Re: I have a valve amp and I am clueless

In article
<717d8100-27d3-438c-a268-2676ea2c5382@xxxxxxxxxxxxxxxxxxxxxxxxxxx>,
Dave
<davesworld100@xxxxxxxxxxx> wrote:

Afraid I don't have any info on the amp, so the following are just
suggestions based on other designs of similar period.


1) On the back is a dial labelled PU Balance which turns 360 degrees.
PU is the phono input but what does this dial do? When I<ve adjusted it
I can<t hear much or any difference but I am nervous about breaking
anything and haven't fiddled much with it.

I don't know the amp, but 'balance' here (and below) might mean a dc offset
adjustment, not channel balance. If so, you'd need some other indicator to
get correct adjustment.

Alternatively, PU may be for ceramic PU, so does not act as intended when
fed with a low impedance source.

2) Another dial on the back has an arrow you could set to points
labelled 4, 8 or 16 ohms. But the dial doesn't seem to work, does it
matter?

May not be a rotary control. May be either a switch or a plug. i.e. you may
have to pull to remove the 'dial', rotate it, and plug it back in with the
relevant number beside the arrow. The setting matters for maximum power,
etc. But almost any setting may play OK, depending on how loud you want the
music, and what speakers you are using.

3) It has a dial on the front labelled Balance but this seems
to do very little, certainly doesn<t act like the balance dial on any
other stereo amps I<ve used which move the sound from one speaker to
another. What is it meant for?

As above. May adjust the bias levels in the amp. So you'd need to observe
something else when adjusting. Incorrect adjustment will degrade
performance and may shorten valve life. Some valve amps have 'test points'
where you connect a meter to monitor the voltages/currents and adjust a
'balance' control to get the correct values.

Or may just be a balance control with a limited range.

If you want more bass or more power, then I suspect your best bet will be a
different amp. :-)

Slainte,

Jim

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