Intro: 0:00 Overhead/Headroom: 3:00 Subwoofer Size Comparison: 5:30 WinISD is not Taking into account Room/Cabin Gain: 7:20 Power Handling: 9:45 Group Delay of the Three Enclosures: 15:58 Why are we seeing more Passive Radiators: 20:00 Why you don't need to Model a Subwoofer Flat: 24:55 How to Model Room/Cabin Gain: 28:48 Linkwitz Transform: 35:15 How to pick the right Passive Radiator: 37:40 How big of a box should I design for a passive Radiator: 41:12 How do you Tune a box without knowing the T/s Parameters: 44:40 Sealed Box Misnomer: 48:56 Add Inductance in WinISD when modeling (*Brian Steele actually said you should do this - I misread it): 52:33 Wrap-up: 56:29
My honest 2 cents on passive radiators. First I will start off with, I never knew what one was. I landed a Job in an electronics store back in the 90s. I was hired as a salesman. Roaming around the basement of this huge store I found a room that had nothing but home speakers out of the box. I found out that they were all defective or returned that the manager did nothing about. One by one I carried each one upstairs and hooked it up to a receiver to find out that each one of them had one or two components that was blown. I asked the owner if he would mind if I repaired them and sold them. This way he could take junk and turn it into money? His answer was yes. Here it comes... I came across one speaker that had 2- 10 inch woofers with no bass at all. I opened it up to find out only one woofer had a magnet a coil and so on. I replaced the one 10 inch woofer and it was back to life. I found this particular speaker sounded better to me than the rest of any size. My ears preferred this single 10 inch woofer with one passive than the dual 12s the single 15 and so on. They were all made by Sansui and the amp I was using was the same brand. I only wish there were more speakers today that had this option. I'm aware that it's cheaper to use a port or go sealed. Makes no difference to me. It's all about the sound to my liking. Now these men can give you all the technical mumbo jumbo I didn't even listen to the video yet.
The other advantage to PRs is that you can initially mount them reversed to you can easily change the weights to tune, and then turn it around when you’ve got it right. Done. When a port isn’t quite right (chuffing, tuned to wrong freq, etc.) it can be a lot more complicated to make and test multiple adjustments, especially with a port with elbows and such.
If I may, I don't believe this to be entirely true. Not true by far... BUT, I believe that only to be in the case of radiators with very large SD component and not those which are produced to make use of incredibly long excursion values. In the case of the latter, I believe that that would entirely hold true for the most part. But in the case of the radiators that are very deep in cone area and in diameter once you flipped it outward you have just added probably considerable internal volume to that enclosure especially if you've got multiple radiators with very large SD. Just a thought to consider it may be a very little change or value but one to consider perhaps. Cheers! --Robert
The tools that I use to understand all woofer/enclosure designs although not to compute them are Newton's second law of motion applied to forced oscillation (this can be found in any first year college physics textbook along with an approximate solution) and the ideal gas laws. Newton's second law is an ordinary second order differential equation. It predicts the frequency response based on three parameters, moving mass, spring coefficient, and damping coefficient. The ideal gas laws explain the force from the difference between air pressure inside the enclosure and outside the enclosure. P1*V1 = P2*V2 where P is the pressure difference between the air inside the box and the air outside the box and V is the volume of the air inside the box, the relative volume of air outside the box being enormous. The force due to differences in air pressure is P*A where A is the area of the cone. It is applied uniformly on the surface of the cone. There is also a mechanical restoring force due to the compliance of the suspension. Using these tools it's easy for me to understand and compare the different conceptual designs. Of all of the designs IMO the best one is the acoustic suspension design which probably should have been called the pneumatic suspension design. Not all sealed enclosures are acoustic suspension. Even its inventor Edgar Villchur didn't fully understand how it worked. In that design the mass is high and the compliance is high making the Fs low, in the range of 17 to 19 hz in free air. It's also of necessity a long throw design. The restoring force is mostly but not entirely the compression and rarefaction of the air pressure inside the enclosure compared to the outside. The enclosure can't be 100 percent air tight or the cone would work like a manometer where changes in barometric pressure in the room would move the neutral resting point. So there should be a tiny amount of leakage, not enough to compromise the design but enough to allow the relatively small mechanical restoring force to bring the cone back to its intended neutral (zero voltage) point. Now here's the kicker I didn't understand and Villchur didn't either. The enclosure has to be filled with fibrous stuffing, typically one pound per cubic foot of internal space. this is not to dampen cabinet resonances. Instead this creates an aerodynamic drag by forcing the motor to push and pull air between the fibers. This drag is proportional to the velocity of the cone. This creates a frictional force converting some of the energy into heat just the way the space shuttle heats up when it reenters the earth's atmosphere at high speed. This is only a tiny amount of heat, most of the heat being generated by the voice coil DC resistance. This aerodynamic drag controls the damping coefficient. It serves the same purpose in this design as the oil filled shock absorber serves in the suspension of your car. Without it there's an undamped resonance which can be high enough to drive the cone past its ultimate limit tearing the suspension apart.Q = 0.707 is called critical damping. It is the highest damping factor which will extend bass response without a peak in its response. Higher Qs will create a peak, lower Qs will cause the bass to rolloff faster than 12 db per octave. In the ported design air moves easily through the port at some frequencies and with great difficulty at other frequencies. It works like a pipe organ giving bass a very high Q. Below system resonance response falls off at 24 db per octave so the system resonance frequency is the effective lower limit of the system. By contrast the acoustic suspension design with a Q of 0.707 rolls off at 12 db per octave and is therefore equalizable within the thermal and mechanical limits of the driver. In the ported design the mechanical restoring force may be applied to a different degree circumferentially and radially creating shearing and twisting forces on the cone. In the acoustic suspension design this doesn't happen because the air pressure is uniform over the entire surface of the cone. There are also air turbulences at the entrance and exit of the port. That's the chuffing sound you hear. This affects the damping factor. Sof for the acoustic suspension design b the damping coefficient and k the spring constant are the same at all frequencies and amplitudes. In other designs they are not. This enables the optimized design to be tuned to any frequency response and any Q by adjusting these three parameters. The price for greater low bass extension is efficiency. Keep in mind that as you add stuffing you are reducing the amount of air in the enclosure. The aggregate surface area of the fibers is enormous so there is plenty of frictional loss. The acoustic suspension design was so successful that it became a world standard for bass reproduction in the 1960s. The ideal driver will have a low Fs say 17 to 19 hz, High compliance, Low Vas, Low Qms. There are no drivers I'm aware of available today that are optimized for the acoustic suspension design. Drivers that can be used either closed box or ported are a compromise. Drivers that were such as Madisound 1259 could only be used for the Acoustic Suspension design.
