Bottlehead Kits > Legacy Kit Products

S.E.X monoblocks - filter caps

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Psimon:
Hi all,

I need to replace the filter caps in my S.E.X monoblocks (one of the earliest kits in use with the foreplay 2).

I sourced some 22uf 500V filter caps to match the ones in there and noticed that the existing are film caps with no polarity marked on. The ones I have bought are electrolytic at the same value (except their tolerance is -10/+30% while the films are +/-10%). Can I use the electrolytic as a replacement? I'm concerned about the polarity as well, as I don't want to blow the caps up. I've attached a photo of the inside wiring and existing cap.

Any advice would be much appreciated. (I'm no techie and didn't build these myself)

Best,
Simon

Paul Birkeland:
What happened to warrant a cap replacement?  Those film caps should last about a lifetime or two.

2wo:
The caps shown look kinda small for film caps of that value and voltage rating. If they were film, they probably wouldn't need to be replaced. I don't remember the original values but I'm sure someone does and can recommend a current replacement...John

Paul Joppa:
There are four versions of the Original S.E.X., none of which had film caps in the power supply. So this is not a stock build. That 10-henry choke isn't original either, nor does the original have any iron under the chassis. So it's a little hard to tell what you have.

That said, the original used two caps of 10 microfarads/450 volts. Assuming these are the power supply caps, your 22uF/500v electrolytics should work well. The ends soldered to the ground wire would be the negative, and the other ends soldered to the choke would be the positive ends.

Because it is an unknown modification of some version of the original, it's hard to know for sure what you have. If you can post a photo of the whole top and the whole bottom, we can probably figure that out.

Psimon:
Thanks for the replies guys.

To answer a few questions:

* I replaced the caps because there was a hum in the right channel. It sounded like a filter cap issue based on the pitch (I compared online with youtube video tutorials)

* The existing film caps are about 2.2inch long

* Yes I understood when I got these amps that they were different from the standard builds. I've attached 3 photos that I hope are useful. The 2 sockets on the top of the amp take 6DN7 tubes, recently replaced, but swapping them from one monoblock to the other makes no difference to the hum. I also eliminated any issue with the Foreplay by swapping output cables etc.

Cheers!

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