Sooo, I've just dropped a CT12 into my JRR NOS 251, which is essentially this build with a 6021 (on the Matador PCB). It's always sounded decent but had a noise floor high enough that I don't reach for it often. It could just be a noisy tube (NOS GE 5-star), but rather than fool with swapping for other 6201's I'm leaning towards reverting it back to the 6072a configuration.
I need to check the components used in the JRR mic, but as I understand it the typical arrangement for switching from 6072a to 6201 would be dropping R17 to 47k. So assuming that's how it's configured, anything else I should take into account before swapping in a 6072a?
