- Pass X250.5 Owner's Manual

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/cur rent 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 distor tion 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 g round 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.

Fortunately 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