Microphone tube socket

[menger66]

My 18watt Liverpool has way to much hiss, while working on it last night, I redid the input jack and volume pot along with bright switch I also tested a bunch off my 12ax7s looking for the quitest one these were my best 12ax7 the all more than acceptably quiet in all my other amps, it seems like the socket is microphone, is this possible? The socket is the type with a shield base. Even tapping on the chassis is causing lots of noise, I'm thinking the socket losses or wiggly could that possibly cause hiss?

[Leo_Gnardo]

I have run across noise-making sockets but I'd suggest a couple things first. What kind of plate resistor on your first triode preamp? Metal film have the lowest noise figure. If you haven't already tried it, swap in MF plate resistor & lets see if that noise drops. Also, if your circuit is built on Fender-style black cardboard, that stuff tends to become randomly conductive. Not enough to cause a sparking short circuit, but definitely enough to provide unplanned connections and they can result in hiss as well as other noises. If these last 2 are not the case, swap out your tube socket & hope that does the trick. FWIW I use ceramic sockets for replacements.

[menger66]

It's got nice Dale mf plate Resistor, but I could swap it easy enough the sockets are those electronics cheap on plastic ones from mojo theare like 65¢ will switch the socket over not shut of maker they say ebythonk, thanks