Any recommended coupling caps?

[JohnJo]

I'm thinking of upgrading the input and output caps of my little Yaqin 6J1 valve buffer and would appreciate any recommendations for suitable upgrades. Nothing too fancy just a decent quality item.

There's no values on the existing ones and they are a bit of a pig to unsolder just to measure but the input caps are twice the physical size of the output caps.

I'm assuming any value between 1 to 4 uf is suitable, is that about right?

B+ voltage is 203V. Does the voltage rating of the coupling caps just need to be comfortably higher than this, e.g. 250V, or should there be more headroom?

Thanks in advance :)
http://i1229.photobucket.com/albums/ee462/castle48/Yaqin%206J1%20Buffer/E17D4436-91FE-4D97-A2D1-063B892A0BDA.jpg (http://s1229.photobucket.com/user/castle48/media/Yaqin%206J1%20Buffer/E17D4436-91FE-4D97-A2D1-063B892A0BDA.jpg.html)
http://i1229.photobucket.com/albums/ee462/castle48/Yaqin%206J1%20Buffer/7BA90D57-7830-40BF-8E4B-306D8B534451.jpg (http://s1229.photobucket.com/user/castle48/media/Yaqin%206J1%20Buffer/7BA90D57-7830-40BF-8E4B-306D8B534451.jpg.html)

[Yomanze]

I would leave that all well alone and change the power caps instead. It's a real minefield experimenting with coupling cap flavours, and fitting it all in with more exotic types, which might just 'change' the sound rather than improve it.

[Bigman80]

I really like a brand called Le Clanche. This is a minefield though lol.

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[walpurgis]

I really like a brand called Le Clanche. This is a minefield though lol.

Make your own! :)

[fatmarley]

I agree with Neil.

It looks like you have polyester coupling caps, so obviously some thought has gone Into them, otherwise they'd use cheaper electrolytic caps. Saying that, I swapped out the Solen polypropylene coupling caps In my cheap Chinese dac for Nichicon standard electrolytics (I don't like Nichicons top audiophile caps). The sound Is now far more natural to my ears and the thin, slightly harsh sound Is gone.

'Better' caps can often sound worse IME.

[Bigman80]

Make your own! :)
I wouldn't know where to start Geoff lol

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[struth]

Make your own! :)

http://www.instructables.com/id/Make-A-Water-Bottle-Capacitor/

this is fun, but be careful folks

[Firebottle]

You'll find the value is marked on the top, i.e. the 'side' that has been glued down to the chassis.

Virtually any polypropylene will be better than a polyester cap. Look for MKP on the capacitor rather than MKT which is polyester.

Cheers,
Alan

[JohnJo]

Thanks for the replies guys. Those homemade water bottle capacitors are pretty cool :D


You'll find the value is marked on the top, i.e. the 'side' that has been glued down to the chassis.

Virtually any polypropylene will be better than a polyester cap. Look for MKP on the capacitor rather than MKT which is polyester.

Cheers,
Alan

Good point Alan regarding the marking being on the top. I had an epiphany and remembered I had a couple of Wima MKPs on another board I had lying around. Only rated to 160V but they're only seeing 52V so should be ok. I take it if a valve shorts internally I could get the full B+ voltage on one of these caps? Unlikely I know but still....hopefully there'll be input caps on the amp!

I've soldered them to flying leads and left them outside the case so I can change them easily if I get something else. Just left the originals in there for now with one leg disconnected.

Already sounding more natural. The disco bass has gone (boo, I liked that but I suppose it shouldn't really stay). The slightly closed top end of the originals has been replaced with more air and overall separation is improved. Will leave them in for a while.

http://i1229.photobucket.com/albums/ee462/castle48/Yaqin%206J1%20Buffer/17C2FD63-6FF5-4007-B195-C1CD6F273F5F.jpg (http://s1229.photobucket.com/user/castle48/media/Yaqin%206J1%20Buffer/17C2FD63-6FF5-4007-B195-C1CD6F273F5F.jpg.html)

[fatmarley]

The disco bass has gone (boo, I liked that but I suppose it shouldn't really stay).

