$500 DIY Subwoofer Challenge!

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Here is a challenge for the "best" subwoofer you can build for $500, total, including driver(s), amp, crossover/electronics, wood, cables and hardware needed to get it completely operational with a normal stereo/home theater system. Assume the builder has all normal tools needed for speaker building. If your design requires PEQ or time correction to the mains (such as with a horn), the electronics for that is part of the $500 budget. Prices should include shipping, local taxes, and be your actual local costs for goods. If your cost are much higher locally, note that or adjust accordingly.

Clearly there is no best design because everybody's needs are different, but the baseline design goals here should be a music/ht sub with good extension (below 30hz) and output for a moderately sized room.

Since this a practical challenge, the winner will be the best all around design - considering performance, practicality, and form. There are no specific perfomance criteria except it must provide impressive, accurate bass for ht and music in a normal sized living room. This should be a project that a novice DIY'er should be able to build with a high degree of confidence that it will work well and look good.

See here for more guidance: http://www.diyaudio.com/forums/subwoofers/227541-500-diy-subwoofer-challenge-3.html#post3328955

- Sine wave output capablity of 106 db @ 1m 4pi @ 45hz
- Reference size of 14"H x 19"W x 7.5"D @ 18.8 lbs
- For each doubling of size, increase output 3db or improve low extension by 1/2 octave

Thus, if you were to double size twice to build a sub 75lb & 14"x19"x30", it should be capable of 109 db 1m 4pi @ 34 hz or 112 db 1m 4pi @ 45 hz or 106 db 1m 4pi @ 22 hz.


I'll start:

15" Dayton Reference HO RSS390HO-4, $150 on sale PE
Behringer NU1000DSP $258
3/4" birch 5-ply sheet $45
Drywall screws $6
Wood glue $6
Paint $5
Roofing mastic $10
Speakon connectors qty 2 $10
10 ft speaker cable $8
RCA to TS adapter $2

Total $500

Model response in WinISD or Hornresp to find prefered tuning. Should be roughly 3.5 to 4.5 cubes tuned to ~20hz. Use one slot port with less than 6:1 aspect ratio and flared ends, area at least 30 sq inches, 45's with any bends. Build with birch ply, brace as desired. Internally coat with roofing mastic. Setup with nu1000dsp amp in bridged mode (~700 wrms @ 4 ohm), set HP filter to avoid over excursion, low pass, EQ, time delay as desired.

Should be quite powerful in most living rooms and sound excellent, this will beat pretty much any pre-built sub under $1000 in output and SQ. Enjoy!
 
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Just wondering if material costs should be local or standardized somehow, birch ply can be silly expensive here. Material cost will be a big variation pending on where in the world you are.

Feel free to go by your own local material, component and shipping costs, or adjust accordingly!

Keep in mind I'm spec'ing cheap 5-ply birch from home depot, not baltic birch. I prefer the 5-ply because it's cheaper, a hair lighter, and stiffer, IMHO, at the expense of a few voids and not being as nice to work with. MUCH lighter and stiffer than MDF.
 
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Since cheating is OK, stealing must be too: Mine is also in a 4 cu ft box:


Infinity 1260 12" woofer $59
Acoustic Elegance PR-15 700 $60
Behringer NU1000DSP $258
3/4" birch 5-ply sheet $45
Drywall screws $6
Wood glue $6
Paint $5
Roofing mastic $10
Speakon connectors qty 2 $10
10 ft speaker cable $8
RCA to TS adapter $2
--------------------------------
$469!
 
Here is a challenge for the "best" subwoofer you can build for $500, total, including driver(s), amp, crossover/electronics, wood, cables and hardware needed to get it completely operational with a normal stereo/home theater system. Assume the builder has all normal tools needed for speaker building. If your design requires PEQ or time correction to the mains (such as with a horn), the electronics for that is part of the $500 budget. Prices should include shipping, local taxes, and be your actual local costs for goods. If your cost are much higher locally, note that or adjust accordingly.

