Has anyone tried to build a line array corner subwoofer.
I know the point in making one would not be for increased sound directivity at the frequencies that it will operate in but it seems like a good way two get multiple drivers in an enclosure that would be relatively easy to place.
You could use like six or eight, eight inch drivers with more modest requirements. So they would be less expensive. Also, the floor comb filtering effect would be mitigated to some degree by having drivers placed at several distances from the floor. This could possibly help to some degree with room modes since the radiating area would be very large compared to a one speaker subwoofer.
Of course high SPL's would have less distortion and since more total air could be moved with each speaker using less motion it seems like the total transient response might be higher. If the drivers were critically damped the sound would be very good and very fast.
Feedback?
Hezz
I know the point in making one would not be for increased sound directivity at the frequencies that it will operate in but it seems like a good way two get multiple drivers in an enclosure that would be relatively easy to place.
You could use like six or eight, eight inch drivers with more modest requirements. So they would be less expensive. Also, the floor comb filtering effect would be mitigated to some degree by having drivers placed at several distances from the floor. This could possibly help to some degree with room modes since the radiating area would be very large compared to a one speaker subwoofer.
Of course high SPL's would have less distortion and since more total air could be moved with each speaker using less motion it seems like the total transient response might be higher. If the drivers were critically damped the sound would be very good and very fast.
Feedback?
Hezz
Mike.e,
Thanks for the info. I have Winisd but not sure if it is the pro version. I've never tried to model a line array and this is area that I need to study up on. After having gone through some of the archives I have come up with a few ideas and I think I want to try and build this quazi line array hybrid. There seems to be good arguments both for using multiple small drivers in a sub and for not using them.
My goal is not high SPL's but high quality HT bass at moderate SPL's. That being the case I will try to get buy with good quality average x-max drivers with moderate amplification.
Although I see the possibility that multiple small drivers can have better definition in the higher bass range it seems impratical to expect them to get down in the 20 - 30 Hz range with any resonable output.
Also small bass drivers don't usually have a low enough Fz for really low tuning so I have hit upon this compromise hybrid system.
My room is not real large and I think that anything more than a good single 15 inch driver will overload the room. However, since it is always possible to turn down the volume I think a little more is better than not enough.
Here is a 3D mockup of my corner design. My idea is to use one 12 inch woofer in a Qts .7 tuned enclosure getting the lowest F3 that I can. The 12 inch will make up about half of the surface area of an equivalent 15 inch driver. I think that a good twelve inch driver with a strong motor assembly can have tighter base than a 15 inch due to stiffer and lighter cone. At least at a reasonable cost.
THe rest of the equivalent 15 inch surface area will be made up of three eight inch drivers vertically mounted above the 12 inch driver. These are the high transient response drivers and will each be mounted in a critically damped Qts .5 sealed enclosure. They are closer to ear level and my hope is that they will kind of fill in the slightly less defined bass that the 12 inch driver will output. The three 8 inch drivers will be 16 ohm if possible and be driven in parallel with one channel of a external stereo amp. The other channel will drive the 8 ohm 12 inch lower driver.
Hezz
Thanks for the info. I have Winisd but not sure if it is the pro version. I've never tried to model a line array and this is area that I need to study up on. After having gone through some of the archives I have come up with a few ideas and I think I want to try and build this quazi line array hybrid. There seems to be good arguments both for using multiple small drivers in a sub and for not using them.
My goal is not high SPL's but high quality HT bass at moderate SPL's. That being the case I will try to get buy with good quality average x-max drivers with moderate amplification.
Although I see the possibility that multiple small drivers can have better definition in the higher bass range it seems impratical to expect them to get down in the 20 - 30 Hz range with any resonable output.
Also small bass drivers don't usually have a low enough Fz for really low tuning so I have hit upon this compromise hybrid system.
My room is not real large and I think that anything more than a good single 15 inch driver will overload the room. However, since it is always possible to turn down the volume I think a little more is better than not enough.
