Quote:
Originally Posted by BrotherJ
Yep, they are in a single row (And horizontal)
Looking from the back of the amp & going from left to right are the two EL34 power tubes, then the four 12ax7's V4(PI) V3, V2 & V1.
The V1 preamp tube on the far right doesn't have any metal shield cover on it.
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Look at your preamp tubes. Does V2, V3 and V4 have a rubber grommet (ring) attached to the chassis between the tube and the chassis? If so, is there one of the rubber grommets on V1? If not, the metal shield is missing and this can be verified by inspecting the area of the chassis around V1. You should see two small cut-outs in the chassis. The cut-outs accept the lugs on the shield. The shield is important in that it cuts down on RF radiation which in layman's terms means noise. Since V1 is the first gain tube, it is important to keep it quiet as possible. Your amp came out in 1996. I see no reason why it would not have a shield on V1. If you determine that the shield is missing, I would try and locate a shield at a TV shop (old Ma and Pa type), or order one from your music store through Marshall.
Marty