What's important is displacement and sufficient power handling to hit Xmax in the range of frequencies you wish to play the woofers. Displacement = Xmax * Cone area determines the maximum SPL. All that low Fs and Q stuff does not matter now that digital equalization is so cheap and can be used to apply a Linkwitz transform filter to get the flat response to the desired low frequency cut off and Q you desire. Of course the sealed box is high fidelity. The other stuff is just late, ringing bass. Ports and radiators are just bass bells and they are not high fidelity.
@@danaolson2871 below the system resonance frequency, response falls off at 24 dB per octave in a ported system. That is not equalizable. The acoustic suspension design with a Q of 0.707 falls off at 12 dB per octave below resonance and is equalizable. 0.707 is critical damping, the lowest bass extension without a bump in the FR at resonance.
@Dana Olson To understand how woofer/enclosure designs work I used Newton's second law of motion applied to forced oscillation and the ideal gas laws. Newton's second law has many applications such as designing the suspension of a car and how it will respond to bumps. Three elements are involved, moving mass, damping factor, and springyness. The acoustic suspension design is the only one where the damping factor and spring constant are independent if frequency and amplitude. Not all sealed designs are acoustic suspension designs. The difference in air pressure between the inside and the outside of the enclosure determines the spring force. The damping is controlled by filling the enclosure with fibrous material. The speaker is forced to work to push and pull air between the fibers which in aggregate have an enormous surface area. The frictional loss is directly proportional to the air velocity. This is how the damping factor is controlled. In a ported design the air moves easily through the port at some frequencies and with great difficulty at others. It's tuned like the pipe in an organ. To make matters worse air turbulence at the entrance and exit if the port really screws up both the springyness and damping of the cone's motion. The high Q means it wants to resonate at some frequencies and half an octave away not move at all. At the resonant frequency the kinetic energy of the cone isn't well damped so it continues vibrating when it's not supposed to.
This video displayed two different personalities that appeal to me in the pursuit of audio. A very technical, build based on strict science parameters type personality and a have enough knowledge to know what you're doing and tweak it and experiment until I like it type personality. Neither is better than the other to me as a casual listener however I can appreciate the achievements that come with both approaches. Love of sound. Agree to disagree with love. Cheers.
51:38 i've been curious about experimenting with different gasses inside a sealed box, like how it sound with sulphur hexaflouride as the atmosphere inside the box!
It has roughly the same compressibility factor as air (meaning same box size), but as it is about 5-6x heavier your Mms would go up and Fs go down, standing waves within the box would also be around 5-6x lower in frequency.
I have a single 15" sub with a fairly large aeroport and I really like it, its kind of loud for a single sub and can also play very low frequencies. Next time though, I'll try 2 15" subs in sealed box size specs with 2 15" passive radiators in probably around the same amount of airspace (4.1-4.2 cubic feet) and I'll see how it does, since I cant really fit a pair of decent 12's unless theyre Sundown SA-12s which I guess I dont really care for as much
Something I did to handle port resonance was to cut a tapered 2x4 and glue it inside of the pvc pipe. It worked but it also made it very difficult to figure out port length.
I used my JL W712 first in a sealed recommended size box then I a recommend custom ported box. The ported box sounded a million times better. It sounded way 🔊 louder and deeper. Amazing.😮 I got complements all the time. High were of course no slouch either. Three sets of original MBquart Q series. $800 a set. Three sets. Sounded amazing.
It totally depends on personal taste. But if you want a somehow linear bass response, a sealed box is easier in a small semi sealed air chamber like in a car. In this small chamber, the deeper bass frequencies are increased anyway by physics. Without EQ tuning, ported boxes sound veeeery boomy. Too much for me, but I prefer ported boxes in bigger rooms (like a living room) or in PA for outdoor use.
I modeled cabin gain on my car (6 feet maximum length, after I'm done sealing the wall to the trunk), and what I found is that a sealed box is only 3db lower around 40 hz and 6db lower around 20Hz compared to a single PR when weighted to make the box as small as possible, the woofer can't go beyond xmax at any frequency, and the box is almost half the size of the PR (only about 1/2 cu ft net volume!). Needless to say I won't be making any ported or passive boxes anytime soon, only maybe if my parents want more oomph in the living room where they can't fit anything larger than their current ported 250W 8" (should be good for a 500W 10" PR box).
