Hey Phillip.... actually, with an open back cab you get what is called phase cancellation where the front sound wave can intermingle with the back sound wave which actually cancels some of the bass response so a sealed cab will actually have more bass. You were right about transient response however being tighter in a sealed box and looser in a open back. Cheers buddy!
How do I know?.... I built custom bass enclosures professionally for 20 years using computer programs and went well beyond mere sealed boxes as in ported or vented as well as 4th order through 8th order bandpass enclosures. The response can be measured with a spectrum analyzer... try it.. you’ll have fun! 😁🤟🏻
Makes sense. It’s also inline with why I prefer open back for slow heavy music (Drone/Doom and clean) and closed back for fast heavy music (black metal, etc).
Since i play mainly rock, blues, and jazz I coverted my small 12 to 15 inch amplifiers cabinets into halfbacks. the overall improved sound is warmer, has better projected mids without losing bass clearing up the treble. I also use a closed back active subwoofer that i keep on a class c power amp that uses a flipswitch.
Great video and explanation. Never knew when I rented a Mesa Boogie cab one time why it came with those jack plugs in the back.. Had I known they were actually important, I would have left them in! The wonder of guitar is that no longer how long I play the thing, there still remain mysteries like this to be revealed. Thanks for the awesome insights about differences between open vs closed back cabs.
That was an interesting explanation. What he was getting at with the sealed cabinet is that air can be compressed. It kind of "springy" in that regard. So as a speaker moves, it compresses the air (which acts as a resistance to the movement of the speaker cone.) As the springy air is compressed and the paper cone presses against it, the travel distance of the speaker is limited by the resistance of the air. So, the cone can't over extend itself in terms of travel. It's being restricted by the air. This resistance from the air keeps the movement of the speaker cone from being "flabby" to some degree. You get a tight sound this way, because of a sealed cabinet. This keeps the frequency response of the speaker box flatter, too. Now, porting changes the whole thing because you can TUNE a cabinet with a port, to make a bump in the bass freqencies with it. He talked about bass reduction with a sealed cabinet, but he didn't talk about accentuating the bass with a port. The length and diameter of the port relate to which frequency, in the bass, will be accentuated. What happens with a port, is as the speaker moves in a backward motion, the air in the port is pushed out of the cabinet. Conversely, when the speaker cone moves forward, air is sucked into the cabinet through the port. So, you get this in and out movement of air in the port. As the speaker moves back and forth, it takes time for the air to move in and out of the port. If the right frequency is hit, the air comming in from the port will be in the opposite direction as the speaker movement. It will also be in the opposite direction of the speaker when the air is leaving the port. This happens at the resonant frequency. So, when the resonant frequency is hit the movement of the speaker stops, and the bass sound comes out of the port. The air comming in and out of the port is in the exact opposite direction as the speaker want so move, but the speaker can't move because it is being held in place by the air moving in and out of the port. The bass sound, at this particular frequency is comming out of the port. There you have why he didn't mention ports, because they DO accuentuate the bass. Now, as far as the open back goes, the speaker itself has not nearly the air resistance that a closed back cabinet would have, so the speaker itself has to self regulate it's own movement. The springiness of the speaker cone is built in by the speaker designer. Some of them have a very tight, controlled movement (stiff cone, etc.) Some of them are looser and more flabby. If a speaker is loose and flabby, you get ringing as the speaker's back and forth motion subsides. When designing cabinets, the designer takes into consideration how well a speaker will stop it's motion. There is my two cents on this issue. I'm going by my memory, and my experiences with building my P.A. boxes (which is great fun, when they work well.)
I'm seriously getting really into your channel. You answer almost everything I need an answer too and explain why that is so. Thanks dude! Learning loads from you Greetings from Portugal
Actually a sealed cabinet (called acoustic suspension) allows the driver to travel more accurately giving a tighter and deeper bass. Because of the resistance (vacuum) it is slightly less dynamic though.
Thank you phill you always get to the point and make what you are saying simple to understand without being condescending. Wish I could have visited your store but I’ll tune in Fridays for the live show.
As I pondered the information presented in this video, I'd have question the accuracy of it. If you've ever designed speakerboxes, you know that when you put a raw speaker in a cabinet, you automatically get more bass. Try taking a raw speaker (with no enclosure) and running sound through it, to understand what I'm saying here. You'll find that with no cabinet, it will be very thin sounding. If you put a back on a cabinet you'll probably increase the bass response. If you port that closed back cabinet, you'll increase the bass even further. An open back would actually decrease the bass, I suspect. Now all of this having been said, the characteristics of the raw speaker play into this too. So, some tonal responses can be build right into the driver.
The air in a sealed cab will stiffen the springiness of a cone, as you say. However, the effect is an increase in bass response at ~50-150Hz. That is both measured and noticed by most players. There are other factors mentioned that shouldn’t be confused: The effect of diffuse sound from the rear of an open cab (in-room fullness) and the effect of a larger baffle (a lower shelf freq…more mid-bass.)
The Thiele-Small measurements and parameters of the driver determines its performance in an open back or closed back cab. A driver cannot make 'more' bass on an open back. The cancellations of the back and front wave within the space and at the edges of the baffle, plus the steep slope, will give the impression of louder ranges within the bass frequencies. One of the reasons some like 8" in 10-12" cabs for a 'fuller' sound. A phenomena noticeable if one walks alongside an open back. It is quieter on the sides where the cancellations are happening. A sealed cab, depending on the q of the driver and size of the box will extend bass further at a gentler slope but at the expense of box size. The front and backwaves do not meet. Comparing drivers open and closed back is not apples to apples if the driver design is geared towards one way. Drivers sometimes have q that can be used either sealed or bass reflex, then one can choose (bass players that need 40hz). Drivers for open designs rarely perform as well in sealed boxes, not in sizes considered practical for guitar use...
