Hello Dave (Gillespie), DR, Terry, Randy et al,
Rainy day up here in Canada so I dusted off the AA-151 and got her done.
Well to a point. Zener are in to drop the voltage and the hammond choke has been installed.
I powered it up and it sounds fine. Critical listening with good speaker is next. I will report back.
It's not optimum, but she's stable and running quite equal on both channels.
Here is the voltage report:
AC in at Pin #8 of the rectifier: 405 VDC
After the Zeners & choke: 381 volts
After the 1k resistor in the power supply: 300 volts
The Bias is at 14.5 volts over a 120 ohm resistor. (I may put back in the 100 ohm resistor in the short term. In time I would like to bias all tubes independently).
The 6AN8 is equal (within 1 volt between each channel) on both channel and close to each other.
Pin #1 is at 234 volts
Pin #2 = 53 volts
Pin # 3 = 65 volts
Pin #4 = 48 volts
Pin #5 = 48 volts
Pin #6 = 55 volts
Pin #7 = 64 volts
Pin # 8 = o volts
Pin # 9 = 1.45 volts
I am still off, but I have come a long way. The amp runs quiet and stable and seems to sound clear.
Do I increase the voltage to the EL84 by +5 volts...or do I leave it as such.
I can easily change the bias resistor for a bit more power (from 10.5 watts to 12.9 watts per channel if I install a 100 ohm resistor).
Comments?
Again, thanks for all your help (Especially Dave G.) and your comments (Death Rex, Terry).
PS: If I find the sound is lacking, I will order the proper choke with a lower DCR.