amazed at how good it sounded. My mother was so happy that it worked but still never gave me any credit for fixing/improving my gift. For years she would say "Do you remember that xmas you took apart your radio?" and I would always ask her if she remembered that not only did I put it back together but that it was better than when I had taken it apart. Never got any credit for that.
Hope you kept that thought process in your older years. You did what 99% of the people won't bother with these days and just throw it away.
@@PauldeVries I still regularly take things apart. Often only to see what's inside. I've gotten a LOT better at putting them back together again as well. lol But yes, 99% of the time I will try and fix it. I'm cheap and would much rather spend a couple of bucks on parts and a little bit of time instead of tossing it out and replacing it. That's one thing my grandparents taught me: Repair it until it can't be repaired any longer and then salvage whatever parts you can and repurpose what can't be salvaged.
@@Enjoymentboy Yes, things are more useful than meets the eye sometimes. Hope you gave yourself credits for that ;)
Pretty sure she would have given you credit if someone had thought her how and why to do it. Don't think she intentionally held back on giving you credit. But yeah man, sometimes those unimportant moments for adults can become lifelong memories for kids.
@@exshenanigan2333 well said
If you wire your speakers backwards and listen to country music, the guy actually gets back his horse, his job and his wife
LMAO 😂
Yes, but now his existential angst is too much to handle, thus Emo is his new jams.
And if you are listening to Blues music, all the above plus it stops raining.
Plus, he quits drinking
you forgot his truck
Years ago, I found I had accidentally wired one of my two subwoofers in reverse (in my mobile DJ rig). When I saw how I had screwed it up, I laughed so hard! I had been struggling for several months with my system - asking myself, "Why can I hear the base coming out of each sub when I stand right in front of it but when I move to the center of the dance floor, I don't hear or feel it?" No amount of EQing or compression made any difference. When I saw I had the cable to one sub wired backwards (positive to negative and negative to positive), man oh man, I was relieved. I still laugh today thinking about it.
So you experienced wave cancellation by first hand 😂
I worked on a recording system that sounded perfectly fine but when you tried to record you got nothing. Someone wired one of the inputs backwards so the mono signals from the mic were being cancelled.... The tech who installed it couldn't figure it out for 2 weeks.
@@BrettDaltonLOL!! It happens to the best of us
Haha that's a good laugh. I mean in the sense that we've all made simple mistakes but genuinely bothered us. Then we happen to stumble upon the solution like it felt sorry for us lmao
Bro’s made of positivity👍
My friend installed his new car battery backwards. Afterwards, his horn sucked, his headlights cast shadows, and his radio listened.
🤣🤣🤣👍👍👍👍👍
TOO FUNNY!!!LMAO!!!!
This one is creative. I like it
At live events you'll often see arrays or fills aimed backstage and wired out of phase. This cancels the sound from monitors and main PA. While the crowd is getting blasted. The crew backstage can speak normally and often don't need ear pro while working. They do the same thing to create "dead zones" in large clubs - areas like the lounge or the bar. Those speakers over the bar that don't appear to be on are actually doing a big job. Theme parks even use phase cancellation to kill mechanical noise.
Fun fact: I once installed a dual subwoofer setup in my Nissan 100NX (yes it's been a while) .. After installation I played some subwoofer test music and was disapointed by the lack of bass from the subwoofers. I didn't understand, I had two subwoofers and still heard almost nothing. It was at this point I thought about polarity and I changed the phase setting (on one of the amplifiers). It was at this moment I learned that I should not have done that while the system was running a subwoofer bass test on 80% volume. The moment I flipped that switch I was scared to death, the system was playing so load suddenly. Learned some lessons that day!
My college roommate blew out his rear glass because he was trying a test and realized a wire came loose or something. Suddenly bbbrrrrrrrtttttt and he was covered in little glass cubes.
Both subwoofer were trading the airflow they were producing.
After I saw a friend of mine fry his car amp doing what you did, I always turn off the power before switching wires around.
I had an NX2000.
Out of principal you should only do wiring with everything turned on 😂....we did that with our cncs also😮
Very simply, when one speaker is out of phase (wired backwards) in a stereo system, they cancel each other out. Mainly heard in the lower frequencies, but also affecting image and sound staging.
It's heard in all frequencies that are pannes with an identical signal to both speakers. It's the same as a common mode interference supressor in a balanced signal chain. There is usually just one bass and bass drums are usually not panned so that is why they dissapear more than other instruments, has nothing to do with them being low frequency though.
I once played at a psytrance party where one of two subs was wired incorrectly, resulting in the bass literally disappearing right in the middle of the dance floor. 😂 Since is was open air, you hadn't even echoes from walls. Super weird.
@@NeovanGoth The person that made those speaker cables really messed up. Should never happen in a PA system since the speaker cabler are hard wired unless there is a phaze switch somewhere in the system.
I heard about phase back in the 70's. I don't recall being able to hear a difference, but I didn't have speakers that reproduced heavy bass. I've always tried to wire correctly anyway.
Is this how noise cancelling headphones work? They layer on top of your audio an inverted waveform of whatever ambient sound you're hearing?
If you have two stereo speakers wired with opposite polarity (a.k.a half a cycle out of phase), you get an interesting effect because the signals cancel each other out in a fringe pattern which generally makes it feel like the sound is coming from around or behind you, because it will bounce off the room walls before it reaches your ears. This effect is used in legend of zelda ocarina of time for the sound of the townspeople in the castle town courtyard, and in the movie twelve monkeys for the mystery voice he hears in his head
Flipping the polarity of one of the channels in a pop song can also work as a useful hack to get something approximating an instrumental version of the track, because generally the vocal is dead centre but the backing is not so the vocal gets cancelled out
my science teacher did this in school with speakers out of phase and made us walk around the room, the volume changed depending on where you were in the room because of the phase cancellation
But that messes with the "dubbing"
The effect is still in play when recorded, and requires micro editing in the DAW where cancelations occur in track adding...