Thank you ! I was wondering about that for the longest time and this was the best explanation I found, short, to the point and complete. Thanks Phillip !
Good video. (1) As an experienced woodworker… Baltic Birch (or Russian) plywood is typically much more uniform than conventional plywood in that it is typically free of voids that can affect both strength and rigidity. And unlike conventional plywood, Baltic Birch plywood will accept router-applied contours at the edges and can be successfully machine dovetailed. The only advantage/upgrade in marine-grade BB plywood is the type of waterproof glue used in the sheets of lamination, hence marine (boat) grade. Other than having a nice marketing ring, there would be no advantage in using marine-grade BB plywood in an acoustic enclosure application whose use will be above the water line. (2) Also having a background in high end audio gear… For some additional basic information, look into at the fundamental differences between bass-reflex and acoustic-suspension speaker enclosures.
That's contrary to what every amp/cab developer has ever claimed about the application of BB in denser, heavier plywood vs lighter vs particle board. According to all, BB's response to lower bass reqs is to amplify and focus them, while lighter materials attenuate them into what they describe as "farty". James Brown and Dave Friedman noted this in their Tone Talk interview just after the one hour mark. It's apparently a function of the stiffness of the cold weather versions of birch along with that added by glue between more layers. Their words.
There is something you can do to an open speaker. It is not the same as closing the cabinet but you can tune the sound. You can cover the spaces in the speaker frame. A stiff product will be used such as cardboard held in place with foil tape. You'll probably have to cover 2/3's of the space to really hear a big difference. Try it. You can glue a damping material over the sealed plug to absorb high frequency. Of course changing speakers or cabinets is best but if you can make this work saves a lot of $.
Thank You Brother Phil, For Providing This Space For All The Kind Souls United Here Around Loves Tools, The Electric Guitar And Amps! They Are The Answer To The Dark Elves! I Live 2Hours From Orlando,A City I've Been To Countless Times With Friends And Family,A City I Love . I Do Not Despair For There Are More Good Kindhearted People Than The Haters. The New Being Reaches For Their Guitar,Not The Gun. So Bless Us All TOGETHER Here Each And Every One. Long May We All Run, Thank You Phil & Everyone. 6/15/16
nice explanation! I'm using a valve head into a 2x12 bass cabinet (closed back) for down tuned doom metal. it's a pretty sweet sound. For blues I have an open back 1x12 cab that definitely sounds more open
The real reason for ported v closed is , a closed cabinet gives you more even frequency response across the range more volume and a tighter attack, a ported cab will give you an amazing sound at a tuned frequency say mid range but only that frequency so it may be tuned to appear to have a better sounds at a given frequency, ported cabs will sound boomier and loose half the power of the speaker because of the porting so porting is a trade off and the porting has to be tuned correctly .
I get some of the advantages & disadvantages of each, but I'll argue the bass theory is more on an open back. Here's the rub with your theory ? The speaker being a woofer produces whatever bass it's going to produce. After that, it's a matter of confining those sound waves. The open back releases sound out the back like you said it does. The closed back confines & restricts those vibrations & sounds and allows them to marinate inside the enclosure. There's really nowhere for that to go but forward thru the front of the speaker. That trapped bass is accumulated and the rumble is enhanced. With an open back, you better have enough amp to fill the room with ambient sound, strategically finding a wall or a corner might help an open back with a deeper rumble, but it's gonna like louder volume levels to fill the room. At a live outdoor concert, the audience is in front and around the front of the stage. It makes no sense to allow volume out the back, there are no walls to capture the sound and the closed back being directional makes more sense for efficiency. An open back is going to be a manageable room size with enough power for the amp to fill the room. Too little amp and the open back is simply going to be overwhelmed by the room. With an open back, you're going to need a bigger woofer for bass an 8 inch in a closed back is so much heavier sounding than the same 8 inch woofer in an open back. Hey, I tried it with the open back combo 8 inch woofer I have. Simply putting a 3/4 inch mdf board against the back of the open area. Granted it wasn't fully air tight sealed, but giving the amp that much wood to block the sound made a huge difference in bass output. I still had some room filling ambient surround sound that still wasn't as heavy as a closed back 8 inch combo amp I have. At a certain point with that open back cab, the bass knob was a worthless turn to try to get a deeper rumble out of it. I bet the open back sounds different in a deeper bass way in a smaller bedroom than it does the living room with a vaulted ceiling. Bet it sounds deeper in the bathroom too. Not only are the acoustics different for each room, the amp probably has a better chance of filling the room with ambient sound. Back to live music though, I'm probably going to want an open back for a stage in the center of an audience, either that or I need a bunch of speakers pointing towards each section of the audience so that they can get what they paid for, instead of hearing the back of the speaker cabinets.
I think a demo would have been really helpful since you had both. I actually watched a lot of videos because I perceive my closed 1960 pretty bassy. The weird thing is, about half of the clips I thought the cab with back opened sounded more open, focused on high frequencies, while the back panel closed it sounded much bassier and punchier. I'm rather puzzled why this happens. In one video I thought it's about micing that loses all the bass when back panel was open but other video had bass frequencies well presented and that still happened. Some other videos on the other hand sounded like you described, tighter and punchier bass when back closed and open being softer.
Another reason they don't put reverb in the head is that the reverb chamber is usually pretty big and many brands put the reverb chamber or spring tank in the speaker box. Obviously there isn't one on a head so they just leave it off. Also the combo is usually considered more of an all-in-one solution for travel and small gigs and practice and beginners. So they try to include everything you might need. Whereas if you have the ability to carry a head and a cabinet you're probably doing a serious show and carrying a pedalboard and everything you need either with roadies or (annoyed) bandmates helping you carry it and you're probably going to use a nicer dedicated effects loop reverb if you want it.
