Distortion 250 Question?

[chris.knudson]

I'm building the Distortion 250 circuit, and I don't have an LM741. I do have a bunch of UA741s, which I know are basically the same chip with different silicone, so I know a UA741 will work. My question is has anyone tried any other Op Amps in the Distortion 250 like an LM308 or a TL072, and if so, what did you think about the results?

 

[SturatMcC]

Tl072 is a dual opamp and won’t work, however a TL071 would be great. I believe LM301s, LM308’s and any other single opamp chip will be suitable.

 

[chris.knudson]

Oh yeah, the TL071 is what I meant -- I know thy'll all work, I was just wondering if anybody has experimented with different op amps on the Distortion 250 circuit.

 

[Bilansley]

I've used a TL071 for this circuit and to my ears the sound is VERY similar. Almost like the debate about what chip sounds best in RAT. From what little differences I can tell the TL071 seems less "edgy" if that makes sense, but its highly subjective and its entirely possible that what I hearing is just my brain wanting to find a difference. *edit* this was in a MXR distortion + circuit with germanium diodes

Honestly if you have the UA741's that is probably your best bet since going for a more uncommon combination of op-amp isn't really worth it.

Ofc if you already have some other single op-amps have at it! I just don't think that buying other op amps for the sake of "doing something different" will take you anywhere. Just my 2c. In my experience for the MXR/DoD distortion circuit the diodes are where the biggest tonal changes come from in terms of component swapping.

 

[andrewsrea]

The single op-amp IC in a DoD 250 Overdrive, will eventually distort and contribute to the distortion sound, but only say one third. However, the 250 is basically a distortion, which gets most off its grit and compression from hard-clipping asymmetrical diodes and its character from the C3 + R7 + A500K gain-pot EQ, which basically gets brighter as the gain gets increased.

IMHO, that is where the IC deployed is important. The LM741 is inefficient and smears the sound, which tames the highs from being harsh. Chips with faster slew rates or which are FET based, will make the top end harsh. That can be tamed by changing the C5 22pF bypass cap between pins #2 & #6 to a higher value.

Additionally, the pro use of a 250 isn't often discussed. Its forte is pushing a thick amp set just past edge of break-up, into a brighter crunchier sound. IMHO, best on British-style amps and disappointing on Fender amps which are not cranked with the treble settings on low.