Clearly there is no best design because everybody's needs are different, but the baseline design goals here should be a music/ht sub with good extension (below 30hz) and output for a moderately sized room.

Should be quite powerful in most living rooms and sound excellent, this will beat pretty much any pre-built sub under $1000 in output and SQ. Enjoy!
Lacking an actual specification to achieve, ie "X dB +/- 3 dB from 30 to 100 Hz" there is no way to judge the winner of your challenge.
Horns can be quite impressive even without time correction, though integration can be better with.

I built a very cheap, decent sounding, reasonably loud, very efficient sub for a lot less than $500. The efficiency opens up many low power (cheap) amplifier options.
The "Tub Sub" was designed to fit in the space that was available between a hot tub and the building wall. Two layers of grill cloth and Duratex paint make it weather proof. The shape would also lend itself to fitting behind a couch or under a bed.

$10 Two 10" speakers, on sale from Parts Express, PE # 299-284 (sold out)
$100 Sub output from used Technics SA EX600 receiver
$90 Two sheets 3/4" Aruco 5-ply sheet
$10 Drywall screws
$10 Wood glue
$20 Paint
$15 Grille cloth
$10 1/4" female connector and plate
$10 Ten foot 1/4" speaker cord
$5 On off switch and plate
$280 total, or $180 considering the Technics sub output was already there when the project was started.

The tapped horn Tub Sub uses two $5 buyout Sammi 10" speakers.
It's sensitivity is 99 dB one watt one meter in half space at 60 Hz (open field) but located against the wall behind the hot tub, 24 Hz is only 3 dB down from 60 Hz, with a "loudness contour" peak at 40 Hz.

The cheapo 30 watt 8 ohm Sammi's are wired in series, 12 volts (about 10 watts into 16 ohms) will hit their 4mm Xmax, doing about 114 dB in half space at that level.
They are wired in series so that the receiver's sub output can also drive the home theater and kitchen sub at the same time without overheating.
The good thing about the speakers is when pushed hard (that would be around 60 watts for the pair), they do not have enough magnetic fource to make them clack or flap.

Although I would prefer to time align the subs, as you can see by the Tub Sub with left and right 2x8T speaker's FR charts, other than a dip around 130 Hz the integration is not terrible. A lot of the peaks and dips are due to the mic placement at ear level instead of ground plane.
IIRC, the top speakers built for the deck integrate a little better, but I lost the files.

If this sub used "real" speakers, it could do some serious damage.
As it is, with about 10 watts driving them I can clearly hear bass lines at my southern neighbor's property line about 800 feet distant from the deck location.
Not bad for $10 in drivers ;^).

Art
 

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Art, that's totally awesome, but tough to say it's the best for all around use....!
In your opinion, what makes a sub "best" for "all around use" ?

You wrote in the OP:
"The baseline design goals here should be a music/ht sub with good extension (below 30hz) and output for a moderately sized room."

The Tub Sub certainly meets those goals, though "a moderately sized room" is as ambiguous as "good extension".
There are many that would consider 700 square feet to be a moderately sized room.

I have a 700 square foot (total) house with 6 rooms, the only room the tub sub would not fit in easily has a tub and a toilet ;).

Art
 
Since cheating is OK, stealing must be too: Mine is also in a 4 cu ft box:


Infinity 1260 12" woofer $59
Acoustic Elegance PR-15 700 $60
Behringer NU1000DSP $258
3/4" birch 5-ply sheet $45
Drywall screws $6
Wood glue $6
Paint $5
Roofing mastic $10
Speakon connectors qty 2 $10
10 ft speaker cable $8
RCA to TS adapter $2
--------------------------------
$469!