Just got a closed back cab for my open back ycv50 and the blend sounds so sweet. The open back part has a creamback and the closed back part has a v30 so the difference in sound is pretty noticeable when played separately. Having one cab specifically designed to hit the lower frequency makes it sound more balanced than the usual pointiness of isolated guitar
Great video. Thanks for the info on the history of the open back vs closed back design. I just picked up a Fender Acoustasonic 40 and I have a feeling it is gonna sound much better to me ear when I pull off that back panel.
Thank you for this. I have an amp head I love and have been researching cabs. Now I know that for blues and jazz I should look for an open back, which cuts the list down a lot!
That was a really good explanation. I have been on the fence about closed verse open. I understand people like to hear things but since we all listen on computers and phones how helpful is it sometimes just the facts are good
Thanks, bro. I had no idea that a closed back cab was like that. For some reason, I thought that baffling an open back would INCREASE bass. Man, was I wrong.
1:14 they were not micing drum kits on stage till long after closed back cabs came about! #2 the closing of the back was for bass cabinets as the air cushion created prevents the speakers from bottoming out and destroying the voice coil. closing of the back in a Marshall moves the bass content up above 200hz into the thump frequency vs actual bass... what we like is that 200hz push of the 4-12
Excellent explanation! Thank you. And I think your comments on Mesa boogie, both in the video and in the comments below, show you are principled. First class stuff!
Good video! You surprised me, I thought closed back would have more low end but obviously I was wrong. One thing I'd be curious about would be the volume difference. Wouldn't a closed back cab be louder and more efficient? As long as you did an apples to apples comparison with the same speaker in each cab. Another thing is the size of the cab. Wouldn't a larger closed back cabinet have more low end than a smaller closed back? I've heard comparisons and the 4x12 closed back cab always has more thump than the 1x12 closed back. The ultimate test would be to build a custom cabinet the size of a 4x12, but mount only one 12 in the middle, no other porting or open speaker holes in the box. Wouldn't such a cabinet just have more low end resonance since it's bigger?
really depends on the resonant peak of the speaker, sometimes a lower frequency peak sounds better in a closed cab. otherwise it just moves and flubbs... i just switched my mesa black shadow from my combo for the celestion vintage 30 from my closed carvin 1x12. made both cabs better. mesa was too flubby with the BS, and the carvin with the v30 was too weak in the lowend. peak of the speakers were night and day.
With a celestion vintage 30 with a RF value of 75Hz with a closed back you actually get a bassier sound with guitar.. Why.. Because the tight closed back space will lift the RF value of the speaker some 35Hz to 110Hz,,, low E note fundamental is at 82.4Hz so that low 75Hz resonance is not that audible with standard guitar tuning.. Also the guitar speakers that have a large 50 oz magnet and a lightweight cone with a limited X-MAX and high sensitivity (100dB) will often have a Total Qts value around 0.5 making them not optimal for an open back cab as exibit cone cry at high volumes.. The closed back keeps these speakers in check.. more controlled and tight.. As eminence suggest,, go from 0.7 or above on the total Qts value when used in an open back cab.. 16 ohm version of the speakers tend to have a higher Qts value than the 8 ohm,, 16 ohm are often a little more tight and bright.. so go for a 16 ohm version if you are going for a british type speaker in an open back.. The eminence private jack 16 ohm has a RF value of 101Hz and a Qts value of 1.02.. Eventhough eminence coin this as a greenback clone to my knowledge It should be a lot tighter and bassier than a typical 25W celestion greenback in an open back situation..
Please do some research. The sound from the rear of a driver is out of phase with that from the front, and so below a certain frequency, relates to the cabinet dimensions, they cancel each other out. That's why open backed speakers have less bass, they roll off at a higher frequency. Closed back speakers have a bass peak related to the cabinet volume and fs of the driver. A well tuned ported closed back speaker rolls off lower, without the peak.
That was totally awesome info...you have a great delivery and personality...you dont offend or ise vulgar angry language like some other youtubers who do comps on different gear...Thanks a milhouse!...Peace!
another good way to open the closed back cab is to get screws that are 1 inch longer than original,and get 1/2 inch square 1 inch long spacers for the screws. and put the spacers between the cab and back panel,thus giving you about a 1/2 of free air all the way around the back cover, i did this to my 65 fender bandmaster cab, and it woke up the lower stuff pretty good. have you ever tried that?
This sounds like a great idea. I have 2 1x10 blackstar closed cabs. I think i'll try your idea on one of them and compare the results. If I do get around to trying this I'll post a video of the outcome.
You could enclose a combo just by simply buying some plywood from your DIY store and cutting it to fit the back of your combo. I never tried it but I might experiment with my solid state amp. Probably not advised on a tube amp due to the heat produced. Nice useful info though Phil as always
I watched a video were it showed studio recordings of this comparison and the results were the exact opposite of what you are saying...maybe I missed some details but I found it interesting.
I'm mostly a metal player but I prefer a partially open back for a 1x12! I can't stand that ultra focused one directional sound in such a small enclosure. Anything else (2x12 or 4x12) has to be closed back.
Had an old ampeg 412 cab that if you pushed in 1 speaker the other 3 would push out, super air tight. Looked terrible, ripped to shreds, but sounded awesome.
I have an open back Transatlantic 1x12 cab, It also has that plug in the speaker jack. It has nothing to do with keeping air in. The left jack is input and the right it output. The plug keeps you from accidentally plugging into the output. The output is to connect another cab.
I liked my Avatar traditional 212 closed back with Neo Creambadk's at first with my 25 watt Marshall jubilee. I tried the Marshal with a little speaker in my Fender Super Champ X2 and liked the sound. Especially clean. The Fender of course is an open box Combo. So I logically opened the back of my Avatar and so far like the sound much better. Probably because I mostly always used Combo's when learning (even playing metal). So my playing style seems to have evolved to using open back without me realizing. Now my Marshal sounds more like a Fender. More of a 3 dimensional richer sound.
