Author Topic: LFO tick in audio path  (Read 1229 times)

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Offline goreTopic starter

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LFO tick in audio path
« on: February 01, 2016, 11:41:51 pm »
Hello. I'm having some trouble with this circuit. Everything seems to be functioning just fine, except there's an audible LFO tick in the audio path. Thinking of decoupling the power supply and separating LFO and signal grounds. Anything else I should keep in mind? Or perhaps there is another way of doing it? ???

Posting a schematic. The bottom one (2) is marked with changes I think of doing.
« Last Edit: February 01, 2016, 11:50:00 pm by gore »
 

Offline Andy Watson

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Re: LFO tick in audio path
« Reply #1 on: February 02, 2016, 12:03:55 am »
There is a sense in which you are mixing the LFO into your audio path - so you will always get a certain amount of feed-through - however, perhaps this is not the "tick" that is bothering you.

I would look at the biasing of Q2. It is being driven by the phase-shift oscillator - presumably at a few volts signal level ? The output of the oscillator is then A.C. coupled into Q2 - so the gate of Q2 will be swinging both positive and negative about ground potential. I believe Q2 is a JFET (?) in which case the gate will go into forward conduction when the signal swings positive with respect to its source pin - I think this is where your ticks are coming from. You need to move the biasing of Q2 such that gate does not conduct.
 


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