9 volts to 15 volts. This switching is independent of the front panel button, so if the amplifier is placed in operating mode by the button, the relay will not turn it off, only on.

So much for essential information.

Speaker Interface

The X Series 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 amplifiers.

If you wish to maximize power or minimize distortion for loads rated below 4 ohms, we suggest that you parallel 2 or more X1000 channels, which will allow multiples of the 20 amp rating. For example, if you desire to achieve 16,000 watts peak into 1 ohm, you will want to use 4 amplifiers in parallel. If you want lower distortion at that figure, you will use more. Remember that running arrays of X1000 channels requires an interface unit from Pass Labs. Feel free to consult the factory for the answers to any questions.

The X 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. The X circuit was designed to be quite happy driving electrostatic and other speakers, since it is unconditionally stable and operates without feedback.

When driving transformer-coupled loads directly, as in some electrostatic 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 DC component, and confirm the DC offset of the amplifier is sufficiently low. This is easily adjusted by a qualified technician armed with the service manual. Again, consult your dealer or call us.

The damping factor of this amplifier is not extremely high as it is with some other high power products, but it is the same at all audio frequencies and occurs naturally without feedback. Some people are concerned that they need high numbers for good bass performance, but it just doesn’t seem to be so. We suggest that you listen with your ears and not your meter.

The Power Line

Please keep in mind that the data we present on output power for this amplifier is based on a solid AC power line. In order to get these high continuous figures, the AC line cannot be allowed to collapse. Typically in maximum power testing, a household line will fall from 120 volts to around 105 volts. This impacts the power that can be delivered on a continuous basis, and it is probable that you will not get full continuous power at specification.

This should not be the subject of great concern, since in audio usage, these kinds of power will only occur as brief transients, and under these circumstances the AC line will not load badly,

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Pass Labs X1000, X350, X600 owner manual Speaker Interface, Power Line
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X600, X350, X1000 specifications

Pass Labs is renowned for its high-quality audio amplification equipment, and their amplifiers—like the X350, X1000, and X600—exemplify their commitment to exceptional sound reproduction and advanced engineering. Each model reflects innovative technologies and distinctive characteristics that cater to audiophiles seeking premium performance.

The Pass Labs X350 is a powerhouse that strikes a balance between power and finesse. It is a Class A amplifier, delivering 350 watts per channel into an 8-ohm load, which translates to incredible clarity and dynamic range across a variety of music genres. One of the standout features of the X350 is its use of the innovative Front End Circuitry, which enhances both linearity and low-frequency response. This ensures that the amplifier can handle complex musical passages effortlessly while retaining the natural timbre of instruments. The X350 also employs the renowned "Pure Class A" operation, resulting in minimal distortion and a warm, engaging sound signature that is particularly pleasing for long listening sessions.

In the range, the X1000 takes performance to the next level. With a staggering output of 1000 watts per channel into 8 ohms, it is designed for those who demand uncompromising power. The X1000 features a fully balanced design, providing superior common-mode rejection and eliminating unwanted noise. This model leverages advanced MOSFET technology, allowing for refined audio reproduction without sacrificing power. The robust build quality, including heavy-duty heat sinks, ensures optimal thermal management, which is vital for maintaining performance during extended use.

If you're in search of an amplifier that combines muscular performance with fine detail, the X600 is a noteworthy option. With 600 watts per channel into 8 ohms, this amplifier takes advantage of Pass Labs' patented technology to deliver nuanced sound without harshness. The X600 also incorporates a unique bias system that automatically adjusts based on the demand of the signal, maximizing efficiency and maintaining sound fidelity. This attention to detail helps in preserving the dynamic range and depth of the audio, making it suitable for both critical listening and casual enjoyment.

In summary, Pass Labs’ X350, X1000, and X600 amplifiers are masterpieces of audio engineering. They each showcase unique technologies and features that cater to a wide range of audiophile preferences—from the balanced performance of the X350, the sheer power of the X1000, to the nuanced detail of the X600. Whether for a sophisticated home theater setup or a dedicated stereo system, these amplifiers stand out for their ability to provide immersive listening experiences that are rich, dynamic, and true to the source.
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