My 1984 Marshall 4x12 (JCM800 LEAD-1960 - Celestion GT-12T 75W) have a 2"x 2" spruce rod in the middle to try to keep the back plate (particle board) from wobbling at high volumes, it`s not even fastened by a screw. The rest of the cabinet is 9-ply spruce...My opinion is that there is no science behind it only that it's durable when drunk and throwing the cab in the van...Not caving in the back and not damaging the speakers
Amazing eye opening info. Thank you so much for this, I was playing my mark iv from a mark 5 and I was trying to pinpoint the missing punch. I love my boogie but when I was drop tuning riffs I I noticed it had the highs but there was a missing low hit. I got it serviced, returned with 6l6 and 12ax6 and still there was a missing factor. Now I'm going to look plug it into a cab. Sence my amp is a combo it's open back, it feels like there is a leak in the bass presence in the chords. I know the quick fix is just to put the amp up against a wall and in a tight space, the only problem is the heat against the tubes. I know this is a newb comment and I don't mean come off stupid but I appreciate anyone's advice.
how does anyone have a mark 5 and not grasp amplifiers?> go to home depot/lowes and ask them to cut you a piece of plywood to the size you require,cover it with tolex and put it in.
A misnomer is something that is wrongly named not a falsely held idea. Closed back cabinets and speakers don't have to be as meticulously designed as speakers in an open or ported cabinet. I believe the ported back cabs are the best of both worlds. They let the speaker breathe and deepen the bass response with punch and the tone sounds good and at a distance. A 60 hz sound wave is over 15 feet high. I don't like closed back cabs because over distance they lose there punch as mids and high mids are still prominient. Closed backs only sound good relatively close up, imho.
Awesome explanation! Thanks...very hellpful. I have a Fender closed back cab..the Fender Super Champ 1x12 Guitar Speaker Cabinet . I was wondering if I could cut out the back and just then you said it was possible. I will pursue this...if you have any ideas how best to do it please let me know....thanks so much LOVE your channel...you have a wealth of knowledge that you just put out there and so grateful. :)
I have the same and it just booms sometimes, far too much muddy bass. I've tried a few different Celestions in it - Greenback 55 (nice but even more bassy, obviously!) Vintage 30, American, G12T 75, Jensen P12N... I'm more used to clearer, breathing, alive open backed combos and so I'm going to remove part of the closed back panel. Sad thing is, these Fender 1x12 cabs are accessed from the front, the back is totally sealed. Guess I'll be using a saw then...
You know of course that the speaker membrane moving back and forth is just volume, not spectrum. How fast the membrane moves determines the frequency content of the signal, not the volume. How far the membrane travels back and forth determines the amplitude i.e. the volume of the signal, not its frequency. Restricting the distance the speaker can travel is not frequency dependent. Of course, then the factor of air compression comes back into the game, meaning more pressure behind the speaker will make the transition from moving to not-moving quicker, which could very much influence the spectral (=frequency) content of the signal, like recovering faster and with less "wobbles" from slow and far (=loud and deep) movement. But the fact remains, just letting the speaker travel less has nothing to do with frequency, only volume.
Very informative, but what I'd really like to know is, what's on the other side of that Mesa 1x12 closed back input jack? Do they simply wire it directly from the jack to the speaker? Or is there any other kind of special mojo going on like a cap/resistor combo?
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Hey Phillip.... actually, with an open back cab you get what is called phase cancellation where the front sound wave can intermingle with the back sound wave which actually cancels some of the bass response so a sealed cab will actually have more bass. You were right about transient response however being tighter in a sealed box and looser in a open back. Cheers buddy!
How do I know?.... I built custom bass enclosures professionally for 20 years using computer programs and went well beyond mere sealed boxes as in ported or vented as well as 4th order through 8th order bandpass enclosures. The response can be measured with a spectrum analyzer... try it.. you’ll have fun!
😁🤟🏻
Good explaination, but a sound check would be nice.
That comment was constructive enough to get me to stop the video right now
Phil does it again…👍 cheers from Down Under 🇦🇺
Makes sense.
It’s also inline with why I prefer open back for slow heavy music (Drone/Doom and clean) and closed back for fast heavy music (black metal, etc).
Since i play mainly rock, blues, and jazz I coverted my small 12 to 15 inch amplifiers cabinets into halfbacks. the overall improved sound is warmer, has better projected mids without losing bass clearing up the treble. I also use a closed back active subwoofer that i keep on a class c power amp that uses a flipswitch.
Also, with closed back you don't need to worry about your cat getting electrocuted!!!!
Hugh Cameron 😂😂😂😂
Hugh Cameron ; Important safety tip!
Electrocuted with ?
Nothing is going to get electrocuted in a speaker cab but cats do other things in boxes that you may not like. :)
Lol brings Back a memory, when i was 9 we found dead Birds from my dads cabinet... Wonder who put them there 🐈
Wow, this video was SUPER educational. I'd love more. I've been playing guitar for 20 years but there's so much more I could learn.
Great video and explanation. Never knew when I rented a Mesa Boogie cab one time why it came with those jack plugs in the back.. Had I known they were actually important, I would have left them in! The wonder of guitar is that no longer how long I play the thing, there still remain mysteries like this to be revealed. Thanks for the awesome insights about differences between open vs closed back cabs.
