Xmax

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ICG

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Joined 2007
To chose a driver for a subwoofer, you have to have a look at how the manufacturer calculates the maximum excursion. Since the most manufacturers use a different calculation, you'll be much better off to use the purely mathematical calculation to chose a driver which is

(winding heigth - pole plate depth)/2

Since the human ear isn't very susceptible to distortion in the bass/sub-bass range, the actual usable excursion is a lot higher, it's still the most objective way to compare the excursion of drivers since most of the manufacturers got their own way to 'calculate' the maximum excursion.
 
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That TH design is 119 liters net (that's big for one 8" driver) and has a passband output at looks to be only 3dB or so more than the output of my "Boom Unit", which is a TL designed around that same driver, that takes up 26 l net and has a wider usable bandwidth with no 10dB out of band peaks to deal with. The "Boom Unit" serves as my multimedia subwoofer.

For HT use, if I had that amount of space available for my use, I'd go for a vented or TL design based on a larger driver, for more linear output capability.
 

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I do have room for a pair of -4cuft (115L) enclosures. I just don’t think I’ll get a pair of VBSS or Marty’s past my wife.

I’m open to suggestions for proven existing designs using lower cost drivers. Not too much over US$100 each preferably. Our currency is shot to bits at the moment.. Plywood and my time is cheap. A second hand Behringer dsp amp isn’t too hard to find either.
 
I do have room for a pair of -4cuft (115L) enclosures. I just don’t think I’ll get a pair of VBSS or Marty’s past my wife.

I’m open to suggestions for proven existing designs using lower cost drivers. Not too much over US$100 each preferably. Our currency is shot to bits at the moment.. Plywood and my time is cheap. A second hand Behringer dsp amp isn’t too hard to find either.


What about a pair of UM12-22 12", recommended box is

Vented 4.0 cubic ft. (net internal, not including driver or port volume) tuned to 20 Hz with a 10" wide by 1.5" high slot port that is 25" long, which yields an f3 of 19 Hz


They seem to fit the bill

 
Out of interest. How far off a flat response is it ok to go before it’s noticeable? See attached. I reduced the box volume by about 20 litres and the simulated response rose by less than one decibel.
 

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Have you seen WES has a new catalogue out, on SB Acoustics PA style drivers, there heaps of subs but being PA big boxes



What about a quintet of DA's SD270A-88 10" DVC Subwoofer 4 Ohm in sealed boxes about 33ltrs, one in each corner and still give you a 4 Ohm load... and a whole $115 ea!
 
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