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6BG6G mono amp sounds great but

Posted by PeterI on June 13, 2017 at 16:14:31:
I recently built a 6BG6G audio amplifier, first of a stereo pair, loosely based on a 1950s Grommes 216BA amp. Sounds fantastic, no distortion. My question is, the cathode voltage doesn't really measure.
I have 395V on plates, 340V on screen (pentode mode), -49V on grid, but I measure .222VDC on the cathode. There is a 50ohm balancing pot between the cathodes, and I just adjust to make them the same for now. Bias is adjustable. It's odd. No red-plating; I'm inclined to leave it alone but wondering if anyone willing to comment on the cathode voltage.

Thanks

Pete