An option for pf value caps

[SILVERGUN]

I recently found and ordered some of these because I wasn't crazy about the mica caps or the other polystyrene I have tried.
These are a little more heavy duty with thicker leads and better construction.
I like em. They ain't cheap, but your highs are worth it.

1786669.pdf (farnell.com)

FSCEX 470PF 1% 630V - Lcr Components - General Purpose Film Capacitor, Film / Foil PS, Axial (newark.com)

[mresistor]

I think JustRadios in Canada has been selling some that are very similar, if not the same, for a while now. The prices also seem similar, but they offer some in 5% and 10% that are less expensive.
 


https://www.justradios.com/polystyrene.html

[HotBluePlates]

I recently found and ordered some of these because I wasn't crazy about ... the other polystyrene I have tried. ...

Go easy on the heat when soldering.  You can melt the polystyrene & change the cap's capacitance.

[pdf64]

LCR are based in Wales, their stuff is excellent, I’ve been using their polystyrene caps since I started with this stuff back in the 80s. They always worked as expected, can’t recall one ever giving problems, and despite a couple of close encounters with my soldering iron, they aren’t as susceptible to damage as typical polystyrene types.
They built custom batches of 0.33uF high stability caps for a company I was with in the 90s.

[SILVERGUN]

I think JustRadios in Canada has been selling some that are very similar, if not the same, for a while now. The prices also seem similar, but they offer some in 5% and 10% that are less expensive.
 https://www.justradios.com/polystyrene.html

I think those are some of the ones I was using previously.
Here's a pic of the 2 side by side. The LCR build quality is confidence inspiring, if nothing else.

[mresistor]

Cool   LCRs it is..   thanks for the info .

[PRR]

Back in the 1970s, some of us got "burned" by how easily polystyrene caps got damaged, and swore off them.

Yes, it just took care and attention but.....

Also note that even these well-endorsed PS caps are rated "-40ºC to +85ºC". The inside of your chassis should not be 85ºC but the hot-spots can come close. The Treble pot won't (you'd burn your fingers) but I'd stay away from the 6550s.

Mica used to be THE all-purpose near-perfect cap for pFs (mmfs). But what I am reading, today's mica isn't what it used to be. (In 1910 you could buy large sheets, by WWII they were working on reconstituted mica.)

Ceramic has a bad rap but below 1000pFd it can be as perfect as any cap. It's 0.01u and up that can suck bad enuff to hear.