Someone once suggested changing the waveform, but it's still the inverse frequency loss to deal with.
I seem to recall an old CD player stereo my sister got for Christmas had this as a feature?
(I think it was intended as a Karaoke mode?) I don't remember much other then it was weird to child me for the vocals to just all the sudden disappear like the vocals were on some different audio channel getting disabled.
If you mess with polarities you'll destroy low freqs and some mids as well
Zackley
You have a gift, dude. I spent decades in the professional audio industry having been born into it with my father coming before me. And you have generated over one and a half million hits to this video sharing something I've known since I was in grade school. This isn't me criticizing you, it's me applauding you. To be able to do this, it's a gift. Things I took for granted surprise me often. I had inherited a half dozen JBL Professional transformers. So common in our shop were these, I literally thought they were garbage
For giggles, put one up for sale on ebay years ago. They started stabbing each other to obtain it. Ended up getting $200 for something I almost threw away and had five more of. Just one example of a pleasant surprise. You should do a video on impedance matching. Reversing the polarity of speaker isn't something that commonly happens with polarity marked on the speakers or speakers with wiring included having these wires color coated. You are correct in stating it does and does not matter if reversed. As a professional, it absolutely matters. Nothing would scream amatuer louder than having screwed up the obvious. Doesn't matter in typical two speaker stereo systems much because two independent channels, etc.
But impedance matching of speakers to amplifiers is not well known at all. Yet is simple and straight forward. And very important. The common person is typically power output motivated when it comes to amplifiers and sound systems. Yet, they are ignorant to what they are referring to because all they know is what salesman tell them. Salesman are always motivated by making bigger, better, and more sales. Usually equally as ignorant as the end user. So, more, more, more and bragging rights for power output rules the world.
Which makes any video you would offer on proper impedance matching that much more relevant to the common consumer of audio amplification and sound reproduction equipment.
You're a good presenter. Don't know your background in audio. You may be another TH-cam creator who presents him or herself as expert, but the we and us they often use to make them look like a great big rolling railroad is non existent. I can hear them justifying the terms used by saying they were referring to their wife/husband or baby children. Can't blame anyone for trying.
Impedance matching is necessary to get all the wattage you thought you really needed when you bought that big power amp or stereo system that put out all that advertised power to actually be used. If the output rating of an amp is 4 ohms for example. Let's clarify at 4 ohms per channel, to get the 100 advertised watts of power per channel you paid for, you need to match the input impedance of the speakers to it. 4 ohm amplifier output to 4 ohm speaker input means all 100 watts of power is available.
Impedance mismatches will still make the amplifier's power output available, but in lesser percentages than advertised. Same example of amplifier with 8 ohm speaker. The mismatch is a factor of two or half. The 100 watts would not be available and only half this, 50 watts, would be. It's always a reduction in advertised power not an increase. So another speaker, listed as having a 2 ohm impedance input connected to the same 100 watt, 4 ohm rated amplifier output, would also produce half the 100 watts of power available and 50 watts of power tops.
Start mixing multiple speakers per channel and that's another complexity all together but on the same level. Since impedance is basically the resistance measurement of an ac device, it increases and decreases in rating same as resistance does. Put two 8 ohm speakers in parallel, and the amplifier does not see 8 ohms but 4 ohms. Put the same speakers in series, now the amplifier sees 16 ohms. In this scenario, on a 100 watt power amplifier with a 4 ohm output, the most you'll see from that 100 watts of power you have is 25 watts being 4 is one forth of 16. Always lose power from mismatches, never gain.
Sorry to lecture. I'm old and too much to do, nothing I really want to. Thanks.
We used a battery to figure out the polarity of the speakers;when trouble shooting a previous installation. A dead give away is solid bass when turned to one channel or the other, but when balanced no bass out of either indicates inverted polarity on one or more speakers depending upon setup. Our shop used to troubleshoot a lot of other shops work. Motor noise used to be a huge issue for some shops.
On a side note, the term phase and polarity are often used to describe the same thing but are actually different.
Polarity inversion (flip or swap)is what is described in this video and is a 180 degree phase inversion.
It is possible to have phase discrepancies that are not a full 180 degrees.
Also, polarity is a reversal of a physical or electrical connection that results in a 180° phase shift.
Many issues can create phase shift. Polarity reversal is just one that has a singular shift.
you must be fun at parties.
You can but they will be different at all frequencies. Simply having one speaker further away from your ears than another will give you a phase change - could be partial or the full 180 depending on frequency.
Yes but phase shift varies with frequency, so you cannot simply apply it to music as a way to counteract poorly-wired speakers.
exactly
It's actually fun to experiment with out of phase speakers and placement. If they are directly facing each other with the listener in between, you get a push-pull effect that's pretty cool. It depends on the spacing and frequencies as well.
I hate that effect. Gives me a weird feeling in my ears.
Deafening silence
@@jnawk83 You do not get silence, only damped bass and the higher frequencies is pretty much unaffected but with weird / cool sound effects of "sound phasing".
It can result in a kind of "fake stereo" effect. When I was a kid I got a kick out of doing that. Even better was setting up an AM radio and FM radio on the same station (here in NZ at the time we had stations that broadcasted on both) for whatever reason there was a significant time difference between the two, causing a fairly extreme slapback echo effect. It was a trip.
You should take a pair of those linear transducers and have them agitate a shallow pool of ~dyed water. In theory, we should be able to see how the delay required to propagate the signals through the media affect constructive and destructive interference at different frequencies, distances, polarities, etc.
Cool idea!
I used the "Chaldini" plates with small metal slivers and video taped them in the 80's. I recall Velvet Underground being quite interesting.
Installing a stroboscope illuminating the water at the same frequency as the waves, will also make it so that the waves appear stationary, so the differences can be pictured better
@@rojirrim7298 I think showing the agitation of the water would be better. Otherwise, when you have a spot with looks like it hasn't moved is that because it cancels or because it just isn't moving at that point.
