DIYtube St-70: Has anyone experience hiss with this mod?

[maxmail12@yahoo.com]

Hi All.
This is my first post on this forum and I need help tackling this problem.
I have a hiss issue with that board when used with the Citation 1, the Dynaco Pas3 and other preamps. All of them are dead quiet when used with my second stock st-70.
Do you have any idea of how to deal with that problem. The gain is so high with whatever the preamp used, the sound is still there for you to hear even if the volume is turned all the way down. When I shot the preamp off completely all noise are gone.
Thanks

[Shannon Parks]

The diytube ST70 driver is very close to the original driver's gain and feedback numbers. Hiss and high gain lead me to believe that the negative feedback is either not hooked up or miswired. Also, be sure that the ground is grounded (though I think it would have been unstable otherwise). Sounds like an easy fix.