• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

aikido voltage swing

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Yes, that's what I'd expect the totem pole to do - and according to Tube CAD it (the input stage) will provide a nice + or - 70V swing into the cathode follower. I'm just worried about the tiny cathode resistor in the cathode follower output stage. When I run the numbers in the current sourced cathode follower model provided by Tube CAD (not a exact match - no place for the upper resistor in that simulation) it give me a very limited voltage swing of only 7 or 8 volts. Should be adequate to drive an amp which needs prehaps a half volt swing, but I wanted to drive the primary of a 4:1 stepdown transformer.
 
No idea what the TubeCAD model looks like you are using looks like. Are you taking the output from the right place ?

The anode of the lower right tube in aikido will follow the first stage to within a few volts. Easily swinging 70 to 100 volts.

Don't forget is the lower right tube plus its cathode resistor that are the load for the top right tube cathode follower.
 
Thanks for the report - as output Z should be only 400 ohms or so without the transformer, there's really no need for me to use one - I just was looking for a place to play with a pair I have on hand.
I'm building the Aikido because the simple little CF I just built has an audible hum. I'm sure that's because I cobbed it together with little attention to the physical layout - will plan (and shield) a little better this time!
 
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