output cap outside foil

[binar01]

So the Beepre is my first bottlehead kit build, and I'm definitely no electrical
engineer. I was successful on the first go luckily and have enjoyed the preamp
for many months.

I've got the itch to mod a little, have bought some Jupiter flat stack caps of the
appropriate spec and am about to swop out the Dayton 10uF caps from the build.

I see the Jupiters have the outside foil lead marked. I understand that film caps
aren't polar but the outside foil connected to the tube plate creates some shielding
benefit.

I've been studying the C4S boards, socket pins and terminal connections for a
while and I think that the plate socket pins are A2 and B2 so if the outside foil
theory is correct I should attach outside foil cap leads to terminals 2 and 17.

I'd appreciate any help seasoned bottleheads may offer.

[Paul Birkeland]

So the Beepre is my first bottlehead kit build, and I'm definitely no electrical
engineer. I was successful on the first go luckily and have enjoyed the preamp
for many months.

Well done!  The BeePre is a pretty lengthy build.

I've got the itch to mod a little, have bought some Jupiter flat stack caps of the
appropriate spec and am about to swop out the Dayton 10uF caps from the build.

Yeah, you've got the bug, that is a very nice choice.

I see the Jupiters have the outside foil lead marked. I understand that film caps
aren't polar but the outside foil connected to the tube plate creates some shielding
benefit.

I've been studying the C4S boards, socket pins and terminal connections for a
while and I think that the plate socket pins are A2 and B2 so if the outside foil
theory is correct I should attach outside foil cap leads to terminals 2 and 17.

The plate end of each 10uF cap will be the terminal with roughly 100V on it, which does wire to pin 2 on each of the 4 pin sockets. 

Let us know how those caps fit in the BeePre.

-PB

[binar01]

Good deal, thanks for the help! I'll need to come up with some way to suspend the caps below the bee quiet resistors and away from the C4S heat sinks as the heat rating on the caps is 180F! I'll post pics when I figure it out.

[mcandmar]

Jupiter flat stack, my favorite

For mounting i found using four zip ties around the cap gives you an easy way to hold onto them.

[binar01]

That seems like a good plan. Have you installed these in a Beepre or another build?

[mcandmar]

Only in a couple of DIY builds.  I would like to buy a BeePre someday, its top of the wish list...

[binar01]

So Jupiters are in and already sound really great
with only two hours!

I'm sure to be scolded for this but I've improvised
a nifty strategy to protect the large Jupiters from
radiant heat from the C4S sinks using heat resistant
silicone coffee cup lids from ceramic double wall
cups that have bit the dust. The ones that look
like generic paper coffee cups, you know, but are
durable (?).

I've rigged up a way to suspend the caps from
the plate from a sticky anchor with a zip tie and
spacer, so that the bottom face of the square
sided cap is flush with and hangs no lower than
the C4S heat sinks. Between the sinks and wood
base is room for the caps and about an inch gap
between cap and sink.

Since the Jupiters are heat sensitive, I decided
use the silicone cup lids to fill this gap to shield
the caps. I ran a small zip tie down to the sticky
anchor for the previous caps and through the
small mouth hole of the lid so it hangs suspended
between cap and sink.

Not elegant but so far seems functional. Silicone
is stable up to 500F so we will see if the sinks
exceed this temp!

Thanks to all for the help and encouragement.

[kgoss]

Way to go!  You came up with a creative and functional solution to your problem. Great job thinking outside the coffee cup😃

You should post a picture. No telling who will be inspired by it.