Re: Op amp distortion


"Mike Faithfull"

As part of a "powered monitor" (not for the PC but wedge-shaped speaker
cab with built-in amp for use on stage) I assembled a commercial power amp
(already tried and tested for several years in another application) and a
'front end' comprising two dual op-amps (LM358 or TL082) to provide two
balanced input preamps and a mixer.


** FORGET using LM358s for audio (other than maybe a guitar stomp box).

Stick with the tried and proven TL072 / 82 series, the NE5532, the RC4558,
4560 series and even the LM833.

All these can be trusted to be free of x-over problems and to have low THD.

Note, the TLs and the LM833 can display a tendency to oscillate at
frequencies in the MHz range if wiring layout or supply decoupling is poor
OR if the output pin is not isolated from load capacitance by 100 ohms or
so in series.

Such oscillation will often result in significant audio distortion.



....... Phil




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