Hehe - I'd swap that Infinity driver out for the Dayton DVC310-88 and use a shelf vent instead of the PR to save that extra $60. The DVC310 can move some serious air (I used to own the Shiva Mk1 on which it is based) and it will utterly spank that 1260 if given the chance (the suspension on those Infinities starts applying the brakes well before you think they should - probably to protect those drivers from overzealous car audio boomers - not so with the DVC310!).
 
Hehe - I'd swap that Infinity driver out for the Dayton DVC310-88 and use a shelf vent instead of the PR to save that extra $60. The DVC310 can move some serious air (I used to own the Shiva Mk1 on which it is based) and it will utterly spank that 1260 if given the chance (the suspension on those Infinities starts applying the brakes well before you think they should - probably to protect those drivers from overzealous car audio boomers - not so with the DVC310!).

Sounds good, that takes the price up to $473.85.
 
I'm pretty sure my build on the Dayton ref 18" sealed sub, with mini dsp and a 1500 watt qsc amp was right around $500.
The Dayton RSS460HO-4 18" Reference driver (out of stock, due 1/15/13) is listed for $249.76 at Parts Express.

A QSC MX1500 goes for about $295.00, it would appear that combo alone would cost over $500 before adding a MiniDSP and the DIY part, a cabinet.
 
Yeah I know :D

I said my build lol I got the amp for $100 and replaced the scratchy pots with new parts from QSC for $20 and the two sheets of Baltic for $56 each then the mini DSP for $125 to EQ flat down to right around 20hz.

So for HT I think the $600 (500 is close enough :p) challenge is pretty spot on in my case ! I'm sure as hell enjoying it
 
Yeah I know :D

I said my build lol I got the amp for $100 and replaced the scratchy pots with new parts from QSC for $20 and the two sheets of Baltic for $56 each then the mini DSP for $125 to EQ flat down to right around 20hz.

So for HT I think the $600 (500 is close enough :p) challenge is pretty spot on in my case ! I'm sure as hell enjoying it

Well, if you want to talk actual costs, I just put together a nice sub using an old B&W 801 bass cabinet and a Craig's List car woofer (MB Quart PWH302) for a total cost of...$75. I plan on adding a granite top, but I bet I still come in under $100.
 
How are you going to determine the winner?

Flattest frequency response?

Average SPL over frequency ? (10hz - 80hz)

Lowest distortion?

I've added the following to the first post:

Since this a practical challenge, the winner will be the best all around design - considering performance, practicality, and form. There are no specific perfomance criteria except it must provide impressive, accurate bass for ht and music in a normal sized living room. This should be a project that a novice DIY'er should be able to build with a high degree of confidence that it will work well and look good.

Say that your friend, Normal Guy Joe, wants you to build him a sub o use in his family room. You will have to decide where practicality trades off with performance......
 
I've added the following to the first post:

There are no specific perfomance criteria except it must provide impressive, accurate bass for ht and music in a normal sized living room.

Say that your friend, Normal Guy Joe, wants you to build him a sub o use in his family room. You will have to decide where practicality trades off with performance......
Turbodawg,
"Impressive" is a useless metric for describing a sub.
"Accurate" is hearsay without frequency response (and some would argue, distortion) measurements.
"Practicality" is meaningless without some size limit.

My home theater uses a pair of Pioneer 12" woofers (under $50 used) in a 28" x 20" x 19" sealed enclosure made from a 2" thick particle board door found in an alley.
My girlfriend and I have often been "impressed" by LF sound effects in movies that the sub does, yet it is only capable of around 105 dB before distortion is objectionable.

The Tub Sub in post #8 can do 114 dB at 40 Hz using only 15 watts or so with distortion under 10%.
If 105 dB is "impressive", is 114 dB "supercalifragilisticexpialidocious" ;) ?

Seriously, put in a "X dB at X frequency, or this thread is useless- otherwise the next post could be a speaker mounted on an open baffle that is actually capable of only an "impressive" 75 dB at 40 Hz :rolleyes:.

Art
 
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