Noise in a Fatdrive - bad tube?

[LowTone56]

I plugged in a SIB Fatdrive and can hear a slight hissy noise through the cab. Increase the Fatdrive volume knob and the noise gets louder. When I remove the Fatdrive from the signal chain, the amp/cab are dead quiet.

Not a big deal when the band is playing, but annoying in the home studio.

Anyone know what might cause the noise? Bad tube?

[bongomania]

Noise has a world of possible causes. Believe it or not, "bad tube" is one of the least likely. More likely would be something wrong with a ground wire or a weak solder joint, or a difference in ground potentials between the pedal and the amp.

You can try a new tube, it's a cheap and easy step to find out whether that will help.

It's also the case that tube preamps very often hiss a little. Out of the couple dozen that I've owned, only a small handful didn't have any hiss.

[LowTone56]

Originally Posted by bongomania

Noise has a world of possible causes. Believe it or not, "bad tube" is one of the least likely. More likely would be something wrong with a ground wire or a weak solder joint, or a difference in ground potentials between the pedal and the amp.

You can try a new tube, it's a cheap and easy step to find out whether that will help.

It's also the case that tube preamps very often hiss a little. Out of the couple dozen that I've owned, only a small handful didn't have any hiss.

Thanks for the suggestion! I will try a new tube just in case. I had a tech check it out and supposedly had a clean bill of health. Your last comment may be the issue. I've never used a tube preamp before and have no experience with the hiss. It's not a major thing. I happen to be used to dead silence through my normal solid state rig. Really liking the tube effect with the Fatdrive.