Under Couch Subwoofer?

[GO-NAD!]

I had been posting my initial inquiries in Annunaki's In-wall Sub thread, but I feel like I've hijacked it, with all my badgering about my own desires. My apologies to all!

Anyway, I got approval to proceed with a DIY sub! Getting a subwoofer out of sight was the deal sealer. I looked at infinite baffle designs, as suggested by Highbar, and thought an in-ceiling would be perfect. Then, I thought about the neighbours and the potential for becoming the neighbourhood leper, due to the noise eminating from my attic. So, back to an enclosed & ported design. Then, I thought about all the work required to not only build the enclosure, but installing it in the attic or wall (whichever way I decided to go). That's a lot more time that I just don't have.

So, now I'm thinking of building a free-standing subwoofer that would slide under the couch. I wonder if those JL Audio 8W1v2's would fit in such an enclosure? I'll measure the available space under my couch when I get home. The approval I received hinged on the sub "disappearing". I just wonder if sitting under a couch would muffle the sound somewhat.

There's also the "Boogieman" design, from Parts Express. Has anybody here built this one? The only parameter I've found for it is a Fb of 29 Hz. The sub I want to build will be for music only, in a 2.1 system. So, it doesn't have to have extremely deep extension. I'd just like low distortion, respectably flat FR down to 29-30 Hz and a healthy output. Any ideas?

The enclosure will be cheap to build, so I wonder if I should get drivers that could be installed in-wall or in-ceiling, sometime in the future, if I don't like the under-couch design...

Sorry if it seems like I'm rambling. I guess I'm just thinking out loud...

 

[j_garcia]

If you are going to put it under the couch, why not just get bass shakers and attach them to the couch instead? No enclosure needed, and they will easily cover the range you are looking for. Your mains would need to cover down low enough that you aren't missing the upper limits of that range. You could also consider behind the couch with a tall/slim design.

It will muffle the sound to some extent, whether you face them up or down, but in the lowest range it will be less of an issue.

 

[GO-NAD!]

If you are going to put it under the couch, why not just get bass shakers and attach them to the couch instead? No enclosure needed, and they will easily cover the range you are looking for. Your mains would need to cover down low enough that you aren't missing the upper limits of that range. You could also consider behind the couch with a tall/slim design.

It will muffle the sound to some extent, whether you face them up or down, but in the lowest range it will be less of an issue.

I thought bass shakers were for inducing vibrations into the seat? Correct me if I'm wrong. I want a sub for music, not speacial effects. Besides, I want a project to build. I just wanna build a sub!! Not that I have lots of time on my hands...but that's a different matter altogether...

Actually, when I measured under the couch, I found that there is only 5" of vertical space. I don't think I can fit anything under there. I guess I have no choice, but to go in-wall or in-ceiling. I'll just have to take the hit in the extra time required.

You may be onto something there about a design that would fit vertically behind the couch. Hmmm, anybody know of such a design and how much space would be needed between the couch and the wall? I just wonder if that would put the drivers too close to anybody sitting on the couch...?

 

[Davemcc]

I honestly don't know the difference between home subs and car subs but I just picked up a Rockford sub for my truck that's only 3-1/2" mounting depth. That would definitely fit under or behind the couch in a reasonably slim box.

 

[Swerd]

There's also the "Boogieman" design, from Parts Express. Has anybody here built this one? The only parameter I've found for it is a Fb of 29 Hz. The sub I want to build will be for music only, in a 2.1 system. So, it doesn't have to have extremely deep extension. I'd just like low distortion, respectably flat FR down to 29-30 Hz and a healthy output. Any ideas?

The enclosure will be cheap to build, so I wonder if I should get drivers that could be installed in-wall or in-ceiling, sometime in the future, if I don't like the under-couch design...

Although I haven't heard a Boogieman, I have heard other speaker and subwoofer designs by Darren Kuzma. He understands what he is doing, and I would trust his designs. In general, I am skeptical of the published performance of Tang Band drivers, most of them are exaggerated. But if Darren Kuzma says the TB 6½" sub is a good driver, then I wouldn't worry.

The Dayton RS series of aluminum drivers that Parts Express sells, which are excellent for the price, are the best example of Darren's expertise and efforts while he was at PE.

I don't know of any other published design of an under-the-sofa subwoofer. If the price is right for you, I'd go for it.

 

[j_garcia]

I thought bass shakers were for inducing vibrations into the seat? Correct me if I'm wrong. I want a sub for music, not speacial effects. Besides, I want a project to build. I just wanna build a sub!! Not that I have lots of time on my hands...but that's a different matter altogether...

