Hoffman 100W Plexi Power Supply Layout

[Ledzepp007]

Hi,

I am rebuilding one of my early attempts at a tube amp... a Marshall Plexi SLP that I built from a Mojotone kit. I did a... poor job. It worked (most of the time), but it was time to redo it, Hoffman style. I did not like the Mojo layout, but I am having difficulty visualizing the layout for the Hoffman style. Attached is a draft of what I thought might work. If you all wouldn't mind giving me feedback, that would be very helpful.

Instead of using a bridge rectifier, I used a two 1N5408 setup in my example with the PT center tap grounded. Can these two diodes handle the rectification duties of a 100W amp?

My PT has the following specs:

178/0/178 @ 300ma
103V Bias tap
3.14/0/3.14 @7.5A

Thanks!

[PRR]

> My PT ...178/0/178 @ 300ma

That PT and that rectifier will give 250V DC.

I don't think this is what you want.

I also have concern about the all-around-town path through rectifiers to first cap. But let's figure the base circuit before fretting the routing.

[DummyLoad]

the PT you have requires a full wave bridge for that application.

you need to use a full wave bridge with CT. you can build the bridge with 4 x 1N5408 diodes, or just buy a bridge module rated for 800V or higher.

copy the model 2203 marshall PS and layout - no need to re-invent this.   

http://el34world.com/charts/Schematics/files/marshall/Marshall_2203%20JMP%20Master%20Volume%20Lead%20100watt.gif

--pete

[Ledzepp007]

This is what I figured. I'll have to mix the original power supply with the Hoffman style layout.

Thanks for the help.

[sluckey]

Hoffman has info on the 100W Plexi power supply right here. Look around. It's not always easy to find.