AW: question about audio OP amp

Haible Juergen Juergen.Haible at nbgm.siemens.de
Fri Jul 10 13:04:23 CEST 1998


	> Am I mistaken, or do some people claim they can hear the
difference
	> between 741's and other more modern opamps and prefer the sound of
the
	> 741's? I've heard this mentioned before... Any evidence to back
this claim
	> up? 

Never heard of anyone who did a real A/B comparison and said
he liked the 741 better, so this is most probably just a myth.

I write this because I might have contributed to this confusion myself
when I wrote about my SEM filter clone. I deliberately left the 741's 
in there. My argument was it doesn't hurt in the original (no one 
denys that the SEM sound excellent), and *maybe* (stress on 
"maybe" ! ) the 741's (as well as other components') limitations
are part of the overall sound.

The point is that you can not decide whether this is the case or not
by simply exchanging the existing opamps with faster ones. If
you replace the opamps, you also change the delay of a closed loop,
so the original compensation capacitors won't be optimal anymore.
(Not speaking about one opamp's compensation, but of the whole loop,
variation of Q at several cutoff frequencies etc.)

So my suggestion is: Don't touch 741s for new developments. 
If you clone something that has 741s try them first, then try TL071 or
anything similar, and keep what sounds better to your ears. Just
don't try to deduct any general statements about some 
"741 benefits" then (;->).

JH.





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