polystyrene cap in xpress...Wow!

[breakfastbuddy]

Orange drops are Polypropylene, high screamers , polystyrene high killers .
or a cap parralell with the anode resistor . 1000p or 1 nf fix the scream .

[paulster]

It's not a bad idea to use a drop of hot glue or non-corrosive silicone sealant under them to anchor them down in an amp build because the leads are so fragile.

That's my top tip for using polystyrene caps. Great caps!

[Jackie Treehorn]

Has anybody used the larger values for coupling caps?

I see most of the ones available are not very large in values.

Reliable Capacitor has a few lines of Polystyrene film and foil caps. I think the RTE is the small values, the RT is the larger values, and then there's another "Multi Cap" line that I can't remember.

I bought some of their .1 mf polystyrene film and foil caps for a speaker crossover project, but never ended up using them. I did listen to them, though. I usually will audition a part in my hifi before I use it to get a handle on the sound. I remember listening to a bunch of different .1 caps I had on hand, the polystyrene Rel Caps, polypropylene 716P's, polyester Mallory 150's, Sprague 730P's, briefly the Mallory PVC polyester, and comparing them to just a wire, so they weren't blocking DC, just in series with the source.

To me, those polystyrene's sounded the worst; very odd, almost like an eq was inserted with the mids scooped. They were pretty expensive caps, too, but I won't even use them in a hifi project because they were so colored.

The regular polystyrenes sound great as treble caps, though. Way better than silver mica, which sound clangy by comparison. Of course, they are a MUST in a wah, too.

On a side note, I've found polypropylene caps, like the 716P or 730P or even the Mallory 170, do not increase brightness or sound sterile. They pretty much simply block DC without impacting the sound much at all. They need to burn in, though, especially the 716P.

Polyester, on the other hand, tends to produce a lot of smearing, which affects the midrange and bass almost as badly as the top. The Mallory PVC is certainly not as bad as the Mallory 150, though. Another area where polyproplene really outperforms polyester is in transient response/slam, which seems to give better speaker/guitar coupling hence good feedback.

[Structo]

I thought that STK made polystyrene caps but when I checked all they list is polyester and polypropylene.

I could have sworn I saw some in an HRM board in a Brown Note amp.

I see on their site they say the polypropylene is the replacement for the polystyrene caps.
So maybe it was recently they quit making them.

The bad thing I guess is that polystyrene does not have a good temperature coefficient.
So they may not behave well in a hot tube amp.

Plus I believe the rolled polystyrene had a bit of inductance to go along with them.