Regulated Supply for Direct Coupled Amp

[fullrangeSR]

This thread is a welcome coincidence – I myself was about to start with this particular circuit. So far I’ve been extremely satisfied with how RH EL84 sounds when built with quality parts, but many respectable people out there keep on saying that 45/2A3/300B are the real thing, so I’ve got to find out if that really is true… So far I’ve ‘narrowed’ it down to the following:

A) the above mentioned circuit (Robin/Lipman)
B) the Tubemaster's 2A3
C) the “Full Monkey”
D) TubelabSE

It turns out that I’ve got almost all the parts needed for the Robin/Lipman amp, so I’ll start with that one…

Originally Posted by kmaier

(...) mine have been quiet for 4+ years of operation in a very similar circuit(...)

Care to share the circuit?

[Sheldon]

Minor variations on these for the input tube:

I'd consider the bootstrapped follower version, even if you don't go with the Loftin White design. Without it, you may have limited high frequency extension.

Either way, these versions have better load lines for the input tube.

[kmaier]

It's similar but I opted to step up the supply voltage for the input stage and bias it just a bit higher. I also used a split balance arrangement... DC balance on the 20-ohm pot and AC balance on the 100-ohm padded pot. It puts out a solid 1.75-watts RMS and have been in service for 4+ years with frequent use.

Regards, KM