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.
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.
7
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.
