[Fwd: Re: Op Amp pinouts was Re: [sdiy] more LM3900 stuff]

[Pat Kammerer]

> >----- Original Message -----
> >To: Synth DIY <synth-diy at dropmix.xs4all.nl>
> >Sent: Tuesday, January 17, 2006 1:55 PM
> >Subject: Re: [Fwd: Re: Op Amp pinouts was Re: [sdiy] more LM3900 stuff]
> >

> >>>I find that at low supply voltages the OP275 distorts undesirably.  I
> >>>find
> >>>that a much better alternative is the OP270.
> >>>
> >>>
> >>>
> >>But at higher supply and signal voltages you might find the opposite is
> >>true - the slew rate of the OP275 is ~10 times the OP270.  The offset
> >>voltage and drift is however much smaller for the OP270 which might be
> >>useful in applications which handle pitch CVs as well as audio.
> >>
> >>Seb
> >>
> >>
> >
> >I find that with a +/- 12V supply, the apparent sound quality (by ear)
and
> >waveshape (as veiwed on oscilloscope) is better in audio applications
such
> >as VCA, preamp, equalizer, and buffer.  I generally use a higher slew
rate
> >amp when summing CVs and related applications.  I have trouble beleiving
> >that the slew rate is the primary cause of the distortion that I have
> >noticed when using the OP 275, wouldn't it mostly indicate that a larger
> >bandwidth is possible without loss in linearity?
> >
> >
> >
> What I meant that the fast slew rate should actually reduce distortion
> for large signals.  There must be other factors that are resulting in
> you finding distortion on the OP275 relative to the OP270.  Personally I
> find the OP275s excellent (only used on +/-15V tho) - I tend to use them
> when I want something better for audio than the TL072.  Or I use the
> NE5532, but these are kind of current hungry.
>

Yes, beleive it or not, that's what I meant to, I just couldn't speak my
mind properly at that moment.  I must agree that the OP275 is bett for audio
than TL072.  I'm beginning to think that my love of the OP270's sound is
something intangable, akin to what an audiophile might experience.  ; )  In
all reality the datasheet would lead me to beleive that the OP275 is a
better amp, but I have yet to leave one in a socket.