[quote author="mik"]ok Milan, I ' ve to coupled R1, R2 with 1µF cap, then flip verticaly ic 2 (
) R9 , R10 100 or 120 ohm ( I guess ) arrangement around K3 is too complex..... ?im looking for some thing for avoid pop 'n tik wen switch on it..
R4,R12 network : are you mean pin 3 on ic to go diretly to the voltage divider R49, R50 ?
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Now that you've added C12 and C13 you can remove C1 and C2.
Can you also remove R12 and make the bias network the same as you have on IC1A and IC1B?
You show 1M variable resistors in the feedback loops of the op-amps. Why so big? If these are just for trimming the gain then I'd suggest, for example, 43K fixed plus 10K variable, to give a range of possible values above and below 47K. I'd also consider missing out the variable resistors altogether. They're expensive and not as reliable as fixed values. Use 1% resistors and I bet your gains will be close enough.
I'm a bit confused about what you're trying to achieve with the arrangement around K3. You say you want to avoid clicks and pops. Can you explain how you think this works? You're going to have trouble with R9 and R10. These are still far too small - almost a short circuit connecting your L and R channels together. Why not just replace this whole arrangement with a DPDT switch selecting between the stereo channels and the mono mix?
Do you expect a clicking problem here? What causes it? Different DC levels on the outputs of the three op amps?
Would it help if you used one DC bias network for the whole system, instead of three? That way you would know that everything was using the same DC reference.
I'm also wondering why you need both K1 and K3 switches. If you're selecting the outputs with K3, does it matter that the mono mix amp is always supplied with signal? You could save a whole relay.
Steve.