Ringing new NOS tube, is it safe?

Dear all,
Need some advices.
I bought NOS 12AX7 tubes from a reputable source (never saw any complaint about the seller) about 3 months ago for my phono preamp.

However, I start hearing ringing sound/noise from the tubes (not from the speakers). Is it safe to keep using it by dampening it with tube damper?
Is it possible that there is something wrong with the preamp circuit that might cause the ringing tube?

Thanks in advance for the advice

Showing 2 responses by atmasphere

No- the circuit is fine. The tube is microphonic. It won't hurt anything, but generally microphonic tubes don't sound as good.

If its still in warranty get it replaced immediately- most warranties are only 90 days.
Generally speaking, if a tube has problematic microphonics, a tube damper isn't going to help.