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From: email@example.com (Glenn Gundlach)
Subject: Re: Filter carrier from subaudio?
Date: 10 Sep 2002 22:04:49 -0700
NNTP-Posting-Date: 11 Sep 2002 05:04:49 GMT
firstname.lastname@example.org wrote in message news:...
> I need to record subaudio waveforms onto a CD for input to a standard
> 20W stereo audio amp. The output will drive an inductive load. I plan
> to use CoolEdit wave synthesis software to generate an audio carrier
> modulated with the subaudio. The question is, what is the simplest way
> to get rid of the carrier frequency, say 5KHz, AFTER the audio amp
> stage? Thus leaving pure subaudio. Can I mix the subaudio and carrier
> in CoolEdit and then filter out the latter using a passive low pass
> network? Or, by recording two stereo channels differently, get the
> carrier to somehow cancel out by recombining after the amplifier. I am
> trying to avoid using a demodulator, if possible. Thanks for any
So how low 'subaudio' are you going? It seems to me you can record DC
on a CD. Numbers are numbers, aren't they? The playback DAC will need
to be DC coupled to pass this through, however. I know you can
generate down to around 1 Hz to 500Hz sweep in CoolEdit because I used
that as test input to an FFT filter to do -1db at 16Hz and -38 at
12Hz. Had subsonic junk in an organ recording. This sounds
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