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Old 16th January 2013, 08:30 PM   #21
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Quote:
Originally Posted by weltersys View Post
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 .

Art
Fair enough. "People" find the bass produced by the Bose Acoustimass 5 system to be "impressive", the cost is compariable, and most normal people would agree that they are very practical for use in a normal living area:

Click the image to open in full size.

Bose Acoustimass 5 Home Speaker System - Surround Speaker System ? Home Theater Speaker Systems
http://products.bose.com/pdf/custome.../og_am5iii.pdf
intellexual net m k i v

From what I can gather and calculate from the information available, the "sub" produces, roughly, at lowest extension and peak output, 109 db @ 1m 4pi @ 45hz. (when powered at the max rated input of 2 x 200w, given a 85 db/w/m/4pi sensitivity, -2db @ 45hz, not accounting for power compression, not sure if the drivers are being pushed to x-mech in that senario, but whatever)

So, figure a sustained sine wave output capablity of 106 db @ 1m 4pi @ 45hz.

Please note the unit's size is 14"H x 19"W x 7.5"D @ 18.8 lbs. That should not be taken as criteria, just a baseline as to what the public typically finds acceptable.

Feel free to make your own tradeoffs of performance vs. size, but you have to beat the bose overall. If you build a sub larger,
it should certainly have the performance to justify it - increase output 3db for each doubling of size or by a comparable improvement in extension.

Last edited by turbodawg; 16th January 2013 at 08:56 PM.
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Old 16th January 2013, 08:58 PM   #22
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Quote:
Originally Posted by turbodawg View Post
Fair enough. "People" find the bass produced by the Bose Acoustimass 5 system to be "impressive"..

From what I can gather and calculate from the information available, the "sub" produces, roughly, at lowest extension and peak output, 109 db @ 1m 4pi @ 45hz. (when powered at the max rated input of 2 x 200w, given a 85 db/w/m/4pi sensitivity, -2db @ 45hz, not accounting for power compression, not sure if the drivers are being pushed to x-mech in that senario, but whatever)

So, figure a sustained sine wave output capablity of 106 db @ 1m 4pi @ 45hz.

Please note the unit's size is 14"H x 19"W x 7.5"D @ 18.8 lbs. That should not be taken as criteria, just a baseline as to what the public typically finds acceptable.

Feel free to make your own tradeoffs of performance vs. size, but you have to beat the bose overall. If you build a sub larger, it should certainly have the performance to justify it - increase output 3db for each doubling of size or by a comparable improvement in extension.
If "People" find the bass produced by the Bose Acoustimass 5 system to be "impressive", they have never heard a real subwoofer .

I have heard them, and under every parameter you have referenced other than size, they are an epic FAIL.

Also, I seriously doubt that the two 5.25" speakers could sustain a sustained sine wave output at 106 dB for more than a few seconds without smoke emitting from the 6th order boombox port.

Although the Tub Sub can go an octave lower, and (at least) 6 dB louder with a tiny fraction of the power, it is 10.93 times larger (12.57 cubic feet compared to the toy sub 1.15 cubic feet).
If you want to penalize 3 dB for doubling of size, it would need to do 138.79 dB, that ain't going to happen for $500.

Does your OP sub pass the +3 dB per doubling of size parameter ?

Art

Last edited by weltersys; 16th January 2013 at 09:23 PM.
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Old 16th January 2013, 09:18 PM   #23
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Quote:
Originally Posted by weltersys View Post
If "People" find the bass produced by the Bose Acoustimass 5 system to be "impressive", they have never heard a real subwoofer .

I have heard them, and under every parameter you have referenced other than size, they are an epic FAIL.

Also, I seriously doubt that the two 5.25" speakers could sustain a sustained sine wave output at 106 dB for more than a few seconds without smoke emitting from the 6th order boombox port.
Well, you asked for criteria and I gave it to you. In summary:

- 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.

Last edited by turbodawg; 16th January 2013 at 09:23 PM.
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Old 16th January 2013, 09:27 PM   #24
lechuck is offline lechuck  Netherlands
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What is the time frame that you give us for building the sub?

I am currently gathering parts for a motional feedback subwoofer build to shake things up a bit at home. I have found a nice driver from Seas with a dual voice coil, I am planning to drive one voice coil and use the other coil for the feedback signal.

