Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: separateness on July 26, 2026, 08:18:44 pm

Title: Cathode follower with a plate resistor
Post by: separateness on July 26, 2026, 08:18:44 pm
Any of you fellas ever seen a cathode follower with a plate resistor?  See attached pic of an oil can unit schematic.  I have a similar unit with a different branding and basically electronically identical except for that resistor and cap on the plate of the cathode follower. I was just wondering why they'd gone and done that.
Title: Re: Cathode follower with a plate resistor
Post by: Willabe on July 27, 2026, 08:59:03 am
What tubes are those?
Title: Re: Cathode follower with a plate resistor
Post by: sluckey on July 27, 2026, 09:59:49 am
What tubes are those?
one tube. 7199
Title: Re: Cathode follower with a plate resistor
Post by: DummyLoad on July 27, 2026, 02:25:59 pm
Standard grounded cathode amp, not a follower per-se. Signal tapped for lo-Z, low level output from from cathode. Like follower, output phase follows input phase.

EDIT: is also summing point for dry signal path. 

--Pete 
Title: Re: Cathode follower with a plate resistor
Post by: separateness on July 27, 2026, 04:25:00 pm
What tubes are those?
one tube. 7199
Correct, I should have said this to begin with.

Standard grounded cathode amp, not a follower per-se. Signal tapped for lo-Z, low level output from from cathode. Like follower, output phase follows input phase.

--Pete 

What exactly is the distinction there?  The presence of a plate resistor?
How does performance differ? Is the gain diminished witht the plate resistor?  I would assume so but what do I know. The echo recovery on my unit is identical aside from the plate resistor and cap.  Do you it would be an improvement to implement the resistor and cap there?