First TMB build, final readings

[JohnJankowski]

Ok, remember what I wrote about my B+ readings a few days ago? Forget that. Wrong amp. Sorry.

Now then, before B+ zener diode install I had 385 at node A. I ran two 15v/5w Zeners in series and got the A node down to 350.

B=319, C=271, D=236. Line volts 124vac.

Tube V1 remains a 12AY7. Pin 1, 136. Pin 6, 95.

V2… pin 1, 135. Pin 6, 211.

V3… pin 1, 198. Pin 6, 203.

V4… pin 3, 11. Pin 7, 346. Pin 9, 320.

V5… pin 3, 11. Pin 7, 348. Pin 9, 322.

With a 180/5watt resistor for cathode bias, I read 11 volts. My bias meters tell me I’m getting an average of 25ma through the 6N14N tubes. This calculates to 8.65 watts PD per tube, or just north of 17watts output.

Close enough to the bullseye for me. Lol.

I’ll set it up and play through it for a few days before I decide is it needs anything else. I have components for the anti-hiss/snubber mod if needed. Time and my ears will tell.

All opinions welcome. Thanks for providing this website.

[JohnJankowski]

And, I’ve put the 12ax7 back in V1. It’s noticeably better. The B+ adjustments plus correcting the bias of the output tubes nailed it.

While this is my first TMB build, it’s not my first amp. I’ve built 10, including this one. Plus a Fender based, Uncle Doug 6g15 reverb unit. Each one has been an education.

This one especially. It was based on a mojotone layout, and an older revision as well. I don’t know that I would have gotten this far with it had it not been for the resources available here. In fact, I’m quite sure I would not.