Alternatively, the stroboscope slightly off frequency, so you can see the waves moving and interacting.
huh huh....you said words.
When you listen to the initial hit of a kick drum there is a definite change of sound and feel with a single speaker wired with reverse polarity. Especially with a PA sub system that covers the 25Hz range. If everything is wired correctly you should feel the air hitting your chest. If the sub polarity is reversed then the kick drum completely loses it's impact. This because the first positive peak of the sine wave is the largest and sound pressure waves in compression have better projection than ratification of sound waves.
Absolutely correct. I was going to post similar comment. If that would be no difference at all then drummer can put his kick pedal in front of bass drum and play that way. But nobody ever played such way in a music history for obvious reason. You need LF sound kick to propagate toward audience. However I agree that it would be no difference in mid and high freq ranges.
very important !
This. Difference between a pressure wave and a lack of pressure wave.
If that were remotely true JBL would have never wired their bass drivers reverse polarity.
@@keithmoriyama5421 😂
Thank you for this. I learned about out of phase speakers in the late 70’s when I took audio engineering classes. It’s hard to explain to the layman. You did it perfectly. You could also add that it’s similar to the way noise canceling headphones work.
Right foot first or left it doesn't matter unless you want to coordinate with another. Just like dancing.
Until you step on your partner's foot.
@@codahighlandThat would impede the good ol' rhythm, no?
Dancing is sinful.
@@BeforeAndAfterScienceI guess Psalm 149:3 is sinful then... maybe the Bible is sinful. Maybe God is sinful. Maybe God is Satan...and Satan is God.
@@BeforeAndAfterScienceNo Scientist makes such an open ended statement without qualifying the parameters thereof.
Coincidentally last week I was installing an home theater in my room (the old style one, not a sound bar) and I was wondering why the speakers had polarity and I was very afraid of inverting wires. Now everything is very clear. Thanks for the video!
Nice, a real home theater! I hope you enjoy your build. I just got a pair of TAD 1601c, some altec 288c, and gauss 1502 drivers /horns. My wife vehemently refused to let them near the living room, so down to the Home Theater they went! The kids love it
Having some education in electronics and a half century experience with home stereo, I can't say I learned from the video. But oh how I enjoyed seeing it explained so well. This young man has a gift for explanation.
I like that it was explained without assuming every member of the audience already knew the basics. People often skip the basics, and those are so important in building a good foundational knowledge. I agree. He did a great job, and his voice is calm and soothing. He makes good eye contact, and speaks without ums and ahs.
Thanks!
Yeah you are right bro, all people can broadcast information however what make difference is the Way of delivering that information. This respectful Guy touched the top of perfection in his explanation.
This just happened to of popped up on my TH-cam. I spent many years in the automotive stereo industry, starting out very young. I could never hear the difference AS long as everything was wired the same. But wire one speaker wrong in a stereo system and you most assuredly can and will hear it. That was almost 40 years when I started, and nothing much has changed. Very important to get it right and right the first time. Nothing worse than having that person coming back because you got it wrong.
Great vid. Last year I had one of my main speakers wired out of polarity. I had a mate over (who works in audio) to tune my subs. He listened for about 10secs and said 'I think your wiring is out of polarity' and of course it was. When I corrected it the only noticeable difference was the imaging, the sound quality was the same but the voice was no longer smeared, it was positioned.
Always learning, thanks!
This is the best audio engineering channel on TH-cam.
Facts
Anyways, thanks for the suggestion!@@corporealundead
Back in the mid 1970's I worked installing PA systems in a grocery store chain, the system was a 70 volt system that was used to play mono background music when it was not being use for announcements. The speakers were mounted in the ceiling of the stores and to keep the speakers from canceling one another out we had to space the speaker properly to take in account the delay of the audio from each of the speakers and we had to switch the polarity of each of the speakers because of that delay to keep them in phase with one another. This was to minimize the locations in the shopping aisle that presented cancellation zones. It worked very good.
Fascinating. I worked on that stuff too.
Although music is all different frequencies, so there's no one distinct phase change, so may as well just keep all the speakers in phase imo.
Yes. But you guys make me think about something here but not here. We don't have it.
Let me imagine this for a moment or so .. Can't we have a button on our so, advanced remote that we can flip polarity around?
You have to do the math between the ohms of the speakers and series and parallel loads on the amp. You just can't hook them all up in parallel like most people would. Thankfully those days of problems are loin behind me. Uh I meant long behind me. Same thing I guess, oh well.
@@TimpBizkit You are correct that music is all different frequencies, but when you reverse the polarity of one speaker you are reversing or changing the phase of all of the frequencies to that speaker in relation to the other speakers by 180 degrees, so *_PHASE MATTERS._*
I noticed a difference in sound decades ago on my Dad's stereo. Maybe it's not noticeable on headphones, but if the speakers are far enough apart, the inverted wiring caused it to sound very hollow.
I knew this but this was the absolute best depiction of the principal I have ever seen. Well done!
Wave addition is such a cool concept. I wish there were more practical applications like this taught in public schools
It is taught in certain math and physics classes, but there is little practical application for most people, except installing speakers, or getting a job that uses math or physics
Wave addition (or cancellation if one signal is reversed) has a very practical application in noise canceling headphones and earbuds. A microphone picks up the ambient noise, which is then reversed and added to the music being played by the speakers in the headphones, the reversed noise cancels out the ambient noise and you hear just the music.
PROLONGED SEMESTER
I don’t think it was mentioned in the video, so I just wanted to add that the common naming when speakers are wired the same is “in phase” and when they are wired with different polarities is “out of phase”. There are some interesting acoustic characteristics when speakers are wired out of phase in a home listening environment where the sound seems to appear diffuse and almost like it’s “floating around your head” with no distinct source. There are some fun examples elsewhere on TH-cam where you can listen to in-phase and out-of-phase white noise that demonstrate this.
