Really thin under couch subwoofer

[askene]

I've been thinking about building a sub to put under my couch for a while and ran across these threads in my search.

(slightly garbled since it's my first post and I can't post urls)

forums.audioholics.com/forums/showthread.php?t=53991&highlight=low+profile

forums.audioholics.com/forums/showthread.php?t=57520&highlight=earthquake+sws

They describe basically the same thing I'm looking to do, so I thought I'd join and get some expert advice


The max exterior dimensions I've got are 26"x62"x5", so I've got ~3 cu feet, or 85L, of space, but only ~3.5" of interior height to work with.

After modeling just about every under 3" depth driver out there in winISD the Earthquake SWS 10" and 12" and JL 13TW5 are the only ones that work with the dimensions I've got. Since the JL is twice the price, earthquake it is!

I modeled the SWS-10" as a vented sub tuned to 25Hz and it was basically linear to 30Hz with a -3dB at 22.7.

The suggestion in the other thread was to use the SWS-12 as a sealed system, but it doesn't look like it goes nearly as deep when I modeled it.

My question is which would work better with the driver so close to the back wall, sealed 12" or vented 10"?

I'm leaning towards the 10" vented...but having never built a sub I don't really know what I'm doing.


I'm also looking at oaudio's bash amps to power it since I've heard good things about them and the price and dimensions are right.

Thanks for the advice!

SWS-10
Fs = 28.45 Hz
Qms = 5.02
Vas = 51.5 liters
Xmax = 28 mm
Sd = 330 sq.cm
Qes = .51
Re = 3.7 ohms
Z = 4 ohms
BL = 22.095 Tm
Pe = 200 watts
Qts = 0.46
2.83-V SPL = 88.2 dB

(pulled from one of the linked threads)
SWS-12
Fs = 24 Hz
Qms = 3.56
Vas = 149.6 liters
Cms = 0.375 mm/N
Mms = 117.3 g
Rms = 4.967 kg/s
Xmax = 31 mm
Xmech = 42 mm
P-Dia = 259.8 mm
Sd = 530 sq.cm
P-Vd = 1.643 liters
Qes = 0.515
Re = 3.7 ohms
Z = 4 ohms
BL = 10.6 Tm
Pe = 600 watts
Qts = 0.45
no = 0.387 %
1-W SPL = 88.03 dB
2.83-V SPL = 89.4 dB

 

[annunaki]

Check out my build for my buddy's in-wall sub. It may help you out some. I had even less interior depth to work with than you!

Check here: http://forums.audioholics.com/forums/showthread.php?t=56779

 

[askene]

Thanks for the link, that's a pretty impressive build! I don't know why I didn't think of looking at in wall sub threads since they've got the same slim limit. There's a serious amount of bracing that you put in that thing.

Also good stuff in GO-NAD!'s under couch thread...I may have to look into serious equalization since the sub won't be moving much once it's in place.

Next up is some design sketches I think.

 

[annunaki]

Do you have areas under the couch that are higher than 5"? Also is the couch against a wall behind you? If so, is there a gap between the wall & the couch?

If there is no gap and it is not against a wall, do you have room for a faux "table" behind the couch. The best place to hide something is in plain sight.

 

[askene]

There is actually 6" of clearance under there, but I was grabbing 1" to keep it off the ground. I could do your suggestion for go-nad and drop that to 1/2" feet and do an upward firing driver instead.

I can maybe squeeze another inch in some spots. The couch has 3 1.5" wide slats, so 4 17" sections in all. I'm sure my wife wouldn't like me removing the lining on it, so 1" might be all the extra space I can get. So actual usable space without being able to see the box under the couch (the goal from the wife's point of view) is 6x27x66.

For placement, I'm in a row house with the couch against one side wall and the TV and mains are against the opposite wall. The ouside door is to the right of the couch and the left wall is basically a double door sized opening into the rest of the house.

Thanks for your tips!

 

[annunaki]

Sketch up what you have so we can see what kind of volume we will be working with to start.

 

[GO-NAD!]

I'm sure my wife wouldn't like me removing the lining on it, so 1" might be all the extra space I can get. So actual usable space without being able to see the box under the couch (the goal from the wife's point of view) is 6x27x66.

I take it you haven't asked her about removing the lining? It doesn't serve any practical purpose, as far as I know. Just remove it when she's not around and if she notices - plead ignorance! (She doesn't read these posts, does she?) It's easier to beg for forgiveness, than to obtain permission. There is a lot of usable volume between those slats. Good luck with your build!

 

[vilbig]

You might consider the Boogieman - very low profile and rocks with only 300 watts.

 

[annunaki]

You might consider the Boogieman - very low profile and rocks with only 300 watts.

My in-wall sub I designed for my friend had significantly better performance with just 300 watts as well.

 

[askene]

The boogieman from PE is actually what started me on the idea to build an under couch sub in the first place. I wanted something that would go deeper though.

I've got tomorrow off and should have time to get some sketches done. I may get rid of the lining and see what I can find...I've got a staple gun so it won't really hurt much will it?

I also found what could be the ideal driver for the size I've got. SB Acoustics SW26DAC76-4 Shallow 10" Subwoofer 4 ohm.

