| New Member from Spain
Hi there,
came across this forum when looking for a Behringer mic calibration file...Interesting stuff from the subwooofer tests, eh. Looks as though none of the subwoofers comply with the subwoofer accuracy requirements laid out by Fielder and Benjamin in their AES paper (as far as I can make out, anyway!). Those guys said high-level bass handling down to 15-16Hz is needed. The subs might be OK if you're getting a lot of low-frequency room gain?
Somebody could be interested in a sub I built for my Home Theatre setup. I bought a massive PA speaker - 400mm driver, cone travel half-inch each way, from an electronic junk shop, thought I'd make a good subwoofer out of it - measured the Ts parameters, Fs 24 Hz, Qts 0.16...ah well, I thought, not a whole heap of use. Anyway I played around with my speaker CAD program and came up with a double-tuned bandpass enclosure - rear enclosure 20 cu ft tuned to 12 Hz, front enclosure 1.5 cu ft tuned to 51 Hz. The sub's -3dB points are 12Hz and 120Hz, and it's flat in between. I've measured it in the room, and it can produce 105dB at 15Hz (it's quite hard to hear this, funnily enough). The ports are wide (6" diameter), but you can hear a bit of chuffing at 15 Hz at this level. The sub fits across the room and functions as my TV stand/home theatre platform, so it's pretty unobtrusive despite its size. Transient response isn't great (like all bandpass enclosures) but helicopters and dinosaurs sound awesome.
I'm trying to calibrate a sound card at the moment - it's a Hercules Fortissimo II. At one time I managed to get a -0.2 + 0.1 from 20Hz to 20kHz, but now I can't get better than +- 4dB from 20Hz to 20 kHz. Don't know what I'm doing wrong - I'm using RMAA with a loopback cable, with all effects turned off. Thinking of buying an EMU 1212M, but I'm a bit bloody-minded and would like to get the Fortissimo working properly...
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05-10-07, 04:09 PM
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