What you describe results because vocals and other instruments that are intended to be front and center experience more interference than those panned more to one side or another because they are essentially equal in each speaker. This causes more cancellation of anything in the center.
Im not 100% sure I am correct, but i heard somewhere over the years that some high end speaker manufacturers using a lot of X-over points design speaker cabs with the low bass drivers intentionaly wired 180 degrees out of phase to take advantage of this phenomenon and give the low end a wider sound stage
@@Angellus502 Interesting idea, however, I wonder about this. Bass frequencies are extremely problematic when out of phase between multiple speakers. I would expect dissonant artifacts that would be anything but audiophile, from such a setup.
I don't know the specific acoustic properties, but in the concert PA world, it's fairly common now to physically reverse several of the subwoofer boxes, but not to create phase artifacts. It's done to acoustically cancel bass frequencies behind the subwoofes. It's the speaker equivalent to phase ports on the back of directional microphone capsules. The steers the bass towards the audience and away from the stage where it can be problematic vibrating the performers, their gear, and the microphones on amplifiers and other instruments.
Every time I wired up my speakers backward's,, They wouldn't play but only listened.
once somebody put the batteries in backwards on the energizer bunny, and he kept coming and coming and coming.
LOL! Seriously! bahahahahahaaaa! *Dad Jokes
Sometimes that's just what we need
I'm a retired mobile electronics installer of over 40 years. About 50% of systems installed by "professionals" are out of phase.
The inverse wiring can be tailored to a room. If you hold dinner parties and want background music, but not so that it overcomes conversation, then put your stereo speakers behind the furniture, but wire one backwards. The people seated can hear the music, but the people standing cannot (or significantly reduced). Also, putting a microphone in your car, and playing the inverse wave back over the speakers will soften the road noise. Great video.
6:14 Fun fact: This is actually how noise cancelation works on headphones, microphones take the sound, and play an inverted version of it in the same ms (some may have a delay if it is a lower end headset)
It's possible to isolate the voice in all songs that have a similar instrumental version by inverting one of the two audio files. It doesn't work perfectly because of audio compression and sometimes the original song includes more or less sounds than the instrumental. But with a bit of luck you can get pretty good results.
Playing the difference between channels (left minus right) usually cancels out the lead vocal and the bass because the lead vocal and bass are usually mixed dead-center. You get some of the instruments and some of the harmony vocals. It can be mildly amazing. Try it on Olivia Newton-John tunes (she's almost a choir). "Saturday in the Park" by Chicago some surprises that cancellation brings to the front.
@@quaztron It all depends on the mixing. Many recordings, to save money or because the engineers have tin ears, record the vocals or guitar solos or bass monaurally, and then pan them to the center of the mix. With a single monaural source it's relatively easy to inject a 180º opposite and thus cancel out the original. With true stereo recordings, not so easy.
@@rcarlberg Just flatten the stereo signal to mono...
@@rcarlberg Just flatten the stereo signal to mono
I saw a perfect example of this in application - there’s a documentary on making of Metallica’s Black Album where the sound engineers had James Hetfield sing in a booth with two monitors wired in opposite phase so that the mic would only pick up his voice. He was having trouble wearing headphones for some reason. It was truly mind blowing how this worked.
I've felt headphones change my head shape, and damage hair follicles. I'm going to have to play with this, someday.
Actually if you wire your headphones backwards and out of phase with the earth's magnetic field, it causes and aluminum foil hat to grow right out of your head between the hairs, this is fed from the years and years of using underarm deodorants and taking excessive jabs (those "j's" especially as hey go right to the brain which is in close proximity) to the "hat" growing area! Napoleon Hill was experimenting with this, you can tell from his pictures, even tho b&w.... you can see the tell tale peak starting to grow - this is probably WHY his book *"Stink and Grow Rich" was transcribed to cassettes later on :P (*Written after "Think" due to people who avoided the deodorants to stop "hat growth")
Called "balancing phase-shifts"
In a world of misinformation, particularly on audio, this channel is such a breath of fresh air! Superbly explained too.
The "audiophiles" as they call themselves are also incredibly toxic. Ask any questions and you'll get smugly talked down to for not knowing. Disagree with them and you'll get the most vile insults. Stay far away from them.
@@PunakiviAddikti Not only will you get ridiculed for not knowing, but you'll be buried under a mountain of wildly inaccurate or downright wrong information right after.
Back when I was building and tuning subwoofer enclosures, and learned all about proper tuning for clipping avoidance, I accidentally mis-wired the internals of one enclosure. (Lousy blue/blue stripe wiring convention!) Anyway, had it all nicely tuned for max wattage at 60hz and I could hear "bass" but it was like weirdly quiet. No boom. No SPL compression on my chest. Yeah. . .a quick recheck of everything, discovering my mistake, fixing it, and retry almost left my ears bleeding. 😂 First hand experience in cancelling sound waves!
Thanks for the vid too! Excellent scientific description of my "oops!"
i "hear" the difference in the snare, but honestly i think it's more about feeling it. the pressure difference in a speaker pushing the note vs pulling the note into existence. sound waves are just a transfer of energy from one object to your eardrum. under normal conditions, the eardrum is pushed first, then pulled by the sound made by the speaker, where as with inverted phase the eardrum is being pulled first, then pushed by the soundwave produced by the speaker, and i think that subtle difference is what people are noticing.
Kind of like the same effect as a fan - there's strong directed flow out of the front, but no strong directed flow into the back?
A snare is usually tuned to ~ 170 hz so that initial "pull" is only 0.0029 seconds (2.9 milliseconds) long before there is a "push" and the cycle repeats.
I'm fairly sure you hear placebo. It makes no difference to a speaker whether it starts the waveform this or that way.
