AO-44 Conversion...a little weak

[420Jazzerciser]

Long time lurker, first time poster...

I recently converted the Hammond AO-44 amp to include the AB763 preamp, as per Sluckey and 1blueheron.  Great threads and glad to have them.  I completed the build, brought it up slowly on the variac, and was a little...underwhelmed.  Thought it would be more powerful with the 2 6GW8 output tubes. 

Voltage were a little low and I didn't think that would effect it, but maybe it does, and that speaks to only having a few years of amp tinkering under my belt. 

I double checked all component values, checked the layout against the pics on the other threads, and pored over the schematic to make sure I have it right. 

I did temp in a 25/25 on the second triode of the 12ax7 and it helped a bit but I dime the volume and its like my SF Champ on 5.  Barely any breakup. 

One difference from the Sluckey/1blueheron build is I did not add the bright switch. 

Voltages
Filter Cap
A - 308
B - 295
C - 278
D - 275

12ax7
1 - 186
2 - 0
3 - 1.35
6 - 182
7 - 0
8 - 1.4

V1A/B (6GW8)
1 - 0 / 0
2 - 1.9 / 21 Triode Cathode
3 - 298 Pentode Screens
6 - 310 Pentode Plates
7 - 9 Pentode Cathodes
8 - 0 Control Grids
9 - 222 / 219 Triode Plates

6CA4 Plates 258 VAC

Where would you go from here?

[PRR]

Welcome.

> Where would you go from here?

To the chalkboard, to draw a schematic. "AO-44 amp to include the AB763 preamp" does not paint a clear picture in my mind.

[dogburn]

I had a low volume problem recently, and it turned out to be a bad volume pot, so you might test that and the other pots.

[sluckey]

To the chalkboard, to draw a schematic. "AO-44 amp to include the AB763 preamp" does not paint a clear picture in my mind.

Probably this...

http://sluckeyamps.com/PeeWee/PeeWee.pdf

[420Jazzerciser]

Yes, thanks, that's the schematic I was using.  Also, this is what initially got me started.

https://sluckeyamps.com/PeeWee/peewee.htm

Looking at my voltages, should I be seeing the 21 volts I am reading on the grid of triode on V2A?

[sluckey]

Looking at my voltages, should I be seeing the 21 volts I am reading on the grid of triode on V2A?

Yes. It's actually quite a bit more but your meter loads that high impedance grid circuit causing the voltage to read lower than what it really is.

It's possible that your weak sound is due to old and tired 6GW8s.

[420Jazzerciser]

One last Hail Mary on some help...here are a couple pics

[sluckey]

Wrong resistor...

[420Jazzerciser]

AHHHH!!!  ROOKIE MISTAKE! 

That was it, switched it out for the correct value and BOOM, amp sounds great! 

Always learning to slow down...I THOUGHT I double checked all the values and I still missed it.

Thanks so much to the community here for helping out and with all the valuable information that is here.  I have no one in the area to bounce questions off of as I try to teach myself this stuff so having this sounding board is incredible.