Marshall JMP 50W Voltage Question

[Mr.coil]

Thanks for the reply Pete...

I am sticking with my earlier theory of... "Jim must have come up short on "normal power tranies", and used these particular ones for a short while. Like I said the two main taps were quite robust compared to the HV winding. In other words it will convert 110 to 220 at a 500 VA rate...while only producing a mere 75 VA for the HV use.

Any how, with the tap switch, the customer was/is happy...I will lose no sleep over it.

Thanks
Steve

[Ronsonic]

[ATTACH=CONFIG]13051[/ATTACH]
I noticed the above Marshall voltage chart in the GT book, which shows the expected power tube plate voltage of 380V for el34, 395V for 6550, 50 watt amps.
It seems bizarrely low, especially compared to the 530V plate voltage of the 100 watters. Pete.

Just under 400VDC is correct for most Marshall 50s. And, yes, they do put out a full 50 watts. Anything much less than either of those numbers and the amp is still broke. It is a bit surprising to see these roaring Marshalls running a lower B+ than a typical Deluxe Reverb, but it is what they do.