Thank you for the video audio tutorial commentary demo editing unbias observation. Lots of haters & complainers in the car audio community. Regardless of the field, experts, professionals & engineers are CONSTANTLY LEARNING, testing, research & development. There's always room to grow without hitting the glass ceiling.
2nd question. Passive radiator location in comparison to active driver? I'd say most agree that being on the same plane as the active driver is not optimal? Is 90° or 180° optimal? Thanks
Q Acoustics are a good example of a very long port. The cabinets are so deep. Polk XT60 is an interestingly cheap passive radiator implementation. Erin has reviewed the whole line and they're definitely showing their price point. I had two shallow sealed 8" Pioneers under each front seat. They were awesome! At the time the patent was still pending.
Passive radiators do not have an x max because they don’t have a motor. They do have a x mech however… right? Great show guys!! Sorry I missed you live.
Depending on the car or truck. Sealed sounds amazing. I had a 12" W7 in my Tahoe. Sounded perfectly. Same sub same box. Didn't sound good at all in my truck
Regarding your current altitude above sea level comments in answer to the question. I think you may discover that temperature discrepancies can contribute more change to speaker behavior than air pressure. Air pressure can vary at the same altitude. Its called barometric pressure values. So you have a Speaker finely tuned and then the inside of the box heats up because of speaker performance and the temp inside the box is now 10 degrees higher than ambient. You are now dealing with a whole new set of values. My determination is to under tune your box development then apply temperature changes using Win ISD and see the changes. If you have a controlled environment 24/7 365 then hats off to you but you still have to deal with the rise in internal temps which you can simulate with Win ISD. Find your happy medium and accept it. You might find that seasonal temperatures may have a larger effect speaker performance than altitude. Let me ask whats the temp inside your truck at Midnight, at Noon or any other given during the course of a Year? All those poor subs in the trunk :D.
I want to make some sealed subs for music. From what I understand, you are better off with multiple 10" subs (a sub 'swarm') than one huge sub, because they can be located to overcome room modes much better.
I always ran 2 woofers in a sealed box, at home and in the car. Both double 10s and double 12s, and you really don't need that much power if you are running 2 of them. Sealed boxes just sound so much better in my opinion, and in the end they'll go loud enough for listning to music, and they go really low.
@@Epic501 My understanding is that DSP can improve that. Also, my understanding is that our ears are quite forgiving of phase differences, because they are encountered anyway in live settings.
Do you ever use Bassbox Pro 6? I have noticed using Winisd some woofers are way off from what they say they are supposed to be, especially the larger sizes. I Don't know what to trust. If I spend a lot of money and time building a set of speaker cabinets I want to minimize any mistakes. It appears Parts-Express uses Bassbox Pro for their box size recommendations. I have read online most of the Pros use Bassbox. I am sure with all of the speakers you have build you have noticed the discrepancy what was your solution? Is Bassbox Pro worth the $132 cost?
When I was talking to parts Express on the phone about passive radiators in my tower speaker diapolito design. They pretty much said I want the airspace in the box to be less than it would be if it was ported and the passive radiators are designed for small enclosures, not normal sized. It's unfortunate if they're offering misinformation Direct example, they were saying I should port the box at 0.75 to 1.0 ft3, Or do passive radiator with the same drivers between 0.5 and 0 75 ft3 max. The driver in question would be a pair of five and a quarter inch SB acoustics mid bass.
In general that's a somewhat smaller box to begin with. Are you sure they weren't referring to your particular application? If I recall correctly, the video said a passive radiator setup takes more space than sealed, but often less than ported. Hence why the epique line now offers a PR for space reduction when tuning low. Because it would need a really long awkward port in a small box.
@@gahbah274 My point was that I think parts express texts aren't as knowledgeable as they think they are or as they should be. If you talk to a tech see at Madison they really know their stuff.
@@gahbah274 My project never got finished, but dual 5.25" and a ring radiator with SBa cousins drivers. The 10" passive will be side firing. I hope that works out well.
I would be interested in a similar discussion from the person of audio quality. I am looking into building my own home audio setup. But what matters most to me is sound accuracy. I want to the records I own as they were recorded.
passive radiators are a good idea to avoid the noise of vented ports. however, you have the same problem of finding the right position or a kind of transmission line to get them in phase at resonance frequency. with the weight adjustment you probably not only adjust the resonance but probably the phase as well. so, when they are in phase, the volume of both radiators add up. if you achieve the right smooth rolloff of your frequency response, you are fine. but that is not guaranteed. at the end you have to adjust it to end up tuning it to get the best smooth roll off in the low end of your frequency response.
Question. In a vehicle where sub is firing forward with port firing to the side, with box placed as far back as possible in the trunk...and it works great, of one was to take that out and try a passive set up, would you say itd be best to install the passive radiator on the side of the enclosure so that it fires towards the same location that the port used to fire in? So sub(s) forward, radiator(s) on the side if not using a ported set up?
@@Luminous.Dynamics the location is only important regarding the phase. and that needs to be simulated. at that low frequency it does not fire in one direction. it is not focused because the membrane diameter is much smaller than the wavelength of the resonance frequency.
