Tremoverb clean channel HUM

[Reeko81]

Hi all! I've recently bought my first rectifier, and it's a beautiful Tremoverb.
I'm a Mark IIIc+ owner too, so I was searching for a rectifier sound and I believe I've found one of the best rectifier sound mesa ever produced.
I've noticed that clean channel as a slight hum ( it obviouly disappear when playing, it's not so strong), even stronger than blues, vintage and modern high gain channel. It's a little strange to hear noise on a clean channel on tube amps...
Has anyone noticed the same thing on your TOV?

I've recently modded my TOV to make the clean/vintage high gain switch footswitchable, added a switch to select the voltage ( export version have different transformer, so I've wired it both 220 and 230V and can select them, to get much headroom) and I also added a new master volume for vintage high gain ( to have a correct volume balance when switching from clean to vintage high gain).
Now it's like having a real 3 channel head...
But I just think about this hum... I've read that old dual rectifier ( 2ch) and tov have this problem..
is it true?
Thanks,
Riccardo

 

[igfraso]

Riccardo,
what power transformer model number (export version) your amp has?
Grazie mila!!

 

[Reeko81]

Riccardo,
what power transformer model number (export version) your amp has?
Grazie mila!!

It has the 561141 PT. It has 5 voltage input ( 100,117, 220,230,240) it's the export version.
Do you think this hum only in the clean channel can be caused by the PT?