Soundcard with 3rd octave eq

On a sunny day (Wed, 27 Jan 2010 17:51:46 +0000) it happened Dirk Bruere at NeoPax wrote in :

Waht do you mean by 'third octav/". Most soundcard equalizers are done in software.

That means you can probably add whatever you want... ?

Thanks. The problem is that my application cannot be the one that actually plays the audio. That would be something like WMP, Zoom, PowerDVD etc. I need the s/w to fit between those apps and the output of the sound card.

On a sunny day (Wed, 27 Jan 2010 21:43:44 +0000) it happened Dirk Bruere at NeoPax wrote in :

Well that is exactly what xpequ can do, I am using it with 2 sound cards. One digitises the sound, feeds it to the xpequ equaliser (and AGC), and xpequ outputs it via the other soundcard. There is a real time delay (latency), can be used for echo :-) I have not bothered to see if I could decrease that delay. It is likely related to the soundcard buffer sizes.

Any idea how long the delay is?

On a sunny day (Thu, 28 Jan 2010 10:34:51 +0000) it happened Dirk Bruere at NeoPax wrote in :

From 10 or so milli seconds to maybe a hundred, sounds like a real echo. There is one issue with this, if you use 2 sound cards, each with their own crystal, you get irregularities if for example data is read faster (say at 44100) then written (also at 44100). If you have a sound card with multiple channels on it, running from the same crystal, it should be OK though. At least this is my theory of what happens, may well be wrong...

For example I have a Creative 32 PCI, and a Soundblaster Live. The Live resamples everything, and has 2 channels, I think on the same clock. I have seen problems using the SB PCI32 as input and the SB Live as output.

IIRC I could send from one channel of the SB live to the other, but thanks to Alsa sound system now installed and replacing OSS sound drivers this no longer seems to work. I had /dev/dsp0 (PCI32) and /dev/dsp1 and /dev/dsp2 (SB Live), and now Alsa no longer seems to see the second dsp device on the Live. So to make a long story short, it may or may not work reliable on your system. Of course it will always work reliable when playing from a wave or mp3 file.

I just tested some things, nice echo bathroom sound if I feed output of both sound cards to a speaker... xpequ -u plughw:0,0 -t plughw:1,0 (PCI32 via equaliser to SB Live). But this way I get an alsa buffer overflow after a while.

That seems to depend on system load too, been running OK now for 10 minutes. So YMMV. Of course you could make a hardware equaliser too :-)

crystal,

written (also at 44100).

crystal, it should be OK though.

Alsa sound system

sound cards to a speaker...

We already buy in a h/w EQ at $300 a shot. A piece of shit as it turns out, but the only game in town so far. Hence the desire for a s/w replacement to run under XP. Even so, if I could get a DSP board that would do 3rd octave, hold 20 presets and be controllable over a LAN (even via ethernet/USB/RS232), SPDIF to SPDIF I'd buy it like a shot for the same price.

Bruere at

echo.

their own crystal,

the same crystal, it should be OK though.

clock.

output.

thanks to Alsa sound system

work.

system.

file.

of both sound cards to a speaker...

minutes.

I would be VERY surprised to get a 1/3 active EQ that actually works = right for less than $1000, used. Do you really need real-time EQ? Does it really need to be 1/3 octave?

less than $1000, used.

Depending on what you are trying to achieve, but in some cases a parametric EQ might be a more suitable alternative.