11
Special Design Features
Thank you for purchasing the Nº432/431 Power Amplifier. While
these amplifiers are straightforward in everyday use, they include
several design features that are responsible for their outstanding
performance. In particular, these amplifiers defy the accepted
wisdom that it is impossible to design a large, powerful amplifier
that also has all the finesse of the finest smaller amplifiers. A few
of the technical highlights that make this possible are described
below.
Massive Power Supply The Nº432/431 features two large, robust power supplies. Each
supply includes a high-capacity, low-noise toroidal transformer,
and four large, low ESR (“Equivalent Series Resistance”) capacitors.
Heavy oxygen-free copper bus bars enhance the efficiency of
power distribution within the amplifier and eliminate variances
introduced by the wiring harnesses that are commonly found in
even high-performance amplifiers. High-frequency power supply
bypass is accomplished on individual PC boards by components
of several film types. The resulting uniformly low power supply
impedance seen by the various circuits within the amplifier lays
the foundation for massive power and extraordinary finesse that
characterizes Mark Levinson amplifiers.
Balanced Design A truly balanced input topology eliminates the need for an input
buffer amplification stage, allowing the first stage differential
amplifier to be driven directly by the source. Matched impedances
are presented to the source. Both signals travel through identical
circuit paths.
Meticulous attention to the layout of the amplifier, including
careful mirror-imaging of circuits to cancel magnetic fields, was
essential to minimize magnetic field distortions that can occur
with such a massive power delivery system. A balanced input
signal remains balanced throughout the voltage gain stages.
Rejection of common mode noise and distortion is achieved in
the final, current gain stage.