Quad comments synopsis

Buck Buchanan voltagecontrolled at home.com
Fri Mar 24 16:54:32 CET 2000

Hi all,

Thanks everyone for the fantastic comments on quads!

I've consolidatated the meat of the responses here for anyone else
interested in using quads.  These are kinda chopped up - hope they're of
use.  And it's only comments specifically related to quads (though the
continuing op-amp discussion has been great).



I tend to consolidate my op-amps for audio because it saves me trying to
buy 12 different parts to do basically the same job. Traditionally I use
LM833 (Dual) or it's quad equivalent, the LM837. IMHO, these things are
wonderful. though they are roughly identical to the NE5532/5534 types.
I don't think you can get those in a quad. The LM833s are generally
by the bucket load and if you can do everything audio with just those
then you don't need to go buy bucket loads of anything else.

I do use the FET input types as well. LF347 etc. I bought a bucket load
them years ago and still have about half a bucket load left. What I do
only use them where I really need their qualities. For the rest of the
time, in audio circuits, I use 833s 837s.
The NE5535 (Single) and NE5532(Dual) are almost identical in performance
to the LM833 (Dual) or LM837 (Quad)
You can't get an LM833 in a single or uncompensated package. So in that
case you'd need to use an NE5534. On the other hand you can't get an
in a quad package so you'd have to use an LM837.

One note of caution regarding the 833/837 is the somewhat high
input bias current of (gasp) almost a micro-ampere.

I like the MC34084 (motorola's 'texture' of TL084) also MC34082,
I've had better luck with it than the TL084. Sometimes the "negative
fuzzies" on the TL084 get me (especially in voltage follower modes...) a
little load will help, or a small series resistor to decouple any load
capacitance...  Fet input, low bias current, fair offset voltage, FAST
(13V/uS) not too hungry on supply current... Can oscillate because of
speed but usually well behaved. My all-around favorite...

AND it fits in the same socket as that piece-of-shit LM324
Yes the LM324 pinout is a "standard" for most opamps...

The TL082 etc will phase reverse but you have to drive pretty hard...
Phase reversal does 'not' have to occur, you can limit the input range
of clamp the device to prevent it...

The TL084 *does* show phase reversal.

  John Blacet...
LM324 for CV mixing, low end audio.
TL074 for audio, high impedance buffers.
TL054 for audio, very stable CV mixing.
VCO design might require a few other, ultra stable types.

  Ian Fritz...
I like the Burr Brown OPA4132 (quad OPA132). Great all-round specs.
(re: cheap like 1458) -  TL074 is still good here.

 Tim Daugard...
TL074 - nicely behaved at cross over.

More information about the Synth-diy mailing list