bad tube diagnosis

[WASHOUT]

I am trying to diagnose a bad preamp tube but I am not sure what I am listening for.I have a mesa stiletto ace and it is new to me. Should the amp be totallyquiet when the volume is maxed and the gain at fifty % in channel 2 with no guitar plugged in . It sounds like white noise or the ocean . Now I have also heard the squealing and the growling noises which I am fairly certain is a bad tube but how about the other noise?
Thanks .

 

[ANIMATED SUSPENSION]

It's normal to hear white noise, the higher the treble and gain settings the more you'll hear it. So what is the real problem, please explain more !!

 

[Timbre Wolf]

There are several kinds of sounds that preamp tubes make when they're dying. One is intermittent flurries of noise, one is steady hissing, one is a non-feedback squeel (microphonic), etc. Your description of excess noise would point to a possible preamp tube problem.

Try replacing one at a time, starting with V1 (closest to your 1/4" jack guitar input).

- T

 

[WASHOUT]

Thanks