@@hughobyrne2588 No, a fan does not produce a waveform (unless you have a rotary subwoofer). A speaker does not blow air like a fan. The only time you feel air move is when you have a vented sub where air starts to move relatively fast or a horn speaker playing bass at loud volume. But since sound is a waveform, there is no front or back per se, it varies like AC varies in electric grid. Doesn't matter which way you put the plug in.
@@Munakas-wq3gp that is true, a speaker doesn't care, but your inner ear does.
Many, many years ago (like 1970s), I installed 2 speakers in my car's front doors for my Pioneer Super Tuner stereo system. Somewhere, I saw an article about adding a 3rd speaker and mounting it on the rear deck of the car. I took a positive lead from the left and right channels and connected them to the 3rd speaker. Whether or not or was good for the electronics, I don't know, but it made for an interesting effect since the only sound coming from the 3rd speaker was the difference between the 2 channels. Like sounds were filtered out.
would this still work or would it be obsolete with newer technology?, im sure i can look this up but i want your opinion and im a little lazy
@@dom_xi-dzopa720 I think it would still work. The signal going to the speakers is analog.
It works... Poor man's surround sound...
this was pseudo quadrophonic sound system developed by a bloke called Hafler. i have had my stereo setup like this using 2 speakers for the rear wired in series but opposite polarity since the seventy's.
What a flashback! I had a 1970 Mustang Mach 1 with a Pioneer Supertuner hooked up to a Pioneer 100W amp. 2 bookshelf speakers with 8 in woofers seatbelted in the back seat, each with about 30 feet of wire. When we were hanging out at the park, speakers spread apart and awesome tunes!
i was taught this about 30yrs ago from some sound engineers for both studio and live situations. there's also been several articles in guitar magazine about this because especially important to the life of your gear and what's going to go on record. the last interview i read about this was from one of the sound engineers who worked on crew for Jimmy Hendrix on tour. it is as follows:
when you wires your speakers backwards your cones hit in reverse. the initial blast from the speaker, i.e. that first vibration should always be the cone pushing outwards to deliver that first hit.
when you wire them backwards the cones take a breath instead. i.e. pull in instead of pushing forward. that's going to affect the sound quality and volume of your session and speakers.
if you got several amps going and one is in reverse, your phase is going to be messed up. it won't be something crazy like a full cancellation but your signals won't be balanced.
over time, if the speakers are wired in reverse, the initial hit from your speakers will lead to damage from always sucking in at first instead of blowing outwards.
That last bit is wrong. The coil and therefore cone excursion is held in an equilibrium and the availability of excursions in and out are the same therefore there is not any damage to the speaker that sucks in first. It does that hundreds or thousands of times, a second anyway.
@@jamesm90 I wonder if damping circuits are expecting specific phase on the initial signal and could that have something to do with whether or not the damping is effective on the first impulse?
I suppose this would be most of the concern for powerful low and very low end signals like sub-bass since now we're concerned with these things down to 5 CPSand such
There is one case in which connecting stereo speakers in reverse polarity is a GOOD thing.
The best imaging and sound stage is acquired by placing a twin set of tweeters and midrange drivers on the outside of your main speakers and wiring them to the opposite channel in reverse polarity to cancel crosstalk. That's how the Polk Audio SDA's work.
I found your comment after I posted mine.
An excellent, illustrated, detailed, demonstration of speaker polarity, an important factor one that I have been promoting for over 50 years!
To some people this video may be useless if I read the comments but let me tell you, not so long ago I've bought a very expensive home entertainment system with pretty decent sound. I had a get together with some buddies and wanted to show off my new set so I disconnected the complete system to play it outside and had a little help from one of my oh so helpful buddies. Eventually everything was connected and when it was time to play, I could only hear the mids and treble but the base was virtually non existing. With two subwoofers connected I looked like a total fool. When doing fault finding we quickly realised that the guy who connected the subs did the wrong way around, not following the colour code. So yes, very important to take note of and this is a very good video for the younger generation starting their sound journey. 💯👌
Years ago when speakers didn't give polarity we used to put them face to face about a half inch apart and reverse the wires on one. Which ever way sounded better is the way you would leave it. We called it putting them in the same phase.
This is true that there should be no audible difference when your DAC, amp, and speaker are all operating linearly. However, in practice there are nonlinearities and biases in all these systems. I would imagine it would be easier to A/B test polarity inversion on cheaper systems or at very high sound pressure levels.
I've said it before but I'll say it again: you are an incredible teacher!
Thank you!
I'm Subbed now. You bring back old memories.@@AudioUniversity
Subwoofers can sound different if wired 180 degrees out, depending on the frequency and distance to the listener. This is why powered subs and often sub amplifiers have a "0/180" phase switch. This just reverses the direction of the subs. You may perceive more bass in one or the other settings.
That is a question I have pondered for years. I appreciate how clearly you explain a subject in such a concise and orderly fashion. My autistic brain totally gets it.
Very professional as a teacher for the audience. Great speaker-tone, good info. You have a gift to teach
Actually, engineer here, speaker does not have positive and negative terminals. As you said it is just a coil, which is an inductor wound to a circle. Some electronic components and machines does have polarity because it is important where does the current flow and in which direction. That is why you must put DC voltage in correct polarity on input. But as you connect coil to an AC power source you can imagine it not just changing the ammount of current/voltage but also its polarity (sine wave). That means it does not matter which way you plug it in. What were you talking about in video (the speaker muting while "reversed") is phase shift. You phase shifted the signal on one speaker so when the signal on number one is in top + section, the signal on second one is in top - section and then they indeed disturb each other.
So what your saying is if I know which way to wire it before hand like if I mark one red and one black and call it forward for up and reverse for down then we will know hownto connected the speaker just in case they make a mistake like in the factory and forget that hey don't wire that speaker backwards because the customer won't know the difference but don't tell them it's a dc speaker. Sounds good 👍 where did you go to school?
i will add more. waveform don't has any connection to speakers.
Its not phase, as phase is time related. It is polarity, because regardless of frequency which is derivative of time, the output of the driver is inverted.