That was an interesting explanation. What he was getting at with the sealed cabinet is that air can be compressed. It kind of "springy" in that regard. So as a speaker moves, it compresses the air (which acts as a resistance to the movement of the speaker cone.) As the springy air is compressed and the paper cone presses against it, the travel distance of the speaker is limited by the resistance of the air. So, the cone can't over extend itself in terms of travel. It's being restricted by the air. This resistance from the air keeps the movement of the speaker cone from being "flabby" to some degree. You get a tight sound this way, because of a sealed cabinet. This keeps the frequency response of the speaker box flatter, too. Now, porting changes the whole thing because you can TUNE a cabinet with a port, to make a bump in the bass freqencies with it. He talked about bass reduction with a sealed cabinet, but he didn't talk about accentuating the bass with a port. The length and diameter of the port relate to which frequency, in the bass, will be accentuated. What happens with a port, is as the speaker moves in a backward motion, the air in the port is pushed out of the cabinet. Conversely, when the speaker cone moves forward, air is sucked into the cabinet through the port. So, you get this in and out movement of air in the port. As the speaker moves back and forth, it takes time for the air to move in and out of the port. If the right frequency is hit, the air comming in from the port will be in the opposite direction as the speaker movement. It will also be in the opposite direction of the speaker when the air is leaving the port. This happens at the resonant frequency. So, when the resonant frequency is hit the movement of the speaker stops, and the bass sound comes out of the port. The air comming in and out of the port is in the exact opposite direction as the speaker want so move, but the speaker can't move because it is being held in place by the air moving in and out of the port. The bass sound, at this particular frequency is comming out of the port. There you have why he didn't mention ports, because they DO accuentuate the bass. Now, as far as the open back goes, the speaker itself has not nearly the air resistance that a closed back cabinet would have, so the speaker itself has to self regulate it's own movement. The springiness of the speaker cone is built in by the speaker designer. Some of them have a very tight, controlled movement (stiff cone, etc.) Some of them are looser and more flabby. If a speaker is loose and flabby, you get ringing as the speaker's back and forth motion subsides. When designing cabinets, the designer takes into consideration how well a speaker will stop it's motion. There is my two cents on this issue. I'm going by my memory, and my experiences with building my P.A. boxes (which is great fun, when they work well.)
great explanation of open vs closed back cabs... my only suggestion is to make it 10 on Friday... two times better IMHO.
Wendell Laffin Maybe 7 on Friday could be the meet in the middle.
yes sir
@@PhillipMcKnight little did you know the 5 on Friday would become the 120 on Friday
I learn several new things with every video you upload.
I'm seriously getting really into your channel. You answer almost everything I need an answer too and explain why that is so. Thanks dude! Learning loads from you
Greetings from Portugal
Actually a sealed cabinet (called acoustic suspension) allows the driver to travel more accurately giving a tighter and deeper bass. Because of the resistance (vacuum) it is slightly less dynamic though.
I have read that too. I will go with Phils assessment until i get a closed back for comparison.
Thank you phill you always get to the point and make what you are saying simple to understand without being condescending. Wish I could have visited your store but I’ll tune in Fridays for the live show.
very well explained, I learned a bit about air flow of the woofer
As I pondered the information presented in this video, I'd have question the accuracy of it. If you've ever designed speakerboxes, you know that when you put a raw speaker in a cabinet, you automatically get more bass. Try taking a raw speaker (with no enclosure) and running sound through it, to understand what I'm saying here. You'll find that with no cabinet, it will be very thin sounding. If you put a back on a cabinet you'll probably increase the bass response. If you port that closed back cabinet, you'll increase the bass even further. An open back would actually decrease the bass, I suspect. Now all of this having been said, the characteristics of the raw speaker play into this too. So, some tonal responses can be build right into the driver.
The air in a sealed cab will stiffen the springiness of a cone, as you say. However, the effect is an increase in bass response at ~50-150Hz. That is both measured and noticed by most players. There are other factors mentioned that shouldn’t be confused: The effect of diffuse sound from the rear of an open cab (in-room fullness) and the effect of a larger baffle (a lower shelf freq…more mid-bass.)
The Thiele-Small measurements and parameters of the driver determines its performance in an open back or closed back cab. A driver cannot make 'more' bass on an open back. The cancellations of the back and front wave within the space and at the edges of the baffle, plus the steep slope, will give the impression of louder ranges within the bass frequencies. One of the reasons some like 8" in 10-12" cabs for a 'fuller' sound. A phenomena noticeable if one walks alongside an open back. It is quieter on the sides where the cancellations are happening.
A sealed cab, depending on the q of the driver and size of the box will extend bass further at a gentler slope but at the expense of box size. The front and backwaves do not meet.
Comparing drivers open and closed back is not apples to apples if the driver design is geared towards one way. Drivers sometimes have q that can be used either sealed or bass reflex, then one can choose (bass players that need 40hz).
Drivers for open designs rarely perform as well in sealed boxes, not in sizes considered practical for guitar use...
Thank you ! I was wondering about that for the longest time and this was the best explanation I found, short, to the point and complete. Thanks Phillip !
changes the attack of the bass response. Closed is tighter for bass and open will do the opposite. Great short explanation.tanks
Good video.
(1) As an experienced woodworker…
Baltic Birch (or Russian) plywood is typically much more uniform than conventional plywood in that it is typically free of voids that can affect both strength and rigidity. And unlike conventional plywood, Baltic Birch plywood will accept router-applied contours at the edges and can be successfully machine dovetailed. The only advantage/upgrade in marine-grade BB plywood is the type of waterproof glue used in the sheets of lamination, hence marine (boat) grade. Other than having a nice marketing ring, there would be no advantage in using marine-grade BB plywood in an acoustic enclosure application whose use will be above the water line.
(2) Also having a background in high end audio gear…
For some additional basic information, look into at the fundamental differences between bass-reflex and acoustic-suspension speaker enclosures.