I have a vehicle with very limited room, there is a company that make a vehicle specific box that mounts in an area that is not very large making the volume of the box approximately .3 cubic feet. It has 2 holes for 6.5 subs with a little less than 5" mounting depth, CT Sounds Tropo Subs will fit, but would it be better to do a single sub with a passive radiator or two subs?
passive radiators will give more output in between the roll off of the two enclosures. so after the sealed has started rolling off and before the pr starts rolling off. but once the pr rolls off it does so FAST, so the sealed sub will probably have more ultra ultra low end
Sealed will sound cleaner usually, but ported is more efficient, so the only way commercially viable in PRO audio. You cannot earn money on sealed enclosures.
Isobaric can be really good with the right drivers and the right box size. They can also be sealed or ported. I actually did a pretty good video where I built some isobaric subs and explained why I used those subs in an isobaric configuration. Here’s the link. th-cam.com/video/CvUjWNwPHDU/w-d-xo.htmlsi=_J79QXcq9xVzWGiL
In my experience a good port has no noise? You can model port velocity, and much over a certain velocity (don't recall, 25 m/s?) you start to get chuffing sounds. Precision Ports seem to allow you to exceed this somewhat, however. But that's what my ears hear anyway.
I calculated the cabin gain like demonstrated and my port velocity and cone excursion were super high! Is this just checking the “free bass” gained from the cabin and won’t actually damage my subwoofer? I don’t have a filter in WINISD for my calculations because it will never reach xmax so a filter is not needed. Just want to make sure I’m not going to blow up my subwoofer. Thanks
Check your port velocity and come excursion before you add the linkwitz transform. If it is good before that, then it’ll be fine. You won’t actually be using a linkwitz transform, this just simulated the organic room gain. Thus it will not have an actual affect on cone excursion or port velocity
Always used a pair in a sealed box. Did a couple of ported boxes but they just don't sound right. A pair of 10s or 12s in a sealed box will give a single one a run for their money. While in a similar sized enclosure.
I had a friend that had 3 10 in a sealed box that's bass was tight but you felt it in your chest no lie that thing hut hard that's when I said dam to me sealed box hit a lot cleaner !!! Port to me sound dirty that's my opinion
I think that happens with a lot of ported enclosures. But I think part of that has to do with the fact that a lot of people don’t take into consideration, such as port, velocity, unloading and port resonance. A good ported box sounds really good.. IMO. Unfortunately there’s a lot of bad ported designs as well.
No lie...Damn I hate that expression. I ain't gonna lie today I'm going to give you the truth today. Normally all I do is lie. That's what that Ebonics/ ghetto talk means.
@@wadimek116 you’re welcome to Google it, but you’ll never get the amount of information that we provided in here with a Google search. In fact, I don’t know anywhere that as this amount of comprehensive information on the subject. But if you do, I’d be very interested to find out where.
@@wadimek116 I highly doubt yiu even watched the entire thing and simply reas the length and decided to complain. No problem if you dismt like it but only attention seekers post aboit things they dont like....or people that still live with thwir mom amdngrt hwr to wasj your clothes and cut up yoir food at dinner. Next time you want to complain, don't save your time amd gobabiut your day
There are way too many variables to answer that generally, but a 15" sealed enclosure could potentially deliver the same SPL as a 12" ported sub of similar enclosure size, and certainly play louder further from tuning.
Just get a pair of 10s or 12s and put them in a sealed box. Or if you got the room 2 15s, but that requires a lot of space. Even in a sealed enclosure In my opinion it sounds better and goes really low.
![[Live] : ONE 168 วันนี้!! "โจนาธาน vs ซุปเปอร์เล็ก"](http://i.ytimg.com/vi/0jIN65KgJsI/mqdefault.jpg)
Intro: 0:00
Overhead/Headroom: 3:00
Subwoofer Size Comparison: 5:30
WinISD is not Taking into account Room/Cabin Gain: 7:20
Power Handling: 9:45
Group Delay of the Three Enclosures: 15:58
Why are we seeing more Passive Radiators: 20:00
Why you don't need to Model a Subwoofer Flat: 24:55
How to Model Room/Cabin Gain: 28:48
Linkwitz Transform: 35:15
How to pick the right Passive Radiator: 37:40
How big of a box should I design for a passive Radiator: 41:12
How do you Tune a box without knowing the T/s Parameters: 44:40
Sealed Box Misnomer: 48:56
Add Inductance in WinISD when modeling (*Brian Steele actually said you should do this - I misread it): 52:33
Wrap-up: 56:29
My honest 2 cents on passive radiators. First I will start off with, I never knew what one was. I landed a Job in an electronics store back in the 90s.
I was hired as a salesman. Roaming around the basement of this huge store I found a room that had nothing but home speakers out of the box. I found out that they were all defective or returned that the manager did nothing about. One by one I carried each one upstairs and hooked it up to a receiver to find out that each one of them had one or two components that was blown. I asked the owner if he would mind if I repaired them and sold them. This way he could take junk and turn it into money? His answer was yes. Here it comes... I came across one speaker that had 2- 10 inch woofers with no bass at all. I opened it up to find out only one woofer had a magnet a coil and so on. I replaced the one 10 inch woofer and it was back to life. I found this particular speaker sounded better to me than the rest of any size.
My ears preferred this single 10 inch woofer with one passive than the dual 12s the single 15 and so on. They were all made by Sansui and the amp I was using was the same brand. I only wish there were more speakers today that had this option. I'm aware that it's cheaper to use a port or go sealed. Makes no difference to me. It's all about the sound to my liking.
Now these men can give you all the technical mumbo jumbo I didn't even listen to the video yet.
