Opinions: On op amp replacement

[Bissell, Harry]

I find the greatest reductions in circuit (audio) noise often come from
replacing Carbon Comp. resistors with Metal Film. The metal films are
usually 1%, which makes summing and diff amps happier at the same time.
Also, faster op-amps somtimes do weird things. I built a phase shifter with
quad op amps (LM324) and replaced them with the TL084 (it oscillated at a
near ultrasonic frequency). It drove my mother's dog nuts (but she couldn't
hear it). Made me want to not fix it (I hated that Dog...... :-)

> -----Original Message-----
> From:	Rene Schmitz [SMTP:uzs159 at uni-bonn.de]
> Sent:	Thursday, January 28, 1999 7:24 PM
> To:	icumedia at flash.net
> Cc:	synth-diy at mailhost.bpa.nl
> Subject:	Re: Opinions: On op amp replacement
> 
> At 11:18 28.01.99 -0500, you wrote:
> >I was recently given the advice to replace all the 741 and 748 op amps
> (on
> >a paia modular)
> >with LM301AN's, and LF351N's--------
> >
> >2 questions.
> >
> >1--Anyone have opinions on *how much* difference this might make? They're
> >relatively cheap (1.10 usd or so) and direct pin-compatible, I've been
> >told, but I'll need about 20, so thought I'd ask.
> >2--Any good projects with which to use the 741/748s that will be left
> over,
> >or are they that useless...?
> >
> >
> >charles morpheus
> >icumedia
> 
> Quoting from the datasheet: 8-pin mini DIP all purpose noise injector. ;)
> One can put them perhaps in a "Grungelizer" or "LoFi-enizer" effect
> module.
> They are OK, if you use them with reduced bandwidth, I once used 741 in a
> poweramp and it was noisy as hell, until I reduced the bandwidth to some
> 7-8 kHz, (I used this amp to drive a 15" speaker)
> 
> bye 
>  Rene
> 
>              ,   : (uzs159 at uni-bonn.de)
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