Polycarbonate Film Caps

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PermO

Well-known member
Joined
Mar 16, 2011
Messages
792
Location
Hilversum, Netherlands
I've always liked what polycarbonate film caps do in an audio circuit.
I've been using an old batch I scored 20 years ago for my DIY projects.

Thingking these are long gone and bye bye...

I found they are still being made;
https://www.ecicaps.com/film-capacitors/mc-series/

Has anyone ever used these ?
Know these ?

Are they crazy expensive ?  ;D
 
what is it that you like about them..?

My old favorite was polystyrene for their neutral (clean) characteristic. The modern substitute for polystyrene is NPO/COG ceramic.

JR
 
I've always found that caps can have an imprint on the sound of a device.

And I don't want that.

I feel there's less of an imprint going on with these, they just sound better to me.

Now this is all subjective, I simply go by what my ears tell me.

25 Years ago I started building DIY tube amps, and in my town was this DIY hifi shop, they designed tube amps and speakers, you could buy kits and it was an electronics parts store aimed at audio specific.
They always used polycarbonate film capacitors for coupling caps and speaker filters and the stuff they build sounded amazing. So I got these caps from them and simply always used these in audio circuits ever since.

But I'm running out in the 400V department...

I've tried Wima MKP, as I see these get a lot of use in high end builds... not that they are bad, but I'm not a huge fan  :(

 
Those caps you showed look a lot like Russian made paper in oils with metal/glass hermetic sealing.
They can be found at a reasonable price on ebay , I havent used them myself although I have seen a bunch someone else ordered , very high quality military surplus . 
 
I never tried PIO.

I like the fact that these are new high quality polycarbonate film caps, a thing of the past.

I checked the stock (MC12 series) and they seem to have every cap I need for my build at 400V rating, I'll send an email to the Ireland office to see if I can get a quote on some.

 
PermO said:
I never tried PIO.

I like the fact that these are new high quality polycarbonate film caps, a thing of the past.

I checked the stock (MC12 series) and they seem to have every cap I need for my build at 400V rating, I'll send an email to the Ireland office to see if I can get a quote on some.

Cool, let us know please.
 
I have always been a fan of polycarbonate myself, and have bought several batches of these EC brand caps over the past couple of years. They seem well made and consistent and I’ve been satisfied with them.


Curious where they get their stock of dielectric grade polycarbonate. It was my understanding that that particular plastic went out of production in the early 00s.


What’s nice about polycarbonate dielectric is that it’s very volumetrically efficient, so caps of a given size are much smaller than polypropylene or polystyrene of the same specs. It’s about as efficient as polyester, without polyester’s shortcomings in audio applications. I usually use Q value measurements to identify old, unknown caps. While Q has limited utility as a figure of merit in audio applications, it’s not coincidental that higher Q generally correlates to dielectrics that are more desirable in audio (particularly filter applications). PP and PS film caps will generally have 8 - 15 times higher Q than polyester for a given capacitance. For PC, it’s only slightly less. And PC just sounds really good to my ears.


All that to say, PC is nice because you get only slightly lower performance than PS but at much higher volumetric efficiency (meaning an equivalent cap will be quite a bit smaller). And you can find more larger value caps with higher voltage ratings than you ever will with PS.

The problem with C0G/NP0 is that you can hardly find any values above 10nF in through hole. Sometimes you can find Kemet brand at up to 100nF, but it’s not common anymore.


PS is still my favorite for filters, but I’ll use polycarb any day.
 
warpie said:
Cool, let us know please.

:-X

I just got an email from the Ireland office.
You can order these from them, no problem, stocklist is on the website.
They come at a price though  :eek:
These are high end industrial caps and cost about $ 100,- each... and up.
(0.1uF / 1uF / 0.47uF 400V rated)

They produce the polycarbonate film themselves, a costly proces.

So not hobbyist territory I guess  :-X
 
;D

Indeed, there are more brands selling caps at these prices, Mundorf comes to mind.

In that case, I would defenitly trow my money at the high end industrial polycarbonate caps.
I would still like to get my hands on a pair of these, no free samples ?  :'(
 
PermO said:
These are high end industrial caps and cost about $ 100,- each... and up.
(0.1uF / 1uF / 0.47uF 400V rated)

We should organise a groupbuy to get one lol
 
JohnRoberts said:
what is it that you like about them..?

My old favorite was polystyrene for their neutral (clean) characteristic. The modern substitute for polystyrene is NPO/COG ceramic.

JR

the NPO/COG are great but they are not available in very high values, polystyrene are also good but are less available, expensive, not a huge range of values and sensitive to heat, which makes soldering more troublesome, In general I am perfectly ok with polypropylene, but I really like polyphenylene sulfide caps (PPS) however they are more expensive than polypropylene. You should check Cyril Bateman's articles on cap distortion in EW.
 
Is there any disadvange besides space to stacking capacitors of the type desired in parallel for the desired value?
 
user 37518 said:
the NPO/COG are great but they are not available in very high values, polystyrene are also good but are less available, expensive, not a huge range of values and sensitive to heat, which makes soldering more troublesome, In general I am perfectly ok with polypropylene, but I really like polyphenylene sulfide caps (PPS) however they are more expensive than polypropylene. You should check Cyril Bateman's articles on cap distortion in EW.
I am well aware of the Bateman capacitor series published years ago. I have been doing my own bench testing wrt capacitors in real world circuits since the 70s. 

I just took a quick look at Polycarbonate and the DF and temperature coefficient is not that great (especially compared to NPO/COG).

For larger values, like passive loudspeaker crossovers I liked polypropylene. Of interest to me is how much current the capacitor is passing which exercises non-ideal characteristics like ESL, ESR, etc, and AC terminal voltage in use that exercises voltage coefficient, DA,  and more.

JR
 

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