The smaller the driver the more musically accurate it's response is to music. Could be the appealment from the accuracy
The other advantage to PRs is that you can initially mount them reversed to you can easily change the weights to tune, and then turn it around when you’ve got it right. Done. When a port isn’t quite right (chuffing, tuned to wrong freq, etc.) it can be a lot more complicated to make and test multiple adjustments, especially with a port with elbows and such.
That’s a great point!
Perfect points EndAll39. 😊🌎✨
If I may, I don't believe this to be entirely true. Not true by far...
BUT, I believe that only to be in the case of radiators with very large SD component and not those which are produced to make use of incredibly long excursion values. In the case of the latter, I believe that that would entirely hold true for the most part. But in the case of the radiators that are very deep in cone area and in diameter once you flipped it outward you have just added probably considerable internal volume to that enclosure especially if you've got multiple radiators with very large SD. Just a thought to consider it may be a very little change or value but one to consider perhaps. Cheers! --Robert
Toids, DIY Justin, & Hexi Base is where it's at : educating & learning simultaneously is neverending
The tools that I use to understand all woofer/enclosure designs although not to compute them are Newton's second law of motion applied to forced oscillation (this can be found in any first year college physics textbook along with an approximate solution) and the ideal gas laws. Newton's second law is an ordinary second order differential equation. It predicts the frequency response based on three parameters, moving mass, spring coefficient, and damping coefficient. The ideal gas laws explain the force from the difference between air pressure inside the enclosure and outside the enclosure. P1*V1 = P2*V2 where P is the pressure difference between the air inside the box and the air outside the box and V is the volume of the air inside the box, the relative volume of air outside the box being enormous. The force due to differences in air pressure is P*A where A is the area of the cone. It is applied uniformly on the surface of the cone. There is also a mechanical restoring force due to the compliance of the suspension.
Using these tools it's easy for me to understand and compare the different conceptual designs. Of all of the designs IMO the best one is the acoustic suspension design which probably should have been called the pneumatic suspension design. Not all sealed enclosures are acoustic suspension. Even its inventor Edgar Villchur didn't fully understand how it worked.
In that design the mass is high and the compliance is high making the Fs low, in the range of 17 to 19 hz in free air. It's also of necessity a long throw design. The restoring force is mostly but not entirely the compression and rarefaction of the air pressure inside the enclosure compared to the outside. The enclosure can't be 100 percent air tight or the cone would work like a manometer where changes in barometric pressure in the room would move the neutral resting point. So there should be a tiny amount of leakage, not enough to compromise the design but enough to allow the relatively small mechanical restoring force to bring the cone back to its intended neutral (zero voltage) point.
Now here's the kicker I didn't understand and Villchur didn't either. The enclosure has to be filled with fibrous stuffing, typically one pound per cubic foot of internal space. this is not to dampen cabinet resonances. Instead this creates an aerodynamic drag by forcing the motor to push and pull air between the fibers. This drag is proportional to the velocity of the cone. This creates a frictional force converting some of the energy into heat just the way the space shuttle heats up when it reenters the earth's atmosphere at high speed. This is only a tiny amount of heat, most of the heat being generated by the voice coil DC resistance. This aerodynamic drag controls the damping coefficient. It serves the same purpose in this design as the oil filled shock absorber serves in the suspension of your car. Without it there's an undamped resonance which can be high enough to drive the cone past its ultimate limit tearing the suspension apart.Q = 0.707 is called critical damping. It is the highest damping factor which will extend bass response without a peak in its response. Higher Qs will create a peak, lower Qs will cause the bass to rolloff faster than 12 db per octave.
In the ported design air moves easily through the port at some frequencies and with great difficulty at other frequencies. It works like a pipe organ giving bass a very high Q. Below system resonance response falls off at 24 db per octave so the system resonance frequency is the effective lower limit of the system. By contrast the acoustic suspension design with a Q of 0.707 rolls off at 12 db per octave and is therefore equalizable within the thermal and mechanical limits of the driver. In the ported design the mechanical restoring force may be applied to a different degree circumferentially and radially creating shearing and twisting forces on the cone. In the acoustic suspension design this doesn't happen because the air pressure is uniform over the entire surface of the cone.
There are also air turbulences at the entrance and exit of the port. That's the chuffing sound you hear. This affects the damping factor. Sof for the acoustic suspension design b the damping coefficient and k the spring constant are the same at all frequencies and amplitudes. In other designs they are not. This enables the optimized design to be tuned to any frequency response and any Q by adjusting these three parameters. The price for greater low bass extension is efficiency. Keep in mind that as you add stuffing you are reducing the amount of air in the enclosure. The aggregate surface area of the fibers is enormous so there is plenty of frictional loss.
The acoustic suspension design was so successful that it became a world standard for bass reproduction in the 1960s. The ideal driver will have a low Fs say 17 to 19 hz, High compliance, Low Vas, Low Qms. There are no drivers I'm aware of available today that are optimized for the acoustic suspension design. Drivers that can be used either closed box or ported are a compromise. Drivers that were such as Madisound 1259 could only be used for the Acoustic Suspension design.
What's important is displacement and sufficient power handling to hit Xmax in the range of frequencies you wish to play the woofers. Displacement = Xmax * Cone area determines the maximum SPL. All that low Fs and Q stuff does not matter now that digital equalization is so cheap and can be used to apply a Linkwitz transform filter to get the flat response to the desired low frequency cut off and Q you desire. Of course the sealed box is high fidelity. The other stuff is just late, ringing bass. Ports and radiators are just bass bells and they are not high fidelity.
