120V versus 240V

[Bombacaototal]

Happy New Year everyone.

I recently converted one of my SSS amps from 240V to 120V and as surprising as it may sound, the amps actually sounds better at lower voltage.

The plates dropped from 456V to 445V (about 10V), bias is set the same at around 35mA. Amps feels quieter in general and sweeter sounding. I am wondering if someone has experienced the same?

At 240V I had an issue with the electromagnetic field of the PT interacting with the coil of the reverb pan causing hum but at 120V this is completely gone, which is understandable as the magnetic field reduced to half.

With half the voltage you double the current too, is there anything to be deducted from this?

[Richard1001]

Happy New Year everyone.

I recently converted one of my SSS amps from 240V to 120V and as surprising as it may sound, the amps actually sounds better at lower voltage.

The plates dropped from 456V to 445V (about 10V), bias is set the same at around 35mA. Amps feels quieter in general and sweeter sounding. I am wondering if someone has experienced the same?

At 240V I had an issue with the electromagnetic field of the PT interacting with the coil of the reverb pan causing hum but at 120V this is completely gone, which is understandable as the magnetic field reduced to half.

With half the voltage you double the current too, is there anything to be deducted from this?

Did you wire the same PT for a lower mains voltage or did you put in an other PT?

I don't see how the magnetic field of a PT would be reduced to half because the same power has to go through the core. It is the current that creates the magnetic field together with the amount of turns of the coil.

A change in frequency (60Hz instead of 50Hz) would make the transformer work a little more efficiënt.

[pdf64]

Another consideration is that the 120 and 240 are nominals; what were the actual measured voltages being fed to the amp at the time these assessments were being made?
Have you moved to a different region with different voltage / frequency, or do you happen to have 240 and 120V supplies? If the latter, is the 240V a 2 phase type, where both mains current conductors are 120V (with respect to earth, of opposing polarity), or a 240V live and a 0V neutral?

[Aurora]

Actually - given the same output power, the mag fields form the PT should have doubled, as the primary current of the PT are doubled going from 240 to 120V..n in order to supply the same amount of power.... 230-240V fully balanced for household (and amplifier) appliances are quite rare.... Norway, Albania and possibly Peru are the only countries that comes to mind...

[Bombacaototal]

Actually - given the same output power, the mag fields form the PT should have doubled, as the primary current of the PT are doubled going from 240 to 120V..n in order to supply the same amount of power.... 230-240V fully balanced for household ( and amplifier) appliances are quite rare.... Norway, Albania nd possibly Peru are the only countries tha comes to mind...

Thanks everyone for the inputs and questions. Answering them, it was the exact same Classic Tone PT, which was first wired at 240V and then at 120V. I have measured the incoming voltage and I had 240V (measured with the Eurovolt and MM) and 119.9V measured with the MM), so I think we are spot on considering both. I have tested the amp at both voltages at my home studio and I am fairly familiar on how things sound there, and have not moved it to a different region or even from my home.

I am using this step down transformer which also shows me the voltage
https://www.aldetronics.co.uk/product/s ... uk-to-usa/

As far as the magnetic field, well, the only thing I can hear is that there is no longer the interference and interaction with the reverb pan, it is a quiet as it gets now at 120V

Attached the PT wiring diagram

[pdf64]

Magnetic field strength is controlled by the core material, the number of turns and the current. It should be the same in either configuration, all else being equal.

.... 230-240V fully balanced for household (and amplifier) appliances are quite rare.... Norway, Albania and possibly Peru are the only countries that comes to mind...

And, I understand, North America.
Whilst regular wall outlets are 120, premises are typically supplied with centre tapped 240V, with a balanced, dual live feed being used for large appliances. The CT being earth referenced and used for the neutral feed for the 120V outlets.