octaver fuzz MPS6515

[benfox]

Hi
I try to make this stuff :
http://www.harpamps.com/schematics/geuoctv.pdf
But i can get any equivalent please help me !!
have a nive day
benfox

[Mark Hammer]

2N5088, 2N5089, BC549, or BC109 will substitute.

This circuit needs a volume control badly.  Where the 39k resistor is, put a 10k resistor and a 50k (log) pot.  The resistor goes to the input of the pot.  The 820R resistor to ground connects to the other outside lug on the pot.  The wiper goes to the "Fuzz" point on the switch.

For the "Struzz" side, you can replace the 10k resistor between the "-" pin and the output of the B op-amp with a 1k resistor and 100k pot in series.  The pot is wired up as a variable resistor.  So the 1k resistor goes from the "-" pin to one outside lug of the pot, and the wiper of the pot goes to the output of the op-amp.  These will allow you to have separate volume levels for the Fuzz and Struzz tones, plus a master gain control (the 1M pot you can already see).

[jmusser]

Mark, have you already built this before? If so, what's it like?

[Mark Hammer]

I think I *might* have made this way back when (the circuit *is* a quarter century old, remember).  At the time I might have made it, I didn't know a fraction of what I know now.  I suspect the stock circuit was in need of a few improvements.  I have a vague recollection of not being impressed by it, other than how well the word "struzz" really seemed to accurately describe the tone of that setting.  As well, given how far back it was, there is absolutely no guarantee I built it properly.  Assuming it is NOT a figment of my imagination (I lived through the 60's but I *do* remember them, so you know thast acid flashbacks are not in my repertoire), I suspect the parts were cannibalized for another project.  That's about as much help as I can be.

[jmusser]

Fair enough! I'll put it on my to do list. Thanks Mark!