@@danaolson2871 below the system resonance frequency, response falls off at 24 dB per octave in a ported system. That is not equalizable. The acoustic suspension design with a Q of 0.707 falls off at 12 dB per octave below resonance and is equalizable. 0.707 is critical damping, the lowest bass extension without a bump in the FR at resonance.
@Dana Olson To understand how woofer/enclosure designs work I used Newton's second law of motion applied to forced oscillation and the ideal gas laws. Newton's second law has many applications such as designing the suspension of a car and how it will respond to bumps. Three elements are involved, moving mass, damping factor, and springyness. The acoustic suspension design is the only one where the damping factor and spring constant are independent if frequency and amplitude. Not all sealed designs are acoustic suspension designs. The difference in air pressure between the inside and the outside of the enclosure determines the spring force. The damping is controlled by filling the enclosure with fibrous material. The speaker is forced to work to push and pull air between the fibers which in aggregate have an enormous surface area. The frictional loss is directly proportional to the air velocity. This is how the damping factor is controlled. In a ported design the air moves easily through the port at some frequencies and with great difficulty at others. It's tuned like the pipe in an organ. To make matters worse air turbulence at the entrance and exit if the port really screws up both the springyness and damping of the cone's motion. The high Q means it wants to resonate at some frequencies and half an octave away not move at all. At the resonant frequency the kinetic energy of the cone isn't well damped so it continues vibrating when it's not supposed to.
@@markfischer3626 I’d bet you designed the studio standard or chat gpt hahaha just a play on yer name
This video displayed two different personalities that appeal to me in the pursuit of audio. A very technical, build based on strict science parameters type personality and a have enough knowledge to know what you're doing and tweak it and experiment until I like it type personality. Neither is better than the other to me as a casual listener however I can appreciate the achievements that come with both approaches. Love of sound. Agree to disagree with love. Cheers.
Enjoying the Podcast while I'm working away... Have a guud week gents!
51:38 i've been curious about experimenting with different gasses inside a sealed box, like how it sound with sulphur hexaflouride as the atmosphere inside the box!
That’s a very interesting idea
Legend has it if you fill it with natural gas you can get massive BOOM! 😂👍
It has roughly the same compressibility factor as air (meaning same box size), but as it is about 5-6x heavier your Mms would go up and Fs go down, standing waves within the box would also be around 5-6x lower in frequency.
been experimenting with different density plugs to reach a good compromise between sealed and ported. with a driver that handles both
I have a single 15" sub with a fairly large aeroport and I really like it, its kind of loud for a single sub and can also play very low frequencies. Next time though, I'll try 2 15" subs in sealed box size specs with 2 15" passive radiators in probably around the same amount of airspace (4.1-4.2 cubic feet) and I'll see how it does, since I cant really fit a pair of decent 12's unless theyre Sundown SA-12s which I guess I dont really care for as much
thank you guys for answering my questions, i will use your knowledge to help my future designs
Something I did to handle port resonance was to cut a tapered 2x4 and glue it inside of the pvc pipe. It worked but it also made it very difficult to figure out port length.
I used my JL W712 first in a sealed recommended size box then I a recommend custom ported box. The ported box sounded a million times better. It sounded way 🔊 louder and deeper. Amazing.😮 I got complements all the time. High were of course no slouch either. Three sets of original MBquart Q series. $800 a set. Three sets. Sounded amazing.
That is awesome!
@@Toid I'm thinking about keeping that JL audio custom $700 box and woofer inside my house for theater. That thing really moves and sounds good. 👍
It totally depends on personal taste. But if you want a somehow linear bass response, a sealed box is easier in a small semi sealed air chamber like in a car. In this small chamber, the deeper bass frequencies are increased anyway by physics. Without EQ tuning, ported boxes sound veeeery boomy. Too much for me, but I prefer ported boxes in bigger rooms (like a living room) or in PA for outdoor use.
Ha, great timing because ive got two extra woofers to use for building a pair of subs ! Gonna pay attention to this
I modeled cabin gain on my car (6 feet maximum length, after I'm done sealing the wall to the trunk), and what I found is that a sealed box is only 3db lower around 40 hz and 6db lower around 20Hz compared to a single PR when weighted to make the box as small as possible, the woofer can't go beyond xmax at any frequency, and the box is almost half the size of the PR (only about 1/2 cu ft net volume!).
Needless to say I won't be making any ported or passive boxes anytime soon, only maybe if my parents want more oomph in the living room where they can't fit anything larger than their current ported 250W 8" (should be good for a 500W 10" PR box).
Thank you for the video audio tutorial commentary demo editing unbias observation.
Lots of haters & complainers in the car audio community.
Regardless of the field, experts, professionals & engineers are
CONSTANTLY LEARNING, testing,
research & development.
There's always room to grow without
hitting the glass ceiling.
2nd question.
Passive radiator location in comparison to active driver?
I'd say most agree that being on the same plane as the active driver is not optimal?
Is 90° or 180° optimal?
Thanks
Q Acoustics are a good example of a very long port. The cabinets are so deep.
Polk XT60 is an interestingly cheap passive radiator implementation. Erin has reviewed the whole line and they're definitely showing their price point.
I had two shallow sealed 8" Pioneers under each front seat. They were awesome! At the time the patent was still pending.
