I clearly stated AFTER commenting on your post, "Apropos some earlier posts..."
While your post stated an error of no small proportion, it was not what I was concerned about or what I was directing readers towards. As I stated. And I hope my obviously joking suggestion (that might work as soon as "when pigs can fly") was meant tongue in cheek.
Sorry to have caused you irritation. But the alternative - pointing out specific posts that seemed far-fetched - would be inappropriate. So I used more generic language, hoping that by saying "earlier posts" it would be clear I did not mean you.
BTW, even if you had a dozen drivers with a Fs of 50 Hz, they will never go as low as one driver similarly "suspended" with an Fs lower. If you are relating your experience, then you have an obligation to try to explain why your setting produces results at variance with what I believe is acoustic theory. If you can do so, we'll all appreciate learning some new technique. (I am not saying the lowest note you'll even hear from any driver is Fs... just that boxes are made to coordinate with Fs.)
Ben
No problem now that you have clarified. I have to agree with Weltersys that you can get output below fs easily. Either higher Qts drivers or long ducts on a slot loaded band pass. Here is a 3.5in driver that has clean, albeit lower level SPL down to 55Hz with an fs of 120Hz in a DCR. More info here:
http://www.diyaudio.com/forums/full-range/252627-viva-la-vifa-curvy-cabinet-dcr-tc9fd.html

Your remark is quite offensive. My comment is indeed from experience and I suppose pigs can fly then - with an actual build based on model and I have measurements. If you are good with an fs of say 50Hz that a 5in driver has, and it has the Qts Bl and Mms combination suited for your alignment then four of these 5in drivers can work well like a 12in driver. Here is the measurement of such a FLH speaker:
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This measurment was made for the purpose of demonstrating a passive line level XO (low pass 2nd order) to achieve a low cost filter for a sub in another thread.
Hahaha... OWNED.
Xrk971's post reminded me of another recent example of usable output well below Fs, though not a sub, in post #6, using a bass reflex port you can see usable output extended to 110 Hz (which also doubles as a handle), octaves below the speakers Fs :Hahaha... OWNED.
http://www.diyaudio.com/forums/multi-way/236037-dirty-dozen-line-array.html
At any rate, Ben is still learning, a good thing to do at (or in) any age 🙂.
Art
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I think if you look at what I actually wrote, I did not say there is no sound below Fs and I did not say all enclosures are equal. What I did say is, "I am not saying the lowest note you'll even hear from any driver is Fs... just that boxes are made to coordinate with Fs."
Pending an opportunity to examine the inventions referenced, to visit the locations where unusual acoustic behaviour has been observed, or to learn that the laws of physics have been repealed, I'll stick with what I said.
And on a serious note, some boxes do a better job of making output below Fs than others. Bass reflex and tuned pipe boxes do a worser job. Horns can do a better job.
I suppose you could design a box with a Helmholtz resonance that pipes-in below the system resonance and so makes a loud one-note sound below Fs when slightly instigated by the driver's motion. In that case, somebody could truthfully post, "But my speaker plays loud below Fs."
But back to the thread, as far as I know, a big one shouldn't be much different than a few smaller ones, other things equal. I say that as somebody who takes radiation resistance seriously (horns??, ESLs??, many years of motional feedback experiments).
But there are various mechanical considerations for choosing one over the other. I once made wonderful sub from 9 8-inch drivers, mounted frontwards and backwards. Or matters of dispersion - which mean little at bass frequencies.
Or for room acoustics, being able to locate drivers at good places around your room - which can be very beneficial.
Ben
Pending an opportunity to examine the inventions referenced, to visit the locations where unusual acoustic behaviour has been observed, or to learn that the laws of physics have been repealed, I'll stick with what I said.
And on a serious note, some boxes do a better job of making output below Fs than others. Bass reflex and tuned pipe boxes do a worser job. Horns can do a better job.
