DC Cathode Follower Mixer


2014-02-23 11:23 am
When I think of triode AF mixers, I think of something like this - a common anode mixer. Example here. https://www.ampbooks.com/mobile/classic-circuits/gretsch-chet-atkins-mixer/

OK as a mixer but not the lowest output impedance for say driving tone stacks, though a low plate resistance (low mu) tube can help.

Conversely, for driving lower impedance loads I think of cathode followers - Example here.


I'm looking to design a triode mixer that takes two inputs - one from a 6SJ7 pentode and one from a 6SQ7 triode - both first stage pre-amp tubes for guitar use and each with their own independent volume control. These would then be mixed (in a pair of triodes) that onward drive a tone stack (type yet to be decided).

Does anyone know if is possible to create a dual, shared cathode, cathode follower? - combining a mixer and cathode follower in one? In this design the output of each first stage tube would connect to the grid of its associated follower but both followers would share a common anode connection and cathode resistor with the output taken at the cathode in the normal way (for a cathode follower).

And then further refine by adopting Merlins DC coupling approach to cathode followers here.The Valve Wizard[/URL]
Yes you can do that. This example takes the output from an anode, but it could be taken across Rc.