@@jenniferwhitewolf3784It's absolutely Phase.
Rubbish. Then why if the pos and neg are reversed does the woofer suck inwards instead of moving outwards? That's right, due to polarity. Try on an old speaker with a 9v battery and you'll see.
A little car audio story.. I was testing two subwoofers. I place one in the trunk and one on the back seat.
They were sounding loud higher than 50hz but weak below 50Hz. ( Had them wired inverted)
Then when inverted the polarity (back to normal), they did the opposite, they sounded weak higher than 50Hz but louder under 50Hz.
With that said, speaker placement is crucial thus all frequencies travel at different wavelengths as well as the environment they are placed in. I was kind of in "awe" when I heard the high frequencies sound louder when there were out of phase at the position they were in. But mind you the bass frequencies were creating nodes and other issues when inverted. So keeping them in phase is always the best idea UNLESS you are doing some weird experiment like I did.
This honestly makes me feel better about repurposing speakers without clear labels on the wiring to a new receiver. They say the positive usually has dashes or text. Well, I had dashes on one wire and text on the other. Took my chances with dashes on positive, and made sure to keep it consistent.
I paused the video to write what will happen when you attach a speaker to a battery. The cone will either go forward or backward and stay there, as long as it is connected to the battery or until the battery goes dead..
if you do not know which terminal is positive, this is a way to find out, with a battery terminal marked positive connected to a speaker terminal, the wiring that makes the cone come forward away from the magnet is the identifying telltale sign. Which ever terminal you have connected to the battery when the speaker cone moves forward, Then the terminal on the speaker that you have the positive wire from the battery connected to is the positive wire on the speaker..
Being in rock bands through the 70s 80s and 90s, I have fried my share of speakers and a few amplifiers
They start speaking Spanish
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Yes
Guandooooooooo
WAOW...
the quality of your content is impressive 😄
So sharp and clear, I love it !
2024 and most of us are still listening to mono audio😂
Why though
This is something i love about beeing an electrician and make 3-Phase electronics and meassuring sine waves so intersting. At the End of it all, it makes Motors turn.
An old trick for interesting "Surround sound" is to connect a third speaker to the positive output of the left and right amplifier outputs and put it behind you... this third speaker only produces the difference signal (out of phase or otherwise), and adds a lot of "depth" to the image produced by the main stereo pair. If you add a speaker-level "L-Pad" in series with the third speaker, you can dial in a lower volume setting.
We used to do this with a single speaker and a modern car stereo rig installed on 60's cars that had a single speaker mounted high up in the middle of the dashboard or back seat cushion, and a pair of door speakers in the front. We would connect the rear speaker to the rear amp outputs and use the front-to-rear fader to control the amount of "surround" output.
Man spent 7 minutes explaining ANC
I did this experiment a few years ago and found that if you connect all speakers the wrong way, that is all negative are connected to positive and all positive to negative, the system plays excellent. Once one speaker is connected differently, the cancellation starts.
Thank you, yes. I'm currently (November 2024) in the process of upgrading my car stereo (2002 Saturn) with an aftermarket SONY head unit. I'm paying careful attention to get positive and negative wires hooked up correctly to the speakers. When I'm finished, I'll put in my "test CD" of sounds released by DENON years ago (including IN PHASE and OUT OF PHASE sounds). I'm sure I'll notice the difference.
When I worked on cars as a Auto Electrician in late 80’s. So many cars had owner installed stereo’s with no regard to polarity! I could hear the dullness and fixed many.
while we're talking about speaker wiring, on the back of a brian eno album, he describes how he takes a wire connected to the positive (or it can be the negative ) of each speaker and connects it to a third speaker. it results in getting a signal that is the difference between the 2 channels. this might be how cheap surround sound amplifiers work. anyway, ive tried it. it works. for those of you who dont know, brian eno was an original member of roxy music.
Extremely clear and methodical explanation. Well done.
Apropos of near nothing, way back afore most of you were born, AR LST was a happening speaker. It was said to be able to handle the output of the Crown DC-300 and SAE amplifiers. They did a multi speaker test using a steady tone to see which speaker could handle how much power. The LST's voicecoil lit up like a lightbulb at 8w and smoked at 12w... but today we have 200 watt speakers - progress!
Waaaay back in the mid 70s we had a stereo console with turntable that wasn't working. I was 14 and I started messing around with the player and all that. Just tinkering I got my hands on Quadrophenia. I had heard it was supposed to be in quadrophonic. Somehow by playing with the speakers and crappy old equalizer, I managed to isolate the whole drum track to Love Reign O'er Me; albeit, I could still hear echoes of vocals and other instruments. It was so good, that before the final drumming piece, I could hear one of the band members either sniffle or cough. I'll have to try it again with my gold cd I have of that album.
There is a fascinating explanation within this video (starting at 5:02) of constructive/destructive interference in wave patterns using sound waves instead of the typical light waves. Well done.
When you wire one bass driver normally and the other one inversed, you can use isobaric push-pull coupling to make them behave like one with double the stiffness. You either mount them cone-to-cone inside a cube-shaped box with a bass reflex tube for an opening, or you can use a big short tube as your bass box and put the speakers on both end facing outwards.
Very clear sir,,I didn't knew that,except that when speakers wire is reverse,the sounds not centered and separated to properly polarized speakers,,that's why polarity is very important in wiring speakers..
As a cinema technician, this is something we have to address carefully. Surrounds on the walls can cancel each other out (note, the word is can, not will, since there is rarely identical audio being output), and also have a habit of decreasing the preceived output of the already lower (than the stage speakers) 82dB (at reference level, sound calibration for stage speakers is 85dB).
Also, although we always test and correct reverse polarity, there are those who argue that as long as every speaker is either out of phase or all speakers are in phase, it's fine. I don't agree, but there are some.
Wow, you had some expert opinions here!
When I was young I was told how important it was to get your speakers wired up correctly, that was the whole thing about stereo!
