"Andy Evans" wrote in message
...
I won't go into technical details here - somebody else can - but I think
the
helpful concept to have is that a transformer can transform down "less" or
"more" according to the output taps (if there are any). Put it on its 15
ohm
tap and it transforms down "less". On the 4 ohm tap it transforms down
"more".
So with the same speaker, the "less" the transformer transforms down the
louder
it will be,

OK


the "more" the transformer transforms down the higher the impedence
the valves will see, so the happier they are in terms of less distortion,
but
the quieter they are in terms of output.


OK


There is an optimum point where it's
both quite loud and quite undistorted. If it goes louder than that it
sounds
woolly, if you go the other way it tightens up the sound, which is
initially
satisfying but steadily becomes unnecessary in terms of diminishing
returns. If
you had 8 ohm speakers, putting the amp on the 4 ohm tap would be cleaner
and
tighter, using the 15 ohm tap would be louder and a bit more ragged.
Neither
will damage anything, and frankly you can set it at whatever sounds
preferable
to your ears.


OK, so you're really saying, all in all, the 4 ohm tap would be best then?
I'll give it a try and see if I can hear an improvement.

Thanks for that - nice to get information from someone who *knows*.... ;-)