I suppose you could design a box with a Helmholtz resonance that pipes-in below the system resonance and so makes a loud one-note sound below Fs when slightly instigated by the driver's motion. In that case, somebody could truthfully post, "But my speaker plays loud below Fs."
But back to the thread, as far as I know, a big one shouldn't be much different than a few smaller ones, other things equal. I say that as somebody who takes radiation resistance seriously (horns??, ESLs??, many years of motional feedback experiments).
But there are various mechanical considerations for choosing one over the other. I once made wonderful sub from 9 8-inch drivers, mounted frontwards and backwards. Or matters of dispersion - which mean little at bass frequencies.
Or for room acoustics, being able to locate drivers at good places around your room - which can be very beneficial.
Ben
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BTW, even if you had a dozen drivers with a Fs of 50 Hz, they will never go as low as one driver similarly "suspended" with an Fs lower.
Ben
Pending an opportunity to examine the inventions referenced, to visit the locations where unusual acoustic behaviour has been observed, or to learn that the laws of physics have been repealed, I'll stick with what I said.
...
I suppose you could design a box with a Helmholtz resonance that pipes-in below the system resonance and so makes a loud one-note sound below Fs when slightly instigated by the driver's motion. In that case, somebody could truthfully post, "But my speaker plays loud below Fs."
There are plenty of ways to load a driver so that the system response goes far below Fs. Tapped horns often function this way.
With the Tapped horn, one has no rear volume so to get the lowest low corner, one needs the driver’s Fs to be somewhat above the low cutoff. For example, it wouldn’t be unusual to have an Fs of 45 or 50Hz with a low corner of 30Hz.
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I just want to offer that bentoronto has been quite civil in this discussion, which does feature more than a token amount of conjecture and hypothesizing. Yes, it is possible to operate a tiny (high Fs) driver below Fs, and it is possible to EQ it to force it to have equivalent amplitude to fewer drivers that are optimized for LF reproduction, but his point was perhaps it is unwise.
There's a lot of talk about proving him wrong and showing him examples (seemingly counterfactual to his claims) - which are not particularly representative.
The Bag End subwoofer that uses a tiny sealed box with a high Fb forcing a very linear 2nd order rolloff then countered by a glorified 2nd order LP at the cutoff frequency is indeed a good example of an approach that has OBVIOUS PROBLEMS.
You are taking what could be a very efficient LF system, and trading off LF efficiency for better performance in the time domain. This is a compromise. Engineering is a compromise.
It is indeed possible for a person off the street to knock out Mike Tyson, but it is unlikely. It is indeed possible to get adequate LF performance out of drivers optimized for something else - but it is unlikely, and requires gimmicks that have DIFFERENT COMPROMISES. Tapped horns have terrible performance in the time/phase domain.
The issue he was trying to gently point out, which was seemingly refuted over and over again, is that GENERALLY most SMALL drivers have a higher Fs than larger (more massive) drivers, and are therefore LESS OPTIMIZED for LF reproduction.
If you have smallish (8" is probably the minimum) drivers that are indeed optimized for LF - ie: are subwoofers and not woofers - than you have a tit-for-tat comparison.
Otherwise, you're arguing the merits of using woofers as subwoofers, and that's probably a bad idea, AS HE REASONABLY SUGGESTED. Just because something's possible doesn't mean it's a good idea. Someone can dig up 8" drivers with low Fs and high Xmax, and hopefully low Le indicative of a decent motor. Alpine Type-R car audio subwoofers are decent in this regard. Then at least we'd be debating using small subwoofers instead of large subwoofers. Distortion is usually proportional to excursion, and so another debate point is that Sd matters more than Vd. I would personally imagine that's a big component in why different LF systems with similar Vd would sound different. (A Ferrari driven at 80 on the freeway is more stable than a minivan at 80.)
I don't like seeing someone deliver years of experience in a straightforward manner be jumped on because someone is nitpicking their word choice.
-Tal
ps: someone bring up how LF reproduction is mostly minimum phase and so EQ will pretty much fix it anyway...
