Coupling caps

[boulos]

Hello,
I'm thinking of changing the coupling caps on my kit (my understanding these are the 0.1uF caps).  The decision (finally) boils down to Mundorf Supreme and WIMA FKP1. I'm leaning toward the WIMA's.  Any thoughts on this?  Note that I'm changing the parafeed caps to ClarityCap ESA.
Thanks
Boulos

[physicsmajor]

They are 0.1uF caps, rated for 630V. One other option to consider is used surplus Russian teflon caps, which run in the ballpark of $10 each after shipping charges. The usual source is Ebay. Teflon caps are an entirely different ball game from the options you've listed. New production ones would cost over an order of magnitude more.

If you check these out make sure you get a 600V version; they also made a 200V version which would not be suitable. I believe mine were from the FT-3 series.

I can attest that there is enough room for both these and the ClarityCap ESA parafeeds in the case (this is exactly what I'm listening to presently  ).

[mcandmar]

There is something appealing about having cold war surplus hardware instead of boutique brands.  Would make a nice pairing with the old American Sylvania tubes i picked up

[boulos]

Thanks for the suggestion!  My fear is that Russian caps may not be made to spec or are not reliable in the long run. (Or maybe this is just cold-war brain washing that anything Russion is no good

I don't know if I would call WIMA a boutique brand. They make caps for many industrial applications, and their caps don't say stuff like "audio grade".

[physicsmajor]

Well, you can get them new old stock and that capacitor type is (chemically and physically) stable. Search this forum for "KK teflons" and you can see some of the other discussions; numerous people have used them over the years with nothing but praise. Perhaps someone with more/longer experience with these will also chime in.

My personal sample size is 2, but I measured my FT-3 caps and they were dead on spec. Exactly matched, within 1% of rated value, and they shouldn't drift because of the aforementioned stability. Brainwashed or no, they might be cheap enough to just try out if you feel like it (unlike pretty much any other teflon capacitor; VCaps run about $125 each!).

If you want more capacitor comparisons than you can shake a stick at - swapped in and out of Bottlehead amps, no less - check out this thread on head-fi. The Russian FT-3 is included in there. Note not all of those are suitable for the S.E.X. due to insufficient temperature or voltage ratings, and prices range from reasonable to ridiculous.

[Grainger49]

Thanks for the suggestion!  My fear is that Russian caps may not be made to spec or are not reliable in the long run. (Or maybe this is just cold-war brain washing that anything Russian is no good    .  .  .  .   

I have been using them everywhere since I discovered them about 10 years ago.  For the price they are impossible to beat!  Hard to beat for less than 5 times the price.  My measurements show most of the 5% caps are 1%. 

My take on Russian quality control for Military components was if you supply the Military bad parts, you disappear to Siberia.  Some of the tubes that they developed after the West quit making tubes are the most rugged things out there.  Being physically rugged makes them much less microphonic than other brands. 

The tubes are not the last thing out there as far as sound goes but for the price, which is extremely low, you can't beat them.  I have all Russian tubes in my Eros.  It sounds great!  The soundstage is wide and deep.  Detail and timber is amazing.

[boulos]

OK, I'm convinced. Thank you for your advice, and especially to the member who sent me pictures of his build.

I learned there are both 10% and 5% versions being sold on eBay for pretty much the same price.

Thanks
Boulos

[Grainger49]

Two values are critical with a capacitor. 

First is the capacitance value.  It needs to be within a range and not too small.  If too small you lose some bass response.  If too large you just waste cash you can use buying CDs, LPs and SACDs.

Then there is a voltage rating.  You must have it high enough that it doesn't explode when you start your amp.  Yes, I'm serious.  A higher voltage rating makes the cap larger and costlier than necessary.

Bottlehead sometimes uses a higher value and higher voltage stock part rather than buying a few lower value and lower voltage parts for a single kit.

This is to say if you stay with stock values you will be just fine.  If you decide to change the stock values ask here first.

[boulos]

So would a 0.1uF +/-10% tolerance 600V cap be OK in this application?

[Grainger49]

Yes, there is headroom in the ratings.  Often one company says 600V another says 630V.  Bottlehead buys from the second company. 

[Paul Birkeland]

So would a 0.1uF +/-10% tolerance 600V cap be OK in this application?

+200%/-20% will be OK.

[boulos]

  Thanks!!

[boulos]

I have yet to receive the Teflon caps, but I went ahead and installed the ClarityCap ESA and the Mundorf Supreme.  The enhancement to the sound was significant. Here are a couple of pictures of the build:

[Grainger49]

Well, I think I can say that you have the cap junkie sickness now.  Congratulations, so do I !

[mcandmar]

..must resist urge.. too late, i have a few mail order Russians on their way

Out of interest did you change them all at once, or in stages.  I would be interested to hear what differences you heard from swapping out each stage.  I'm finding it hard to fault the stock setup which is why i'm really curious.