JRUBBO770 wrote:

I have a 1950s Stromberg Carlson PA integrated tube amp with a 2-6L6
push/pull output. It is a three channel amp each with a Vol. control
(1 meg). With the three Vol. controls turned all the way down, a
moderate signal will still pass thru to the output on any channel.
What is the cause of this?

Bad design
Bad grounding
Capacitance in the wiring and the potentiometers.

Also a signal put into any channel will
bleed thru to the other channels.

I presume that there is no input selector switch, and that the volume
controls make up part of an variable input mixer.

If you are using this amp with most modern sources, and even most legacy
sources, dropping the volume controls down to 100 K pots, combined with
corresponding drops in the resistors from the potentiometer outputs to the
summing point will at least partially alleviate most of these problems.