Anyone try a JTM pre into cathode bias (18W)?

[MakerDP]

Just wondering if it's worth the trouble trying to do this... JTM/Plexi/Bassman preamp into a typical 18W cathode-bias poweramp section. I have an 18W kit inbound and was toying with the idea of converting it.

[Colossal]

I know it's been done. You could employ the shared cathode JTM layout on V1 but maybe tame the bass a bit by lowering the cathode bypass cap from the traditional 250uF value to something sensible like 3u3 to 5uF. If needed adjust the coupling caps on the Bright and Normal channels. I would keep the 18W PI and power amp the same. You may want to experiment with the power amp cathode bypass cap, stock being 47 to 470uF, on up to 2200uF, depending on the sound and feel you want.

[pdf64]

An 18 W runs open loop, so a lot more gain than a JTM45. So a type 4 master vol, either a preset trimmer or front panel control, may be handy.

[MakerDP]

Thanks guys, great suggestions. I figured a master volume of some sort would be a must. I just was curious if there would be enough clean headroom in a live setting while still being able to drive it hard when needed too.

It is 6V6-based and I am also considering just converting it to fixed-bias at the same time... maybe buy a premade JTM45 empty turret board from AES/CE or do it PTP.

I dunno maybe I'll just leave it as-is too. I was wanting a new amp to pair well with my new Les Paul. This one is a Trinity Super Plexi 6V6 and I never really bonded with my Lite IIb, so to save some cash I am moving the transformers from that build over to this one.