Toying around with a Red Snapper overdrive: ...do opAmps matter ? (spoiler: maybe yes)

[nooneknows]

Hi there,

since I've always been a strong believer that opamps don't matter in overdrive circuit, at least in TS derivatives, I was messing around with a Red Snapper clone I've just built (15 years ago I had an original 90s one, I sold it and I beat my head for this bad idea since then) when I told my self, Let's try some of opAmp to confirm my guess.

Well it didn't went the way I thought. I checked, double checked several times and, althought they're really really close, well I hear differences.
I even tried this: I put some little black tape patch over them, just a pencil on the side of the mark to put them in the right orientation, picked one by one randomly and I choose the best ones to my ears in order, discovering I put it more or less in the same order (at least the extremes)

I tried:

1458
JRC4558D
LF353
TL072
TL082
NE5532
AD712
OPA2134

The winner is undoubtedly the JRC4558, the OPA2134 closer, NE5532 good but a bit flat, 1458 and AD712 in the middle, the TL072 and the LF353 are somewhat edgy like there is a overly ringing something, I had a doubt with the TL082 I don't remember in which position of the hit list I put it, I believe it was close to JRC4558 but since it must be closer in topology to TL072, maybe I got it wrong.

Red Snapper is an asymmetrical soft clipper with a low count parts, maybe the single element effect is more audible, I also have to say I use the RS with the Bite pretty low, meaning the bass cut is lowered, when the Bite is higher (with a bass cut more TS style) differences disappear to my ears, is there something about crossover bass dist?

Any opinion about it? I used to mark the golden ears people as biased, but the 'blind' test I made makes me feel unconfortable.

 

[Fama]

Op amps have different specs, so it makes sense there can be audible differences. I think "it doesn't really matter which op amp you use" is more rooted in a "you won't hear the difference in a live setting or a recording" or "whatever op amp works in the circuit, in most cases".

I would also point out that these ones are the best in this case, but it could be that in a different situation something else could be better. Maybe for a distortion pedal someone could prefer some op amp with more of a specific distortion type, for example.

But definitely an interesting post, and I especially appreciate how you did a blinded test instead of just working off confirmation bias, great work!

 

[hamerfan]

Definitly i will order some JRC 4558 next time - just for s&g, but i ran out of TL072s. Interested also in the TL082.