Polystyrene caps in SMR4v2 filter - worth it?

Is it worth replacing the four 1 nF film caps near IC7 on the SMR4v2 Shruthi filter board with polystyrene caps (which seem to be north of $4 each). Or would that be gilding the lily?

$4? They are $.035 at Small Bear and about the same at Reichelt and Mouser.

Different caps types don’t sound that different, some just have better tolerances which makes a difference if your circuit needs very close tolerances. For the 4PM this helps, for the SMR4 it doesn’t.

All those classic analogue synths people rave about aren’t using any magic caps :slight_smile:

Whatcha guys said. Get some Beer for the savings, makes your life better than Styros in the SMR-4

No point having posh caps and then cheap cables, it all needs upgrading :wink:

I believe the capacitor fairy would consider these thoughts to be blasphemous.

I’m going to try “normal” caps on a 4PM, just to see what it sounds like. I have the polys just in case.

@sammy123: On element14/Farnell, they appear to be over $5 each. But you’re right, they are over an order of magnitude cheaper on Small Bear. I wish I had ordered some when I bought V2164D chips from them…

sorry for the weird question. . . but how would the material the cap is made from possibly change the sound, given a constant case temperature and the same measured capacitance value?

Tolerance. I imagine tuning the filter and getting a predictable response is easier with the upgraded caps.


Piscione is right. A Cap doesn’t “sound” in a Filter, what you will hear is how tight the single poles fit to each other in terms of cutoff frequency. This is especially important for Resonance, there won’t be much resonating if the feeding pole in the filter has a different frequency than the receiving…

“Piscione is right.” Wow, I don’t get to hear that very often around my house, thought I would just enjoy the moment.

Since I already have one working 4PM, I am curious to find out what the difference is when I try the new one with the normal caps.

Technical statements and wife/kid statements differ greatly, regardless of the geological location on this planet !

You must be doing something wrong, over here I’m right by definition.

Being right and being told you are right are different…

Anyway, Piscione I am curious by your 4pm experiment too. I am building myself one, and decided to take the shortcut and source some normal caps locally. I am not so sure of this being ok, therefore it would be way cool if you share your experiments´results!

Good point @Varthdader. I’m just waiting for some MIDI ports to arrive so I can finish the 4PM and then I will certainly keep y’all updated.

@fcd72, I think I have pointed out before that you have a very special spouse. Or an imaginary one.

Best feature is she is inflatable.

But the batteries!? Oh oh, I think we’re heading down that slippery slope…

Mains powered……