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X250.5 Owners Manual
The Pass Laboratories™ X250.5 is optimized for loads nominally rated
at 4 ohms and above. You can r un the amplifiers into a lower nominal
impedance without difficulty, and we are not aware of a speaker on the
market that presents unusual difficulty with these amplifiers.
The X.5 series amplifiers do not care par ticularly about the reactivity
of the load. Reactive loads typically will have slightly less distor tion
at a given voltage/current level than resistive loads, but will make the
amplifier r un a little hotter. T he X.5 circuit was designed to be quite
happy driving electrostatic and other difficult speakers.
When driving transfor mer-coupled loads directly, as in some elec-
trostatic and ribbon designs, some attention must be paid to the DC
character of the situation. If the transfor mer primar y is being driven
raw with no protection from DC and your source has DC voltage, or
in cases where the small offset of the power amplifier is still too much,
you may create distortion in the transfor mer and get less than optimal
perfor mance from it. Generally this is not the case with transfor mer-
coupled loudspeakers, but it does occasionally surface. In these cases,
take special care that the source does not contain a differential DC
component, and confir m the differential DC offset of the pre-ampli-
fier is sufficiently low. T his differential voltage is easily adjusted by a
qualified technician ar med with the appropriate ser vice documents.
We have a general recommendation about interconnects, which is that
they should cost less than the amplifier, and be f lexible enough to work
with. We have tried a lot of products and most of them work well, but
as a practical matter we cannot make blanket recommendations.
The amplifier is not sensitive to source interconnects or ground loops.
It is also not sensitive to radio frequency pickup, which allows some
flexibility in choosing source interconnects without shields, though
shields are always in g ood taste.
We prefer speaker cables that are thick and shor t. Silver and copper
are the prefer red metals. If you find any cable made of g old, please
gift us a couple hundred meters.
For tunately the amplifier is not sensitive to the capacitive/inductive
character of some of the specialty speaker cables, so feel free to ex-
periment.
We have found that about 90 per cent of bad sounding cables are in
reality bad sounding connections, and we recommend that special at-
Speaker Interface
Interconnects and Speaker
Cables