Ceriatone Plexi50 Lead Amp

[TD_Madden]

Bought one of these assembled, with master-volume added to the front-panel and cabinet included. Nice wiring job, all JJ tubes (with the exception of one JJ ECC83-S that just died).

However, I'm not sure about the master...wired as PPIMV. When all volumes are at zero (with nothing plugged-in), moving the master past 50% gives VERY noticeable noise,...downright annoying.

Do these amps (without a MV) have that noticeable of a noise floor with nothing plugged in?

[drewl]

Depends on the assembly, wire routing etc.
With the master all the way up the amp should be no noiser than a standard non-master Marshall style amp.
What kind of noise is it? Hum? or white noise?

[TD_Madden]

mostly white noise.....a bit of hum as well.

The problem is that I don't know how loud these 1987s are at idle.

[TD_Madden]

Found an old tech article in "The Tube Amp Book".......says to lift the wires on pin 2 and 5 of V1 and pin 2 of V2 away from the chassis (described as "low-level signal wires).

Of course, pin 5 carries filament voltage, so I guess that's a missprint....what other pin on V1 might he be talking about?

[TD_Madden]

btw, lifting the two pin 2 wires away from the chassis DID help.

[TD_Madden]

problem totally solved.

I lifted the wires on pins 1,2,6, and 7 on V1 away from the chassis.
I lifted the wire on pin 2 on V2 away from the chassis.

NO more noise!