There's a lot of talk about proving him wrong and showing him examples (seemingly counterfactual to his claims) - which are not particularly representative.
The Bag End subwoofer that uses a tiny sealed box with a high Fb forcing a very linear 2nd order rolloff then countered by a glorified 2nd order LP at the cutoff frequency is indeed a good example of an approach that has OBVIOUS PROBLEMS.
You are taking what could be a very efficient LF system, and trading off LF efficiency for better performance in the time domain. This is a compromise. Engineering is a compromise.
It is indeed possible for a person off the street to knock out Mike Tyson, but it is unlikely. It is indeed possible to get adequate LF performance out of drivers optimized for something else - but it is unlikely, and requires gimmicks that have DIFFERENT COMPROMISES. Tapped horns have terrible performance in the time/phase domain.
The issue he was trying to gently point out, which was seemingly refuted over and over again, is that GENERALLY most SMALL drivers have a higher Fs than larger (more massive) drivers, and are therefore LESS OPTIMIZED for LF reproduction.
If you have smallish (8" is probably the minimum) drivers that are indeed optimized for LF - ie: are subwoofers and not woofers - than you have a tit-for-tat comparison.
Otherwise, you're arguing the merits of using woofers as subwoofers, and that's probably a bad idea, AS HE REASONABLY SUGGESTED. Just because something's possible doesn't mean it's a good idea. Someone can dig up 8" drivers with low Fs and high Xmax, and hopefully low Le indicative of a decent motor. Alpine Type-R car audio subwoofers are decent in this regard. Then at least we'd be debating using small subwoofers instead of large subwoofers. Distortion is usually proportional to excursion, and so another debate point is that Sd matters more than Vd. I would personally imagine that's a big component in why different LF systems with similar Vd would sound different. (A Ferrari driven at 80 on the freeway is more stable than a minivan at 80.)
I don't like seeing someone deliver years of experience in a straightforward manner be jumped on because someone is nitpicking their word choice.
-Tal
ps: someone bring up how LF reproduction is mostly minimum phase and so EQ will pretty much fix it anyway...
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Many, many thanks... and also for your wonderful phrase, "feature more than a token amount of conjecture and hypothesizing". Wish I had said that.
More to the thread, when resonances and wave-contortion are used to gussy up the bottom-most end, you are achieving "different compromises", in the very civil words of taloyd. But I would emphasize what taloyd says with admirable technical restraint: these are compromises that result in poor sound, as audiophiles reckon it. Except for extending bass lower with motional feedback.
Subwoofing is a big topic. If you've spent much time watching your music on a real-time spectrum analyzer, you'd wonder why anybody would bother trying to get bass below 40 Hz since there is practically no music down there (and your brain fills in what the speaker doesn't play anyway)*. Maybe trying to get great sound just down to 40-45 Hz is the compromise that makes the most sense.
Ben
*wife and I heard Saint-Saens' Organ Symphony in a large church with a large organ (hundred year old Casavant Freres) and a very enthusiastic orchestra two weeks ago. The crowd cheered so much at the end that they played the whole last movement again as an encore. What a treat.
More to the thread, when resonances and wave-contortion are used to gussy up the bottom-most end, you are achieving "different compromises", in the very civil words of taloyd. But I would emphasize what taloyd says with admirable technical restraint: these are compromises that result in poor sound, as audiophiles reckon it. Except for extending bass lower with motional feedback.
Subwoofing is a big topic. If you've spent much time watching your music on a real-time spectrum analyzer, you'd wonder why anybody would bother trying to get bass below 40 Hz since there is practically no music down there (and your brain fills in what the speaker doesn't play anyway)*. Maybe trying to get great sound just down to 40-45 Hz is the compromise that makes the most sense.
Ben
*wife and I heard Saint-Saens' Organ Symphony in a large church with a large organ (hundred year old Casavant Freres) and a very enthusiastic orchestra two weeks ago. The crowd cheered so much at the end that they played the whole last movement again as an encore. What a treat.
