The Amp Garage

Charlie So what I did was I injected a signal into the amp and then checked AC voltages at the power tubes pin 6. In order to get the tubes balanced , I had to turn the potentiometer completely counterclockwise , Out of travel point, that put one tube at 29.04 and 29.6. There was no discernible diff...

Charlie Thanks for the reply. As far as Balancing or unbalancing goes , everything that I read from five years ago talked about the Tweedledee and how to balance the phase inverter and or unbalanced to phase inverter. The commonality with what everyone said is that right around 6 V differential crea...

Charlie

Warmed amp up 10 minutes.

At pin 8 of PI is 47.8 VDC
At 4.7 K side from pin 8 is 47.5
After 4.7 K is 45.8

If you need more voltage checks let me know. I have the back off
And on the bench

Ian

Let me know. With the 1 meg resistor, I was able to get
About a 5 volt differential. With the new resistor, the total
Voltage swing was only 1.6 volts

Ian

I have the same voltage on v2 pin 7 after the resistor swap. Also,
My previous voltage was 19. In addition , I noticed that you cannot adjust the phase inverter to have any imbalance of more than 1.6 volts. Did you try to adjust your inverter yet?

I fixed my grounding issue , now on to another question With this new resistor arrangement, the max phase inverter AC swing is 1.6 volts using 1000 hertz Input. That is The most you can get end to end. Would this resistor change have this affect , along with only 3.5 volts at pin 7 of the phase inve...

Well after reading Charlie’s post about the one mega resistor that should’ve been a 10 meg, I decided to change it out today and give it a listen. I did not perceive anything different but I do have a question. After changing this should I readjust my phase inverter trim pot? Also here is a link bel...

Let the build begin!! Your thoughts on a 1/2 power switch? Also how does it sound? Any clips?

Thanks for the reply, that sounds like the way to go ! Was going to use same power I use for a 5E3 : Magnetic Components Deluxe PT Transformer and Hammond 1750 OT. In addition was going to install a bias pot. I also have some Russian PIO coupling caps that I was going to try instead of Mallory. (unl...

Has anyone built a 5F6A driven with a Deluxe Reverb transformer with a 8 ohm OT and s single 12 or two 10 inchers

Yep I agree. 330-0-330 with a gz34

Thanks for the info. So a 350-0-350
Should work

Regards

Mark

Do you remember what your unloaded voltages were on your Heyboer? MM transformer is 380-0-380. I'm thinking of changing out to a 350-0-350 or a 330-0-330.

Using MM Tone Clone FTBP 59. Power with a MMF050BM-2 output and a FC 2.84 choke.

I'm thinking of calling MM about the spec on this transformer. I want 400 on the plates.

Regards

Mark

Thanks ! I'm wasn't comfortable with the 480 Vdc on the plates. No red plating or any issues. Sounds great, but I find that the amp has a nicer break up at the lower voltage. The 5881's are, in fact, nos from 1960 or so. The Russians I believe are Nationals and are NOS from the 60's. Was going to ad...