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P a g e
contracting may become a bit ‘loose’ and not hold the valve pins as tight as they should.
This can lead to noise and more commonly, sudden drops in volume or complete lack of
sound.
It is an easy task to re-tension the valve sockets and this can be done with a small flat
blade screwdriver such as this:
Important! Please ensure the amplifier is not plugged into the mains and has been off for
at least 30 minutes before removing any valves so all of the high voltages have dissipated.
Carefully remove each valve in turn. The pre-amp valves have a sprung-loaded screening
can fitted over each one so turn this through 90 degrees or so until it pops off. Then using
the slow circular motion, pull the valve from the socket. The output valves are retained
by spring clips which can just be slid off the top of the valves.
Please ensure that the valves go back into the same sockets as they are optimized at the
factory for best position relating to gain, noise, & microphony. This is easily achieved if
you just do one at a time; take it out, re-tension then re-insert and go to the next one.
You will see that the valve bases have small 2-part metal clips in each hole and these
need to be pushed together to make a tight connection on the valve pins.
