can anyone explain this to me?

[rbryerton]

So then tell me this....if i used the 100 watter and use a bridge, can anyone tell me what my plate voltage would be?

~490 VDC

[iknowjohnny]

Thats a bit much i suppose. Guess i'll stick with the 50w for now and see how it holds up. Thanks.

[Jana]

The 50 watt marshalls use a bridge rectifier--two diodes and a center tap to ground.

The 100 watt marshalls use a full wave bridge rectifier--4 diodes and the center tap of the PT is used to create a half voltage point to tie the junction of the filter caps (two caps in series). You don't need to use the center tap if you don't want to.

I'm with Andy, I like to run the voltages on the lower side for B+. The best sounding 50 watt marshall, any marshall actually that I ever owned and played had 370 volts for the B+. Sweet sounding amp.

[FYL]

So then tell me this....if i used the 100 watter and use a bridge, can anyone tell me what my plate voltage would be?

~490 VDC

More exactly 490V unloaded, 450V loaded for the 40-18024 on US 120V mains, silicon bridge recto. And 480V unloaded, 440V loaded for the 40-18023, silicon full wave recto.

[iknowjohnny]

I'm with Andy, I like to run the voltages on the lower side for B+. The best sounding 50 watt marshall, any marshall actually that I ever owned and played had 370 volts for the B+. Sweet sounding amp.

Doesn't that mean more compressed, less dynamics tho? also, if you use such a low voltage PT, how do you keep the preamp voltage high enough, assuming of course thats what you want? (i do) parallel nodes?

[Andy Le Blanc]

It doesn't necessarily mean that, it's more the "V" and load (DCr) relationship.
There's always a sweet spot for power vr's relative amounts of even and odd order harmonic distortion.
An you don't have to be so so strict with pre "V" either, readjust the R down the
graduated filter chain and look for a similar "I" relationships in the pre stages

[funkmeblue]

most of the recently produced transformers can run quite a bit hotter than the old ones due to advancements in insulation and what not

[Jana]

"if you use such a low voltage PT, how do you keep the preamp voltage high enough, assuming of course thats what you want? (i do) parallel nodes?"

Standard 50 watt plexi: 20k resistor to the PI B+ node, 10K to each B+ node thereafter.

[iknowjohnny]

But right now i have 8.2k for the PI, then another 8.2k after that for V2 and finally a 2.2k for V1. Thats with a PT that gives me 475 at the EL34 plates. So if i go down 100V how could i ever keep my preamp voltages near where they are? i played around a lot with preamp voltages and i really don't like the tone when it gets much lower than it is now.