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The Peasant 9th November 2006 10:49 PM

Favorite film capacitors for DC blocking?
For many years my favorite DC blocking capacitor was the original IAR Wondercaps. Alas, I have finally depleted my NOS stock of these parts and am looking for a replacement.

Is there any consensus at all regarding which brands sound the best? Perhaps someone has posted some comparisons somewhere on the net?

I always thought that the Wondercaps used a teflon dialectric, but I don't know for sure. This is primarily for solid state work, so I'm not sure that I should consider paper/oil caps or stick with standard polypropylene, polystyrene, or teflon film types.

I sure don't want to have to purchase a few of every type available and spend many days making comparisons, so any advice is appreciated!

Take care,

The Peasant 16th November 2006 12:25 AM

Hello... anyone out there?
Parts Connexion has a huge selection of quality film capacitors. How do you choose? Doesn't anyone buy film caps anymore?

Take care,

AndrewT 16th November 2006 08:44 AM

I have seen reports on teflon di-electric and they seem to be tops.

Most cannot afford these and accept next best as polypropylene.
These are good for coupling/DC blocking.

It appears that the X & Y rated types intended for mains use perform as good audio caps.

Then come all the other film caps that are there to save space and/or money.

I would be very surprised if IAR are teflon.

Geek 16th November 2006 11:41 AM

MKP series from may manufacturer's give good bang for the buck. Wima, Vishay, Solen and the STK MP series sound pretty good too :)

jacco vermeulen 16th November 2006 11:53 AM

A year ago i've rediscovered polyprop LeClanché capacitors, from Switzerland.
By stumbling on a NOS batch, noticed at a later date that the brand has been gaining audio popularity.
LeClanché's tinfoil line caps are pretty ok by me, although i doubt that i'll buy them again for the going rates. Not to mention the size downsides.

AMV8 16th November 2006 12:45 PM

I have been experimenting.

I found that I much prefered the sound of polystyrene caps and teflon second and polypropylene/polycarbonate third.

The problem with the polystyrene and teflon is the size. I do have a lot of all the above types that I bought some time ago but most are too large to use in values over 1 or 2 uf.

I experimented further and found that I prefered even more the sound of polycarbonate (1 to 10 uf) in parallel with polystyrene. ( 0.05 to 0.01uf )My second choice was polypropylene ( 1 to 10 uf ) in parallel with polystyrene. ( 0.05 to 0.01uf ) I found that parallelling gave me the crystal clear treble that goes with polystyrene/teflon coupled with the low base that goes with higher capacitance values.

I could not find any electrolytics that gave as good a performance as the polycarbonate or polypropylene.

I performed listening tests on a Krell and a Passlabs preamp that does not need a blocking capacitor. I could not hear a real difference when the parallelled capacitors were inserted. It may just be my ears - who knows. I found a greater difference in the preamps that I have designed and built myself when I chage semiconductors than by changing capacitors. Nelson Pass I believe commented that in his view semiconductors were less linear than capacitors. I find the same. ( NP if I misquoted you apologies and please correct me )

I found the best sound and also the best value for money by using parallel polycarbonate and polystryene.

Hope this helps

AndrewT 16th November 2006 12:59 PM

it's a shame polycarbonate caps are made from unobtainium film.

I didn't realise my soon to run out stock would be so much better than the PES that has come to replace them.

Nordic 16th November 2006 05:21 PM

I have punted them before but I believe the Ampohm FK-CP series of polyprop caps are real good value for money, They are terribly big but I have yet to get something better (that I can afford), Even these caps are not all that cheap at about $10 each, but worth it in my view.

AMV8 17th November 2006 11:07 AM


Until I read Andrews post yesterday I had not realised that polycarbonate capacitors were no longer available. ( I have large stocks of various types and rarely need to buy parts )

However I still have a capacitor test rig set up at the front end of my preamp so last night I did further testing of various combinations of capacitors to find a cost effective and this time available combination. I found paralling polystyrene (or teflon) ( 0.05 to 0.1 uf ) with polyester sounded OK to me. The polystyrene/teflon gave a clean treble. The base was good if I used good quality polyester capacitors. I found that to my ears this sounded better than simply using polypropylene. Also much more cost effective.



Geek 18th November 2006 07:02 AM

Polycarbonate are available:

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