Then I studied more secrets of life... let me tell you one...
Remember the "snail house" that is your inner ear? It allows higher frequencies to travel deeper and tiggle the little hairs on the sensitive cells more.
-They have no idea about synchronisation-. They feel when certain frequencies are present, and they make us feel happy when they can jiggle a little with their friends, that's why we really love chords.
But they have no idea when any of the jiggling starts.
So please....
This principle is used in the music industry. Where events are regulated with maximum DBc Levels. Usually 80-100m behind the stage.
We turn the subwoofers 180 degrees facing backwards and let them play out of phase. This results in lower dbs in the back and a little boost in the front. Works great if you want to go loud but not get fined.
Simple explanation: its an electromagnet aka the coil will change it's magnetic field to fight against/with the magnets current. When you wire it backwards it will still create a simmilar frequency due to it still moving up and down at the same rate. You will still want to wire it correctly just in case you have several speakers fighting each other. Hope this helped!
For a single frequency of sound, when two speakers are separated in space, there are positions in the room where the sound waves constructively interfere (such as the point exactly between them) and places where they destructively interfere (such as a point between them that is a bit closer to one speaker than the other (the "bit" being exactly one quarter of a wavelength). If you plot out these points of constructive and destructive interference, you get lines of constructive and destructive interference that are separated by distances in the range of 1/4 of the wavelength. Even when the speakers are wired "correctly", you STILL get spots that have destructive interference, but where the spots are depends on the frequency/wavelength of the sound.
Flipping the polarity of one of the speakers should just move the various quiet and loud spots around the room. If one speaker is flipped, the position half-way between the speakers is one of those destructive interference spots. Importantly, this spot has destructive interference for EVERY frequency of sound.
Middle C is around 256 Hz, so about 78 cm of wavelength, with higher frequencies having shorter wavelengths. For the very low frequency sounds (60Hz has a wavelength of around 5.3 metres (18.3 feet), the destructive interference zone would be a large part of the room. Thus you probably would be unable to notice a reversed polarity speaker for any of the high frequencies, but could for the lowest frequencies.
Thus, if you have mismatched polarity on your pair of speakers in two corners of the room - the centre line of the room will be quiet for all frequencies, and for the lowest frequencies, the quiet area will extend well beyond this centre line. For higher frequencies, even a little distance from the room's centre line, all other places in the room will sound pretty much the same as if the speakers were "properly" hooked up.
I learned in the 1960's that wiring stereo speakers at opposite polarity diminishes the bass output of the woofer speakers. Because when one speaker is pushing air, the other speaker is pulling air. This cancels the bass sonic energy that gives music it's punch. My old tube stereo amplifier had a polarity switch that would switch the polarity of one of the speakers. I could really notice the difference!
Heard the difference right away. Running subs out of phase makes the timing off just enough to emphasize the bass notes and makes audio much cleaner.
While teaching physics I did a little experiment involving these waves. Take a simple minded tone generator and using a relatively low (ie slow) wave put it through both speakers. and you will find that the wave cancels in certain locations in the room. Of course this problem is nearly undetectable with actualy music since actual is changing all the time.
I’ve got a video with this demo coming up for next week!
Just to clear some things up here. If the driver is wired to move outwards at DC, this does not mean that it moves outwards for a positive voltage across the entire frequency range. Below its fundamental resonance frequency, it does move outwards for a positive voltage (assuming one polarity of the two choices). However, then it moves INWARDS for a positive voltage at higher frequencies well above it fundamental frequency. This is typically also what you want, because the inwards movement will result in a positive pressure when the driver is loaded with a free-field-ish condition, which a room pretty much is at higher frequencies (excluding at lot of details here). This goes against most acoustical engineer's intution, but the theory as well as simulations will reveal this. So the battery test is merely a proxy for what is actually going in the frequency range of interest; the pass-band of the driver.
If you're standing perfectly in the middle between two speakers, then even perfectly opposite waves will not cancel each other out perfectly because they won't reach your ears at the same time. In fact, they may even add up constructively! For example, take an A note at 880Hz: since sound travels at 343m/s, the wavelength is 343/880 = 0.39m. And your ears are about 0.20m apart, which is almost exactly half a wavelength. So opposite waves will actually add up constructively around your ears! Of course, if you just move 0.2m towards one speaker, the waves will now cancel out. So the polarity really doesn't matter much when we're talking about these "normal" frequencies.
However, if you consider a very low pitch sound, say at 20Hz, and do the same math, then you will find that its wavelength is over 17 meters. So no matter where you are in the room, the waves will cancel out. This explains why the problem is mostly noticeable for low pitch sounds.
It also depends on your position relative to the speakers. If you walk far away from both speakers, remaining at an equal distance from both, then the sound waves will take approximately the same time to reach your left and right ear from both speakers, and the problem may become noticeable, even at higher frequencies.
in fact this was the topic of my Master study in Physics. I discovered that the non-linearity of our hearing system can make polarity differences audible. This was the case with headphones and in the anechoic room with signals with distinct higher harmonics. In a "normal" room, the reflections mess up the phases of a the frequency components (Fourier) and there is no more interference with the auditory distortion products. Therefore, in a normal room you cannot hear the effect of polarity.
The best argument I have heard for monaural polarity is regarding long excursions for bass drums. the theory is that a bass kick needs to go outwards because that is where the speaker cove is strongest and most efficiently moves air for that single pulse. it does make sense. Well, it makes more sense than anything else I have heard.
Whether or not there's an audible difference will depend on the driver and/or enclosure. The signal is identical, but if the driver performs differently when pushing out vs pushing in, for dynamic audio (basically anything except a tone generator) it will color the sound differently. Like the snare hit example, the largest amplitude is in the 1st movement. If the cone is not equally flexible in both directions, and more flexible in the direction of 1st motion, that period will be louder than when the signal changes direction electrically (i.e. moves under the line).
