Some good options for the IC in MXR DIST +?

[WorkBench]

I have the stock IC in a block logo Dist +.  I use this pedal as a boost mainly, with the Dist level all the way down and the level at 3 o'clock.  any thoughts on an upgrade to that chip?  Thanks!

Chris

[Caferacernoc]

I don't know what a good chip replacement would be since I don't even know what is stock in that pedal. I'd guess a TL072 would be a good upgrade. But, if you are looking for boost over distortion, I highly recommend raising the clipping threshold on the diodes. Double or triple them up or change them to LED's which clip at a higher voltage. You could even cut them out completely. I have a ROSS which is a similar circuit and I modded it to be a lead boost. I added to the input and output capacitor values for a more full sound and I added to the diodes for more output over distortion. I bought the eight pack of germanium diodes from this website and did 5 in one direction and 3 in the other for a soft asymetrical clip. This thing went from being a fuzzbox to being a LOUD punchy overdrive.

[radio]

I used an OPA134 , but my ears might be different from yours

Greetings JME

[petemoore]

  I think the DIST+ Sounds 'right' with the LM741, which is a big part of the sound of the Distortion circuit.
 Replacing that with...well just about any other chip's going to 'beat' the 741 in terms of 'performance' or 'hi fi'...just makes a DIST+ sound buzzy/sterile IMO.
 Check out Liquid Drive @ Fuzzcentral...it's 'Dist+like', but uses 'upgrade' componenents.

[Mark Hammer]

I think I've since lost the file, but I posted a clip last year which demoed several different chips in the same Dist+ board.  Some sounded warmer and others sounded nastier.  None were necessarily better or worse than others, just different.  If I recall correctly, comments from people (and that thread is buried somewhere in the archives) reflected a wide range of preferences. People said they liked something that I personally thought of as undesirable, and vice versa.

To some extent, the 741 is the "ideal" chip since the design appears to rely partly on the weaknesses of that chip.  Lift the diodes and you will hear that the chip distorts on its own, without needing the diodes.  This is not necessarily true for other op-amps.

[majormono]

When I built a slightly modified clone recently a had a little opamp shootout (including the 741 and others) and my personal winner was the trusty old LF351 followed closely by an OPA637.
Regarding the difference in price vs. tone I chose the LF351 and feel good with the situation ;-).
I also recorded a soundfile for proper comparison but I can't find it anymore, oh well...

[WorkBench]

thanks for the replies!  Ya' know, now that I take acloser look, the chip says ECG 941M on it.  Is this the same as the 741M, or is it different?  Would it be advisable to try switching it out with a 741M, or is this chip cool?  Thanks again!

Chris

[brad]

Never heard of it...but here's some info I found:
http://www.nteinc.com/specs/900to999/pdf/nte941m.pdf

They probably got a good deal on 'em or something!  

Is the Distortion+ you have one of the Dunlop reissues by the way? 

[burnt fingers]

I'll agree that the 741 folllowed by thelf351 would be my choices.  I just built my friend a DOD250 clone which is very similar to the D+.  I tried several chips but the 741 is what is in it and he is very happy with it.

Scott

[Connoisseur of Distortion]

try and source an LM321. get some crossover! yayyyyyyyyy! 

[WorkBench]

I do not believe it is a re-issue Dunlop.  It is the block logo, probably amde around 86-90 somewhere?  There is no Dunlop printed anywhere, but I am not sure, could be?  It sounds good, especially for using it as I do, just for a boost.  I still wonder what the difference is between the 941M and the 741M?!?  Thanks!

Chris

[mac]

I tried a lot of chips, TL071, LM201, RC4558 (different pin out), but finally I decided to use the infamous 741.

mac

[WGTP]

From other post.

I'm still working with diodes and have decided that the different diodes may not sound as different as the RATIO of OP-AMP clipping to DIODE clipping.  For a given level of distortion, using GE's will result in mostly diode clipping (because of the low .3v threshold), but using LED's will result in a lot more op amp clipping mixed with the LED clipping (because of the high 1.8v threshold).

You essentially go from a single clipping stage to a dual clipping stage distortion.  If you have lots of distortion with LED's, lift them and you can hear just the op amp distortion.  IMHO the contribution of the op amp distortion is overlooked many times.   

The op amp is probably more important in a Dist + type circuit because it doesn't have the limiting of the op amp by the diodes in the feedback loop the way a TS type circuit does.

Having said that, I think the op amp used is more noticable with high clipping threshold diodes than with GE's.  Using a rail-to-rail op amp will result in a cleaner signal for driving the diodes to clipping.  The 741 will probably clip pretty early, which may be a good thing.   

[radio]

Forgot to mention I used 3 OA 118 assym.clipping!

Greetings JME

[Guitar Toad]

try and source an LM321. get some crossover! yayyyyyyyyy! 

Does this mean using the LM321 as an additional boost to whatever chip is already in use? Or would the LM321 be in parallel and blend the two signals at the output?