Here is a 3D mockup of my corner design. My idea is to use one 12 inch woofer in a Qts .7 tuned enclosure getting the lowest F3 that I can. The 12 inch will make up about half of the surface area of an equivalent 15 inch driver. I think that a good twelve inch driver with a strong motor assembly can have tighter base than a 15 inch due to stiffer and lighter cone. At least at a reasonable cost.
THe rest of the equivalent 15 inch surface area will be made up of three eight inch drivers vertically mounted above the 12 inch driver. These are the high transient response drivers and will each be mounted in a critically damped Qts .5 sealed enclosure. They are closer to ear level and my hope is that they will kind of fill in the slightly less defined bass that the 12 inch driver will output. The three 8 inch drivers will be 16 ohm if possible and be driven in parallel with one channel of a external stereo amp. The other channel will drive the 8 ohm 12 inch lower driver.
Hezz
Attachments
I think your idea seems good in principle to the layman, but the idea in theory and practice I think will actually be quite bad. Your stalling point is that you have a very narrow bandwidth for each set of drivers, and also a crossover between them. Crossovers are bad as they introduce phase and group delays.
Also it's a myth that smaller drivers are faster or have better transient response -- you will find that if you design your sub right with a single 12 inch it will be fine. Think of a how a big heavy Porsche can still stop, start handle better and go faster than a little shopping hatchback
Finally, you re trying to get fast bass and good transient response, then sticking the sub in a corner. You will make more difference than ANY sub design will ever make simply by placing the sub somewhere else in the room. Corner is the worst place to put a sub as it drives the most room modes and often sounds most uncontrolled -- totally negating all your effort in designing a good box.
Also it's a myth that smaller drivers are faster or have better transient response -- you will find that if you design your sub right with a single 12 inch it will be fine. Think of a how a big heavy Porsche can still stop, start handle better and go faster than a little shopping hatchback
Finally, you re trying to get fast bass and good transient response, then sticking the sub in a corner. You will make more difference than ANY sub design will ever make simply by placing the sub somewhere else in the room. Corner is the worst place to put a sub as it drives the most room modes and often sounds most uncontrolled -- totally negating all your effort in designing a good box.
theorie und praxis
Hello,
if you use a sub above 100 Hz than it is no sub.
May be your experience ís no large, do you ever listen to a
Klipschhorn or something equal.
My experience shows that in this case it will be the best way.
If you want 120 dB you better take a Shearerhorn,
if it is for HomeHiFi below 100 dB, my solution are much better
than every 12" in BR, think about moving mass etc.
below 100 Hz there is sound, contour, transparens and so on,
with large drivers you can´t get that, only more SPL.
Look the ALPHORN 135L brutto down to 30 Hz, Klipsch owner
are completly floored by listen to it.
If you will take the bass over 200 Hz than better take the
HELIKON with a 10" driver.
Hello,
if you use a sub above 100 Hz than it is no sub.
May be your experience ís no large, do you ever listen to a
Klipschhorn or something equal.
My experience shows that in this case it will be the best way.
If you want 120 dB you better take a Shearerhorn,
if it is for HomeHiFi below 100 dB, my solution are much better
than every 12" in BR, think about moving mass etc.
below 100 Hz there is sound, contour, transparens and so on,
with large drivers you can´t get that, only more SPL.
Look the ALPHORN 135L brutto down to 30 Hz, Klipsch owner
are completly floored by listen to it.
If you will take the bass over 200 Hz than better take the
HELIKON with a 10" driver.
Hezz said:
What type of budget are we talking here?
IMO For the cost of 6-8 8" drivers, one can get 2 15" drivers and mount them IB in a ceiling or wall for modest SPL. The Qts of the drivers becomes your system Qtc. Near transient perfect bass.
Also IMO it's easier making an ugly manifold/line array that is hidden and doesn't impose as its not in the room.. as opposed to a large box that one must finish to match something in room.
