amplifier distortion, It will already be exceedingly low on
the XL-600 as you receive it because each amplifier chan-
nel has been factory adjusted using a typical loudspeaker
load. But when the XL-600 is connected to your own
speakers, careful readjustment by a technician may yield
some slight improvement. The test is as sensitive as one’s
hearing, and much more precise than available measure-
ment technology because it is able to reveal the audible
effect of
all
distortions - even those which have not yet
been identified or quantified!
This is a very useful amplifier comparative technique which
supplements conventional distortion measurements. With
the XL-600, the
total
of all residual distortion products will
be on the order of 60 dB or more down across the audio
band - a substantial improvement over other amplifiers,
where 40 dB figures are among the best. Only a few
amplifiers cannot be subjected to this test: those which are
phase inverting, and those which have floating (not
grounded) outputs, or those which cannot tie together the
output grounds.
The XL-600 provides a unique internal adjustment for “fine
tuning” each channel when it is connected to
your
speakers. This “tweaking” may fairly be described as
significant only to those persons with “golden ears”. The
rest of us who simply wish to indulge ourselves with fine
sound need not be concerned with this consummate pur-
suit of perfection.
The range of adjustment provided is within the defined
operating specifications of the amplifier. Misadjustment
will not damage or impair the performance of either
amplifier or speaker. The region of change is several
octaves above the range of human hearing. Yet we have
found that minute differences in absolute linearity can be
heard, and this “tweaking” can minimize them. Do not
change the factory’s setting until you have at hand the
appropriate gain control circuit described below. You will
need the special tool provided, patience, quiet, and good
hearing, but no test instruments to complete the task.
Because the amplifier must be operated with the cover off,
and high voltages are exposed,
this should only be
undertaken by a qualified technician.
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