That's contrary to what every amp/cab developer has ever claimed about the application of BB in denser, heavier plywood vs lighter vs particle board. According to all, BB's response to lower bass reqs is to amplify and focus them, while lighter materials attenuate them into what they describe as "farty". James Brown and Dave Friedman noted this in their Tone Talk interview just after the one hour mark. It's apparently a function of the stiffness of the cold weather versions of birch along with that added by glue between more layers. Their words.
There is something you can do to an open speaker. It is not the same as closing the cabinet but you can tune the sound. You can cover the spaces in the speaker frame. A stiff product will be used such as cardboard held in place with foil tape. You'll probably have to cover 2/3's of the space to really hear a big difference. Try it. You can glue a damping material over the sealed plug to absorb high frequency. Of course changing speakers or cabinets is best but if you can make this work saves a lot of $.
Thanks. I've been wondering about the science behind open and closed cabinets for the longest time.
Thank You Brother Phil, For Providing This Space For All The Kind Souls United Here Around Loves Tools, The Electric Guitar And Amps! They Are The Answer To The Dark Elves! I Live 2Hours From Orlando,A City I've Been To Countless Times With Friends And Family,A City I Love . I Do Not Despair For There Are More Good Kindhearted People Than The Haters. The New Being Reaches For Their Guitar,Not The Gun. So Bless Us All TOGETHER Here Each And Every One. Long May We All Run, Thank You Phil & Everyone. 6/15/16
what
Just what I was looking for, great and easy explaination. Good job.
Sorry man I thought I was already subscribed to your channel. But huge thumbs up man, very simple and comprehensive explanation of what and why.
Thank you Phillip. It's important to have the basics covered before moving on, good job!
nice explanation! I'm using a valve head into a 2x12 bass cabinet (closed back) for down tuned doom metal. it's a pretty sweet sound. For blues I have an open back 1x12 cab that definitely sounds more open
The real reason for ported v closed is , a closed cabinet gives you more even frequency response across the range more volume and a tighter attack, a ported cab will give you an amazing sound at a tuned frequency say mid range but only that frequency so it may be tuned to appear to have a better sounds at a given frequency, ported cabs will sound boomier and loose half the power of the speaker because of the porting so porting is a trade off and the porting has to be tuned correctly .
I get some of the advantages & disadvantages of each, but I'll argue the bass theory is more on an open back. Here's the rub with your theory ? The speaker being a woofer produces whatever bass it's going to produce. After that, it's a matter of confining those sound waves. The open back releases sound out the back like you said it does. The closed back confines & restricts those vibrations & sounds and allows them to marinate inside the enclosure. There's really nowhere for that to go but forward thru the front of the speaker. That trapped bass is accumulated and the rumble is enhanced. With an open back, you better have enough amp to fill the room with ambient sound, strategically finding a wall or a corner might help an open back with a deeper rumble, but it's gonna like louder volume levels to fill the room. At a live outdoor concert, the audience is in front and around the front of the stage. It makes no sense to allow volume out the back, there are no walls to capture the sound and the closed back being directional makes more sense for efficiency. An open back is going to be a manageable room size with enough power for the amp to fill the room. Too little amp and the open back is simply going to be overwhelmed by the room. With an open back, you're going to need a bigger woofer for bass an 8 inch in a closed back is so much heavier sounding than the same 8 inch woofer in an open back. Hey, I tried it with the open back combo 8 inch woofer I have. Simply putting a 3/4 inch mdf board against the back of the open area. Granted it wasn't fully air tight sealed, but giving the amp that much wood to block the sound made a huge difference in bass output. I still had some room filling ambient surround sound that still wasn't as heavy as a closed back 8 inch combo amp I have. At a certain point with that open back cab, the bass knob was a worthless turn to try to get a deeper rumble out of it. I bet the open back sounds different in a deeper bass way in a smaller bedroom than it does the living room with a vaulted ceiling. Bet it sounds deeper in the bathroom too. Not only are the acoustics different for each room, the amp probably has a better chance of filling the room with ambient sound. Back to live music though, I'm probably going to want an open back for a stage in the center of an audience, either that or I need a bunch of speakers pointing towards each section of the audience so that they can get what they paid for, instead of hearing the back of the speaker cabinets.
I think a demo would have been really helpful since you had both. I actually watched a lot of videos because I perceive my closed 1960 pretty bassy. The weird thing is, about half of the clips I thought the cab with back opened sounded more open, focused on high frequencies, while the back panel closed it sounded much bassier and punchier. I'm rather puzzled why this happens. In one video I thought it's about micing that loses all the bass when back panel was open but other video had bass frequencies well presented and that still happened. Some other videos on the other hand sounded like you described, tighter and punchier bass when back closed and open being softer.
Geez, I damn near forgot to "like" this vid. Pretty informative.
Very enjoyable and informative. I typically use my Mesa Combo sitting on top of my Mesa Ext cab and I get a sound that appeals very much to me.
Another reason they don't put reverb in the head is that the reverb chamber is usually pretty big and many brands put the reverb chamber or spring tank in the speaker box. Obviously there isn't one on a head so they just leave it off.
Also the combo is usually considered more of an all-in-one solution for travel and small gigs and practice and beginners. So they try to include everything you might need. Whereas if you have the ability to carry a head and a cabinet you're probably doing a serious show and carrying a pedalboard and everything you need either with roadies or (annoyed) bandmates helping you carry it and you're probably going to use a nicer dedicated effects loop reverb if you want it.
Just got a closed back cab for my open back ycv50 and the blend sounds so sweet. The open back part has a creamback and the closed back part has a v30 so the difference in sound is pretty noticeable when played separately. Having one cab specifically designed to hit the lower frequency makes it sound more balanced than the usual pointiness of isolated guitar
Nice to see another Traynor fan ! I have the same amp as you ;-)
As always it was nicely outlined and explained simply for easy consumption. Thanks Phil!
