• 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.

Vacuum State RTP3C

I am trying to use 2 Salas boards from one HV raw supply to feed R&L channels. I just couldn't understand how to connect grounds. So I went the easiest way - just disconnected 1 channel and tested each SSHV with its own channel. But before that I changed all the grid resistors from 100 Ohm to 1K. Hum was gone. Not sure what cured the problem - resistor change or channel isolation. Anyway, now I know that everything works perfect with each channel supply separated and I need to decide which way to go - 2 separate supplies for SSHVs and also heaters or to revert to 1 raw supply and see what comes out.
 
On the production RTPs we (better: I) wire the ground like this: SRs to the chassis star point, ground pin of the umbilical to the star point, ground of the RCAs to the star point. The grounds of the amplifier modules are connected to the feeding SRs then, the ground ends of the 1Ms after the line stage coupling caps to the chassis star point or recently now to the ground of the pre amp out RCA.

The grid stoppers on the PCB version (RTP3E) are 330R now (expectantly more parasitic C and L with the PCB), instead 100R in the hardwired version (RTP3D and earlier).


Thomas Brüntrup
Vacuumstate
 
Start of RTP3 build

I've just started building my own RTP3 having read this thread and buying a copy of Allen's excellent pre-amp cookbook. What an inspiration the man was.

Knocked up the first super reg today. Will try and post regular updates of my build.
 

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