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I watched the Jim Marshall amplifier documentary a couple of nights ago.
They developed the 4*12" cabinet to go with their 50W amplifier.
Then they came out with a stacked array for the "new" 100W amplifier.
The stacked array is two 4*12" cabinets stacked vertically.
The "array" is two wide by four high.
That will go loud and it will "project" a bit more energy forward compared to single 4*12" cabinet.
each 12" driver was seeing just 12.5W
Each 4*12" cabinet would perform very similarly to a 24" driver in a cabinet, except that the 4*12" is slightly wider and taller and thus projects a little bit more forward at the lowest frequencies.
Admittedly that was all about "guitar" and performance music.
But the principles are the same for music reproduction.
An array of smaller drivers is always "larger" that the equivalent single driver of the same total Sd. Thus the trend towards omni-directional will occur at a slightly lower frequency.
Xmax is not a big problem in that high sensitivity large drivers have a relatively low Xmax, many are lower Xmax than bass/mid drivers of ¼ the diameter.
They developed the 4*12" cabinet to go with their 50W amplifier.
Then they came out with a stacked array for the "new" 100W amplifier.
The stacked array is two 4*12" cabinets stacked vertically.
The "array" is two wide by four high.
That will go loud and it will "project" a bit more energy forward compared to single 4*12" cabinet.
each 12" driver was seeing just 12.5W
Each 4*12" cabinet would perform very similarly to a 24" driver in a cabinet, except that the 4*12" is slightly wider and taller and thus projects a little bit more forward at the lowest frequencies.
Admittedly that was all about "guitar" and performance music.
But the principles are the same for music reproduction.
An array of smaller drivers is always "larger" that the equivalent single driver of the same total Sd. Thus the trend towards omni-directional will occur at a slightly lower frequency.
Xmax is not a big problem in that high sensitivity large drivers have a relatively low Xmax, many are lower Xmax than bass/mid drivers of ¼ the diameter.
Admittedly that was all about "guitar" and performance music.
But the principles are the same for music reproduction.
An array of smaller drivers is always "larger" that the equivalent single driver of the same total Sd. Thus the trend towards omni-directional will occur at a slightly lower frequency.
Maybe so, but for subwoofers I can't see how this might be relevant: the transition will occur in the hundreds of Hz.
Ben, while I'd agree that a lot of music is fine with 40Hz extension, there's an awful lot that goes lower. A lot of double basses are tuned to low-B, with a 31Hz fundamental. Of course, there's a large supply of synthesised sounds that can go waaaay below 40Hz. Again, a lot depends on personal taste.
Chris
the transition to "omni-directional" will depend on the SIZE of the array.the transition will occur in the hundreds of Hz.
the transition to "omni-directional" will depend on the SIZE of the array.
Of course, but I'd argue that, for any remotely domestic environment, room effects will be dominant at LF well before any steering from array size comes in.
Chris
Tal,1)The Bag End subwoofer that uses a tiny sealed box with a high Fb forcing a very linear 2nd order rolloff then countered by a glorified 2nd order LP at the cutoff frequency is indeed a good example of an approach that has OBVIOUS PROBLEMS.
2)Tapped horns have terrible performance in the time/phase domain.
3)If you have smallish (8" is probably the minimum) drivers that are indeed optimized for LF - ie: are subwoofers and not woofers - than you have a tit-for-tat comparison.
4)Distortion is usually proportional to excursion, and so another debate point is that Sd matters more than Vd. I would personally imagine that's a big component in why different LF systems with similar Vd would sound different. (A Ferrari driven at 80 on the freeway is more stable than a minivan at 80.)
1) Yes, as I mentioned in the link, the OBVIOUS PROBLEM of using a driver below Fs in a small sealed box is reduced efficiency. That, contrary to Ben T's statements, does not preclude output to VLF, it simply reduces SPL, though the SPL can certainly be more than the OB Ben uses- OB are the least efficient sub design I'm aware of.
