Everything You
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to achieve less of what you hear as preamp distortion and more output-tube
distortion, you can also try using a 5751
in the phase inverter position, which is
usually the last preamp tube before the
output tubes.
Even tubes of exactly the same type can
sound quite different, depending upon
their manufacturer and small changes in
their design and production. The fact that
tubes distort so organically also means
that no two tubes distort or even amplify
exactly alike. For one thing, while tubes
slightly different readings for gain and
other factors. Put enough of them up on
a tube tester and some will even fail to
meet required minimum standards. That’s
the way it is. Aside from giving different
readings, these tubes will each sound just a
little different, and other makes, both NOS
and current, will sound different again.
What does this mean for the guitarist?
For one thing, it behooves you to get
your hands on as many different makes
and types of tubes as you can reasonably
afford. Try swapping a few around to see
which ones help you to best achieve the
tone you are seeking. The first preamp
tube position usually affects the tone of
that part of the amp the most (read your
amp’s tube chart or owner’s manual to
make sure you know how to change tubes
safely, and are changing the right tube,
and please don’t touch any hot tubes! Let
them cool down first). Try three different
makes of 12AX7 or their equivalent in
that position, and I’m willing to bet you’ll
notice a slightly different voice from each.
Search the internet and read up on what
other players consider to be the best cur-rent-manufacture tubes coming out today
(there’s too much detail on that subject to
go into here). Also, see if you can find any
affordable NOS tubes, or perhaps you can
pull some used but functioning examples
from old junker radio or hi-fi systems that
you find at garage sales and swap meets.
Experiment a little, and see which ones
work for you. Preamp tube tasting can
become addictive, and it’s also a great
way to fine-tune your tone.
NEXT MONTH: PART 2 -
Output Tubes
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are manufactured under fairly rigorous
conditions, they are stillCYimperfect devices. Every little fluctuation in assembly
or materials results in a slightly different
sound and performance from each tube
that comes along.
CMY
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That’s why good tube distributors need to
routinely test tubes they sell: put even two
high-quality NOS preamp tubes from highly
respected American or British manufacturers on a tube tester—say, a pair each of
Mullard or RCA 12AX7 preamp tubes that
came out of the factory on the same day
in 1963—and they will most likely have