Passive radiators do not have an x max because they don’t have a motor. They do have a x mech however… right? Great show guys!! Sorry I missed you live.
Both of you did such an amazing job explaining things! Very useful video for understanding why things are designed the way they are designed.
Depending on the car or truck. Sealed sounds amazing. I had a 12" W7 in my Tahoe. Sounded perfectly. Same sub same box. Didn't sound good at all in my truck
I think the air space inside the vehicle plays a part in how a sub sounds.
I had a 18 " Boston acoustics power sub and it was insane
I did HUGE box whit a high quality 12 inch SBacoustic (not maried) luckely !
It’s more about personal sound preference than anything
can added noise of a port be a personal preference?
If you combine a small enclosure (passive radiator design) to a large ported enclosure via encapsulated PR. You'd be surprised on the results
Valuable information!, THnak you.
Regarding your current altitude above sea level comments in answer to the question. I think you may discover that temperature discrepancies can contribute more change to speaker behavior than air pressure. Air pressure can vary at the same altitude. Its called barometric pressure values. So you have a Speaker finely tuned and then the inside of the box heats up because of speaker performance and the temp inside the box is now 10 degrees higher than ambient. You are now dealing with a whole new set of values. My determination is to under tune your box development then apply temperature changes using Win ISD and see the changes. If you have a controlled environment 24/7 365 then hats off to you but you still have to deal with the rise in internal temps which you can simulate with Win ISD. Find your happy medium and accept it. You might find that seasonal temperatures may have a larger effect speaker performance than altitude. Let me ask whats the temp inside your truck at Midnight, at Noon or any other given during the course of a Year? All those poor subs in the trunk :D.
I want to make some sealed subs for music. From what I understand, you are better off with multiple 10" subs (a sub 'swarm') than one huge sub, because they can be located to overcome room modes much better.
That’s a good point. Multiple subs have a few benefits and that can be a good one with proper placement.
I imagine it would be tricky to overcome phasing nightmares for more than one listening position with many subs though
I always ran 2 woofers in a sealed box, at home and in the car. Both double 10s and double 12s, and you really don't need that much power if you are running 2 of them.
Sealed boxes just sound so much better in my opinion, and in the end they'll go loud enough for listning to music, and they go really low.
@@Epic501 My understanding is that DSP can improve that. Also, my understanding is that our ears are quite forgiving of phase differences, because they are encountered anyway in live settings.
My 21" Pierce Audio Subwoofer has coils rated to 360 degrees Celsius!!! You could slow roast a turkey!
Do you ever use Bassbox Pro 6? I have noticed using Winisd some woofers are way off from what they say they are supposed to be, especially the larger sizes. I Don't know what to trust. If I spend a lot of money and time building a set of speaker cabinets I want to minimize any mistakes. It appears Parts-Express uses Bassbox Pro for their box size recommendations. I have read online most of the Pros use Bassbox. I am sure with all of the speakers you have build you have noticed the discrepancy what was your solution? Is Bassbox Pro worth the $132 cost?
When I was talking to parts Express on the phone about passive radiators in my tower speaker diapolito design.
They pretty much said I want the airspace in the box to be less than it would be if it was ported and the passive radiators are designed for small enclosures, not normal sized.
It's unfortunate if they're offering misinformation
Direct example, they were saying I should port the box at 0.75 to 1.0 ft3, Or do passive radiator with the same drivers between 0.5 and 0 75 ft3 max.
The driver in question would be a pair of five and a quarter inch SB acoustics mid bass.
In general that's a somewhat smaller box to begin with. Are you sure they weren't referring to your particular application? If I recall correctly, the video said a passive radiator setup takes more space than sealed, but often less than ported. Hence why the epique line now offers a PR for space reduction when tuning low. Because it would need a really long awkward port in a small box.
@@gahbah274 My point was that I think parts express texts aren't as knowledgeable as they think they are or as they should be.
If you talk to a tech see at Madison they really know their stuff.
I enjoyed the sound of a passive radiator compared to sealed or ported.
@@gahbah274 My project never got finished, but dual 5.25" and a ring radiator with SBa cousins drivers. The 10" passive will be side firing. I hope that works out well.
A pasive ratiator box should be smaller, that is the point.
The box should be the same same as a sealed box aprox. But behave as a borted box.
Passive radiator all the way
I would be interested in a similar discussion from the person of audio quality. I am looking into building my own home audio setup. But what matters most to me is sound accuracy. I want to the records I own as they were recorded.
passive radiators are a good idea to avoid the noise of vented ports. however, you have the same problem of finding the right position or a kind of transmission line to get them in phase at resonance frequency. with the weight adjustment you probably not only adjust the resonance but probably the phase as well. so, when they are in phase, the volume of both radiators add up.
if you achieve the right smooth rolloff of your frequency response, you are fine. but that is not guaranteed. at the end you have to adjust it to end up tuning it to get the best smooth roll off in the low end of your frequency response.
Question. In a vehicle where sub is firing forward with port firing to the side, with box placed as far back as possible in the trunk...and it works great, of one was to take that out and try a passive set up, would you say itd be best to install the passive radiator on the side of the enclosure so that it fires towards the same location that the port used to fire in? So sub(s) forward, radiator(s) on the side if not using a ported set up?
@@Luminous.Dynamics the location is only important regarding the phase. and that needs to be simulated. at that low frequency it does not fire in one direction. it is not focused because the membrane diameter is much smaller than the wavelength of the resonance frequency.