Great video. Thanks for the info on the history of the open back vs closed back design. I just picked up a Fender Acoustasonic 40 and I have a feeling it is gonna sound much better to me ear when I pull off that back panel.
Thank you for this. I have an amp head I love and have been researching cabs. Now I know that for blues and jazz I should look for an open back, which cuts the list down a lot!
Excellent video on closed vs open cabs.
thanks
Always wondered about that. Mystery solved (2 in one days with your Ohms vid). Keep them coming please.
Excellent video and the most concise explanation I’ve heard to date. Thanks for posting.
Another incredible video by +Phillip McKnight !!!
Nice vid! Another reason you dont have reverb in heads (spring reverb) is because the transformers reek havoc on the springs.
That was a really good explanation. I have been on the fence about closed verse open. I understand people like to hear things but since we all listen on computers and phones how helpful is it sometimes just the facts are good
Hey could you do a 4x12 vs 2x12 cab video?
No bullshit, just The stuff i wanted to know.
Thank you!
Thanks, bro. I had no idea that a closed back cab was like that. For some reason, I thought that baffling an open back would INCREASE bass. Man, was I wrong.
1:14 they were not micing drum kits on stage till long after closed back cabs came about! #2 the closing of the back was for bass cabinets as the air cushion created prevents the speakers from bottoming out and destroying the voice coil. closing of the back in a Marshall moves the bass content up above 200hz into the thump frequency vs actual bass... what we like is that 200hz push of the 4-12
+patfurlan True, don't cut up a closed-back cabinet, because the speakers may not be able to handle the extra air motion!
Excellent explanation! Thank you. And I think your comments on Mesa boogie, both in the video and in the comments below, show you are principled. First class stuff!
Good video! You surprised me, I thought closed back would have more low end but obviously I was wrong. One thing I'd be curious about would be the volume difference. Wouldn't a closed back cab be louder and more efficient? As long as you did an apples to apples comparison with the same speaker in each cab. Another thing is the size of the cab. Wouldn't a larger closed back cabinet have more low end than a smaller closed back? I've heard comparisons and the 4x12 closed back cab always has more thump than the 1x12 closed back. The ultimate test would be to build a custom cabinet the size of a 4x12, but mount only one 12 in the middle, no other porting or open speaker holes in the box. Wouldn't such a cabinet just have more low end resonance since it's bigger?
I've tried all kinds of combinations. All had varying results.
Excellent explanation!
A fine explanation!
really depends on the resonant peak of the speaker, sometimes a lower frequency peak sounds better in a closed cab. otherwise it just moves and flubbs... i just switched my mesa black shadow from my combo for the celestion vintage 30 from my closed carvin 1x12. made both cabs better. mesa was too flubby with the BS, and the carvin with the v30 was too weak in the lowend. peak of the speakers were night and day.
With a celestion vintage 30 with a RF value of 75Hz with a closed back you actually get a bassier sound with guitar.. Why.. Because the tight closed back space will lift the RF value of the speaker some 35Hz to 110Hz,,, low E note fundamental is at 82.4Hz so that low 75Hz resonance is not that audible with standard guitar tuning.. Also the guitar speakers that have a large 50 oz magnet and a lightweight cone with a limited X-MAX and high sensitivity (100dB) will often have a Total Qts value around 0.5 making them not optimal for an open back cab as exibit cone cry at high volumes.. The closed back keeps these speakers in check.. more controlled and tight..
As eminence suggest,, go from 0.7 or above on the total Qts value when used in an open back cab..
16 ohm version of the speakers tend to have a higher Qts value than the 8 ohm,, 16 ohm are often a little more tight and bright.. so go for a 16 ohm version if you are going for a british type speaker in an open back..
The eminence private jack 16 ohm has a RF value of 101Hz and a Qts value of 1.02.. Eventhough eminence coin this as a greenback clone to my knowledge It should be a lot tighter and bassier than a typical 25W celestion greenback in an open back situation..
excellent comment
Please do some research. The sound from the rear of a driver is out of phase with that from the front, and so below a certain frequency, relates to the cabinet dimensions, they cancel each other out. That's why open backed speakers have less bass, they roll off at a higher frequency. Closed back speakers have a bass peak related to the cabinet volume and fs of the driver. A well tuned ported closed back speaker rolls off lower, without the peak.
Clear explanation, thank you from Spain
That was totally awesome info...you have a great delivery and personality...you dont offend or ise vulgar angry language like some other youtubers who do comps on different gear...Thanks a milhouse!...Peace!
another good way to open the closed back cab is to get screws that are 1 inch longer than original,and get 1/2 inch square 1 inch long spacers for the screws. and put the spacers between the cab and back panel,thus giving you about a 1/2 of free air all the way around the back cover, i did this to my 65 fender bandmaster cab, and it woke up the lower stuff pretty good. have you ever tried that?
Great info thank you for posting
no prob,wish i had more.
This sounds like a great idea. I have 2 1x10 blackstar closed cabs. I think i'll try your idea on one of them and compare the results. If I do get around to trying this I'll post a video of the outcome.
You could enclose a combo just by simply buying some plywood from your DIY store and cutting it to fit the back of your combo. I never tried it but I might experiment with my solid state amp. Probably not advised on a tube amp due to the heat produced. Nice useful info though Phil as always
all i know is pulling the back panel off my MG15DFX made it sound a lot better. you should do a demo comparing the two.
throwing it out makes it sound even better,try it(your wife will love it)
you could always get an open back and screw a wood pannel to it that covers the opening better than cutting the closed back
Great video, clear explanation! 👌 Thanks Philip!
I watched a video were it showed studio recordings of this comparison and the results were the exact opposite of what you are saying...maybe I missed some details but I found it interesting.
You can cover the back of your open back by setting it against the wall or strapping on a piece of plywood etc. Play around with it
Today I learned something. Thank you!
