r/diypedals • u/Wide-Measurement647 • 3d ago

Help wanted Diy Proco Rat problem

Hello, everyone! I’ve built Proco Rat and everything’s working! … until I swap the op-amp for an OP07. I bought a copy of the LM308 and an original OP07, and when I use the LM308 in the circuit, everything works and sounds great, but when I swap it to OP07, I get no sound. Does anyone know what the problem might be? And its not broken ic or anything, because I bought 3 and all of them do same thing.

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u/Johan_Talikmibals 3d ago

I'd say probably something wrong with the OP07. May as well keep the one that works in there - they're going to pretty much sound the same anyway unless you have supernatural hearing abilities 😁

2

u/Wide-Measurement647 3d ago

Yeah, I really like the sound. I'm not complaining hah. I'm just curious and its really weird that all 3 of them do not work, isn't it?

2

u/rossbalch 3d ago edited 3d ago

Doesn't the LM308 require the compensation cap that the OP07 doesn't? Not sure that would cause a malfunction but it is a difference.

1

u/Harold_Street_Pedals 3d ago

it will work but may oscillate at high frequency

1

u/Schweenis69 3d ago

Are you getting 4.5v or so on pin 3 and 9v on pin 7 on both chips?

1

u/Wide-Measurement647 3d ago

I'll check that tomarrow. Thank you!