[sdiy] DIY TR909 : noise !

[Jörg Schmitz]

Hi all !

at last I have managed to built my own TR909 - bass drum pcb. It works prettty well (see http://www.analog-synth.de/synths/tr909/tr909.htm for details), but I found one problem :
the output is a bit noisy. You can hear a little hissing noise, which seems to correspond to the envelope and therefore VCA activity of the VCA between the output amplifier and distortion diodes (controlled by "decay").

What would you suggest to eliminate that (not very loud) noise ? (Of course, this is not the noise of the noise generator, bleeding through somehow, this is tested...)
Another opamp for the output-amplifier ? Something better than the TL072 ? Something better than the BC549 for the VCA's ?

cheers, Joerg
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