Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: TWANG on January 22, 2020, 01:51:04 pm

Title: 18 W build and test V.
Post by: TWANG on January 22, 2020, 01:51:04 pm

I could not find a signal for sooooo long. everything checked out on the meter.
over and over. Then, on a bored frustrated whim, I replace a wire, to the gain pot.
and it worked.
I could have screamed bloody murder.

I was concerned about the bias but I guess I'm ok, after reading much about EL84 in PP.

V1/V2
1   230   231
3   1.9    76.7
6   168    235
8  .849   77

V3/V4
3    12.32    12.31
7    343       342
9    328       327

3-7   330
cathode 150R
v over cathode 12.33
htrs. 6.66 (that explains the mystery wire!)

13W diss.
39mA plate current.

I was concerned that I got over the 12 W you always see recommended, but I found so many people claiming to run 13W and much higher mA.  I have no redplating.
two JJ 12AX7, two JJ EL84, one JJ EZ81 rectifiers.
Classis tone PT and OT.