I bought one used and really cheap. But it´s very noisy compared with my Tubescreamer.

If I change the 741 op to a TL072 (I know about the pinouts, etc) will this eliminate some of the noise? Is this worth doing? Will the sound change a lot?

And, is it worth doing it true bypass? (A little complicated but I think I can do it)

Thanks, guys!

Using a TL072 should reduce the noise considerably.
Any effect that is not true bypass is worth converting to true bypass, if it's possible to do so.

Hi Willy,

TL071 is the direct replacement but in my clone I didn't notice any improvement in noise level with the swap.  A 5534 would be a definite  improvement though.

Jim

Oh, yeah. Duh.
The TL072 is a dual opamp and the TL071 is a single opamp, which is what the 741 chip is. The NE5534 is a very quiet opamp with all around good performance. That would probably be your best bet.

I have noticed reasonable improvement in noise levels with a TL071 over 741 and TL072 over RC4558.  I use the TL071 in my distortion+ clones.  I also use a 1N4148+1N4004 pair of diodes, for a smidgen of asymetry in the clipping.  Cheers

I tried out Dave Barber's suggestion of stacking/paralleling op-amps yesterday, replacing the 741 in my Dist+ clone with a piggybacked pair of 5534's.  YOWZA!  Daddy like!  

Thanks, guys! I´ll do the 5534 mod. I´ll post the results...

Is the 5534 frequency compensated, or not?  I thought it wasn't.  Is that (ie no compensation) part of the "magic" that Mark is reporting?  Or is it strictly the piggybacking?  (and why would paralleling 2 op-amps do anything special?)

(However, when Mark H says "Daddy like!" Brett wakes up and gets his soldering iron ready!)

Agree.  Isn't the 5534 the one used in a Rat?  Doesn't it require an extra 100pf (or so) cap that a 741 doesn't?

The 5534 is *compensatable* but it doesn't NEED to be compensated to function suitably.  A 5532 is essentially a pair of 5534's in one package, the way a TL072 is a pair of TL071's, and a 1458 is a pair of 741's.

If you read Dave Barber's thread/posting, the idea behind the parallel element use is that it is capable of delivering more current.  The 5534/5532 already is capable of delivering more current than a number of other op-amps (which is why they are often used as headphone amps), so doubling up just increases that.

That's just post hoc BS, though.  The real story is I used it because a guy kindly gave me a generous handful of them and I had enough that I didn't feel stingy about experimenting with them!  Not having tried the parallel-chip thing with anything else, I can't say whether a pair of 5534's is *best*, but I do find I like the sound better.  As Dave suggests, you get more note definition.

Those of you *real* EE's out there, I'd like to know more about why the capacity to dump more current would have that sonic outcome.  I'm vaguely familiar with how higher current-delivery can help to keep clock pulses in a BBD sharper and squarer, but that's the only analog to this particular context that I can think of.  Please, someone make me smarter about this.

:shock: Yeah me interested too, and quess many others too. I tried beefing opamp headphone amp circuit somewhat same method, and was not sure what I heard, but bass response sounded noticeably better and defined. One fuzz project I made for a relative´s bass player kid I put few stages parallel just for fun. It did sound better with bass than my similar circuit with non parallel stages, though I fiddled with some cap values. But I faintly  remember I tried to fiddle my previous project´s cap values and it started farting, so...

Maybe it is some ill-sounding distortion at low freqs, that is hard to notice and measure, but piggybacking somehow cancels it.  :?

so to run opamps in parallel would be to stack them then?  Like on top of each other, I mean.

Yes.  

Dave Barber included nice closeup pictures in his posts on this topic.  I would recommend tinning the leads of both of the chips so that they form a nice joint when you "sweat" them.  I don't know about you but I find my chips don't always have the cleanest leads.