2) The tapped horns I have designed (and many I have reviewed) have phase response similar to a sealed sub, much flatter phase response in the pass band than a bass reflex design with a similar F3. Like all horn cabinets, the "time of flight" through the horn path requires the top cabinets to be delayed for proper time alignment. Ben has recently discovered the sonic benefits of time alignment.
3) I use 6" subs in my travel trailer, they provide more than sufficient SPL down to 35 Hz. Some would find 3"-4" subs adequate for their low SPL listening preference.
4) "Usually" being the operative word, there are many exceptions.
Regarding the automotive analogy, I find most minivan drivers more stable at 80 MPH than Ferrari drivers, who tend to weave through traffic much more. Personally, I know I am less stable driving my Mustang than my (former) minivan😉.
Art
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Ben,If you've spent much time watching your music on a real-time spectrum analyzer, you'd wonder why anybody would bother trying to get bass below 40 Hz since there is practically no music down there (and your brain fills in what the speaker doesn't play anyway)*. Maybe trying to get great sound just down to 40-45 Hz is the compromise that makes the most sense.
I have spent the last 35 years watching music on real-time spectrum analyzers, since the transition from the LF limited vinyl recording media to digital recordings I have witnessed the LF in pop music drop an octave from around 50 Hz to 25 Hz.
With long excursion, low distortion subs and power amps available to drive them at a fraction of the cost per watt that would be required just a decade ago, there is no reason anyone but a truly poor person can't afford response down to 20-25 Hz, regardless of whether they chose to use multiple small subs (like I use in my work shop) or a single large sub (like I use in my home theater) for their listening pleasure.
Art
"I am not saying the lowest note you'll even hear from any driver is Fs... just that boxes are made to coordinate with Fs."
Wrong, or at least very myopic. There are many reasons to tune below fs, sometimes WELL below fs.
I suppose you could design a box with a Helmholtz resonance that pipes-in below the system resonance and so makes a loud one-note sound below Fs when slightly instigated by the driver's motion. In that case, somebody could truthfully post, "But my speaker plays loud below Fs."
What you describe is a very badly designed ported box. It is widely known that in order to design around room gain, it's generally advisable to design for a rising response. This necessitates tuning below fs in a ported box as it will allow for a gently rising response to offset room gain for a flat response down to tuning. The "loud one note sound below fs" comes from a box that is too large, providing a big peak at tuning. That's just bad design.
Furthermore, as someone pointed out, tapped horns generally want a driver with fs at least 1/2 octave above the enclosure tuning. And if you want a rising response from a tapped horn you can use a driver with fs a full octave, and as much as 2 full octaves above the enclosure tuning.
Front loaded horns also work best with drivers with fs above the box tuning.
Transmission lines are similar to ported, so the comments above about ported boxes apply.
And as we all know, sealed boxes are commonly used down to almost dc despite having an impedance peak several octaves higher than that. Sealed boxes are the most popular design for reaching single digit frequencies.
A few minutes with a simulator would show all of Ben's comments to be untrue. But I won't bother since Ben doesn't believe simulations are accurate.
Also, as Weltersys pointed out, measured phase of tapped horns is really not bad, and tapped horns sound wonderful. I have one that I've actually listened to. Ben has never heard a tapped horn despite his unrelenting criticism of them.
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And as we all know, sealed boxes are commonly used down to almost dc....
That's amazing. I want one of those.
No...maybe I read that wrong. Did just a guy mean Baltimore which is almost down to Washington, dc?
Ben
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No, I meant the dozens of guys at avsforum (among other places) that use sealed subs to get down to as low as their signal chain will allow. A few are flat down to 5 hz or so in room with appropriate dsp where needed. Some don't need much (if any) signal processing if there is enough room gain, like solid concrete basements.
Were you not aware of this? These days it's pretty common. There are even a few threads about systems like this on this forum. They aren't exaggerating either, there's measurements available for those that care to find them.
Were you not aware of this? These days it's pretty common. There are even a few threads about systems like this on this forum. They aren't exaggerating either, there's measurements available for those that care to find them.
