Casio SA-20 Circuit Bending (3Band EQ +More)

[BFF Chili]

I bought an SA-20 off of somebody on craigslist for $5 a few months ago and I'm wanting to turn it into a fuzz machine. I've got some basic short circuits I'm going to use, but I'm wanting to also build a 3 Band EQ filter to add some versatility. I was thinking I might could use this tonestack schematic.

http://www.runoffgroove.com/tonemender.html

I have a few questions about it, though. The Casio's output into the current headphone jack is 2V peak RMS at 100ohm impedance. There are also the 2 speakers on each side making a total of 1watt output. I'm not sure if this is the same output signal, but I'm wanting to take the speaker line signal and run that through the EQ and eventually to a 1/4" jack. Could I just ignore the OpAmp in the tonestack and run the signal straight into the EQ network? If I did that, I'm pretty sure the output would still be larger than a guitar signal (for using pedals and an amp etc.). Would the output be too hot for the TLC2272 even if I did want to use it? I couldn't find anything on the TLC2272 datasheet, but I also may not be looking in the right places.

http://www.ti.com/lit/ds/symlink/tlc2274.pdf

Any guidance on this would be appreciated as well as SA-20 bends I should maybe check out.

[mysteriousj]

Could I just ignore the OpAmp in the tonestack and run the signal straight into the EQ network?

Mmmm I think it'd be best to leave those opamps(at least the last one) in the tonestack. I'm not sure about this tone stack but most of them will attenuate 12db or more. Also,or more importantly, see those resitors/pots in the tonestack -mostly like 100k+, this will give you a high output impedance.. even if you have a 'hot' signal, it won't be hot after going through them. You really need a gain recovery stage/low Z output after the tone stack. You could bypass the input opamp no problem, you really don't need it but I'd leave the one there on the output. It'll work okay without it i'd assume but may be noisier. It will also depend on what you're connecting it to and it's input impedance.

TLC2272 - nope you won't damage it at all, to damage it you'd probably need to put in a voltage higher than VCC or whatever the maximum input voltages are (it'll be in the datasheet somewhere.) The inputs of an opamp are a high impedance so only a really small current flows through it.

[BFF Chili]

Thanks. That helped a lot. I think I'm gonna use them both since the IC has 2 opamps in it.