Chalk this up as crazy HT idea #427. Several small subwoofers spanning the area below a projected screen.
Example: Nine 16"x16"x12" ported boxes with 10" drivers mounted in the 12" face. Displacement would be just short of three 18" subs, or a single 18 with 3X the xmax of the 10s.
Good idea, bad idea, or just insane?
PS: crazy HT idea #426 was a HUGE floor firing bass horn in which the horn itself acts as the screen for the projector.
Example: Nine 16"x16"x12" ported boxes with 10" drivers mounted in the 12" face. Displacement would be just short of three 18" subs, or a single 18 with 3X the xmax of the 10s.
Good idea, bad idea, or just insane?
PS: crazy HT idea #426 was a HUGE floor firing bass horn in which the horn itself acts as the screen for the projector.
I dont think putting a screen over the horn mouth would be a good idea in any circumstance, but you could use say the side of the horn to project upon
Crazy, never!!!!!
good idea, debatable.
Cons (as I see it): Alot of wood😱
alot of money- depending on drivers of course
Cheap drivers probably will have high fs, not good for ht. you can eq, but then maybe distortion.
lose alot of floor space.
need alot of amps
sealed might be better for real low extension, f10 vs. f3
18's ( the right ones) would have high sensitivity high power handling, high excursion and low fs, that's what you ultimately want for ht.
you'll have to invite me over
if your married your wife will have a bunch of new places to stack plants and knick-knacks
Pros: LLOOUUDD😀
Look cool as hell
You can simultaneously eliminate excess time and money, we all have this problem.😀
BTW, what 10's and what 18"s were you thinking of?
good idea, debatable.
Cons (as I see it): Alot of wood😱
alot of money- depending on drivers of course
Cheap drivers probably will have high fs, not good for ht. you can eq, but then maybe distortion.
lose alot of floor space.
need alot of amps
sealed might be better for real low extension, f10 vs. f3
18's ( the right ones) would have high sensitivity high power handling, high excursion and low fs, that's what you ultimately want for ht.
you'll have to invite me over
if your married your wife will have a bunch of new places to stack plants and knick-knacks
Pros: LLOOUUDD😀
Look cool as hell
You can simultaneously eliminate excess time and money, we all have this problem.😀
BTW, what 10's and what 18"s were you thinking of?
BassAwdyO said:
For the Horn::
You are correct, nobody should put a screen over the mouth.. The projector will display on the side opposite the wall and the mouth would be aimed at the floor. Current pencil sketch has the mouth 24" off the floor. Taper rate and length put it at about 26Hz with a mouth area of 16sqft.
It is only folded once, and it is BIG. The projection surface is 8' by 6'. My original sketch came out to 10 sheets of particleboard before I made some major revisions. I think the current version is down to 7.
For the Multiples::
If i figure correctly, I can bang out nine of the 16x16x12 boxes with only 2 and a half sheets of particle board with an internal volume of 1.36cuft each.
nunayafb said:
I think there is some mixup in what I am proposing. 🙂 I only mentioned the 18"s as a comparison of cone displacement. (9x10") vs. (3x18")
Going for the cheap, I had considered the PYRAMID WX102 for my 10" of choice. This is a 'car' driver, but I thought the specs looked like they might actually work. Fs 40Hz and Vas of 1.72cuft. Their Xmax is only 3.55mm but with nine of them thats approx the same displacement as a single 18" with an Xmax of 10mm. My mental math might be on the blink, but with an SPL of 92db, doesnt that make nine of them top out over 101dB/W?
Nine speakers also work well with a series/parallel combination for impedance and power, so only one large amp is needed. (I've got an old Peavey DECA700 gathering dust in the corner) And I most certainly wont have them anywhere near that level of output.
Also, with nine drivers, I am sure it will have to be EQ'd to get anything close to a flat responce out of them. Efficency in the upper-sub-bass will be very high, so a crossover point of 80hz or even lower will probably be needed.
Nine of the boxes will use a bit of floor space, but it is space that has to be kept clear for the projector anyway. Apart from knick-knacks (i feel your pain) they would also most likely be pulling double duty as speaker stands for my mains and center channel.
If I have the layout correct, I can bang out nine of the 16x16x12 boxes with 2 and a half sheets of 3/4" particle board and have an internal volume of 1.36cuft.
Use four 15" PA drivers in four independent ported enclosures. The drivers doesn't need to either have particularly low Fs or particularly high Xmax but high efficiency is desirable, and the enclosures doesn't need to be sized to produce flat output to particularly low frequencies, they may be a bit undersized and start to roll-off below 45Hz but must be tuned low around 30Hz.
Mutual coupling between the four drivers when everything is thightly placed together will do the trick. Efficiency will be boosted by up to 6dB/W, cone displacement will be less than half the predicted value for a single enclosure and you may expect the cutoff frequency of the enclosures to be lowered by half an octave or more.
The same principles apply to an array of 10" drivers, but efficiency will be a bit worse, and building 9 enclosures is far more costly than building just 4.
Mutual coupling between the four drivers when everything is thightly placed together will do the trick. Efficiency will be boosted by up to 6dB/W, cone displacement will be less than half the predicted value for a single enclosure and you may expect the cutoff frequency of the enclosures to be lowered by half an octave or more.
The same principles apply to an array of 10" drivers, but efficiency will be a bit worse, and building 9 enclosures is far more costly than building just 4.
