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Special Design Features
While the Nº33H Monaural Power Amplifier is straightforward in
everyday use, it includes several design features that are responsi-
ble for its outstanding performance. In particular, it defies the
accepted wisdom that it is impossible to design a large, powerful
amplifier that also has all the finesse of the finest smaller ampli-
fiers.
Massive Power Supply The Nº33H features a 3.47 kVA low-noise toroidal transformer in a
fully balanced power supply—a design that provides separate
power supplies for the amplifier’s inverting and non-inverting
halves. In addition, each Nº33H uses four 60,000 µF low-ESR
capacitors.
Heavy bus bars enhance the efficiency of power distribution with-
in the amplifier and eliminate variances introduced by the wiring
harnesses commonly found in even high-performance amplifiers.
High-frequency power supply bypass is accomplished using indi-
vidual PC boards that use 32 components of several different film
types. The resulting uniformly low power supply impedance seen
by various circuits within the Nº33H lays the foundation for mas-
sive power and extraordinary finesse.
AC Power Regeneration The detrimental sonic effects of noisy, unbalanced AC power
supplies are widely known. Commercially available passive AC
line conditioners provide some measure of AC power filtering and
surge protection for line-level components such as preamplifiers
and digital audio processors. However, these line conditioners
cannot handle the large, instantaneous currents that power ampli-
fiers require. In effect, the line conditioner becomes a bottleneck
in the otherwise free flow of power through the amplifier and
loudspeakers, greatly reducing the dynamic impact of the signal.
To avoid these performance bottlenecks, the Nº33H uses built-in
line conditioning techniques. When AC power is delivered to the
Nº33H, it is rectified, filtered, and regulated into positive and neg-
ative DC voltages. A portion of this DC power is used to drive an
oscillator circuit that regenerates a pure 60 Hz sinewave. This
sinewave is then used to power a separate power supply dedicated
to all voltage gain stages. The dedicated power supply benefits
from a truly balanced source as well as the total elimination of AC
noise and fluctuations. As a result, the Nº33H’s critical voltage
gain stages operate in a truly optimized environment, passing a
musical signal with outstanding low-level resolution and detail.