Face Melter IC

[spi]

I’ve etched a board, but haven’t built it yet. I’m curious about the opamp, too. I’ve read different things; any dual will work all the way to you have to use THE one.

well obviously THE one has the mojo.

Gotta have that BIMOS tone.

 

[Laundryroom David]

TL061 sounds dandy. This is a fun distortion! The ”moist” () switch is not subtle. I’m going to see if other single op amps make an audible difference. I am confident a TL072 or other appropriate dual would work just fine in place of the stock op amp. I made no changes other than converting to a single op amp and using VCC and Vref from my protoboard rather than breadboarding the power section from the schematic. I tried bs170 and 2n7000 and could tell no difference.

edit to clarify - I don’t expect the op amp to make a noticeable difference to the moist switch … it is not subtle, but I’m curious to see what if any difference a different op amp makes in the pedal’s overall sound.

 

[Laundryroom David]

I’ve etched a board, but haven’t built it yet. I’m curious about the opamp, too. I’ve read different things; any dual will work all the way to you have to use THE one.

I’s be curious to get your take on it after you build. This was totally off my radar till I happened across this thread but now I’m kinda digging it.

 

[Laundryroom David]

How about configuring the breadboard for a single opamp? The 2nd opamp on the board does nothing. Then you could try CA3130, CA3140, TL071, LF351, LM308... shit, you could even try a 741!

So this is interesting. I’ve now tried a TL061, LM308, OP07, 741 and a CA3130 (w/a 47pF comp cap on 1 and 8). The CA3130 does something the other don’t. They all sound perfectly fine and would be impossible to tell apart in a mix. But up close and loud, the CA3130 is notably more … present? The circuit sounds more oomph. Highly technical. Honestly, they all sound great.

 

[DGWVI]

So this is interesting. I’ve now tried a TL061, LM308, OP07, 741 and a CA3130 (w/a 47pF comp cap on 1 and 8). The CA3130 does something the other don’t. They all sound perfectly fine and would be impossible to tell apart in a mix. But up close and loud, the CA3130 is notably more … present? The circuit sounds more oomph. Highly technical. Honestly, they all sound great.

The 3130 does similar in a straight up Rat, too. Has a fairly aggressive midrange that isn't present with other chips

 

[Laundryroom David]

The 3130 does similar in a straight up Rat, too. Has a fairly aggressive midrange that isn't present with other chips

Gotta try that!

 

[xefned]

I’ve etched a board, but haven’t built it yet. I’m curious about the opamp, too. I’ve read different things; any dual will work all the way to you have to use THE one.

I should have recorded my tests. I swapped 4 different op-amps. They all sounded the same to me in this circuit.
Couldn't tell the difference between a TL072 and the CA3240.

The good news is: they all sound great! Really fun pedal.

 

[Chuck D. Bones]

I believe they sound the same. All of the distortion is in the LEDs & Q2.

 

[Guardians of the analog]

shit, you could even try a 741!