Hi all, i have built a quad 10" subwoofer for my home theatre room as an experiment as i sold my SVS downfiring years ago once i had kids, now getting back into movie watchin i thought i could make a decent sub for much less than a decent off the shelf sub.
SO what i have done is made a heavily braced box with 4 10" speakers (budget friendly) each speaker is powered by its own seperate amplification channel, so each is being fed its own personal 100watts. All of these amps are then connected to one main line to feed the sub out on my main amp so that each speaker is fed the exact same signal.
As these speakers are all closer than a 1/4 wavelength as its only used under 100hz that means i should be gaining +3db for every doubling of speakers. So 1 to 2 then 2 to 4 so effectively +6db correct? THEN i am also running my own individual 100watts to each speaker so that nets me another +3db for each doubling or is it for each individual speaker? This last part i am lost on.....am i gaining only +6db extra or +12db in this scenario then asding ontop the +6db from mutual coupling.
I would love a definitive +db answer as im looking at making another sub the same way.
Thanks for the help!
Attached a photo as everyone loves a photo.
SO what i have done is made a heavily braced box with 4 10" speakers (budget friendly) each speaker is powered by its own seperate amplification channel, so each is being fed its own personal 100watts. All of these amps are then connected to one main line to feed the sub out on my main amp so that each speaker is fed the exact same signal.
As these speakers are all closer than a 1/4 wavelength as its only used under 100hz that means i should be gaining +3db for every doubling of speakers. So 1 to 2 then 2 to 4 so effectively +6db correct? THEN i am also running my own individual 100watts to each speaker so that nets me another +3db for each doubling or is it for each individual speaker? This last part i am lost on.....am i gaining only +6db extra or +12db in this scenario then asding ontop the +6db from mutual coupling.
I would love a definitive +db answer as im looking at making another sub the same way.
Thanks for the help!
Attached a photo as everyone loves a photo.
Thanks Rob. So +12db in total, so effectively doubling the loudness perceivable to my ears and some.
+10dB sounds roughly twice as loud at 1kHz, +5 dB sounds roughly twice as loud at 20Hz:
Adding a second 4x10" may sound twice as loud at low frequencies.
The drivers excursion will be cut in half for the same level as the single 4x10".
Thanks for the reply. Not quite sure how to read the graph but if your saying im actually gaining substantially more db perceivable at low hz then thats even better.
Just shows you the power of multiple subs in the one enclosure. Why are their not more companies doing multiple drivers running seperate amps to each one in a single enclosure. I always see massive 1000w + subs when couldnt you just run 2-4 in the one enclosure with 100-200w per sub and have something can put out much higher spl?
Am i missing something???
Just shows you the power of multiple subs in the one enclosure. Why are their not more companies doing multiple drivers running seperate amps to each one in a single enclosure. I always see massive 1000w + subs when couldnt you just run 2-4 in the one enclosure with 100-200w per sub and have something can put out much higher spl?
Am i missing something???
I have modelled my situation as best i can in WinISD and my box size hasnt made much of a difference if i was to have made it double the size maybe +3db diff at 50hz if it was double the size, but considering all of the extra db i am gaining from seperate amps and mutual coupling, the smaller box is a worthy tradeoff.
Impressive looking, but with 4 woofers you could hve built 2 push-push woofers. 2 to even out the room response and push-push so that you can have active reaction force cancelation to dramatically reduce the vibrational load on the box. 15mm quality ply with some somple bracing works well.
dave
dave
Dave, I like opposing drivers in push-push too. But... looking at the OP's pictures, in this practical application the opposing drivers would be facing into either walls or cupboards.
Of course, there is the ideal situation of low frequencies being considered omnidirectional, in free space. But does close proximity of the drivers to other planes destroy this and/or causes other artifacts in the response?
Of course, there is the ideal situation of low frequencies being considered omnidirectional, in free space. But does close proximity of the drivers to other planes destroy this and/or causes other artifacts in the response?
The red lines are "equal loudness" curves, for instance 100dB SPL @31.5Hz sounds about equally loud as 80dB at 1kHz.
The "equal loudness" curves vary with SPL, relatively more SPL is required for equal loudness at lower SPL levels.
Two and four driver subwoofers are relatively common in professional sound.
Separate amp channels are not required to provide the same voltage/power to each driver, multiple channels drive up cost.
Cost vs performance and cabinet size (and aesthetics and marketing..) dictate what sells to the consumer.
Consumers often don't have a good idea of what to compare when making a purchase.
The plan was to always make 2 of these cabinets, one on either side of centre channel, as they were fairly cheap to make.
I have now started work on a quad 12" that will take this ones place and will make a second later in the year. Here is a picture of the size difference.
Thanks for the reply weltersys. I understand the graph now. Yes a large single sub boasting 1000+ watts does "sound" more appealing off the shelf.
Vatzat,
If you consider output- would you prefer a ported SVS PB13Ultra (22.5”x 20.5”x 28”) with 1000 watts and 113.6dB @20hz, or the more expensive, larger driver, smaller sealed cabinet SB-16Ultra with ~1500 watts and 103.1 dB (-10.5dB less) at 20Hz?
Your sealed 4x10" could have the same output at 20Hz as the SB-16 if the drivers used can do about 9.75mm excursion, but they would require ~30mm excursion to match the SVS PB13 Ultra's 20Hz response.
