On Mar 4, 5:18 pm, wrote:
I have a very old valve radio from a company called Lafayette.
It has 6 valves which are
6v6 gt
6x5 gt
6sq7 gt
6sk7 gt
6sa7 gt

This radio was working fine but recently has developed the following
problem, when the volume is increased the sound is distorted
completely,
it can only be heared ok when the volume is very low, and putting the
ear onto the speaker. Any ideas?

The problem is likely to be a bad resistor or capacitor, somewhere in
the last two audio stages (6SQ7 and 6V6). The plate of the 6SQ7
should be somewhere around 50 volts. The cathode to grid voltage of
the 6V6 should be around 20 volts (negative side on the grid!).
Anything wildly different than that may be a problem.

I would replace all the wax capacitors in that area just on general
principles. They're probably at least a bit leaky and will not be
getting any better over time.

Also check the resistors, they tend to go up in value.

And oh, it could be the speaker rubbing-- try moving the speaker cone
by hand to see if it rubs or is stuck.