This thread, with all it's backwards and forwards, amuses me because it reminds me a little of youtubes comment section 😀
As is usual with arguments like this on DIYA I think the general answer can be summed up as 'it all depends'. One could make a comment saying something like 'all things being equal', but rarely, especially in a case such as this, are things equal.
I have been dipping in and out of this thread since it was created but haven't posted and have forgotten a lot of what I read back then, but I figured I'd add in my 2 pennies worth (or maybe a bit more 😉)
The first thing that I will say, as a large generalisation, is that 'impact', or whatever you want to call it, is simply defined by a system being able to reach a given SPL, but without gross thermal compression coming into play.
Now if we want to generalise again one could say that it makes no difference whether you're using multiple subs or a single large sub. Now lets say for sealed systems, you would match the volume displacement of both the multiple sub system and the single sub system. This would give both the ability to reach the same overall SPL for a given frequency.
Now how are we going to balance the parameters of the drivers?
As has been mentioned before, the larger sub will most likely, in it's optimal enclosure size, go deeper than the smaller subs, but we could engineer the parameters of the smaller subs so that this doesn't necessarily have to be true. If we went this route, their sensitivity would obviously drop, but then we would be using several of them, rather than the single large driver, so they would possibly make up for some of this.
The other option would be not bothering with that and just accept that the smaller subs are going to roll off faster than the large sub.
Off the top of my head I'm guessing that this would give the smaller subs higher efficiency above a certain point, but less below that point.
From an instantaneous SPL point of view, both systems will reach roughly the same gross output regardless of their design, providing you've got enough power.
From the thermal point of view it's a mixed bag. The larger driver only has one voice coil. The multiple approach has several. Now there's no reason why the voice coils of each individual sub couldn't be exactly the same size as the larger driver. This should give them vastly superior results where thermal compression might be concerned.
In the first case you'd have and equal frequency response from each system, but the multiple sub system might have lower overall SPL. This would require a little bit more power to compensate for, but shouldn't impact too heavily on the thermal compression issue because you've got more voice coils to dissipate the additional power.
In the second case the multiple sub system would probably be more efficient than the single sub above where the EQ really kicks in and worse efficiency below. The lower efficiency wouldn't result in poorer thermal compression performance unless the power levels required went pretty high, because again, you've got lots of coils, instead of just one.
I'm guessing here that the multiple sub system would probably end up on top overall. Then there's the fact that you're going to have a much more even sound field, in room, with a properly configured multiple sub set up.
I know which I prefer anyhow!
From that I am sure you can come to conclusions for other box alignments. Sealed has a natural advantage when it comes to applying gross amounts of EQ below the system resonance. Ported or bandpass type things are a mess when they unload, but this doesn't mean that it isn't possible. Certainly from my point of view, if you were going to attempt to do a single large sub vs multiple small sub comparison with vented designs, you would absolutely need to pick drivers tailored for the role, otherwise I think you would really run into difficulties in reproducing say 20Hz with smaller drivers.
With regards to applying EQ below a systems resonance, there is nothing new to this, people do it all the time. Bass boost button or loudness button anyone? 😀 As far as I am concerned though, it is all about doing what the drivers allow you to. Certainly systems become less linear below resonance and some will flap about like a door in a hurricane if you're not careful. But providing you are not exceeding a drivers thermal or mechanical capabilities, then there is no reason not to do it. Yes, distortion is going to increase as you crank the driver harder, but unless it's being over driven, this is unlikely to be much of a problem.
As is usual with arguments like this on DIYA I think the general answer can be summed up as 'it all depends'. One could make a comment saying something like 'all things being equal', but rarely, especially in a case such as this, are things equal.
I have been dipping in and out of this thread since it was created but haven't posted and have forgotten a lot of what I read back then, but I figured I'd add in my 2 pennies worth (or maybe a bit more 😉)
The first thing that I will say, as a large generalisation, is that 'impact', or whatever you want to call it, is simply defined by a system being able to reach a given SPL, but without gross thermal compression coming into play.
