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Old 1st February 2007, 12:31 AM   #1
chume1 is offline chume1  United States
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Default Help with Sub design

OK I'm a rookie at this... I've read and searched these boards for hours looking for a question close to mine with no luck so...

I'm trying to build to 15" subs. (they will be used with a surround sound system consisting of a center channel (2-8"s and 2 1"), two front satellites (5 and 1) and 2 10" rears...

I've loaded my parameters into WINSD PRO and the vented diagram looks awesome
Fs 29Hz
Qts .67
Qes .80
QMS 3.97
Vas 4.6
SD .0491M
SPL 90 dB 1W/1M
Xmax = 16mm

The problem I'm having is with the box size! It says it needs 21.46 ft3 with a 4" vent 1.81" long.

I've really only got 21" wide by 27" tall by 32" deep.

Can anyone help me with a box design? Also, any tips on crossing these over (what freq and how steep)

thanks alot,
Greg
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Old 1st February 2007, 01:08 PM   #2
Wizard of Kelts
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Vented boxes with a Qts over 0.5 usually are considered boomy and distort a lot. Some members have used some circuits to correct that, I haven't, so I thought I would let you know.

Fs = 29 Hz seems awful high for a 15 incher you'll be using as a sub.

Also, I believe your Sd should equal something near 0.08 sq M, not 0.049 sq M, which would seem to be the Sd of a 12 incher.

The Vas = 4.9, is that cubic feet?

Judging by the Thiele-Small parameters you gave, I am not sure this driver was meant to be used as a home theater sub at all. I think it would do nicely as the woofer in a large sealed enclosure of 5 cu ft or so.

If you loaded this speaker into your 10.5 cu ft enclosure, (that's what the dimensions you gave come to), sealed, you'd get some pretty decent bass, but probably not the depth you were hoping for. It wouldn't be bad, it just wouldn't be earth shatteringly great, either.

But if you came across this sub fairly cheap, it certainly would do pretty well until you came across something really big that could really pound. Your enclosure is so large, at some point you will probably want to get a different sub driver for it. But this won't do badly until then.
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Old 1st February 2007, 03:22 PM   #3
chume1 is offline chume1  United States
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Thanks for your reply!
I guess I should of said that I'm still in the planning stage. The dimensions I provided are really the sizes available in the entertainment/wall bookshelf I'm having built.

I also should of mentioned I was surfing ebay (as others on here have noted to do...) and I came across a pair of these VOLFENHAG ZX-4715 DVX for about $150 for a pair including shipping...

If you have a tip or recommendation for another sub that will hit hard low, I"M ALL EARS

I've really searched this board for tips, but it seems like volume drives most selections...

so, for my subs and center channels I'm really working with 32" of depth max, and 27" height max. I've got a little flexibility in width,

any suggestions would be greatly appreciated!
thanks
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Old 2nd February 2007, 04:41 AM   #4
Wizard of Kelts
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Subs? Are you planning on building one or two?

If you are planning on one, with a 10 cubic foot cab, here is one selection. It has been awhile since I built a sub, so I have not used this driver. But it seems to have the features you need, including a shorting ring, which is a very nice feature to have for a reflex sub.

Dayton Titanic 15".

I would put it in a 10 cu ft cabinet, tune the cab to 18 Hz, using a precision port flared 4 inch port 18.5 inches long. This will take you down to 18 Hz and pack quite a wallop.

There are other good 15 inchers around, including those by Adire, (whose Thiele Small parameters I cannot click on in the website), Stryke, and others. But if you are looking for a recommendation, understanding that I have not used this sub, I think this one should pack the kind of wallop you are looking for. So will the others I mentioned, for that matter. Those will be much more suitable than the Volfenhag you mentioned.
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Old 2nd February 2007, 02:13 PM   #5
chume1 is offline chume1  United States
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Thanks for your reply... I went and checked out those Daytons. They have some nice numbers... while there I also checked out some MTX thunder 5500.

I am building 2. So cost is a little factor too... The Dayton is about 33% more... any opinion on which?

thanks again!!!
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Old 2nd February 2007, 03:10 PM   #6
Wizard of Kelts
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I'll check the MTX numbers a little later.

But let me get this straight. You have room for two bass cabs, each 21" by 27" by 32". Is that correct?

That's 21 cu ft of volume, both cabs put together.

Will you be driving them with a sub amp, like Parts Express or Madisound sells, or with a conventional amp?

Also, will they be close to each other physically? Because if they are, you might consider buying one sub amp and having it drive both subs. Since those sub amps give their greatest power into 4 ohms, your best bet would be to parallel two 8 ohm speakers.

Just trying to get a feel for what you are trying to do.
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Old 2nd February 2007, 04:05 PM   #7
chume1 is offline chume1  United States
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Yes, I'm trying to build to separate subs each with ~21w x 27h x 32d. They are physically separated by about 80".

The entertainment center is supposed to be (starting from the left, this is the base of the entertainment center)


|--21" (sub)--|--21" (drawers) --|---42" (ctr chans)---|--21"(drawers) --|--21" (sub)--|

This base unit will be ~21+21+42+21+21=126" Wide x32" deep X 27" tall.

(I realize the center channels will be rather low (<27") but I'll have two satellites sitting above the subs on shelves (above the base unit will be 8' of shelves and stuff...)

Thanks again for your help!

I have an old receiver that i'll likely replace with a 5.1 type surround sound system. So, hopefully it'll power the subs, but I'm hoping to find a surround sound with just a preamp output for the subs. I think I still need to cross everything over (3 way) and after researching that, I'm thinking of going with an active device. thoughts???

thanks again!!!
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Old 2nd February 2007, 04:05 PM   #8
chume1 is offline chume1  United States
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I also forgot to ask about Dual Voice coil or Single Voice coil..

pros and cons?

For DVC I realize that if both are 4Ohms, i can series each sub to 8Ohms then paralell the 2 subs so that the AMP sees 4ohms (I'd like to get an amp that will run at 4ohms)

thanks
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Old 2nd February 2007, 06:44 PM   #9
hooha is offline hooha  Canada
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Stryke?
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Old 2nd February 2007, 07:30 PM   #10
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chume1,
If you want an amp that will run at 4 ohms (or even 2 ohms), look for an Aragon 4004 MK II.
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