Cathode Follower TMB

[highway1]

Hello all, !st post though I've been reading here alot. I finished up a 5 watt SE build which I like but somewhere along the way I caught the bug. So I'd like to build a 2 chan Marshall clone. Ch 1 will be like the 18 watt lite and Ch 2 will be a tmb with a cathode follower tonestack. I've read alot about Fender's Bassman and the Marshall's that followed it and I do like the sound. Problem is, I don't fully understand the circuit. The input grid seems to get both the signal and the hi vdc; i.e. there is no blocking cap...Is this correct? Does the circuit act like a transistor emitter follower which inverts the input? And what is the typical gain from this circuit. I would really appreciate learning more if anyone knows this circuit well. Thanks so much for offering this site and your collective knowledge without fee. I sincerely appreciate it.....highway1

[MrMike]

I presume you are talking about Ritchie's TMB schematic from the downloads?

The CF in the 18W is not specifically use for any phase inversion or gain, just impedance matching so the tone stack does not drag down the signal. The CF is approx unity gain - so no amplification. There is no coupling cap between the V1a and V1b as the plate voltage of V1a provides the bias (coupling caps are used to prevent plate DC from getting to the following tube and screwing up its bias - in this case the CF uses the plate DC as its bias).

mm