Pass Labs X1000.5 specification

Speaker Interface

Interconnects and Speaker Cables

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-

X1000.5 specifications

Pass Labs X1000.5 is a high-performance power amplifier that has earned a stellar reputation among audiophiles and sound engineers alike for its exceptional sound quality and robust design. Created by renowned audio engineer Nelson Pass, the X1000.5 exemplifies the fundamental principles of Pass Labs: simplicity, purity, and musicality.

At the core of the X1000.5's capabilities is its Class A operation, delivering 1000 watts of power into 8 ohms and effectively doubling that into 4 ohms. This Class A architecture ensures minimal distortion and a linear response, allowing for an incredibly accurate reproduction of sound across the entire frequency spectrum. The soundstage is wide and immersive, enabling listeners to discern subtle details in both music and vocal performances.

One of the standout technologies employed in the X1000.5 is the use of a complementary output stage consisting of high-speed MOSFETs. This allows the amplifier to manage high instantaneous current demands without sacrificing control or transparency. The use of MOSFETs also contributes to a warm and engaging sonic signature that is characteristic of Pass Labs' designs. The amplifier’s circuitry is designed with an emphasis on low negative feedback, which further enhances the natural sound quality.

The build quality of the X1000.5 is equally impressive. Housed in a robust chassis designed to minimize resonance and electromagnetic interference, the amplifier features a dual-mono configuration with separate power supplies for each channel. This not only provides ample power but also ensures channel separation and coherence in sound reproduction. It also incorporates high-quality components such as low ESR capacitors and a custom-made toroidal transformer, which contributes to its excellent performance.

Additional features include an easy-to-use input stage that supports both balanced XLR and single-ended RCA connections, making it compatible with a wide range of source components and speaker systems. The X1000.5 is also equipped with protection circuitry that prevents over-temperature and over-current situations, safeguarding both the amplifier and connected speakers.

In summary, the Pass Labs X1000.5 is a masterful blend of power, precision, and artistry. With its Class A operation, advanced MOSFET technology, solid build quality, and user-friendly features, this amplifier is a compelling choice for audiophiles seeking to elevate their listening experience to new heights.