Using it as a tool to run my amps to spec is really all I use mine for. Maybe a tad under-spec on my Marshall JTM45/100 at 110v. 560 volts on the screens is hella hard on modern KT66’s.
If your rectifier is from the 90’s like mine, it will actually run more in-spec if you run it at ~117VAC instead of modern voltages (122-126V average).
The amp runs hotter at 120-125VAC. Like I mentioned, I went off the heater voltages and made sure they’re running at their intended voltages...
I have installed an adjustable bias (using the 25K return send pot since I also performed the series loop mod and I currently use the same Variac he used but I only drop to around 115VAC so that the heaters are seeing 6.3v for power and preamp tubes and 5v for the rectifiers. Otherwise, they...
For four years, I both lived in Colorado and had good bud. lol. But that’s my company name. I work on and build guitar effects. Then started working on and building amps when covid hit. But now I have **** bud living back in Texas. lol
I think to better illustrate this, I’d be better off...
I believe I’ve compiled a fairly accurate chart indicating approximate idle dissipation, idle current, and associated Mesa Color coding at ~475v Plate Voltage. This chart does not apply to Simul Class amplifiers, btw.
On my 90’s Dual Rec, I installed an external bias control to more-closely...
I made a couple charts of estimations of approximate plate dissipation at 470v, idle plate current, and Mesa Color codes for 25 and 30 watt tubes in NON Simul-Class Mesa amplifiers (Rectifiers and such).
As you’ll see below, I wouldn’t shoot for 70% plate dissipation. Mesa shoots for around...
This is what a proper conversion should look like if you want it to look stock. Switchcraft 112A jack and this configuration.
PS - I got rid of that solder blob after this pic. 😂
Yeah, the no load pot trick wouldn’t work on the loop. It would remove the wet signal instead of the dry signal.
I’ll upload a pic of the serial loop mod I did yesterday. I forgot to take a pic when I did it so I’ll have to open the amp back up.
So you have to have a cable connected for it to work? Then, he did it the easy way and not using a shunting mono jack for the return jack and a link between jacks when fx loop not in use.
I also have a theory that I can’t believe no one has posed: using a no-load pot to take out all 100% of...