In case this helps someone at @FractalAudio comment on this, here's a waveform along with a spectrum analysis on the whining sound. The way I produced this:
1. Put two FET boosts in series, directly from input to output,
2. maxed out drive, tone and level (on both),
3. set noise gate threshold at -100dB,
4. had nothing plugged in,
5. engaged preset select mode, and
6. recorded the output with the s/pdif output. (I checked, and the same happens with the analog output also, unsurprisingly.)
First off, you can clearly see that the envelope is very "well behaved" and follows the led blinking frequency.
Second, you can clearly see a peak of about 24 dB above the noise floor at 4,8 kHz, and also a clear second harmonic at 9,6 kHz (about 12dB). You can also see a bit of the third and fourth harmonic also, and a bit of a subharmonic.
The peak being at 1/10th of the sample rate makes me curious, but I guess there could be something else running at that rate also...
1. Put two FET boosts in series, directly from input to output,
2. maxed out drive, tone and level (on both),
3. set noise gate threshold at -100dB,
4. had nothing plugged in,
5. engaged preset select mode, and
6. recorded the output with the s/pdif output. (I checked, and the same happens with the analog output also, unsurprisingly.)
First off, you can clearly see that the envelope is very "well behaved" and follows the led blinking frequency.
Second, you can clearly see a peak of about 24 dB above the noise floor at 4,8 kHz, and also a clear second harmonic at 9,6 kHz (about 12dB). You can also see a bit of the third and fourth harmonic also, and a bit of a subharmonic.
The peak being at 1/10th of the sample rate makes me curious, but I guess there could be something else running at that rate also...
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