Actually, when I measured under the couch, I found that there is only 5" of vertical space. I don't think I can fit anything under there. I guess I have no choice, but to go in-wall or in-ceiling. I'll just have to take the hit in the extra time required.

You may be onto something there about a design that would fit vertically behind the couch. Hmmm, anybody know of such a design and how much space would be needed between the couch and the wall? I just wonder if that would put the drivers too close to anybody sitting on the couch...?

Bass shakers are for filling out the bottom octave, much of which is percieved as vibration. If you ran your speakers large and they go low enough, you could get away with this setup without a sub, though the setup and wiring is similar to a sub.

For behind the couch, you would still be blocking the sub in some way, so you will lose some of the sound. Depending on whether or not your couch is flat or angled at the back, you could pretty much come up with anything that fits back there.

 

[njedpx3]

Can you do in-wall ?

There are some great in-wall subs. You didn't say what your bufdget was, but an ultimate in-wall speaker is the the JL Audio IWS Fathom, but it costs $2,200.

The PSB CSW10 in-wall sub is $2,100
http://www.psbspeakers.com/products/In-Wall-In-Ceiling-Speakers/CWS10-In-Wall-Subwoofer
http://www.audiophileliquidator.net/index.php?manufacturers_id=34&sort=&filter_id=37

Here is a more affordable solution but it is passive ( you need an external amp) JBL HTI-88 - HTi Series Dual 8" In-Wall Passive Subwoofer

http://www.jr.com/jbl-hti88/pe/JBL_HTI88/



Good Luck!

Forest Man


P.S.- A SVS PB12-Plus would make a good end table

 

[GO-NAD!]

Bass shakers are for filling out the bottom octave, much of which is percieved as vibration. If you ran your speakers large and they go low enough, you could get away with this setup without a sub, though the setup and wiring is similar to a sub.

For behind the couch, you would still be blocking the sub in some way, so you will lose some of the sound. Depending on whether or not your couch is flat or angled at the back, you could pretty much come up with anything that fits back there.

I don't think I need a bass shaker then.

I suppose I should amplify my requirements a bit. This is a 2.1 system and I have bookshelf speakers and a subwoofer. They are supplied from a 2 -channel integrated amp - no crossover.

I'd like to do a DIY sub to replace the present model. The justification that passed WAF was making a sub that would "disappear". My original idea was to go with an in-wall design, similar to the one in Annunaki's thread. Then, I thought about going in-ceiling instead. I really like the concept of the infinite baffle, but I don't want to annoy my neighbours with bass thumping from my attic. I suppose I could drag my sub up into the attic and see how loud it is, but I'm not sure it'll fit through ceiling hatch. Then, I thought of the extra work required to install it in a wall/ceiling.

That is what prompted my inquiries about a sub to fit under my couch. But, when I measured the space, I figured that it was too low to accept any design.

I'm now wondering about a design to fit behind the couch. Maybe a trapezoid shape, with 2 down-firing 8" drivers (or 4 x 6 inchers?). The angle of the back may allow the sub to be wider on the bottom, tapering towards the top. I'll have to take some measurements to see what the maximum space would be, behind the couch. I won't be able to drag it out too far, as it'll strain the WAF. I'll post the measurements of that space later.

I repeat, this is for music only! I do not need to shake the foundation! If it has a nice flat FR down to 28 - 30Hz, low distortion and good output, that's what I want. I want accuracy. I do not want the thumping that I hear from some cars these days!

If I can't find a design that meets those parameters and can go behind my couch, it's back to the in-wall/in-ceiling route. Oh, and I want to build it myself. The budget is $500-$600.

Thanks for all the suggestions! Keep 'em coming!

 

[GO-NAD!]

Nope, I won't be able to put anything behind the couch. The back is straight and I'd have to pull it out from the wall too far to be acceptable. So, I guess I'll do the extra work and go in-wall or in-ceiling. Oh well, that'll just make it more of a challenge.

 

[GO-NAD!]

Alright, I just got some clarification on which way to go: "I don't want anything in my walls!", makes in-ceiling the default location. I guess I'll start a new thread now soliciting some advice for that. Man, I'm such a pest...

 

[j_garcia]

What kind of floor do you have? You can do it in a sub floor and use a register vent so it looks completely stealth.

 

[Nemo128]

Look at the Earthquake SWS12.

 

[GO-NAD!]

What kind of floor do you have? You can do it in a sub floor and use a register vent so it looks completely stealth.

I thought about that. But, it's a hardwood floor and the thought of cutting a hole, or holes in it fills me with dread. I prefer in-ceiling because placement will be much more flexible and if I need to remove the sub (for whatever reason), I can patch a ceiling hole so that you would never have known it was there. I don't think it would be that easy in a hardwood floor.

