In article ,
Raymond Koonce wrote:

John Byrns wrote:
In article ,
Raymond Koonce wrote:

Hi John,

Not entirely my idea. A friend built an amp using this tube and liked
it. I had several pairs and some appropriate transformers, so I decided
to build something with what I had. About the only thing I didn't have
on hand was the copper chassis. All in all it's a nice amp, but I still
have some issues with the 816s to resolve. I would like to have a small
(2uF or so) cap on the input to the PS, but the 816s don't like it.

I don't follow you, why would you like a 2 uF capacitor on the input to
the PS, is the B+ too low?

Yes, I'd like the B+ just a little higher and it's easy to do with a
small cap if you're using a vacuum rectifier. The amp is pretty nice as
is though.

What B+ do you have now and what do you want? Here is a crazy idea that
might or might not work, it's tempting me to fire up my old computer
that has Spice on it and see what happens with a simolation.

Idea, add an input capacitor considerably larger than 2 uF and then add
enough additional impedance between the rectifiers and the added
capacitor to keep the repetitive peak current to 500 mA as per the 816
spec. The added impedance could be an input inductor of smaller than
normal value, but large enough to control the repetitive peak currents,
or there is a chance even a resistor might work as the added impedance,
depending on the currents involved, although it would get fairy warm.


Regards,

John Byrns

--
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