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The Sound
Mark Levinson products have always been highly regarded for their sound quality and the Nº502 is no exception. Towards that end, every part of the audio path from the input to output was carefully considered and designed to ensure optimal sound quality.
Starting with the chassis, it was designed to double as an integrated radio frequency (RF) shield providing immunity from the RF emissions that are commonly radiated by other devices. These emissions are a common source of noise that can find its way into the sensitive audio circuits and degrade sound quality. Another way for noise to enter a system is through the input and output connectors which are usually connected directly to the chassis, providing a direct path for noise to get in. To prevent this from occurring in the Nº502, the input and output connectors are physically isolated from the chassis.
Inside the chassis, the Nº502 utilizes two AC power transformers to completely isolate the digital and analog signal paths. A digital power transformer is used to power the digital circuits, and a toroidal power transformer is used to power the analog circuits. In addition, both power supplies are carefully shielded in a chamber inside the chassis to further prevent transformer noise from leaking into the delicate analog circuits and degrading sound quality.
Another method employed to reduce noise is the use of eighteen-layer circuit boards with minimal surface etches. They help to lower radiated emissions from inside the chassis. We also isolate the control signals from the audio signals to ensure that they do not interfere with them. In the event that any common mode noise is present inside the system, all of the analog audio signals are routed inside the chassis as differential (balanced) signals, to cancel this noise out.
To reduce jitter and digital noise, a specially designed low voltage differential signaling circuit is utilized. A proprietary direct digital synthesizer frequency lock loop controls the audio master clock resulting in extraordinary jitter performance. This closed loop control algorithm improves bandwidth and resolution.
Great care was also taken in the implementation of the level controls for the Nº502 which offer an adjustment range of 120dB, preserving the full resolution of the signal. Fewer passive components were employed to reduce noise and distortion, and digital quantization noise is exceptionally low, even at the lowest volume settings. This ensures that the level controls do not significantly degrade the sound of the audio passing through them, common in many other less rigorous designs.
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