Converting a amp with solid state preamp to valve, what circuit

[blindboybenton]

Hi all

I got a customer with a Roland Bolt 60 Combo with 2 x 6L6GC output and Tube pi. he want to have the whole amp valve. keep the output tx and most likely replace power tx as possibly under powered

He likes a clean sound with no od channel, Plays mostly blues and jazz.

I'm looking for idea's on what circuit you would choose? Whatever circuit you think is best let me know, Anybody out there use a all valve amp for jazzy blues ?

many thanks

BBB

[gui_tarzan]

Here you go, the power section of the Bolt schematic with a Fender 5F6 Bassman pre-amp.

[gui_tarzan]

Seriously, a pair of 6L6 should be plenty for Jazz, especially since you'd likely mic it for bigger venues anyway.

[bluto]

It might be worth considering a 6SJ7 pentode for the preamp, Gibson used them in many of the old BR and GA series amps and they sound GREAT for blues and jazz....I play similar stuff (bluesy jazz), have a real BR-6F (6V6 PP)and a PA converted to a GA-50 (6L6 PP), both use a 6SJ7 as V1. This was a VERY common tube back in the day so they are easy to find NOS or used for reasonable prices (even more so for a 12SJ7)...also FWIW the metal can helps to keep noise and hum low. Adding a single preamp tube tube would increase the B+ load by a negligible amount and only bump the filament load up by roughly 15% so reusing the existing PT should be feasible.
A schematic for the GA-50T is below, I followed this for my PA to GA-50 conversion (minus the tremolo section)