Noise on Mark IV

[madmax]

Hi, got myself a sweet MKIV amp some months and the first thing I noticed when I played it was the insane amount of noise in it. Especially on the lead channel. When I asked another guy who owns a Mk IV, he said his didnt make as much noise as mine. So I bought a 12ax7 tube and replaced it with the one next to the shielded one. Seemed like it was a bit better at first but now Im not so sure. The noise seems to stop when I start playing and immediatly comes back when I begin. Anyone had similar problem?

 

[Bobby Marshall]

The shielded one is the V1. That is the slot where you usually want your least microphonic preamp tube to go. If you have noise in V1 it gets amplified by the other preamp tubes (all of them when using the Mark IV lead channel).

Get a reissue Tung Sol for $15 and put it in there. I did this on my Studio Pre and it cleaned up the noise. This is the cheapest solution I am aware of.

I had a Mark IV and just couldn't get her to keep quiet. Sent her to Mesa and they said she was operating within spec so it really comes down to good preamp tubes. Using noise gates are okay but only for certain styles.

Good luck taming her.

 

[madmax]

Haha, thanks. Well I just sent it to a shop some days ago to have someone look at it. Guess that cant hurt, but I think I'll get one of those tubes you mentioned anyways. I read through the manual, but what functions each tube has sort of went by me. Would be nice to know Also, has anyone here built a cab before? Just bought the speaker elements and wired together?