Favorite quad op-amps for synth design?

danial stocks diode at hotmail.com
Wed Mar 22 16:16:25 CET 2000


>At 11:06 PM 03/21/00 -0500, Harry Bissell wrote:
>
> >LM324:  I hate this op-amp. If I was on Apollo 13 and likely to die I'd 
>use
> >it... if the pinout matched...
> >But seriously folks... Its single supply only. Dual supply has a 
>crossover
> >notch
> >that makes it suck for audio. Some say a resistor to the negative rail 
>fixes
> >it...
> >but to me thats like "Taking something that tastes bad and making it hard 
>to
> >eat too..."
>
>Heh Heh. Actually I like the 324.

Me too! never use for audio, but the fact that these [and the 358 dual vers] 
have output swing to the gnd [or v- in a dual supp] makes them ideal for any 
dc app.. lfo's, driving the bias on an OTA etc..
>
>I've seen people trying to use 3900s for audio too. Great if you like
>noise. Otherwise...
>
> >4136: wierd pinout... avoid
and for some reason the + ins are next to the o/ps.. makes all the nice neat 
feedback loops design on the pc board a real bugger! and they oscillate 
pretty often so you're always out with a bag of small capacitors padding it 
down! but if you do actually get it stable, it runs ok, lowish noise..

> >LM3900 Norton: these operate quite differently from normal op amps.. it 
>makes some interesting apps possible, saw a novel vco design with one, but 
>well normal op amps work well in normal op amp apps, so maybe keep the 
>exotics for the special tricky stuff..

I myself tend to use anything on hand which suits the apps... in dual op amp 
nice low noise ones also are 4560, 4580, AN6552, M5218.. these are all 
probably nigh on impossibe to find in a shop, but can be gotten in large 
quantities from Japanese built gear, of which there is a lot of thrown out 
around here.. check out surplus stuff often... high grade parts can be 
gotten for next to nothing..

cheers,
Dan
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