Mark Levinson 433 - Manual (Page 11)

11
Nº433 Power Amplifier
Special Design Features
Thank you for purchasing the Nº433 Power Amplifier. While this
amplifier is straightforward in everyday use, it includes several
design features that are responsible for its outstanding performance.
In particular, this amplifier defies 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 Nº433 features three large, robust power supplies. Each supply
includes a high-capacity, low-noise toroidal transformer, and two
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 intro-
duced by the wiring harnesses that are commonly found in lesser-
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 the massive power delivery 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,
minimizes magnetic field distortions that can occur with 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.