The downside is that you can't move your sub(s) around. Although its only drywall.
Ok guys,
A few things. First is that I have no options for subwoofer placement except in a certain corner. The corner is the best place for bass reinforcement but perhaps not for sound quality. The best place for any sub is room dependent depending on room mode boundries.
Next, I don't need anything more than 100 - 102 SPL. Also this is an attempt to build a good sounding sub with low cost drivers. Target budget is 25 - 40 USD for 8 inch drivers and 80 - 140 USD for the twelve inch.
I already have a couple of Dayton 8 inch drivers so they could be used.
The folded horn is a nice idea but I don't think that I have room for that as the size requirement is very specific and this thing tucks behind an existing keyboard rack that is sitting angled in the corner.
Where low cost drivers are concerned I am quite certain that the 8 inch drivers will have better tansient capabilities than the larger ones. At least if they are will designed inexpensive speakers.
It's been a long time since I've heard some Klipshorns. The ones I heard had slow ponderous bass in large quantities. Maybe with newer drivers they are better.
There will be no crossovers used as the design relies on the natural mechanical and electrical properties of the drivers to help with what they do best. Both upper and lower sections get the entire HT bass effects channel information and are likely to be crossed over at about 80-100 Hz since the front speakers will be nearly full range.
This is kind of like mixing a fat bass sound with a more delineated and better imaged one on a mixing board to get a certain effect. Creative tonal blending if you will.
The plan is two use a Pro stereo two channel amp that has level adjustment so that the upper and lower sections can be balanced for best integration.
Hezz
A few things. First is that I have no options for subwoofer placement except in a certain corner. The corner is the best place for bass reinforcement but perhaps not for sound quality. The best place for any sub is room dependent depending on room mode boundries.
Next, I don't need anything more than 100 - 102 SPL. Also this is an attempt to build a good sounding sub with low cost drivers. Target budget is 25 - 40 USD for 8 inch drivers and 80 - 140 USD for the twelve inch.
I already have a couple of Dayton 8 inch drivers so they could be used.
The folded horn is a nice idea but I don't think that I have room for that as the size requirement is very specific and this thing tucks behind an existing keyboard rack that is sitting angled in the corner.
Where low cost drivers are concerned I am quite certain that the 8 inch drivers will have better tansient capabilities than the larger ones. At least if they are will designed inexpensive speakers.
It's been a long time since I've heard some Klipshorns. The ones I heard had slow ponderous bass in large quantities. Maybe with newer drivers they are better.
There will be no crossovers used as the design relies on the natural mechanical and electrical properties of the drivers to help with what they do best. Both upper and lower sections get the entire HT bass effects channel information and are likely to be crossed over at about 80-100 Hz since the front speakers will be nearly full range.
This is kind of like mixing a fat bass sound with a more delineated and better imaged one on a mixing board to get a certain effect. Creative tonal blending if you will.
The plan is two use a Pro stereo two channel amp that has level adjustment so that the upper and lower sections can be balanced for best integration.
Hezz
Isn't this the worst of all worlds? With all drivers covering the same frequency range, the sound will certainly be no better than the worst driver in the bunch. The FR will also likely end up rather odd because the 8" and 12" drivers will have different F3 and sensitivity, which will likely lead to exagerated 60-100Hz and an even sharper rolloff for the subbass.
Richie00boy,
While your Porche analogy sounds good remember that the Porche cannot be built to do what it does at the budget car price.
The resources that I have are woodworking tools, creativity, and some acoustic and audio knowledge and experience. THe money resource for this project is limited both for drivers and amplification.
This is an attempt to get high end bass tonal quality as the first priority in a non negotiable space requirement at a budget price.
Hezz
While your Porche analogy sounds good remember that the Porche cannot be built to do what it does at the budget car price.
The resources that I have are woodworking tools, creativity, and some acoustic and audio knowledge and experience. THe money resource for this project is limited both for drivers and amplification.