Choices, choices 😉
Art
If you consider output- would you prefer a ported SVS PB13Ultra (22.5”x 20.5”x 28”) with 1000 watts and 113.6dB @20hz, or the more expensive, larger driver, smaller sealed cabinet SB-16Ultra with ~1500 watts and 103.1 dB (-10.5dB less) at 20Hz?
Your sealed 4x10" could have the same output at 20Hz as the SB-16 if the drivers used can do about 9.75mm excursion, but they would require ~30mm excursion to match the SVS PB13 Ultra's 20Hz response.
Choices, choices 😉
Art
I would definitely go the pb13 ultra. BUT in my circumstances a pb13 ultra in aus would fetch me $3000 aud. I could literally make 6 of my quad 10" subs for that price and have a room full of even dispersion of bass. Definitely pays to go the DIY route in most scenarios.
This is an excellent example of a red herring where reference to 1w/1 meter is buried in the sand along with the reality of cancellation nulls from one source where long wavelengths are concerned in 3d space.
another DIY fail. Building 4 seperate boxes and placing them about the room would have been far more effective sonically on all fronts and easier to integrate visually than that hulking bit of stage backline looking self indulgence. Makes me sad 😢
another DIY fail. Building 4 seperate boxes and placing them about the room would have been far more effective sonically on all fronts and easier to integrate visually than that hulking bit of stage backline looking self indulgence. Makes me sad 😢
Haha. Mate its not really that big, and i quite like the look of the 4 drivers, although in saying that next one will have a grill over the front. I was never going to consider doing 4 smaller boxes. A) it costs more. B) My room doesnt have space for rear subs.
I agree that it would blend much better having 4 seperate subs, but i always intended on making 2 of these in the front stage, im instead now going 2 quad 12" boxes, 1 either side of the centre channel to even out the bass around the room. So it was never intended as a single quad. Is there any other reason why this diy sub is a complete fail other than you think its too big and it could have been better to divide the 4 subs into 4 boxes?
Thanks
I agree that it would blend much better having 4 seperate subs, but i always intended on making 2 of these in the front stage, im instead now going 2 quad 12" boxes, 1 either side of the centre channel to even out the bass around the room. So it was never intended as a single quad. Is there any other reason why this diy sub is a complete fail other than you think its too big and it could have been better to divide the 4 subs into 4 boxes?
Thanks
So bass wavelengths for starters……long and prone to room interaction and reflections….these points of wavefront interactions either produce deep nulls where the wavelengths are 180 degrees out of phase or huge humps where the phase is aligned…….add in the distance, floor bounce and lobing from the 4 collocated drivers and you’ve got a hot mess.
4 separate boxes……shorter panel lengths….less cabinet resonance…..lighter and more manageable to move. Smaller footprint easier to integrate into the space. Drivers closer to the floor so less bounce and instead, uniform boundary gain. Load these into the 4 corners of the room?…..now you’ve got as much as another +3db per box.
Four sources….same content….exponential more cancellations BUT magnitudes lower in amplitude……picture an enclosed pond with thousands of little ripples…..the whole thing resonating as one.Now take your Tsunami generator and visualize the response….and the mess. Make more sense now?
Add in yet another Tsunami?…..maybe side by side?…..going for the whole Fukushima kill it all thing Hugh?…..get it going with enough current and you can get the unified wavefronts to really peak….maybe some 20db in spots….hmmmm….that’s gotta sound great.
Two would just be failure on a different scale…..epic maybe…..and what a waste of all that displacement. Instead build 4 boxes each with 2 opposed drivers per box……dampen nearly all resonance and rocking modes through mechanical force offset.
4 separate boxes……shorter panel lengths….less cabinet resonance…..lighter and more manageable to move. Smaller footprint easier to integrate into the space. Drivers closer to the floor so less bounce and instead, uniform boundary gain. Load these into the 4 corners of the room?…..now you’ve got as much as another +3db per box.
Four sources….same content….exponential more cancellations BUT magnitudes lower in amplitude……picture an enclosed pond with thousands of little ripples…..the whole thing resonating as one.Now take your Tsunami generator and visualize the response….and the mess. Make more sense now?
Add in yet another Tsunami?…..maybe side by side?…..going for the whole Fukushima kill it all thing Hugh?…..get it going with enough current and you can get the unified wavefronts to really peak….maybe some 20db in spots….hmmmm….that’s gotta sound great.
Two would just be failure on a different scale…..epic maybe…..and what a waste of all that displacement. Instead build 4 boxes each with 2 opposed drivers per box……dampen nearly all resonance and rocking modes through mechanical force offset.
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I would have just said that the diversity of multiple sources can help with room modes.
That's not to say that a pair of stereo quads couldn't be the basis of a workable setup. Setting constraints that way might create challenges but additional subs may not necessarily need to be large or to intrude on the room to be used beneficially.
That's not to say that a pair of stereo quads couldn't be the basis of a workable setup. Setting constraints that way might create challenges but additional subs may not necessarily need to be large or to intrude on the room to be used beneficially.
Here i was just wanting to make a fun DIY sub.....anyhow you clearly are much more knowledgeable than me in this regard. Would having 2 of these quads in the front with EQing from DSP help eleviate these issues of disgust you have with my design?
On another note i see plenty of people with dual front firing cabinets from big brands and also many people stacking enclosures on top of one another. Are these also no good for lobing and other issues you speak of?
Thanks