- Pass Stereo Amplifier Owner's Manual

X1000.5 Owners Manual

The Pass Laboratories™ X1000.5 is optimized for loads nominally

rated at 4 ohms and above. You can run 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 am-

plifiers.

The X.5 series amplifiers do not care particularly about the reactivity

of the load. Reactive loads typically will have slightly less distortion

at a given voltage/current level than resistive loads, but will make the

amplifier run a little hotter. The X.5 circuit was designed to be quite

happy driving electrostatic and other difficult speakers.

When driving transformer-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 transformer primary 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 transformer and get less than optimal

performance from it. Generally this is not the case with transformer-

coupled loudspeakers, but it does occasionally surface. In these cases,

take special care that the source does not contain a differential DC

component, and confirm the differential DC offset of the pre-ampli-

fier is sufficiently low. This differential voltage is easily adjusted by a

qualified technician armed with the appropriate service documents.

We have a general recommendation about interconnects, which is that

they should cost less than the amplifier, and be flexible 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 good taste.

We prefer speaker cables that are thick and short. Silver and copper

are the preferred metals. If you find any cable made of gold, 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