[Amps] Advice needed for SS amp

[Bill Turner]

ORIGINAL MESSAGE:          (may be snipped)

On Wed, 05 Jun 2013 09:58:11 -0700, you wrote:

>
>Why such a large capacitor for the power supply? Surely 680 uf, one tenth of what you plan 
>to use, would be more than enough, even given the low impedance of the load. The extra 
>capacitance just makes the PS more dangerous in the event of a short or arc, and will take 
>longer to discharge when you turn it off.
>
>You might need to take some extra precautions to protect your diodes from transients if 
>the PS is connected directly to the line.

REPLY:

Why such a large capacitor? 6800 uF with an eight amp drain gives about a
1.5 % ripple. 680 uF would be ten times more and I think that's too much. 

By comparison, a typical commercial tube type amp running 3 kV at 800 mA
with a  50 uF filter has a bout 2.2% ripple, and that seems to be
acceptable. 

I could go down to 4700 uF if I could find one.  These really hi cap hi
voltage units are kind of rare.  

Transient protection is probably a good idea, but with such heavy diodes and
a massive capacitor, any transients are likely to be absorbed. Remember,this
is a full wave bridge so transients of either polarity would be absorbed. At
least I hope so.  :-)

73, Bill W6WRT