H User Manual

Fully 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 and 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. The input signal

remains balanced, and rejection of common mode noise and

distortion is achieved in the loudspeaker’s voice coil.

True Voltage Source The Nº33H operates like a true voltage source—maintaining the

appropriate voltage at a given time (based on signal demands)

without particular regard for the current demands of the associated

loudspeakers. Whether the loudspeakers require a 1 or 50-amp cur-

rent, the Nº33H will deliver.

Forty output transistors distributed throughout the four main heat

sinks conduct and control the flow of power to the associated

loudspeakers. Ten complementary pairs of output transistors are

used in both the inverting and non-inverting output stages.

No known high-quality loudspeaker can continuously absorb the

full power of the Nº33H; but many loudspeakers require these

extreme bursts of power on a short-term basis when reproducing

music at realistic levels. The Nº33H provides these short bursts

without creating power supply sag or altering sonic performance.

Its imperturbable nature is reflected in the authority and control

with which it reproduces musical signals.

Extensive Protection The Nº33H is designed to shut down if it senses certain fault

conditions that could cause damage to itself or associated

loudspeakers. These fault conditions include:

• The presence of DC (direct current) at the output

• Sustained output current (≥40 amps), indicating a

short-circuit across the outputs

• Over or under-voltage conditions at the ~ac mains

connector

• Unsafe operating temperatures in a critical area within the

amplifier.

When powered on or placed in standby, the Nº33H will

automatically power off—as if the rear panel power switch had

been set to the off position—if a fault condition is detected. It

will not power on again until the fault condition is corrected. To

restore normal operation, remove the cause of the fault and power