Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: joesatch on August 12, 2023, 04:33:55 pm

Title: cathode shared by 3 triodes.
Post by: joesatch on August 12, 2023, 04:33:55 pm

trying to understand why V2 (really V1B) in this schematic is sharing the cathode of the clean stage triodes (parallel'd) . is it just to save on parts or is there some tonal reason for this?  if i wanted to run a separate cathode resistor/cap for V2 could i do it? What values?

Title: Re: cathode shared by 3 triodes.
Post by: shooter on August 12, 2023, 07:06:34 pm

my guess is there is some tonal effect, how much, type, i'm clueless, that's why they invented experimentation.

Title: Re: cathode shared by 3 triodes.
Post by: Williamblake on August 12, 2023, 08:07:02 pm

They make room for more switching shenanigans but 1k5 for three cathodes seems to be rather high.

Title: Re: cathode shared by 3 triodes.
Post by: joesatch on August 12, 2023, 08:18:50 pm

well i have the room and i have the parts. it dont feel right runnin 3 triodes thorough the same resistor/cap

Title: Re: cathode shared by 3 triodes.
Post by: sluckey on August 12, 2023, 08:34:47 pm

Make V2 cathode look just like V1 cathode.

Title: Re: cathode shared by 3 triodes.
Post by: pdf64 on August 13, 2023, 04:26:43 am

It’s just about saving on parts. Despite the smallish bypass cap, the channel switching means that there can’t be any signal interaction between the channels at the shared cathode.