C12, ELA M250e, 1k8 or 2k7 for cathode, higher or lower cathode bias??

[Shattersignal]

My apologies, Tim.  Yes, I realize that I misspoke.  The B+ is divided down to produce the capsule voltage.  Good to know you recommend 110 operating V (55v to the capsule).  I seem to have mis-remembered that figure to be 100v/50v.  Thanks very much for the correction.  Your capsule is a work of art!

(I edited my previous post to not promulgate false information regarding your recommended capsule polarization voltage)

Actually I recommend 55v/110v

 

[Shattersignal]

Thanks a ton, Matador!

I would first try switching to a 12AT7 tube, as you can get a bit more gain (it has a higher gm) from the circuit with only relatively few/minor changes.

Otherwise, you need to change the R12/R13 ratio, and add a resistance between the polarization pins P2 and P3 where the polarization switch attaches to the screw terminal(s) in the PSU.  This would create a voltage divider that would reduce the higher B+ back down to 120V max.