This is an attempt to get high end bass tonal quality as the first priority in a non negotiable space requirement at a budget price.
Hezz
Tiroth,
you make a good point about the sound not being any better than the worst driver and it is possible that I may need to low pass filter the larger driver but in the world of the best sounding high end speakers an approach like this is often used and works very well in reality.
Check out the Wilson speakers and the dual sized woofers that they employ. As far as frequency response goes. It is rare for any speaker to have a flat response and so long as it doesn't have a grossly unbalance response things seem to work well.
Hezz
you make a good point about the sound not being any better than the worst driver and it is possible that I may need to low pass filter the larger driver but in the world of the best sounding high end speakers an approach like this is often used and works very well in reality.
Check out the Wilson speakers and the dual sized woofers that they employ. As far as frequency response goes. It is rare for any speaker to have a flat response and so long as it doesn't have a grossly unbalance response things seem to work well.
Hezz
Hmm, I'm sorry but I think you will be able to achieve so much more if you were willing to change your design. You would be much better off using one decent 12 inch drive unit, or two cheaper 12 inch drive units, than the mismatch you have there. I'm sure this would stay within your cost constraint as well. As Tiroth said, you are likely to end up with a rather bad case of one-note bass. It may work in the design you mentioned, but I'll bet they aren't trying to do it all within such a narrow bandwidth.
It really is a myth that smaller drive units have better transient response. A cheap 12 inch one can whoop a bunch of 8 inch ones in that department if you choose wisely, its not really much to do with price.
It really is a myth that smaller drive units have better transient response. A cheap 12 inch one can whoop a bunch of 8 inch ones in that department if you choose wisely, its not really much to do with price.
Richie00boy,
From a cost point of view it would be just about the same price to use two 12 inch drivers. Maybe even a little less if I don't use some existing drivers that I already have. THis is an option that can be easily achieved but other than stating your opinion about this design you have not given me any good technical reasons for your point of view.
The one note bass syndrome is exactly what I am trying to get away from as this is the fundamental characteristic of nearly all lower priced commercial subwoofers. And even a lot of the higher priced ones sound bad because of too high Qts.
If you will realize that high bass output is not my design priority but better bass timbre and tonal quality then you might see the genesis of this design idea.
Hezz
From a cost point of view it would be just about the same price to use two 12 inch drivers. Maybe even a little less if I don't use some existing drivers that I already have. THis is an option that can be easily achieved but other than stating your opinion about this design you have not given me any good technical reasons for your point of view.
The one note bass syndrome is exactly what I am trying to get away from as this is the fundamental characteristic of nearly all lower priced commercial subwoofers. And even a lot of the higher priced ones sound bad because of too high Qts.
If you will realize that high bass output is not my design priority but better bass timbre and tonal quality then you might see the genesis of this design idea.
Hezz
Hezz,
I believe the Watt/Puppy is specifically designed so that the rolloff of the mid complements the rolloff of the woofer, and even creates a hump to correct for the baffle step This can only be achieved by very carefully matching the drivers and their alignments. You can't just put random drivers together and hope that they integrate.
I think 1.5 way would be better; the drivers can share operating range but the lower-Fs driver is used merely as a fill-in. I can't comment on how this approach works in the real world, although I have contemplated it myself. The problem I have is that if your 8" drivers go sufficiently low, then it's hard to find a 12 that has significantly more extension. You end up choking the 12 and preventing it from reproducing much--at least that is what I fear.
I believe the Watt/Puppy is specifically designed so that the rolloff of the mid complements the rolloff of the woofer, and even creates a hump to correct for the baffle step This can only be achieved by very carefully matching the drivers and their alignments. You can't just put random drivers together and hope that they integrate.
I think 1.5 way would be better; the drivers can share operating range but the lower-Fs driver is used merely as a fill-in. I can't comment on how this approach works in the real world, although I have contemplated it myself. The problem I have is that if your 8" drivers go sufficiently low, then it's hard to find a 12 that has significantly more extension. You end up choking the 12 and preventing it from reproducing much--at least that is what I fear.