Now if we want to generalise again one could say that it makes no difference whether you're using multiple subs or a single large sub. Now lets say for sealed systems, you would match the volume displacement of both the multiple sub system and the single sub system. This would give both the ability to reach the same overall SPL for a given frequency.
Now how are we going to balance the parameters of the drivers?
As has been mentioned before, the larger sub will most likely, in it's optimal enclosure size, go deeper than the smaller subs, but we could engineer the parameters of the smaller subs so that this doesn't necessarily have to be true. If we went this route, their sensitivity would obviously drop, but then we would be using several of them, rather than the single large driver, so they would possibly make up for some of this.
The other option would be not bothering with that and just accept that the smaller subs are going to roll off faster than the large sub.
Off the top of my head I'm guessing that this would give the smaller subs higher efficiency above a certain point, but less below that point.
From an instantaneous SPL point of view, both systems will reach roughly the same gross output regardless of their design, providing you've got enough power.
From the thermal point of view it's a mixed bag. The larger driver only has one voice coil. The multiple approach has several. Now there's no reason why the voice coils of each individual sub couldn't be exactly the same size as the larger driver. This should give them vastly superior results where thermal compression might be concerned.
In the first case you'd have and equal frequency response from each system, but the multiple sub system might have lower overall SPL. This would require a little bit more power to compensate for, but shouldn't impact too heavily on the thermal compression issue because you've got more voice coils to dissipate the additional power.
In the second case the multiple sub system would probably be more efficient than the single sub above where the EQ really kicks in and worse efficiency below. The lower efficiency wouldn't result in poorer thermal compression performance unless the power levels required went pretty high, because again, you've got lots of coils, instead of just one.
I'm guessing here that the multiple sub system would probably end up on top overall. Then there's the fact that you're going to have a much more even sound field, in room, with a properly configured multiple sub set up.
I know which I prefer anyhow!
From that I am sure you can come to conclusions for other box alignments. Sealed has a natural advantage when it comes to applying gross amounts of EQ below the system resonance. Ported or bandpass type things are a mess when they unload, but this doesn't mean that it isn't possible. Certainly from my point of view, if you were going to attempt to do a single large sub vs multiple small sub comparison with vented designs, you would absolutely need to pick drivers tailored for the role, otherwise I think you would really run into difficulties in reproducing say 20Hz with smaller drivers.
With regards to applying EQ below a systems resonance, there is nothing new to this, people do it all the time. Bass boost button or loudness button anyone? 😀 As far as I am concerned though, it is all about doing what the drivers allow you to. Certainly systems become less linear below resonance and some will flap about like a door in a hurricane if you're not careful. But providing you are not exceeding a drivers thermal or mechanical capabilities, then there is no reason not to do it. Yes, distortion is going to increase as you crank the driver harder, but unless it's being over driven, this is unlikely to be much of a problem.
Is this correct?The "loud one note sound below fs" comes from a box that is too large, providing a big peak at tuning. That's just bad design.
A larger box gives a lower Q.
A smaller box gives a higher Q.
A Q > Butterworth (1/sqrt(2)) gives a humped response.
i.e. a too small box gives a rising response. Combine this with a bit of room gain and the "hump" in the response can become quite large.
The "loud one note sound" comes from a box that is too SMALL, providing a big peak at tuning.
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That's true for a sealed box. In a ported one, the box's Helmholtz resonance relies on coupling with the driver to damp it. The larger the box relative to the driver, the less it is damped. If the driver was negligibly small or absent altogether, the box resonance would have a Q of about 7.
So, if you build a ported cabinet too big, you get a fall-off like a low-Q sealed cabinet, then a big peak at the box frequency. It sounds awful. Don't ask me how I know this. 🙁
So, if you build a ported cabinet too big, you get a fall-off like a low-Q sealed cabinet, then a big peak at the box frequency. It sounds awful. Don't ask me how I know this. 🙁
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