Anyone try polystyrene caps?

[dwp]

Hello all, has anyone tried polystyrene caps in lieu of silver mica for the PF/bleed ranges, bright caps, etc?
Read somewhere they're supposed to me mo betta than Silver Mica, cannot elaborate, not sure what better means. But since I'm forced in to navigating Mouser again, thought I may try them for the 330pf/390pf treble caps, unless I hear some negative press.
Or how about anyone else's issues with Silver Mica caps, and what you've found for an alternative.
Thanks in advance, dwp

[LooseChange]

Today.. I had two new 250pf Silver Mica caps bad right out of the box... Shorted.
So, whatcha got?

[dwp]

thanks LC. There's one. I have similar experiences every time I use anything other than a 100pf on a volume pot. Think I've had those go haywire too. And the more adventurous I get on builds, I'm buying odd values from surplus sites not even sure of what their usage is intended for, just getting the PF right may not be enough. Mojo sells a 480pf polystyrene, subbed for a 500pf Silver Mica I can't tell the difference, other than it worked, my ears have been in the construction trade for over 30 years now, so finite tonal debuts elude me. But a story to go with the cap? priceless. I will pull the trigger on a group of assorted polystyrenes, less someone else trys to stop me.........
Thanks again, dwp

[overtone]

In England we tend to call them by one of the brand names - Styroflex. Is that the ones you mean?
They are small round transparent and silver, sometimes with a red band, and I have a heck of a job reading the print on them. They do come in very different voltage ratings, I would keep an eye on that. I have a few amps by a 1970's British company called Burman that used these and they built their reputation by only using top notch components.

Over in Germany last year I read a couple of forum stories of modern silver micas failing. There was no conclusion but it cemented my preference for the old domino style micas.

[stingray_65]

The only real drawback to PS caps is that they require good soldering skills and techniques.

With heavy handed soldering and lack of a heatsink clip the polystyrene can melt.

I have not used one since I was a kid and ruined a few projects unknowingly.

My skills have improved immeasurably since.

It may pay to look into their temperature operating range, inside a tube amp may not be conducive to long life and trouble free operation.

Ray

[LooseChange]

How about using good old ceramic?

[Fresh_Start]

How about using good old ceramic?

I've never tried ceramic caps inside an amp but did compare ceramic vs. green chiclet (polyester?) from Rat Shack as guitar tone caps when first starting this adventure.  I'm not sure that I could hear a difference between the green chiclets and Orange Drops, but the ceramic caps definitely sounded worse to my ears - gritty?  harsh?  It's been a long time and describing tone always is a challenge.  I avoid ceramic caps.

That said, I know that old Fenders used some ceramic caps for smaller values (like where you'd use silver micas today).  Also, Ken Fisher would sometimes parallel a ceramic with a silver mica or other type of cap to get a particular tone in his TrainWrecks.

HTH

Chip

[jojokeo]

"green chiclet (polyester?) from Rat Shack"  never heard them called that. They are every bit the same as ODs I believe as they are polyester too BUT they are only 100v caps so use them where applicable (which is not much) but you can say that you're amps are more "green" and environmentally friendly 

I've used (and liked very much) polystyrene caps over ceramic or others for low value pF range caps when I was very into ss circuits. The are really noticeable in op amp gain loops and the like. I would use them in geetar amps but maybe only in the tone stack or for treble bleed caps? Can't say for sure if they'd make much difference as coupling caps or bypass caps? But now my interest is piqued.

Ray is correct about them being easy to overheat (and hard to read). It's a little scary that silver mica's can be bad right out of the shute? It sort of confirms my testing most components before installation if for nothing more than to make sure I have the right value so I can prevent a stupid mistake like getting orange & red colors mixed up (wouldn't be the first time).

[bluesbear]

I've never had a bad silver mica cap. Something else to worry about!! The only bad cap I've ever found new was a Sprague Orange Drop. My friend Mike (used to be KomboKing... I miss his chassis) built an 18 watt'er that just couldn't be made to work right. It turned out to be a bad cap. I stick to Mallorys and never have problems, although I've read here they've changed since my last bulk purchase. Hope it's not too much for the worse.
Dave

[overtone]

I've never had a bad silver mica cap. Something else to worry about!!

Dave, I think we can sleep tight.
I took a look again at that Forum in Germany. They counted 18 bad silver micas during eighteen months & the production batch date was thought to be 2008-2009. The forum has over 3000 members and after over 3000 views the thread died down last summer, so 18 is not many. They probably just abused those 18 poor little things! Soldered to hot, bent the legs all over the place or just fried them with too high voltage.
Best, tony

[pullshocks]

Not to hijack this thread, but Tony I am curious about your Burman amps.  I received a promotional book from them during their brief attempt to break into the US market.  The gut shots were very impressive.  But how do they sound?

[overtone]

Yes that could be a whole new thread!
Briefly: someone much more knowledgeable than me said they are like a cross between a rabid Hiwatt and a Twin on steroids. (Or was it the other way around?).
I was gigging with a heavy Music Man twin (HD130?) when I was 18. One night it was dead so I borrowed an even bigger and heavier combo from the other band. That was how I was introduced to the 4 x KT77 Burman. People call them the British Boogie and back then I tried the woody Mesa MkII (with a graphic EQ) but stayed with the Burmans. That was some time ago!

[HotBluePlates]

Hello all, has anyone tried polystyrene caps in lieu of silver mica for the PF/bleed ranges, bright caps, etc?
Read somewhere they're supposed to me mo betta than Silver Mica, cannot elaborate, not sure what better means.

I've tried them before in a tube amp.

They are "better" in that they function more like an ideal cap than a lot of other types of dielectric.

I haven't looked lately, but you generally see them available only in the pF range (maybe a couple-thousand pF and less). Like any "ideal dielectric" (teflon, air, etc), they are physically large for a given rating compared to more common cap types. They are (were?) also a lot more expensive. They are easy to damage and melt when soldering.

I tried them when I bought a few at dirt-cheap prices from a place akin to an electronic junkyard. I couldn't hear any noticable difference in a blackface Princeton Reverb. I haven't used any since (that was maybe 13 years ago).

[jojokeo]

I tried them when I bought a few at dirt-cheap prices from a place akin to an electronic junkyard. I couldn't hear any noticable difference in a blackface Princeton Reverb. I haven't used any since (that was maybe 13 years ago).

That's why I think trying them in the treble bleed/bright switch, part of the tweed tone control/FMV tone stack, or bypassing places would be their only real places of merit. But again, w/ an op-amp's gain loop and such, where things are much more sensitive or responsive - these do make a difference you can hear. Therefore it should be worthwhile in our amps in a few selective places.