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.
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.
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
