I put together Tonepad's MXR Envelope filter and I'm getting barely any signal from it. I have to crank my amp just to hear it. Right after R1, the voltage drops to around 2.8 volts and the same is for all of the 406X's... Is this normal? Should the voltage be higher? I used a 3k resistor for R1 as opposed to 3.6 k... would that be the problem? TIA for any assistance...
Hi. R1 is the output resistor and should be at 0V DC. The bias on the 4069s is set by R14 (62k) and R16 (100k). Some people, including me, change that to 100k and 100k or 62k and 62k, so that the bias point is 1/2 the supply voltage. Why MXR would make the bias point off-centre is a bit of a mystery (to me at least).
If your supply voltage (after R4) has dropped to 2.8V, then you've probably blown one of the ICs. Sometimes you can tell which one because it will actually get hot. Otherwise, replace them one at a time. It took me 2 sets of chips to get mine going.
good luck
This is my second set of chips. I found one erroe I made and that was that I put a 39k in place of a 3.6k, But still nada. I mis-spoke before about R1. It's the 3k that comes right off the 9v input. It was the right resistor. When I measure the voltage on the other side of that resistor, it's 2.8v. There are 2 diodes connected there that I will check... I know they are in right but one might be bad...
Make sure you don't use a TI chip for ic3, i don't know why but if you use one there, it won't wha.
Good luck!
Thanks for the help Gringo! I replaced all 3 IC's with ON Semi chips and all the sudden it works. Gunna check the spec sheets and see why one brand would work and the other don't...
Glad i could help. Now play that funky music, white boy :D