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In Reply to: RE: CCS and SRPP posted by andy evans on February 27, 2025 at 12:44:15
You can read the reply #4 through the given link. It has mentioned that CCS in SRPP.
"You can use a choke for the upper cathode resistor in an SRPP configuration, making it a mu follower with fewer parts and no capacitors. My experience is that it sounds good but a C4S sounds better"
I think Paul meant using a C4S instead of the top tube.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
...mean what Tre' said.
I thought the C4S had no low output Z capability?
For sure, put a single MOSFET in place of that triode, and it can still have the source/cathode output. Make it even 'harder' by adding a second in cascode. With the advent of 1kV depletion-mode 'FETs, the 10M90 is not needed anymore...LOL
Or build a cascode with a triode on bottom and a pentode on top. Couple voltage ref's to separate them by enough voltage to do the job and give it a BIG 'R-set' resistance... :)
cheers.
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
My mistake; I was only considering taking the output from the lower plate. Some 20+ years ago, we decided that sounds better than the mu follower, and I haven't re-visited that conclusion since.
So, the mu follower current source is a moderate current source, and the solid-state current sources are by and large superior - if the output is taken from the lower plate. The half-mu stage with a choke at the upper cathode does have two available outputs, as does the full mu-follower. The choke does not have to be large, since its inductance is effectively multiplied by mu.
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