Hi there,
I've got a Stanford Omega nuvistor tube-based microphone that is exhibiting unwanted microphonic behavior. Otherwise, it operates as intended and has surprisingly low self-noise, but it rings out at a high frequency sometimes. It produces this ringing even when decoupled from all floor borne vibration, and it is excitable by sources as quiet as acoustic guitar (so it really sings when placed as a drum kit overhead
).
I understand nuvistors are particularly prone to going microphonic, so I'm assuming and hoping the tube is the culprit. So, is there a best replacement nuvistor for this mic? And, assuming the tube tests properly on a hicock, is the only way to test it for microphonic behavior within the circuit/microphone itself? Can one physically dampen a nuvistor? Or maybe the problem lies with the capsule?
Additionally, the power supply is labeled high impedance, and is assumedly unbalanced at the out. Any insights into what ratio transformer to wire in (I think UTC A or even O series will work), and whether or not to simply wire it in series with the current output circuitry?
Thank all of you for this and for your general collective brilliance