The parts and costs for my sub so far are:
10" Seas driver with dual voice coil (secondhand); 50 euro
18mm MDF for enclosure: 22 euro
8mm MDF for frontpanel: 8 euro
Screws and glue: 10 euro
cloth for frontpanel: 7 euro
20cm speaker cable: 0.20 euro
Amplifier parts (passive and active parts): 88 euro
Big heatsink: free :-)

The total money spend at the moment is 185.2 euro, or 247.28 dollar. I am still in doubt whether I want to spray paint the enclosure or use some nice wood veneer to match my speakers.
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Old 16th January 2013, 09:31 PM   #25
jbell is offline jbell  United States
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Quote:
Originally Posted by turbodawg View Post
- 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.
That's easy... the box size you state, ported to 40hz. Hits 109db in 4pi at 45hz @24v per driver

(2) mcm 55-2421 drivers - $30 each
(1) Yung 300w plate amp - $99

all done dirt cheap. Build a pair of them and enjoy.
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Old 16th January 2013, 09:51 PM   #26
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Quote:
Originally Posted by turbodawg View Post
Well, you asked for criteria and I gave it to you. In summary:

- 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.
Jbell's entry in post #25 appears to be the current winner by the new rules.
4pi is in my opinion, a poor way to rate subs, a perfect corner does not exist in reality.
Half space is the professional standard for rating subs.

You should repost the revised rules in your OP (you can edit OPs).

Sine waves contain 3 dB more power (3 dB crest factor) than an AES (6 dB crest factor compressed pink noise) rating, the Dayton Audio RSS390HO-4 15" Reference HO Subwoofer 4 Ohm you use in your entry handles 800 AES, which would be 400 watts sine wave.

You may want to delete your offering, a 4.5 cubic foot speaker with 87 dB sensitivity powered by 400 watts sine wave reaches 113 dB, but is 3.9 time larger than the Bose, so needs to do 117.74 dB .

Art
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Old 16th January 2013, 10:00 PM   #27
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Quote:
Originally Posted by weltersys View Post
Jbell's entry in post #25 appears to be the current winner by the new rules.
4pi is in my opinion, a poor way to rate subs, a perfect corner does not exist in reality.
Half space is the professional standard for rating subs.

You should repost the revised rules in your OP (you can edit OPs).

Sine waves contain 3 dB more power (3 dB crest factor) than an AES (6 dB crest factor compressed pink noise) rating, the Dayton Audio RSS390HO-4 15" Reference HO Subwoofer 4 Ohm you use in your entry handles 800 AES, which would be 400 watts sine wave.

You may want to delete your offering, a 4.5 cubic foot speaker with 87 dB sensitivity powered by 400 watts sine wave reaches 113 dB, but is 3.9 time larger than the Bose, so needs to do 117.74 dB .

Art
4pi space is full space, free air, anechoic.....

Criteria for doubling size twice or 4x is as I provided above:

Quote:
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.

Last edited by turbodawg; 16th January 2013 at 10:20 PM.
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Old 16th January 2013, 10:06 PM   #28
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45 Hz? Not much of a subwoofer. Also, it makes it easy to cheat.
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Old 16th January 2013, 10:15 PM   #29
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Quote:
Originally Posted by 454Casull View Post
45 Hz? Not much of a subwoofer. Also, it makes it easy to cheat.
There are plenty of horn subs that only get down to there or so, plus I provided the criteria for increasing size vs. extension.
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Old 16th January 2013, 10:18 PM   #30
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Quote:
Originally Posted by weltersys View Post
Sine waves contain 3 dB more power (3 dB crest factor) than an AES (6 dB crest factor compressed pink noise) rating, the Dayton Audio RSS390HO-4 15" Reference HO Subwoofer 4 Ohm you use in your entry handles 800 AES, which would be 400 watts sine wave.

You may want to delete your offering, a 4.5 cubic foot speaker with 87 dB sensitivity powered by 400 watts sine wave reaches 113 dB, but is 3.9 time larger than the Bose, so needs to do 117.74 dB .

Art
I think you'll find you're a bit off on the Dayton. Spec sheet calls for 800 wrms, not AES.

Dayton Audio RSS390HO-4 15" Reference HO Subwoofer 4 Ohm 295-469
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