5
INT-150 Owners Manual
the distortion as identical as possible on both polarities of the balanced
output.
It is easier to make distortions in the two halves more identical than to
remove them with feedback, and this is the operating principle of X
amplifiers.
Since the X1000, Pass Labs products have continuously evolved toward
higher performance. The Class AB “X” series was joined by the Class
A “XA” amplifiers. Subsequent improvements to the Class AB “X”
amplifiers resulted in the “X.5” products, and their phenomenal success has
led to the Class A “XA.5” series.
As always the goal has been the best musical and objective performance
possible with minimal parts in the signal path and minimal feedback. This
process is not completely quantified, and many of the improvements are
the result of trial and error and extensive listening.
Measurement of performance is important to us, and we feel that well-
designed product sounds good and measures good. Apparently it is
possible to make an amplifier which measures well but which does not
please the ears, and so we let our ears be the final judge.
The X amplifiers deliver more output power per dollar, and the XA
amplifiers have a better subjective performance. All of the amplifiers drive
known loudspeaker loads without misbehaving, and all are unconditionally
stable into low impedance and reactive loads.
All the usual performance metrics - power, distortion, noise, input
impedance, damping factor and bandwidth have all been improved in this
latest generation. The power supplies are larger, with fast rectifiers gating
to larger capacitor banks. The increases in AC line noise worldwide have
been addressed with heavier EMI filtering and dramatically quieter power
transformers. In addition, through improved biasing regulation, the circuits
give much more consistent performance under varying AC line voltages
and over a variety of ambient temperatures.
All this is very nice, but only if it improves your listening experience. We
listen very carefully and critically to our amplifiers with a wide variety of
associated equipment and we take our time with it. Musical performance is
most important, and is the basis of our success over the years.
It’s true that we also value the other things. The design and manufacturing
decisions have to balance subjective performance against reliability, cost,
specs, and ego (in approximately that order). That is why we make more
than one amplifier, but all are built with the same commitment to quality.
The Pass Laboratories INT-150 Integrated Amplifier was designed
specifically to bridge the gap between so called high-end audiophile product
and the need for a simple “no nonsense”, convenient, user-friendly, high