 

[annunaki]

What are the other dimensions for the under couch option? The 10W1v2 will fit in there if designed correctly!

I just need to know how much volume we are looking at. Don't give up so easily!

The mounting depth on the 10W1v2 is only 4.34". If you can at some point under the couch squeeze an extra .25"-.50" You could get one under there.

With a 1.9ft^3 enclosure tuned to 24hz you would have an anechoic f3 of 24hz. You can go as small as 1.5ft^3 net volume vented with this driver, but the vent starts to get long.

It will all depend on the amount of total volume you can get out of the underside of your couch. Just an option.

 

[GO-NAD!]

What are the other dimensions for the under couch option? The 10W1v2 will fit in there if designed correctly!

I just need to know how much volume we are looking at. Don't give up so easily!

The mounting depth on the 10W1v2 is only 4.34". If you can at some point under the couch squeeze an extra .25"-.50" You could get one under there.

With a 1.9ft^3 enclosure tuned to 24hz you would have an anechoic f3 of 24hz. You can go as small as 1.5ft^3 net volume vented with this driver, but the vent starts to get long.

It will all depend on the amount of total volume you can get out of the underside of your couch. Just an option.

Guess what! I'm a dunderhead! I had measured to the floor from the bottom of the couch's perimeter frame, which is actually about 5 1/2", after I measured it again. But, the really positive news is that inside that perimeter frame, there's about 7" of usable vertical height! That perimeter frame is divided into 3 "bays" by 2 cross members. I can fit a box of 7" x 27" x 20" in each of the bays. That would give an inch or so of clearance around the box. However, that 7" does not include feet, so the height of the enclosure would have to be reduced accordingly.

I could make more space, if needed, by removing the cross members and spacing them further apart in order to create a larger bay. I don't think I'd want to remove them completely, as I wouldn't want to weaken the frame that much.

I'm concerned about imaging and having the sub so far from the mains. The imaging is not good right now, which is something I hope to improve with a new setup. Would the DCX help in that regard, by attenuating that standing wave issue that I have right now, regardless of sub placement?

 

[GO-NAD!]

Oh, and one more question. The couch in question has a "skirt" around the bottom, same material as the upholstery. It hangs down to about 1" from the floor. Is that going to muffle the sound. The SQ of this sub is going to be important to me, so I'd like to be sure. Then again, since I'm building the enclosure myself, it'll be cheap to make. If it doesn't sound right, I can tear it all apart and do an in-ceiling sub. Wouldn't want to go through all that work for nothing though...

 

[annunaki]

How many bays? What is the height between the bays with the bracing? 5"?

If you could string the two bays together for air, we would have around 2.5ft^3+ for net volume to work with.

This would open up some potential options.

 

[GO-NAD!]

How many bays? What is the height between the bays with the bracing? 5"?

If you could string the two bays together for air, we would have around 2.5ft^3+ for net volume to work with.

This would open up some potential options.

There are 3 bays inside the perimeter frame, the bays are created by the 2 crossmembers. The usable height from the floor to the underside of the "springy part" (hey, I'm not a couch expert!) is 7". I say usable height, because I'm allowing a bit of space for the couch to settle lower when somebody sits on it. Each bay is approximately square in shape. I could probably spread the placement of the crossmembers, within the frame, a few inches further apart, but I don't think I could remove one completely. I'll have to check to ensure that the crossmembers aren't also supporting the "springy part". That might complicate matters.

What I should do, is post a photo of the underside of the couch, as it will give you a better idea of what I'm trying to describe. I'll do that latter today. Oh, and did you get a chance to read my last post regarding the skirt around the base of the couch...?

 

[GO-NAD!]

Here is a quick and dirty sketch of something that just entered my head. It would require no modifications to the couch. The centre section of the enclosure could be 5 1/2" high, outside dimensions and the 2 "wings" would be about 3 1/2 inches high, outside dimensions. which would give me space for 1 1/2" enclosure feet. Is that enough distance from the floor for a downfiring sub? The whole enclosure could be about 60" wide by 24" deep. I calculate about 2 cubic feet for inside volume, but that does not take bracing or damping material into account. The section housing the driver could also be offset to either end. That would make constuction slightly simpler and I'm guessing that venting would be easier to integrate that way as well. How does the concept look? I may be able to add a few inches to the width and depth of the enclosure, but I'll double heck that later.

 

[annunaki]

Can you post a rough sketch up of the under couch framing? Both a side and an overhead profile? Or, get some photos of the couch's underside?

I would like to see what we have there. We need to maximize as much volume as possible. It may require a slightly more complicated build but realize better results.