Trust your ears. If you liked them, they should stay.

Amp manufacturers (good ones at least) will voice their products to sound enjoyable because there Is no such thing as perfect sound. Naim use Tants because they obviously like the sound (they are not cheap and don't measure great either). Rega use a lot of Samwa electrolytics In the signal path. IIRC they use Nichicon In their higher end products.
In my own Onix OA21 amp I've tried loads of different feedback and coupling caps. Polypropylene always sound harsh, thin or just wrong. Polyester sounds similar to polyrop but are often a bit dull as well. The old Elna Silmic 2 that was supposedly the cap to get years ago sounds bloated and dull In my Onix (sounded the same In my old Naim amps too)
It's quite Interesting Googling high end amp Internals. You don't often see large film caps.

I know It's hard but the best thing to do is to forget what the cap Is made out of, and listen to what sounds the most enjoyable and not what sounds the most detailed. The best way to do that Is to live with your new caps for a period of time and then swop back to the old ones.

EDIT: I just noticed your amp Is a valve job. I get the Impression that there Is some kind of synergy with valves and polypropylene caps because the two of often seen together (I'd still swop back after a week or two just to make sure).

[RothwellAudio]

I get the Impression that there Is some kind of synergy with valves and polypropylene caps because the two of often seen together.
Valve amps often don't need very large values of capacitance but they do need quite high voltage ratings. Polypropylene match those criteria quite nicely and polypropylene is one of the best dielectrics, hence their popularity in valve amps. I don' think there's any particular sonic synergy between valves and polypropylene as such.

[Firebottle]

Good point Alan regarding the marking being on the top. I had an epiphany and remembered I had a couple of Wima MKPs on another board I had lying around. Only rated to 160V but they're only seeing 52V so should be ok.

You will find that the coupling cap will almost certainly see the maximum voltage across it at switch on before the valves warm up, if you have silicon rectifiers.
If the rectifier is also valve then the case is different.

Measure the voltage at the moment of switch on. If you get 203V for only a short period then I'd say you are unlikely to get a failure, but that's not to say you won't.

Good to know you have got 'more air and overall separation'.
:)

[IslandPink]

Mundorf Zn for me.

[Firebottle]

I think everyone in the Universe knows that Mark :eyebrows: ;)

Very fine capacitor choice though but possibly bettered by Le Clanche (tin foil construction, the same as Zn) when encountering a lower stand off voltage.

YMMV of course :)

[JohnJo]

Cheers Alan. Measured the voltage across the caps at power up. Voltage just builds steadily over a Couple of seconds to 52 or 53 volts and I'm using a good quality DMM with fast bar graph display.

It is solid state rectification with CRC, see photo below.

I was missing a bit of the bass weight from the old caps so in an attempt at best of both worlds I paralleled both sets of caps and it works :eyebrows:

Sounds great :D

http://i1229.photobucket.com/albums/ee462/castle48/Yaqin%206J1%20Buffer/E17D4436-91FE-4D97-A2D1-063B892A0BDA.jpg (http://s1229.photobucket.com/user/castle48/media/Yaqin%206J1%20Buffer/E17D4436-91FE-4D97-A2D1-063B892A0BDA.jpg.html)

[JohnJo]

Mundorf Zn for me.

Those look reasonably priced Mark, exactly the sort of thing I was thinking of but don't think there's room in here:(

[IslandPink]

Film/foils are always a bit hefty, admitted. The Zn's are a sleeper as people think the more expensive ones are better ... he he !
Never heard the Le Clanche ones Alan - that's a new one on me but I'll check up on them.
In phonos it's a been a tough call between Mundorf Zn and Rel PCU (copper/polyprop) , I may have one of each in each channel in my phono.

[Yomanze]

Russian mil-spec PIOs bypassed by teflons. I have some spares if anyone is interested. They are big and heavy though.

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[JohnJo]

Russian mil-spec PIOs bypassed by teflons. I have some spares if anyone is interested. They are big and heavy though.

Sent from my SM-G920F using Tapatalk

Thanks for the offer Neil but not a lot of room in here!