Polystyrene Caps for original SMR4 filter board

Good Morning Everyone. I was wondering if someone could tell me which caps to replace on the SMR4 board for the best results. I have some polystyrene caps coming and I want to try them out.

I found a lot of 4 Pole discussions when searching, but nothing on the original SMR4. Thank you.

I replaced the 1n ones around the 074

@ altitude, I bought some 1n polystyrene’s a while ago but never got around to swapping em. Is there a noticalbe difference other than seeing some polystyrene’s through the case?

I never A/B them. I used those ridiculous Russian 1% ones I found on ebay so it was a one time operation putting them in (I had to move the bypass caps to the back of board to even make them fit)

@altitude Thanks for the tip. I will compare that to the photo in the thread I reference below.

@qp When I searched the forum for polystyrene info there were a few people saying there was a very noticeable difference in the 4pm.

I plan on trying them out in the SMR4 and the Dual SVF.

Here is the thread I was referencing. http://www.mutable-instruments.net/forum/discussion/373#Item_24

I still have some of these…

@fcd72 Do you have the correct values for the SMR4? I only ordered the 220p for Dual SVF and I believe 220p applies to the 4PM.

Some of these.

By the way the big square Russian ones were nowhere near 1%, that is Russian electronics for you! You would be better off getting the standard cylindrical 1% ones which really are 1%!

@fcd72 Thanks Frank, but I will pass on the giant Russian caps. Maybe on my next order with Mouser I’ll pick up some 1n polystyrene.

btw, I just emailed you about the Shruthi Programer. It looks great. I cannot wait to work on it.


I just tested 10 of the ones I have they are all within 1% by a decent margin (my meter reads down to 1 pico)

same here, although i wouldn’t trust my Meter to be within 1% when it comes to Medical Application and Spaceflight…

who cares about tolerance, those guys are huge ! at least they look impressing

Going back to the manual for mkI filter, I now see that the cap locations for the filter core are shown in the capacitor installation section. Oops.