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DIY sub - 2nd try ... want do it right this time!

post #1 of 4
Thread Starter 
Hello folks,

long time member, mostly a lurker ...

I built a roughly 3 cu ft closed sub for my NHT 1259 driver, only to find out after a couple hours of searching I had never bought one. Haha, I know, dumb! But I obught a lot of drivers and then let them sit for 4 or 5 years before I started building things.

Anyway, I had a 10 inch driver instead. It's stamped "Acoustic Research ARW 250 S-CPS 4140 I" and according to the seller has the follwoing TS parameters:

Fs - 31.64hz
Re - 3.5 ohms
Qes - .3
Qms - 6.39
Qts - .29
Mms - 55.86 grams
Cms - .45 mm/N
Vas - 75.18 liters
BL - 11.41 N/A
L @ 1K - 1.97 mH
L @ 10K - .81 mH
Diameter - 209.5 mm
Sd - 342.98 sq.cm
Vd - .206 liters
Xmax - 6 mm
X mech - 9 mm
Rms - 1.749 kg/s
SPL - 1 watt/1 meters SPL of 90dB, and 2.83 Volt/1 meter output of 94dB

Having already built the standard enclosure for a different driver I just slapped this one inside and lived with it. I didn't know much about speaker building and had no test equipment or anything at the time. It sounds decent, but I have no reference to judge it against.

Fast Forward 4 or 5 more years to today.

Now I want to do it right and make a second sub using the other AR 10-inch driver I bought originally. Using BassBox or similar it seems my original sub has an F3 of around 80 Hz. Maybe I'm missing something (and I don't mean whatever is from 20-60 Hz!!!), but again the sub sounds decent enough.

I've played around a little and can get an F3 of right around 29 Hz with 2 or 3 inch port(s) and 2.5 to 3.5 cu ft internal volume. I figure I'll build another cube and see how it compares. If it is as different as I am hoping I think I can just go back and add similar port(s) to the first sub I made.

Note: I just got the DATS system from Parts-Express, but haven't really figured it out yet. it could be the TS parameters are wrong or something.

I have a few questions if there is anybody kind enough to help I'd really appreciate it:

(a) Does 29Hz-ish make sense. The port(s) is(are) tuned to somewhere between 25 and 30 Hz from what I remember. Or does it sound like I'm way off track somehow?

(b) Cube vs rectangular box? Does it matter? S/W likes to make a "tower", I'd rather have something shorter, maybe laying on it's side or a cube.

(c) Port(s): back or front? Does it matter?

(d) Do I need a high pass filter (at 15 or 20 Hz maybe)? BassBox showed an option for an active HPF where I could get down to an F3 of 22Hz pretty easily with a 3-ish cu ft enclosure, but that might be a topic of it's own.
post #2 of 4
Thread Starter 
Original DIY sub along with extreme redneck open baffle version on left. That's the 2nd driver I want to give a nice new home!

post #3 of 4
a. seems reasonable.
b. doesn't matter
c. doesn't matter much
d. for a ported enclosure that will get lots of power for home theater, a high pass should be used
post #4 of 4
Thread Starter 
Cool, thanks for the advice/sanity check!
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