Hezz said:
The fundamental problem is basically as Tiroth pointed out that the twelve will not go hugely lower than the eights and you will end up with a lot of output in a narrow band due to both sets of drivers working. If you attempt to filter so that the twelve only comes in to extend then you are adding a crossover which will only make the sound worse.
Hezz said:
I fully realise that quality reproduction is your goal that is why I am quite strongly trying to steer you away from your original design. I would speculate that what you find bad about the sound of subwoofers is not all down to high Q. In fact the Q is probably quite a minor factor. The filters and other controls used play a large part in the sound as does the drive unit itself, i.e. under dynamic conditions the parameters may change somewhat. And room placement is the biggest factor of all.
I urge you to use a single type of drive unit to maintain an even and predictable sound. It should be a larger rather than multiple smaller units because it will be much more likely to go lower and do so easier. As a bonus it will probably be louder, too.
It is perfectly feasible for a smaller drive unit to have a higher Qts than a larger one. As I keep saying, smaller drive units are not intrinsically faster or better at reproducing transients.
A pair of 8 inch units has roughly the same cone area as a single 12 inch. However, the 8 inch units require 2 lots of cones, chassis, magnets, voicecoils, assembly, etc. which weighs and uses much more than 2x the materials of the 12 inch. So for the same price point a manufacturer can make the 12 inch unit better.
OK, I do see both of your points and they seem to be good ones. Perhaps I was sticking to this original line array idea too much. If I was to use any crossover at all it would be the 1.5 kind of idea. But really I wanted no passive crossover at all between the Amp and the speakers because of needing to adjust speaker cabinet volume in a slightly guessing game kind of way from having inline resistances changing driver Qt.
Tiroth used the Watt/Puppy example but I was thinking more of the MAXX or X1 as the bass module is designed as kind of a 1.5 but then again the upper driver is probably going up higher into the 300 Hz range. So this places the crossover points further apart. However if there was no crossover on the upper driver would crossover interaction in a narrow band be an issue.
My original idea with this was not to have the upper array and lower driver split frequency duties. Which is what I think both of you are or were thinking. But rather to layer or mix the sounds of the smaller drivers with the larger one in the hopes of getting more micro dynamic detail. It is obvious that a well designed 12 inch speaker can have better transient response that a poorly designed 8 inch. And while producing the signal the sound should be the same. The issue is the starting and stopping of the driver cone in as fast as possible a manner without any overhang. this is easier to do at a modest cost with an 8 inch driver. Also, all other thigs being equal the 8 inch driver cone should be more rigid. This alone should help make the sound cleaner as the cone does not flex as much when accelerated by the motor.
The WATT was originally designed as a stand alone near field studio monitor so early iterations of the WATT/Puppy ran the watt at full range as I recall. Perhaps that is why newer versions of the speaker have gotten more praise for bass sound integration as there was been adjustments to this design issue.
Since this subwoofer is designed primarily to be for sound effects it might be wise to go with the simpler and likely more dynamic dual 12 inch drivers. My main goal is for seamless integration with the main speakers given my placement constraints. And I hate boomy one note bass.
I would rather the speakers did not even make themselves known untial they were called upon to reproduce the needed effect.
I still feel that the acoustic sum of the drivers with the original idea would work better than you guys are thinking. but I am starting to think that maybe since this is an effects speaker and not a music reproducer that I should be thinking more in terms of dynamics. In this case I'm sure the dual 12 inch would be superior.
Hezz
Tiroth used the Watt/Puppy example but I was thinking more of the MAXX or X1 as the bass module is designed as kind of a 1.5 but then again the upper driver is probably going up higher into the 300 Hz range. So this places the crossover points further apart. However if there was no crossover on the upper driver would crossover interaction in a narrow band be an issue.
