Help with El84 SE design

[then1xon5]

I double checked the wiring. It looks good. After I replaced the socket it didn't arc anymore but I still have squeal. I moved the input wire away from the output wires and there was no change.

Two thoughts, the output transformer I am using has three wires for output. The green wire is the main output. There is a yellow wire that comes from a center tap and the black wire of course is ground. Currently I am using the green wire and then black to ground. I have a wirenut on the center tap since I believe that this was a 4ohm output connection. Could this be causing the problems?

I also replaced both the 12AX7 and the EL84 with no change.

I did the old tap around with a chopstick test and found that when I tap the plate wire on the EL84 (the same terminal that created the mini arc welder) it starts squealing. I turn down the volume until it stops, turn it back up a little and tap the plate and it starts again.

The preamp is working just fine at this point.

suggestions?

Thanks again.

Scott

[tubeswell]

Also, there's no NFB shown on that schematic so that wouldn't be the problem.

So you're right (I should've looked at the schematic first - instead of just assuming there'd be an NFB in an SE circuit)

[then1xon5]

Stumped

So, could it be that the 12AX7 is mounted to close to the EL84? I have found no wiring, ground, or shorts anywhere in the circuit. I have checked and checked the wiring. I moved the V+ wires away from the signal wires. I'm not sure where to look at this point.

Thanks,

Scott