• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

12B4 PSE build thread

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OK boys & girls....I'm off & running come this Thursday...as my parts 'present' arrives from the States. Inside is all the correct resistors, caps, sockets, pots...for me to get started in all honesty. Building a tube amp has been bantered about now since 07. It all started when I bought Morgan Jones book in about 05.....Moved to Argentina shortly there-after. Since we all (Whole extended family) brought our 110VAC stuff we wound up having to get step-down transformers 220-110.
Well...my father-in-law had a US spec Freezer & Dryer. Contacting a local builder he wound up getting a monster to spec transformer(I'll get-cha a picture),... hearing how much he paid for the beast appx $250 USD......got me thinking about tube-amps???
OK, this is the deal, bantered, dreamed..over time learned as much as possible or so...perhaps the tipping point was my wifes long lost blackballed sister shows up.....my wife re-connects & develops a relationship. While visiting one day at her place...she tells me of this "stuff" I might be interested in "He used to work at a long since shut-down TV shop"" Big box-O-tubes!!!!
While perusing thru the Forums someone pulls up a Parallel 12B4 SE schematic...as usual I save it....(You should see how many circuits, images,renderings I have..bazillion!)
So here I am sorting tubes & I've got a few 5AR4 rectifyers, a few more of 12AU7s, & five 12B4s' Ta Da.........My acquaintance here sends me a pair of sockets for the 12B4s.
Fast forward another year or two....my sister-in-laws going to visit "Would you like anything from the States??"" Damn it all...."Honey? I want some electronic supplies OK?" "Is that for that stupid thing you've been always talking about?"" ###This coming thursday###
OK.....this is the circuit......If this is an original, as in "That's My circuit!"....well, what can I say....I will be building this circuit & a functional amp will result.
Couple of questions, How much will both channels consume in Ma?
Can I use a SMPS to drive the 5V heater for the 5AR4? I would think not.
Just a little more time(1-2) yrs. Ha, Ha!


I have...A dedicated 220 primary 12vAC RMS? dual bobbin TX for the 12AU7 running thu a 317 @6.3VDC...a healthy heatsink.
The chassis components complete with a chunk of Quebracho for the "frame" an Aluminum plate 4-5mm thick (I know it will be tricky).
The tube compliment with spares, sockets
What obscure winding can I use for a 5-10H coil for the PS??
OPTS will come from a local source, the 220-220 isolation B+ TX is still in the works.
I have an IEE socket with MOV/Cap? the one with the big "rubber band around it, a SPST 220VAC/10A switch pirated from a coffee maker. power cord, with an IEE on it. I will have to run a true ground to terra firma via a solid core wire.



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Progress report

Her it is so far, in the picture we see an MOT I'm working with, The wood is cut chassis is coming together. The mains transformer is positioned where it is to be, flanked by a pair of 5U4GBs for full-wave rectification. The quad of 12B4s in a straight line with the 12Au7 in the middle....all five, straight line up front, gotta use your imagination here.



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