# LM4558 vs. RC / JRC4558



## droneshotfpv (May 30, 2021)

I searched and couldn't find an exact answer, and I apologize in advance for what is probably a stupid question, but here goes.

I am building the Muffler Noise gate, and it calls for an LM4558. NOBODY has them in stock anywhere I have looked (I could also be blind, as I have scoured the internet lol) , and trying to compare data sheets, I am not getting that "I am satisfied this works" answer for myself, so I wanted to ask the most amazing forum and it's members my stupid question.

When dealing with the 4558 chips, is this LM4558 the same / equivalent to my JRC4558 and RC4558 chips? Would I be alright using these in this circuit?
From what I have looked at, they are relatively similar, with some tolerance differences here and there, but I wanted to be sure before ordering something else that is equivalent from mouser or small bear.

Thanks in advance guys, you are all amazing!


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## spi (Jun 1, 2021)

Yes, and you can probably use almost any 8 pin op-amp IC (TL072, etc.)


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## Chuck D. Bones (Jun 2, 2021)

There may be some subtle differences that may or may not be detectable, depending on the circuit.  Dirt pedals that rely on saturating the opamp to get their signature sound are the most likely ones to reveal the differences.  There is little or nothing in the datasheet to inform us as to how an opamp will sound when overdriven and the manufacturer can change the recipe any time.  Since the Muffler is not supposed to distort, I'd say it's fair game to sub any dual opamp with the right footprint.


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## droneshotfpv (Jun 3, 2021)

Thank you for your answers! I was thinking it would be ok to sub in the other 4558's, but I wasn't sure with the nature of the muffler / noise gates, if there would be any issues in doing so. The more I get into this with your help, the more I understand. I LOVE learning all this stuff. I plan on getting one of the books that helps you understand these circuits deeper, and plan to build my own scratch circuit very soon!
Much appreciated!


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