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What exactly is a cathode follower?

9/28/2000 12:19 PM
What exactly is a cathode follower?
What exactly is a cathode follower? I've heard it used relative to tone stacks and elsewhere.  
9/28/2000 4:19 PM

Have a look at the following:  
The second triode in the second tube is a cathode follower. The voltage at the output (RHS) will "follow" the voltage at the grid. This means the stage has a gain of (slightly less than) 1.  
Why would anyone want an amplification stage with a voltage gain of less than 1? It's basically a buffer. This means that it can supply current without loading the input very much.  
Summary: amplification stage with high input impedance, voltage gain of approximately 1, commonly used to drive tone stacks.  
Someone please correct me if any of this is BS. I've got a bit of a hangover.:D

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