Hello All,
I am building an audio filter to try and make 8 bit wav file a bit less
crappy sounding. The pdf shows a six pole audio filter using sallen-key topology
that I am hoping will help.
I was using the LM324 OP AMP in the design but it doesnt seem to like
capacitors as it causes a very non-linear output when driven with a sine wave.
I don't know if I got a batch of bad chips but they all do the same thing.
For this application I would think any general purpose op amp would work.
I changed the op amp to a LF353 OP AMP and it took care of the non-linear problem.
With the LF353 OP AMP I added some gain in the last stage and that also caused
non-linear output. Not nearly as bad as the LM324. In both cases I was driving the
stage with a sig generator with a d.c. bias halfway between the VCC and ground.
Attached is a pdf of my circuit. Does any one know why these op amps would
act this way.
I am building an audio filter to try and make 8 bit wav file a bit less
crappy sounding. The pdf shows a six pole audio filter using sallen-key topology
that I am hoping will help.
I was using the LM324 OP AMP in the design but it doesnt seem to like
capacitors as it causes a very non-linear output when driven with a sine wave.
I don't know if I got a batch of bad chips but they all do the same thing.
For this application I would think any general purpose op amp would work.
I changed the op amp to a LF353 OP AMP and it took care of the non-linear problem.
With the LF353 OP AMP I added some gain in the last stage and that also caused
non-linear output. Not nearly as bad as the LM324. In both cases I was driving the
stage with a sig generator with a d.c. bias halfway between the VCC and ground.
Attached is a pdf of my circuit. Does any one know why these op amps would
act this way.
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