Well I've got a pair coming this week so I'm quite excited.
After looking at the curves of all these transmitter types and listening to various conversations at Simon's do concerning class A2 operation, I have decided to go for zero bias class A2 with these valves.
I very very briefly tried zero bias A2 operation with my 801A amp last night.
I has to slug down the HT to try this and bypass the voltage droppers to the inputs and drivers. Even then, I was still exceeding the max anode dissipation of the 801A.
Terrified as I was of frying my lovely 801As, the experiment was necessarily very brief indeed, maybe around 45 seconds of A2 operation. The sound that came out was big, powerful and just as detailed as with my normal mode of operation with the 801As.
In one way this was quite a surprise to me as I had not been expecting much. After all A2 needs power driving circuitry and all I was doing was driving with cap-coupled AC/P1 small power tubes. These, although having a lowish Ra, were certainly not supposed to be anywhere near ideal for driving an A2 power stage. Yet drive it they did, very loud, very clean and nary a hint of distortion.
What's that all about then? I thought you either needed DC coupled cathode followers, or step-down interstage transformers for successful A2 work, yet these 801As seemed very easy to drive with the AC/P1s.
The 4304CBs have a gain of 11 against the 801A's 8, so should be even easier to drive
Googling for the 4304CB tube turned up this WAVAC amplifier from Japan that uses them. Must say they look frightfully cool when lit up.
I'm looking forward to trying them out.
Top-cap connectors might be a bit of a problem to get hold of though.
Steve
I like 'em too but....
you could DC bias the outputs by the grid bias of the CF's. Which sounds much more complicated than it really is. 
