Hi All,

As an added bonus of asking RAT's about adding a choke to my
Heathkit aa-151 power supply, Patrick Turner had a once-over
of the schematic and made a few excellent suggestions. The
next one I'm going to tackle is changing the single cathode-
resitor-bypass-cap to the 6BQ5's.

The aa-151 is a PP 6BQ5 "ultra linear" integrated with a 5AR4
rectifier and cathode biasing, and aside from 6EU7's instead
of 12AX7's is like the Heathkit SA-2;
http://www.mods.com/heath-hifi/sa2ma...2schematic.gif

I've done the obligatory newsgroup search for this topic.
Maybe surprising, but some people have experienced negative
effects from going from one cathode resistor-cap to four
separate ones. The general argument being about improved DC
balancing with shared resistor-caps per channel (in PP).

So... I'm going to go half way, changing the one resistor-cap
into two, one for left, one for right.

Currently, shared between all four 6BQ5's cathodes is a 100ohm-
7watt resistor and a 50uf-25V bypass-cap. Patrick suggested
four separate pairs with 200ohm and 1000uf, a BIG change!

The 6BQ5 spec-sheet states for PP class AB two tubes, a typical
cathode-bias resistor of 130ohm.

What I'm wondering is the RAT's-eye-view of the values for these
resistor-cap pairs. I'm thinking 165ohm-5W and 80uf would be OK,
but maybe a bit conservative.

Thanks!