Open back adds space in a small room, but it wastes the bass energy. The front and back waves diffract and cancel each other out.
KanyeTroll no they dont
I'm mostly a metal player but I prefer a partially open back for a 1x12! I can't stand that ultra focused one directional sound in such a small enclosure. Anything else (2x12 or 4x12) has to be closed back.
spot on
So if you are wanting that closed back sound, but have an open back amp/cab, would it be a good idea to convert your amp/cab to a closed back?
Outstanding lesson. THank you so much
Hteat in theory, but there's frequency responses for cabinets and closed backs are slightly flatter below 200
Very useful clear explanation. Thank you. I've subscribed for more.
This answered so many of my questions
Had an old ampeg 412 cab that if you pushed in 1 speaker the other 3 would push out, super air tight. Looked terrible, ripped to shreds, but sounded awesome.
I have an open back Transatlantic 1x12 cab, It also has that plug in the speaker jack. It has nothing to do with keeping air in. The left jack is input and the right it output. The plug keeps you from accidentally plugging into the output. The output is to connect another cab.
Very helpful video! Thanks!
Thanks, very helpful, getting ready to build a speaker for the boy and this helps.
Thanks Phil,
Great stuff !
Thats why i have a Mesa/Boogie halfback 4x12 cab.....best of both worlds.😉
That was helpful! I knew part of that, but that was a more complete picture, thanks!
Excellent video
Excellent 👍🏼
I liked my Avatar traditional 212 closed back with Neo Creambadk's at first with my 25 watt Marshall jubilee. I tried the Marshal with a little speaker in my Fender Super Champ X2 and liked the sound. Especially clean. The Fender of course is an open box Combo. So I logically opened the back of my Avatar and so far like the sound much better. Probably because I mostly always used Combo's when learning (even playing metal). So my playing style seems to have evolved to using open back without me realizing. Now my Marshal sounds more like a Fender. More of a 3 dimensional richer sound.
We may ask Page, Gilmour, Iomy, Angus which that one's do prefer to
this was super informative and helpful. thank you!
Thank you Phillip. Great explanation.
My 1984 Marshall 4x12 (JCM800 LEAD-1960 - Celestion GT-12T 75W) have a 2"x 2" spruce rod in the middle to try to keep the back plate (particle board) from wobbling at high volumes, it`s not even fastened by a screw. The rest of the cabinet is 9-ply spruce...My opinion is that there is no science behind it only that it's durable when drunk and throwing the cab in the van...Not caving in the back and not damaging the speakers
Excellent video! Thanks!
Amazing eye opening info. Thank you so much for this, I was playing my mark iv from a mark 5 and I was trying to pinpoint the missing punch. I love my boogie but when I was drop tuning riffs I I noticed it had the highs but there was a missing low hit. I got it serviced, returned with 6l6 and 12ax6 and still there was a missing factor. Now I'm going to look plug it into a cab. Sence my amp is a combo it's open back, it feels like there is a leak in the bass presence in the chords. I know the quick fix is just to put the amp up against a wall and in a tight space, the only problem is the heat against the tubes.
I know this is a newb comment and I don't mean come off stupid but I appreciate anyone's advice.
how does anyone have a mark 5 and not grasp amplifiers?> go to home depot/lowes and ask them to cut you a piece of plywood to the size you require,cover it with tolex and put it in.
air pressure moves sound differently and crunches better in a closed box
Great info!
thanks for that. Finally a straight answer to the question! One less thing to fuel my Insomnia =) Cheers
"One less thing to fuel my Insomnia" LOL
thumbs up for 5 on friday keep it going
A misnomer is something that is wrongly named not a falsely held idea. Closed back cabinets and speakers don't have to be as meticulously designed as speakers in an open or ported cabinet. I believe the ported back cabs are the best of both worlds. They let the speaker breathe and deepen the bass response with punch and the tone sounds good and at a distance. A 60 hz sound wave is over 15 feet high. I don't like closed back cabs because over distance they lose there punch as mids and high mids are still prominient. Closed backs only sound good relatively close up, imho.
I bought a MESA oversize 3/4 back with a V30 sounds awesome!!!
Thanks for the video I have always wondered about this subject... I think I will go open back
Awesome explanation! Thanks...very hellpful. I have a Fender closed back cab..the Fender Super Champ 1x12 Guitar Speaker Cabinet
. I was wondering if I could cut out the back and just then you said it was possible. I will pursue this...if you have any ideas how best to do it please let me know....thanks so much LOVE your channel...you have a wealth of knowledge that you just put out there and so grateful. :)
I have the same and it just booms sometimes, far too much muddy bass. I've tried a few different Celestions in it - Greenback 55 (nice but even more bassy, obviously!) Vintage 30, American, G12T 75, Jensen P12N... I'm more used to clearer, breathing, alive open backed combos and so I'm going to remove part of the closed back panel. Sad thing is, these Fender 1x12 cabs are accessed from the front, the back is totally sealed. Guess I'll be using a saw then...
Great Video. Very informative
You know of course that the speaker membrane moving back and forth is just volume, not spectrum. How fast the membrane moves determines the frequency content of the signal, not the volume. How far the membrane travels back and forth determines the amplitude i.e. the volume of the signal, not its frequency. Restricting the distance the speaker can travel is not frequency dependent. Of course, then the factor of air compression comes back into the game, meaning more pressure behind the speaker will make the transition from moving to not-moving quicker, which could very much influence the spectral (=frequency) content of the signal, like recovering faster and with less "wobbles" from slow and far (=loud and deep) movement. But the fact remains, just letting the speaker travel less has nothing to do with frequency, only volume.
Very informative, but what I'd really like to know is, what's on the other side of that Mesa 1x12 closed back input jack? Do they simply wire it directly from the jack to the speaker? Or is there any other kind of special mojo going on like a cap/resistor combo?