Hi,
In a separate post and discussion the conclusion was given that subs
had to be placed along a wall and not in free floor space, that only
4 subs would be needed to provide smooth bass, their was no
advantage in using any more in terms of response smoothness.
Note that these 4 are distributed, e.g 2 on front wall, 1 each side wall.
I can't see the point of 9 10" drivers with 3.5mm xmax.
4 12" drivers with 10mm xmax will give ~ twice as much volume displacement.
4 10" drivers with 10mm xmax is still 40% more.
🙂/sreten.
In a separate post and discussion the conclusion was given that subs
had to be placed along a wall and not in free floor space, that only
4 subs would be needed to provide smooth bass, their was no
advantage in using any more in terms of response smoothness.
Note that these 4 are distributed, e.g 2 on front wall, 1 each side wall.
I can't see the point of 9 10" drivers with 3.5mm xmax.
4 12" drivers with 10mm xmax will give ~ twice as much volume displacement.
4 10" drivers with 10mm xmax is still 40% more.
🙂/sreten.
multi driver sub
www.parts-epress.com has a great project in its showcase that sounds like it is right up your alley. It utilizes four very impressive 6.5" subs in a hideable enclosure. also the drivers are very affordable.
www.parts-epress.com has a great project in its showcase that sounds like it is right up your alley. It utilizes four very impressive 6.5" subs in a hideable enclosure. also the drivers are very affordable.
The Boogieman is an interesting design. I would like to see some real-world measurments from it though. I just cant see using it in a downward firing configuration with only the 1" rubber feet as spacers.
I'm all for crazy ideas ... too many subwoofers, is there ever such a thing?
I'd be wary of using cheap drivers - low SQ is one problem overall, but also limited upper useable bandwidth can mean they just don't sound good with a higher crossover point, in which case you have to cross them low and your mains still have to reproduce a lot of bass.
Larger drivers usually offer better value - 12s are usually a good compromise, 10s are barely cheaper and 15s are great value but tend to require much larger boxes.
Using a number of drivers do add up displacement although to get the full advantage of this in terms of SPL they need to be close to each other. The theoretical 6db output increase each time you double the power and number of drivers is not achieved if they are scattered through the room. Hence to match the output of a larger driver with smaller ones you might stack them in a corner, in which case you are probably better with a single 15" sub with some decent excursion.
Multiple subs can improve room response in that they can excite room modes differently and this can give a smoother in room response.
The boogeyman looks novel for very space limited applications but if you can handle a number of 10s around the room then I think you'd be better with a single 12 - much better quality driver like the reference series 12 http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-466
on special now
Those cheap car subs have an fs around 40 hz but I'd expect that this may in fact be the upper limit you could use!
If you want the crazy but cheap experimentation path with cheap drivers, how about going with the horn idea?
Not sure if I get the horn idea, but this is the direction I'd consider. Make a large horn similar in arrangement to the Lab sub - dual 12" drivers. My sims in hornresp indicate that you can get some degree of horn loading down to 20 Hz (or close) with a sub that is 2.6 x 2.6 x 0.5m. It can fire in to a corner which extends the mouth and the screen can go over one of the sides, so it is not blocked. If the horn doesn't fire into the corner then it must be MUCH bigger for a given result. If that's a bit extreme then a smaller sub like the lab sub of around 1.1 x 1.1 x 0.57 could be worth a shot, although this now isn't really suitable to mount a screen on the side. A sub like the first can hit 120db @ 20 Hz with very little power and an xmax of 6mm only is required. You could stack two subs with 2 drivers in each and do it quite possibly with that driver.
I'd be wary of using cheap drivers - low SQ is one problem overall, but also limited upper useable bandwidth can mean they just don't sound good with a higher crossover point, in which case you have to cross them low and your mains still have to reproduce a lot of bass.
Larger drivers usually offer better value - 12s are usually a good compromise, 10s are barely cheaper and 15s are great value but tend to require much larger boxes.
Using a number of drivers do add up displacement although to get the full advantage of this in terms of SPL they need to be close to each other. The theoretical 6db output increase each time you double the power and number of drivers is not achieved if they are scattered through the room. Hence to match the output of a larger driver with smaller ones you might stack them in a corner, in which case you are probably better with a single 15" sub with some decent excursion.
Multiple subs can improve room response in that they can excite room modes differently and this can give a smoother in room response.
The boogeyman looks novel for very space limited applications but if you can handle a number of 10s around the room then I think you'd be better with a single 12 - much better quality driver like the reference series 12 http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-466
on special now
Those cheap car subs have an fs around 40 hz but I'd expect that this may in fact be the upper limit you could use!
If you want the crazy but cheap experimentation path with cheap drivers, how about going with the horn idea?
Not sure if I get the horn idea, but this is the direction I'd consider. Make a large horn similar in arrangement to the Lab sub - dual 12" drivers. My sims in hornresp indicate that you can get some degree of horn loading down to 20 Hz (or close) with a sub that is 2.6 x 2.6 x 0.5m. It can fire in to a corner which extends the mouth and the screen can go over one of the sides, so it is not blocked. If the horn doesn't fire into the corner then it must be MUCH bigger for a given result. If that's a bit extreme then a smaller sub like the lab sub of around 1.1 x 1.1 x 0.57 could be worth a shot, although this now isn't really suitable to mount a screen on the side. A sub like the first can hit 120db @ 20 Hz with very little power and an xmax of 6mm only is required. You could stack two subs with 2 drivers in each and do it quite possibly with that driver.
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