I've never heard of SB Acoustics, are they any good?

I modeled it in a 3 cu ft. enclosure tuned to 19Hz and was really surprised by how nice the curve is.

Here are the specs from madisound:

Nominal Impedance 4 ohm
DC Resistance (Re) 3.2 ohm
Voice Coil Inductance (Le) mH
Effective Piston Area (Sd) 312 cm2
Voice Coil Diameter 75.5 mm
Voice Coil Height 30 mm
Air Gap Height 6 mm
Linear Coil Travel (p-p) 24 mm
Maximum excursion (p-p) T
Magnet Weight 281 g
Net Weight 3.43 kg
Free Air Resonance 24 Hz
Sensitivity (2.83V/1m) 86 dB
Mechanical Q-factor (Qms) 9.47
Electrical Q-factor (Qes) 0.56
Total Q-factor (Qts) 0.52
Moving Mass (Mms) 133.08 g
Force Factor (BL) 10.63 Tm
Equivalent Volume (Vas) 44.19 l
Compliance (Cms) 0.33 um/N
Mechanical Loss (Rm) 2.31 kg/s
Rated Power Handling 200 Watt
Overall diameter 290 mm
Cutout diameter 244 mm
Flange thickness mm
Depth 71.5 mm

 

[vilbig]

My in-wall sub I designed for my friend had significantly better performance with just 300 watts as well.

But I can move mine.

 

[annunaki]

The boogieman from PE is actually what started me on the idea to build an under couch sub in the first place. I wanted something that would go deeper though.

I've got tomorrow off and should have time to get some sketches done. I may get rid of the lining and see what I can find...I've got a staple gun so it won't really hurt much will it?

I also found what could be the ideal driver for the size I've got. SB Acoustics SW26DAC76-4 Shallow 10" Subwoofer 4 ohm.

I've never heard of SB Acoustics, are they any good?

I modeled it in a 3 cu ft. enclosure tuned to 19Hz and was really surprised by how nice the curve is.

Here are the specs from madisound:

Nominal Impedance 4 ohm
DC Resistance (Re) 3.2 ohm
Voice Coil Inductance (Le) mH
Effective Piston Area (Sd) 312 cm2
Voice Coil Diameter 75.5 mm
Voice Coil Height 30 mm
Air Gap Height 6 mm
Linear Coil Travel (p-p) 24 mm
Maximum excursion (p-p) T
Magnet Weight 281 g
Net Weight 3.43 kg
Free Air Resonance 24 Hz
Sensitivity (2.83V/1m) 86 dB
Mechanical Q-factor (Qms) 9.47
Electrical Q-factor (Qes) 0.56
Total Q-factor (Qts) 0.52
Moving Mass (Mms) 133.08 g
Force Factor (BL) 10.63 Tm
Equivalent Volume (Vas) 44.19 l
Compliance (Cms) 0.33 um/N
Mechanical Loss (Rm) 2.31 kg/s
Rated Power Handling 200 Watt
Overall diameter 290 mm
Cutout diameter 244 mm
Flange thickness mm
Depth 71.5 mm

It does relatively well in 3.0ft^3, however that is A LOT of volume to find under a couch.

Dual 8w1v2's will hit the same output level at around 22hz. However, the (dual) 8w1v2's have a 3db output advantage from about 27hz-92hz. This is figuring a 2.68ft^3 enclosure tuned to 25hz with a 2nd order infrasonic filter at 20hz with only 250 watts rms.

 

[annunaki]

But I can move mine.

True.

If you redecorate, however, with a new sofa/couch it may no longer fit? In-wall means there is never a worry.

 

[GO-NAD!]

I've got a staple gun so it won't really hurt much will it?

Depends on what you plan to do with it.....

 

[vilbig]

True.

If you redecorate, however, with a new sofa/couch it may no longer fit? In-wall means there is never a worry.

True, also. One thing that is cool about the Boogieman design, is that it, like other subs, can be built in any configuration, as long as the slot port tuning remains the same. I have built 4 so far for friends/family - all different. The last for my brother was 8 X 7 X 83. It fit behind the couch without moving it. I have since moved mine to under the bed status in the MBR.

 

[walter duque]

Maybe this will give you some idea in link below.
http://www.sourcespeaker.com/SW10PANCAKE-12-09.html

 

[askene]

If that weren't $1200 I'd probably just pick that up. Building one is a good excuse to finally get a router though

I've got some overly complicated sketches I made of the couch, but they'll have to wait for my next post.

 

[askene]

So this is what I've got.

Unfortunately after measuring the couch more closely it looks like the three slats in it go down to 4.5" off the ground in the middle, so I'm going to have to segment the sub no matter what I do since I doubt I'll get the volume I want with 4.5" total height.

The up side is I can push up to ~7" in each section. It looks like if I use ALL the volume under there I can get 4.5 cu ft....but that would be a pretty massive sub that would never fit under anything else.

(edited total volume...i forgot to include MDF thickness)

 

[Shock]

If the couch is a rockin'.......

 

[j_garcia]

http://www.parts-express.com/projectshowcase/indexn.cfm?project=Boogieman

Even the boogieman won't quite fit. You'd need to elevate the couch slightly, as it is 5" tall without feet.