I have a vehicle with very limited room, there is a company that make a vehicle specific box that mounts in an area that is not very large making the volume of the box approximately .3 cubic feet. It has 2 holes for 6.5 subs with a little less than 5" mounting depth, CT Sounds Tropo Subs will fit, but would it be better to do a single sub with a passive radiator or two subs?
It would typically be better to run two in that application.
Can you put passive radiator in inverted? That way you could adjust the weight for turning.
Yes
Aren't there passive enclosures that could actually take up less space than a sealed for the same output?
passive radiators will give more output in between the roll off of the two enclosures. so after the sealed has started rolling off and before the pr starts rolling off. but once the pr rolls off it does so FAST, so the sealed sub will probably have more ultra ultra low end
Sealed will sound cleaner usually, but ported is more efficient, so the only way commercially viable in PRO audio. You cannot earn money on sealed enclosures.
Great Stuff Guys!!!
Thanks Donnie!
a DBA or SBA is also nice but you need min 4 bzw 8 woofers
Just seeing this video. How about isobaric enclosures? Dual Subs in one box? Would like to hear your opinion. Thx
Isobaric can be really good with the right drivers and the right box size. They can also be sealed or ported. I actually did a pretty good video where I built some isobaric subs and explained why I used those subs in an isobaric configuration. Here’s the link. th-cam.com/video/CvUjWNwPHDU/w-d-xo.htmlsi=_J79QXcq9xVzWGiL
Overall i think passive radiator are better cz it removes noice from speakers
I've always avoided ported mainly because of port noise
In my experience a good port has no noise? You can model port velocity, and much over a certain velocity (don't recall, 25 m/s?) you start to get chuffing sounds. Precision Ports seem to allow you to exceed this somewhat, however. But that's what my ears hear anyway.
@@gahbah274 but there are cases where you can't make good ports anymore. this is where a passive radiator comes in
Open Baffle!!! for the win.
I calculated the cabin gain like demonstrated and my port velocity and cone excursion were super high! Is this just checking the “free bass” gained from the cabin and won’t actually damage my subwoofer? I don’t have a filter in WINISD for my calculations because it will never reach xmax so a filter is not needed. Just want to make sure I’m not going to blow up my subwoofer. Thanks
Check your port velocity and come excursion before you add the linkwitz transform. If it is good before that, then it’ll be fine. You won’t actually be using a linkwitz transform, this just simulated the organic room gain. Thus it will not have an actual affect on cone excursion or port velocity
@@Toid Wow thank you and this was a real informative video. You guys killed it! Glad my sub will be ok 👍🏼
Always used a pair in a sealed box. Did a couple of ported boxes but they just don't sound right.
A pair of 10s or 12s in a sealed box will give a single one a run for their money. While in a similar sized enclosure.
What about horn loaded though?
I had a friend that had 3 10 in a sealed box that's bass was tight but you felt it in your chest no lie that thing hut hard that's when I said dam to me sealed box hit a lot cleaner !!! Port to me sound dirty that's my opinion
I think that happens with a lot of ported enclosures. But I think part of that has to do with the fact that a lot of people don’t take into consideration, such as port, velocity, unloading and port resonance. A good ported box sounds really good.. IMO. Unfortunately there’s a lot of bad ported designs as well.
yep, a well designed ported enclosure sounds 95% as good as a proper sealed enclosure imo. but sealed is way easier to design and build
No lie...Damn I hate that expression. I ain't gonna lie today
I'm going to give you the truth today.
Normally all I do is lie. That's what that Ebonics/ ghetto talk means.
The bigger the box is, bigger the tweeter you need to make it scream. 😁
If you had only known you would have held onto those chickens with their golden ovals
I ended up keeping them 😂
Holy jeez… and hour video to explain what I can explain in 5 minutes??? Brutal!
I kinda hate it, dont have time for it. Its faster to google. For the same reason I don't watch audioholics
it's also a podcast. not a scripted pre recorded video. and they talk about a lot of different aspects of the different boxes
You absolutely could not have delivered the information given in this video in five minutes, regardless that this is unscripted and improvised.
@@wadimek116 you’re welcome to Google it, but you’ll never get the amount of information that we provided in here with a Google search. In fact, I don’t know anywhere that as this amount of comprehensive information on the subject. But if you do, I’d be very interested to find out where.
@@wadimek116 I highly doubt yiu even watched the entire thing and simply reas the length and decided to complain. No problem if you dismt like it but only attention seekers post aboit things they dont like....or people that still live with thwir mom amdngrt hwr to wasj your clothes and cut up yoir food at dinner. Next time you want to complain, don't save your time amd gobabiut your day
open baffel speakers?
👍
Would a 15” woofer in a sealed enclosure give you the same output as say 10-12 inch passive/ported woofer.
There are way too many variables to answer that generally, but a 15" sealed enclosure could potentially deliver the same SPL as a 12" ported sub of similar enclosure size, and certainly play louder further from tuning.
Just get a pair of 10s or 12s and put them in a sealed box.
Or if you got the room 2 15s, but that requires a lot of space. Even in a sealed enclosure
In my opinion it sounds better and goes really low.
It’s headroom not overhead
Sounds the same to me
@@gahbah274 Its the proper term. No need to get butt hurt about it
Get over it. Over an hour to answer 3 simple questions? WTF? My time is more important to me.
Too much theory, nothing in practice. Time wasters.
Watching speaker cones move does not look good. High volume with zero visible movement is beautiful.