NAD Introduces Powerful, Paradigm-Breaking M2 Direct Digital Amplifier

Revolutionary Masters Series Amplifier Implements New Digital Correction Technology for Dynamic, Efficient, Musically Revealing Performance

Sydney, April 13, 2010 – NAD Electronics, the highly regarded manufacturer of high-performance audio/video components, introduces the Masters Series M2 Direct Digital Amplifier. The culmination of a decade long research project, it delivers a new level of amplifier performance. Immensely powerful, dynamic, efficient, and musically revealing, the M2 is a true digital amplifier that sets new benchmarks for both measurable performance and subjective musical quality.

Superior to any previous digital amplifier, the M2 can be thought of as a Digital-to-Analogue Converter (DAC) that directly drives a loudspeaker, but with the same precision as the very best low-level DACs. The M2’s technology is far more sophisticated than the Class D analogue amplifiers that are often erroneously referred to as ‘digital.’ In fact, the M2 is the first digital amplifier that can match the best linear amplifiers for low noise and distortion, delivering better than Class A sound with Class D efficiency. At the same time, the M2 is capable of delivering startling power, 250 Watts to each of two channels at 4 or 8 Ohms continuous power, and 500 Watts IHF Dynamic power.

NAD has long been a leader in amplifier technology, extending back to the late Seventies, and has been responsible for many groundbreaking innovations. NAD published a scientific paper in the 1980s defining the importance of Dynamic Power for an amplifier reproducing recorded music. This led directly to the Power Envelope, PowerDrive and Soft Clipping circuits. More recently NAD's Director of Advanced Development, Bjorn Erik Edvardsen, has developed a unique Distortion Cancelling Circuit and Adaptive Anti-saturation Clamp (BEE Clamp) first introduced in the Masters Series amplifiers.

NAD has also long been committed to creating a digital amplifier — but only if it could meet or exceed the performance levels of its own best analogue amps, in contrast to the many manufacturers that have ‘gone digital’ with cost savings their primary goal. The M2 is the amplifier NAD has been waiting for, and working toward — a true digital paradigm breaker.

The M2 can also be said to represent a number of firsts. It is the first digital amplifier to fully exploit the resolution potential of HD audio and a fully digital signal path, the first audio amplifier to use high-speed digital error correction to reduce distortion while maintaining full HD resolution, the first digital amplifier to fully implement digital closed-loop processing (a.k.a. error correction); and the first digital amplifier to implement a new technology called Direct Digital Feedback developed by UK-based Diodes Zetex Semiconductors Ltd. during its collaboration with NAD on the M2 project.

Reinventing Feedback

The M2 takes in a digital signal and outputs an analogue signal to drive the loudspeaker. It avoids the limitations of conventional error correction or 'feedback' approaches used to achieve very low distortion by generating a feedback signal through comparison with an extremely pure reference, then converting the signal to the digital domain at a 108MHz sample rate before using it for correction. Direct Digital Feedback simply determines the pulse area error, no matter the cause, and passes the information to the digital domain for compensation.

The M2 possesses an extremely wide data path that allows compensation without truncating any information in the original signal. The result: very low noise and distortion in the audio band, combined with blinding speed and precision.

Streamlined Signal Path

Since the M2 can accept a digital PCM input directly, it completely eliminates the noise and distortion added by the cascaded analogue amplifying stages typically found in traditional Class AB or even Class D amplifiers. Such streamlining of the system architecture can also reduce the residual noise and distortion of the overall system by eliminating several amplifier stages. The result is a stunning sense of musical intimacy, a feeling of being closer to every performance.

The M2 also includes a DSP which is custom programmed with NAD’s high-resolution digital volume control possessing a broad attenuation range and perfect channel balance. A five-position digital impedance compensation filter allows fine-tuning the top octave to match the selected speaker impedance, resulting in a perfectly flat frequency response at 20kHz.

Unmatched Versatility

The M2 is also equipped with a fully balanced, state-of-the-art Analogue-to-Digital Converter (ADC) to accommodate existing analogue audio sources and because some owners will want to use a traditional analogue preamplifier. The analogue input buffer amp and the ADC are the highest quality available, and accept both a single-ended input and a balanced XLR input.

A unique Digital Processor Loop allows advanced users to insert external digital filters into the signal path. For example, the M2’s optical TosLink jack allows fuss-free connection to Macintosh and PC computers, which can access a wide library of crossover filters and room correction programs. Digital outputs in both coaxial and optical formats make it possible to use multiple M2s for the bi- or tri-amplification of advanced loudspeaker systems.

Power and Control Integrity

The M2 employs three power supplies, all highly efficient switch mode types. Each channel receives its own high current power supply in a dual mono configuration. The input stage and control sections also receive dedicated power supplies with multiple regulated secondary voltages for individual sections.

The M2’s Digital PowerDrive™ circuit further refines loudspeaker performance by maintaining optimum power delivery and the lowest possible distortion. The M2 has excellent dynamic power capabilities, unlike most digital amplifiers without power reserves. NAD’s Digital Soft Clipping™ prevents the harsh sound and potential speaker damage that can result when a severely overdriven amplifier clips the tops and bottoms of the sine wave. The M2 completely controls this behaviour with digital precision.

Equally important, the M2 has been carefully engineered with multi-stage fail-safe protections to prevent amplifier or speaker damage under fault conditions. It handles short circuits, DC offsets, overheating, and over current faults instantly, while displaying an indication of the fault on the front panel. The M2’s RS-232 serial interface allows it to be controlled from a PC or through advanced control systems like those from Crestron and AMX. A 12V Trigger and IR input permit other popular control options, and add flexibility for home and studio use.

NAD’s M2 Direct Digital Amplifier is available from April 2010 from Southport hifi