Ah, the dreaded phase inverter adjustment. The problem with this whole issue is that what really needs to be measured here is AC voltage and not DC. But without a scope it's rather difficult to get good AC measurements. Wiith my balanced tube, getting a DC voltage swing like the manual states and like you're seeing was impossible. Atleast with the size trimmer on the amp. But it's quite visually and measurably noticable observing the AC shift with a scope.

What I did and my only advice would be to put back in the balanced tube and set the trimmer at halfway, then move it CW when facing the trimmer from the PI tube in small increments while strumming a chord with some nice harmonic content going and see if there's a position that makes the chord and then notes ring longer/better. IMHO, it's all very subjective, and if you think the old tube sounds "better" (and where you had it set) then that's what is best.

I have mine set about 1:00 facing the trimmer or 11:00 looking at the trimmer from the front of the amp.

Hey blues, do you use the clean channel or OD channel when rubbing the strings? I guess my question is...overall is there settings aside from presence (ie: gain levels, rock/jazz switch, etc.) that makes it easier to hear the "sweet spot"? I used the OD channel when adjusting, but didn't know for sure what was best.

I'm not an expert on the subject, but I guess you can use both. I you use the clean channel, listen for sparkle in open G chord. If you use the OD listen for the OD overtones or even feedback.....the point where you can feedback easily is THE point.

Many people try to turn this subject into a Dumble voodoo for the selected few. IMO it's not that hard to adjust. It takes max 5 min. after the get the chassis out of the head cab.

Thats right, at least thats my experience. Think it's due to the fact that the HRM and BM has a little less midrange than the Standard (RF) amp.

However, the HRM's (Bluesmaster and HRM) seem to blend in more easily. I usually bring my Bluesmaster to rehersals or gigs, but love to play the standard amps at home with feedback and all. Te Standard amps are more of a soloist amp - think RF or Santana.

Using a Dumbleator relly helps the amps to breath and feedback at low volumes, because you run the master(s) around noon and adjust master level on the Dumbleator.


Yep, this is a fact. A new amp sounds harsh, but after a couple of months of exercise, it mellows and opens up nicely.

Hey I played with my PI yesterday, I also adjusted the phase inverter.
I decided to just play with it until it sounded good to me. I ended up at about 1:00 exactly just like Soundperf, or 11:00 from the front. I used only the clean channel and rubbed palm on strings as suggested to listen for harmonics and around the 1:00 mark is where I heard the most. Very subtle change though. I am surprised I ended in the same spot as Soundperf though because the setting should depend on the tube in V3.
Anyways guys thank you for taking most of the guess work out of this for me.

Todd

Wilcox and Mojo,

Great you found the sweet spot on your PI's - now lets play!!

As I'll swap the power tubes in my amp I guess I have to check both bias and trim the PI, correct?
 
I don't have the equipment (scope and all) but I'll try to do it by ear.
Hopefully I'll find the G-spot
(8th fret of B-string)