lowering the plate volts ?

[rp]

and for peoples info you need the part ending in "K" to get cathode to case. 

I'm a pretty good googler and I couldn't find, so thanks. Holy $%#& they've gone up. They were always pricey but like $12 IIRC way back. At least I know they're there, too bad I can't afford to put a few aside. Wonder why nada in the Mouser, Farnell, etc catalogs?

[rp]

save someone some googling:

[thejaf]

You're talking about a master volume amp, correct? If it were me, I'd start by reducing voltage in the preamp by increasing the size of first dropping resistor (one after the choke). Measure the voltage drop across existing to figure out current, then do the math to decide your value change. See if that puts you in the ballpark.

Alternatively, just double the existing value (10K to 22K) and see if you like it. Easy to change out either way.

In my own experience, changes in preamp supply voltages really effect the tone and feel of the amp.

[matt h]

(deleted)

[M Fowler]

The part number AK indicates it is reverse anode which you drill a hole through the chassis and directly bolt the diode to the chassis without an insulator.

[matt h]

(deleted)

[rp]

To the OP: I couldn't remember where I saw this, it was posted here I think and here it is again, near the last paragraph about not needing the mica insulator:

[jamme61]

Can achieve the same results using a variac? I have an old general radio w5mt laying around. I figured I could dial this down to 100 ac an get the same results. Bad idea?

[tubeswell]

Can achieve the same results using a variac? I have an old general radio w5mt laying around. I figured I could dial this down to 100 ac an get the same results. Bad idea?

All depends whether its just a high H.T. winding or whether all the secondaries are high. No point in lowering the 6.3V winding to 5.5 Volts.

[jamme61]

yea that's right that would mess with the heater voltage - not good

[martin manning]

Not that big a deal though. I think you'd be fine running the heaters as low as 5V. See: http://ampgarage.com/forum/viewtopic.ph ... 104#337104

[pops]

You could always replace the choke with a larger one that can handle the power tube and put it in the circuit before the first filter cap. It will lower the voltage nicely. You can read about it in Dave Funks book.