9
XP-15 Owner’s Manual
grateful to Georg Simon Ohm for sharing his discovery with us,
but leave the math of all the 256 perturbations to those so inclined.
From a practical standpoint the 9 values indicated are likely sufficient
to cover the needs of all but the most obscure cartridge.
After you have selected a resistive cartridge loading that gives the
best overall spectral balance and the most dynamic presentation you
may choose to add or subtract capacitive loading to slightly trim the
high-end response.
Please understand the loading of a moving coil cartridge is a very
inexact science at best, specific recommendations should be taken
(and offered) very lightly. I encourage you to think separately from
the cartridge manufacturer and choose your resistive loading values
accordingly. The cartridge maker may have for example anticipated
a transformer being used as the initial stage of gain, the XP-15
with its active elements is a very different proposition. As an added
complexity part of the cartridge loading is provided by the lead-in
wiring, the resistance, and reactance of that wire must be accounted
for in choosing loading values in the XP-15. As long as you derive
your final setting empirically you may ignore these effects, your
moving coil cartridge will not.
An improperly loaded cartridge will suffer every unwanted sonic
anomaly, ranging from lack of definition and bass to a very strident
and screechy high end. Making the mistake of not loading channels
identically adds additional confusion. Please verity that loading for
one channel is duplicated in the other accurately.
Cartridge loading is a compromise between what works best for
the cartridge and what sounds best for the listener. Specifically we
are looking for a compromise loading which sounds best across the
whole audio spectrum.
I suggest you start with the following:
Always, ALWAYS mute or turn the volume of you pre-amp to a
minimal setting (better yet, turn your power-amp off) before making
any adjustments to the XP-15. Changes made to the XP-15 loading
have the possibility of sending pulses to your pre-amplifier that could
damage speakers if the volume of the pre-amplifier is set sufficiently
high.
Once the volume setting is reduced and the power amp turned off
set the loading to 100 ohms (switch position 4 “on” and positions
