LM358 as an audio amp

Nov 04, 2009 5 Replies

The LM358 datasheet doesn't specify EIN or S/N. I assume that's because it's not very good, but using one would simplify my circuit greatly as I only have +5V available without a lot of extra work. I need to buffer an audio signal and add a gain of 2. The input is about 1VRMS.



THD is not super important, but I wouldn't like to add a lot of noise.



Has anyone used a LM358 in a similar situation successfully?


- Mike

"Mike Warren"

** For non critical applications, within the audio band and with a gain of only 2 - there is no problem.

However - 2 times 1 volt rms is MORE than 5 volts peak to peak !!

Beware: If the output of the LM358 is cap coupled to the next stage, then a load resistor to ground is essential to eliminate severe x-over distortion.

See the Nat Semi 1994 data sheet - page 6.

..... Phil

Thanks, Phil. That's enough for me to build a test circuit.

- Mike

It looks like it will do what you need.

Have you thought about using a LMV358 ? THat operates at 2.7..5.5 volts.

THe LPV358 is also lower in current but does introduce more noise. Which seems to be a big jump compared to the first 2.

Page 8 in the Oct 2005 edition.

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