[sdiy] Faster LM358 replacement

Tom Wiltshire tom at electricdruid.net
Mon Feb 26 00:14:00 CET 2018

Could you change the filter design instead?

A MFB filter will give you better performance higher up in the stop band than a Sallen-Key for example. You might be able to design around the op-amp limitations.

Some discussion here:


The other big difference is that one is inverting and the other isn’t, but you might be able to fix that by flipping the DAC data upside down.


       Electric Druid
Synth & Stompbox DIY

> On 25 Feb 2018, at 21:30, sleepy_dog at gmx.de wrote:
> Hey,
> say, what opamp could I use as a faster replacement for the LM358?
> Should be able to work with GND as negative supply and get the output (almost) there like the LM358.
> Would be nice to have one that also can run up to +15V, but for my scenario at hand, 5V supply is enough.
> And it would be nice to know one that's also not very expensive. It's probably hard to beat lm358 price... but let's not exaggerate ;)
> The application is an active filter to treat the DAC output for CV. Turns out the LM358 doesn't do such a good job there even at just a few kHz, i.e. the response curve starts to become less steep at the higher end quickly. (which even LTspice predicts, but I didn't bother to try the circuit with a LM358 model until now)
> - Steve
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