wrecking solutions

[Andy Le Blanc]

In the spirit of the trainwreck papers Ive jumped into adding a universal
gain stage to and amp with a proven circuit but a completely foreign layout.
In general terms, its an express, as to the circuit topology, but trouble shooting
the results is the real challenge.

The first real issue was a severe instability and motor boating associated with
the tone controls. This was a layout problem. The original amp has the PT
and OPT on opposite ends of the chassis with long exposed B+, plate leads
to the power tubes and secondary taps for the output. This was fine for a
lower gain circuit but as soon as the gain was raised it coupled with the caps
in the tone control and would motorboat.

The fix here, because I cant move the wires was a strategic application of
aluminum tape (grounded) to cover the exposed wire bundle, which worked very well.

Beside power supply ripple being apparent with the increased gain, the
only other significant issue is the blow from the first gain stage. This seems
to be independent of tube choice (so far) and poses a real issue.

Any good ways to reduce bad wreck breath?