So, if you have good ears, and you have good drivers and enclosures and yet you can hear a difference when reversing the wires that's actually an indication that your drivers or enclosures aren't good as they do not perform equally in both directions of cone movement. With good equipment, good ears will be just as oblivious to this kind of phase change as bad ears.
Years ago, when Dick Smith made electronics kits, I remember building one and reading his words (paraphrasing) "No matter what anyone tells you, speakers are not polarized". While this is technically true, it's a terrible splinter to put into a young mind as it implies the +/- designations are completely meaningless, which is only the case while you're working with a single, directly connected driver.
Wiring the speakers opposite will give you a wider perception of the sound , THX did a kinda similar thing in the rear channels but instead of reversing one signal they have both sides constantly phase-shifting
I like to hook the plus wire to the minus terminal on both speakers, and the minus wire to the plus terminal on both of the used speakers I bought. That way all of the electrons that have piled up in the speaker boxes over time can drain back out so the speakers won't start sounded muffled. You might say I'm just a troublemaker, but all of the best audiophiles know to switch their speaker leads back and forth every month. It's like rotating a car's tires. My buddy told me I'd blow up my speakers by reversing the leads, but he's no audiophile, so I guess I showed him. Hah! Now I'm saving up for an $800 low-oxygen, Litz-wire AC power cord. I hear they are the best! All the audiophiles say so!
Great video, really enjoyed the explanation! It made me think, though - some people seem to believe that wiring speakers backwards doesn't make much of a difference, while others claim it drastically affects sound quality. I’m not sure where I stand, but it’s definitely an intriguing debate. What do u think?
Thank you for a simple and understandable demenstration . I've always been very careful when hooking up my speakers correctly . Just never knew how important the audio results would be ...........DGR
As long as everything is wired backwards it doesn't matter, it's all relative. For instance wiring a subwoofer backwards can cause issues at the crossover frequency but can sometimes actually do the opposite and fix those issues, this helps if you don't have a variable phase knob and you can only invert polarity
I really liked you on 3rd Rock from the Sun, Gordon 😂 j/k great video.
Thank you for explaining. I now finally know WHY speakers have magnets and WHAT happens if I wired them backwards! :D
To conduct a proper phase cancellation test, you should ensure that both the normal phase and the inverted phase signals are on the same channel.
Additionally, when you switch your stereo system to mono mode and position the speakers to face each other, it’s crucial to set one speaker to be out of phase to optimize the response.
Experimenting with phase inversion on a mixing console’s inputs can lead to nearly complete signal cancellation.
However, attempting to achieve 100% cancellation with speakers is challenging due to off-axis coloration. It’s also a common error to tamper with the phasing between two channels, such as the left and right, on a loudspeaker system. This is because these channels often do not carry identical signals.
since its just the polarity/direction of the coil, it mean up will be down & vice versa ... wich can either just sound "off" or breaks the speaker! but overall its not THAT much of a difference, because the soundwave will still be "up/down" wich for our ear equals "down/up"
Make the test with a decibel meter. It makes a difference, however much less pronounced.
As a Retired Disc Jock, I have seen and heard a reversed speaker under heavy Audio Load give out what is called "Baffling." This occurs when the backside of the Coil recoils against the rear of the Magnet Enclosure Housing. This can also result in structural deformity of the said Coil. MJ. in B'dos.😢
This is related to how you can detect subtle differences in different versions of an audio recording: You reverse the polarity of one and layer it on top of the other and look at what's left over.
Awesome Video! You did a great job of explaining and clarifying! Demonstrations and visuals were spot on. Well done sir, and thanks!
I think the hearing of the snare differently does happen but only when the speakers are a distance away from your ears.
With your headphones on, they are right next to each other thus any air pressure difference is directly picked up.
With speakers a distance away, however, the following effect gets more pronounced - how blowing (outward movements) go forward strongly like a laser and sucking (inward movements) suck from all around.
This is why your speaker playing a sine wave can actually blow a net force of air forward and blow out a candle -- and means that the initial spike of the snare will be stronger if it starts in the positive and you are a distance from your speakers - as the air pressure will travel further if the cone moves outwards
Just stumbled across this video. I've always heard about this and always made sure to wire correctly, but now I feel like I need to experiment and actually listen to this cancelling effect.
Reverse emplifying is used by headphones to silence environmental noise. It reverses the phase of environmental noise by 180⁰ and cancel it out. It's as well used by expensive cars to cancel out noises from outside and car vibrations.
I remember installing speakers in my one car well over 30 years ago and was wondering when I centered the balance that I lost almost all bass response in my 6 x 9 speakers. I flipped the polarity of one after tracking my wires down and it was correct then and sounded way better. Although I'm usually very careful about wiring, somehow that one got past me. That was a phenomenal system.
Hello! You seem to know about audio equipment and some of it's untold features. So I think you're just the right person to ask.
From the very first days back then when I got my PC and speakers with mini-jack plug I can remember I've noticed strange yet COOLEST effect which I want to be described at last by some professional like you. It really helps distinguish electric guitar from the whole set of instruments which was great from because I just started to dive into rock music.
The effect can be achieved like this: you take mini-jack plug into your device (PC audio card, MP3 player, CD player). Open some rock music (for example, a "Weeds" cover played by Pro-Pain). Now hold the plug and start pulling it out very slowly. At some narrow point you will notice that an electric guitar sound is what you can clearly hear at the moment - other sounds alongside with the vocalist are somewhere at the deep background.
What is it? How it works? Why is it that only the electric guitar remains audible? And why does this remind karaoke option of a cheap Realtek audiocard?
Thanks in advance!
A super-simple way to check polarity of (moveable) speakers with a stereo amplifier, is to just point both speakers towards each other (less than 100mm between them is good). If incorrectly phased (wired polarity) the sound will not diminish very much. If correctly phased, the sound will be very noticeably attenuated.
I am quite familiar with this concept but this video was very well done to explain it to those who are not. Bravo.