@zeb. Hmm. I've never heard of that one. Sounds like there is most likely a short circuit somewhere.. it's possible you put the wrong value component somewhere (for instance used too high of a resistor value in the mixer inputs) but I would put my money on short circuit OR maybe a cold solder joint. The solution for both potential problems is to go over the whole board slowly with an iron and look for problem solder spots where there may be too much or too little solder. If you have an oscilloscope you can pretty easily diagnose the problem by tracking the signal from the oscillator (the right most TL074 IC) to the PWM circuit (the top right TL074 IC) and then to the volume pot, THEN to the mixer. All of the components are labeled on the schematic and on the board so it is relatively easy to track your signal. Hope that helps!