OT - Bass preamp PS

[pedro]

sorry this is a bit OT but I figured a few of you would remember me from the start of this forum ?

I'm building a Bass rig using Kevin O Connors single tube 12ax7 bass preamp design and running into solid state power amp and horned bass cab.

question is the plate supply only needs to be around 200v but the only spare mains TX i have is a 325-0-325 secondary winding.

Can i just drop the voltage down with power resistors in the string, and pretend there is a power section in there which just isnt being fed from the PS ? I have some power Zeners as well so maybe I could use zener between mains CT and earth to shed some voltage.

Meantime - my 50w HRM is getting put back to Non HRM set up which I think I prefer over time. The cleans on this amp are beautiful.
I have a Zen on order from ALf as well so what a great set up this will be - cleans with Zen or OD channel - HEAVEN !

I havent posted for so long because I'm just so happy with the amp and have been gigging lots instead of tweaking !!!

Any ideas on the Bass preamp welcomed.

Rgds
Pete C

[MarkB]

That's a lot of voltage to drop. A resistor in the B+ line would give you huge sag, which I doubt you want for a bass. You can drop it at the CT with zeners, but you'll be dissipating a lot of heat in the chassis. If it were me, I'd bite the bullet and get another transformer. Hoffman sells a toroid for a preamp on his site.

http://tinyurl.com/hn6fm

[pedro]

thanks Mark - thats made my mind up !
cheers
Pete