SITE UPDATE: Subscriptions are now available, for image uploads and no ads. Check the sticky thread in Recent Discussions for more info.
AC30 with 2 el84s pulled - Rectifier options?
Measured voltages & bias with 4 el84s, came out as 15.4 watts/ valve, 128 %
Pulled 2 el84s, so now I guess it's an ac15, and changed the cathode bias scheme to accommodate - it's now two pairs, each biased with a 120r/100uf pair.
I've switched from a 5AR4 to a 5V4G to stop the B+ rising too much, it's gone up by 15v (thought I think 3 of those were the wall voltage going up in the time it took me to re-wire the cathode bias scheme) which puts the 2 el84s at 16.9 watts/ valve, 140%. And that feels a bit reckless.
Is there another rectifier that'll drop in and sag things a little more? 5Y3? I've also got a voltage bucking transformer that'd knock 12v off the mains, but I wouldn't mind a bit more sag anyway....
As to the "why" of it... I want to put a celestion blue in, it's a 1x12 combo...