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tem and live with it a bit, but not be too
impressed until I go back to where I
started from and THEN realize how big
a difference there was.
Although it is always best to use the
same track of music to evaluate per-
formance, don't wear out that track and
yourself. It is important to choose a
piece of music and familiarize yourself
with how it sounds on the system with
no DUT (Device Under Test) in place.
Stop, add the DUT, then listen to the
same music and note the differences.
Often I do this with the same cut, and
become numb to the differences. Once
you think you've noted some changes,
play two or three other, familiar cuts to
confirm the changes.
Keep the volume is identical!
A common mistake is not having exactly
the same volume level for the two parts
of the test. This may be particularly
hard with the Power Plant, because it
requires you to switch off your equip-
ment each time you activate the Power
Plant. I have an Audio Research pre-
amplifier that "forgets" its volume setting
whenever it is unplugged. So, I count
the number of clicks that it takes to set
the volume, write that number down,
then easily reset volume when I return.
Enlist a friend.
Another opinion is always valuable to
backup yours, or maybe your friend will
notice things you have not. I ask a
friend to switch Power Factors for me,
for instance. Here are my rules: I don't
want to know WHERE you switch, just
WHEN you switch. Suppose I ask my
associate to switch between 60 Hz and
120 Hz. I ask for position "A" (he points
upwards), position "B" (he points down-
wards). I take notes. On three different
pieces of varying music, I preferred B to
A. "OK," I ask, "which setting was B and
which was A?"
I guess it's important to be as scientific
about the evaluation as possible. But,
don't get so scientific that you forget that
listening is a sensual art.
Sometimes the music is of such a com-
plex nature that it is difficult (at best) to
clearly define the individual nuances that
make up the differences between the
familiar system and the DUT.
Remember too, listening properly for
changes can be as simple as "I don't
know, it just sounded better!" That's OK
too.
A list of things we would
like you to know:
Power Factors.
We have noticed, on some pieces of
stereo equipment, that their internal
power transformers buzz or "sing" when
the higher Power Factor frequencies are
activated.
After you've made your evaluation of the
effects of the Power Factor increase
(sonically), turn the music off then raise
and lower the frequency to see if your
equipment also makes a mechanical
noise that is objectionable to you. The
possible noise I refer to does not come
out of the speakers; if present, it will
emanate from the unit itself.
If you do hear such a noise, note how
close to the unit you must be to hear it.
(It may be wholly inaudible from your lis-
tening position.) Also, raise and lower
the Power Factor control through each
step. In many instances, we have found
that the unit's transformer will "sing" at
one frequency, but that it will stop at the
very next frequency. Experiment to find
which Power Factor works best with
respect to sound and to the lowest level
of transformer "sing" possible. The
"singing" transformer phenomenon is not
at all harmful to your unit.
Plugging in vs. switching on.
A potential problem area is method of
switching on. We prefer that you first
switch the Power Plant on (or leave it
on), then switch on each piece of equip-
ment, one at a time. Example: I have a
CD player and a DAC unit plugged into
the Power Plant. The Power Plant is on.
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