Mercury Magnetics Tone Clone PTs

[KingCameron]

MM Axiom Transformer installed

Mercury Magnetics agreed to send me an Axiom series transformer to compare with the "Tone Clone" transformers I was using.

Tone Clone = 380-0-380
Axiom = 350-0-350

After installing this transformer I test the following

12AY7_P1=154.8V
12AY7_P6=158.8V
12AY7_P8=1.5V

12AX7_P1=190.8V
12AX7_P6=216V
12AX7_P8=31.46V

1_6V6_P3 =341.4V
2_6V6_P3 =328.8V

5Y3GT_P8 =363.7V

Volt drop_1 = 311.9V (Pin 4 of power tubes)
Volt drop_2 = 249V

Cathode resistor = 16V (Pin 6 of power tubes)

The amp is not fully sound tested, yet....

[lmolter]

Just out of curiosity, what would a vintage 5E3 sound like nowadays with the higher line voltage? Would we be hearing the same distortion as being reported from those folks using the Tone Clone PT's?

I just finished an 5F6A using a MM Tone Clone PT. The output voltage was advertised as 380-0-380 and produced a rectified DC about 20% higher than the voltages marked on the schematic. However, the disclaimer on the schematic was that the voltages can be +-20%, so I was still in range. The result? The amp is fine.

I, too, asked Patrick at MM the same questions and he explained as Bruce did that these transformers were built the same as the originals and expressed no concern at all that there would be a problem. And there wasn't.

All said and done, I plan to start building a 5E3 next and I think I'll buy the voltage-corrected PT.

Larry

[Five_E35]

I often get 126VAC, so I built one of these into an old ISOBAR powerstrip with a switch to drop 6 or 12 volts.

http://www.geofex.com/article_folder...t/vintvolt.htm

BTW - some of the older ISOBAR's can be easily modified to incorporate galvanic isolation.

[KingCameron]

Go with Bruces's statement (no higher than 370V)

I strongly recomend sticking with Bruce's statement that you do not want the B+ to get higher than 370V on the 5E3.

I can undoubtedly state that the 350-0-350 removed the distortion I was hearing at all settings.

I now get a nice fat tone below ~4 on the volume settings, and also get a rocked out tone when going higher. So, after listening to 5E3 demos online, I can now say that my amp is behaving as it should.

I can also say that the 380-0-380 transformers, produce this distortion, as I wired three amps, using different cap configurations among them, some were wired to be fixed adjustable bias (6G3 style), one was completely stock...all of these amps had the same type distortion. I surmize that the distortion was coming from the power-supply/output stage, as I was able to modify one circuit to get the pre-amp portion to the suggested levels, and it still had the distortion.

I took the completely stock amp, and installed the FTDP-350(350-0-350), and hello coolness... It is the solution...great transformer for this application!!

Even though I took the long road to this solution, I am glad I did, because I know I have the right solution for this amp.