My original idea with this was not to have the upper array and lower driver split frequency duties. Which is what I think both of you are or were thinking. But rather to layer or mix the sounds of the smaller drivers with the larger one in the hopes of getting more micro dynamic detail. It is obvious that a well designed 12 inch speaker can have better transient response that a poorly designed 8 inch. And while producing the signal the sound should be the same. The issue is the starting and stopping of the driver cone in as fast as possible a manner without any overhang. this is easier to do at a modest cost with an 8 inch driver. Also, all other thigs being equal the 8 inch driver cone should be more rigid. This alone should help make the sound cleaner as the cone does not flex as much when accelerated by the motor.
The WATT was originally designed as a stand alone near field studio monitor so early iterations of the WATT/Puppy ran the watt at full range as I recall. Perhaps that is why newer versions of the speaker have gotten more praise for bass sound integration as there was been adjustments to this design issue.
Since this subwoofer is designed primarily to be for sound effects it might be wise to go with the simpler and likely more dynamic dual 12 inch drivers. My main goal is for seamless integration with the main speakers given my placement constraints. And I hate boomy one note bass.
I would rather the speakers did not even make themselves known untial they were called upon to reproduce the needed effect.
I still feel that the acoustic sum of the drivers with the original idea would work better than you guys are thinking. but I am starting to think that maybe since this is an effects speaker and not a music reproducer that I should be thinking more in terms of dynamics. In this case I'm sure the dual 12 inch would be superior.
Hezz
If you are trying to do the "sub on a budget" thing and can go vertically as tall as you like, then I'd suggest dropping the 12" completely and doing a line of 10" or 8" drivers (or even cheap 12" ones if you can find decent ones that fit the budget).
You'll then have to compare the final costs of this line of 10's or 8's vs. one or two high quality 12" or 15" drivers, and take a very close look at the final extension, SPL, and expected distortion (distortion is not going to be all that easy to predict... start by comparing for a given SPL the percent of Xmax achieved by the line array vs. the single driver, then try to adjust for the inherent linearity of the drivers used if you can find any such data).
You'll then have to compare the final costs of this line of 10's or 8's vs. one or two high quality 12" or 15" drivers, and take a very close look at the final extension, SPL, and expected distortion (distortion is not going to be all that easy to predict... start by comparing for a given SPL the percent of Xmax achieved by the line array vs. the single driver, then try to adjust for the inherent linearity of the drivers used if you can find any such data).
There's a lot of merit in using multiple 8 inchers, and I've also been pondering a 8 inch line array. Actually, what I was thinking is 4 x 8ohm 8 inchers in series/parallel. Effective load 8ohms. 2 woofers on the front of the "tower", 2 on the back, hence vibrations cancelling.
The beauty of 8" woofers is that there are a huge number to choose from, large heat dissipating area (multiple coils), better cone control in the upper range, better form factor, and narrower baffle (greater rigidity).
Cost & displacement should be should be similar to 2x12" woofers.
The beauty of 8" woofers is that there are a huge number to choose from, large heat dissipating area (multiple coils), better cone control in the upper range, better form factor, and narrower baffle (greater rigidity).
Cost & displacement should be should be similar to 2x12" woofers.
Hezz said:
I thought you would use an active crossover if anything as you hinted at using a pro amp channel per driver bunch. Don't even think about passive crossovers for anything lower than 200Hz. The inductors will be large and expensive and the response garbage due to the massively varying impedance over the full wanted bandwidth.
Hezz said:
Crossover interaction is not the issue. Simply having a crossover is. Every filter introduces delay and phase variances. This would be compounded by you trying to filter in such a narrow bandwidth.
Hezz said:
I'm not sure how you managed to come to that conlusion. Maybe I need to shout
As I have mentioned at least twice and Tiroth at least once, if you don't filter you will likely end up with one bass.Hezz said:
That is indeed the issue. However, starting and stopping without overhang is exactly what transient response is all about. As I have already said it is a myth that a smaller driver can be better at this than a larger driver. At least intrinsically.
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