View single post by Dr. Heinz Doofenshmirtz
 Posted: Dec 13th, 2014 03:36 AM
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Dr. Heinz Doofenshmirtz



Joined: Nov 17th, 2013
Location: Liberty, Missouri USA
Posts: 300
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Somebody call AAA, there's about to be a break down!
Okay dude.....I cant trouble shoot your circuit via the internet 300 miles away.....

Stefan is right, you have infinite input and output impedance. for input I would start with 1Mohms, output start with 10K.... The first half of your circuit looks pretty good......IC3 is where it starts looking kind of funky...depending on your feedback resistor from the output, you have zero resistance feeding back into the inverting input.....on both IC3 and IC4.....you are not giving these opamps a reference voltage of half supply...it is probably causing a phase cancelling effect. Also, there is no decoupling cap at the end of your chain....so you may have DC volts coming out.....which could be potentially hazardous for whatever you are plugging this into.....
I would try breaking down the circuit into parts......use an mp3 player or a cd with regular music on it, that way you can hear what is going on better......check output after each gain stage to see where your breach is at. but before you plug this dude back into your mic pre or sound card, i would throw a 103 .01uf cap inline with the output to kill any DC that might be leaking through.