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NAD M25 7-Channel Amplifier

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MASSIVE POWER

More power is always better when it comes to sound quality. Power is required not only to play loudly, but also to play cleanly without audible distortion. When an amplifier is asked for more power than it was designed to deliver, it can only respond with distortion.Fortunately the M25 is one of the most powerful amplifiers on the market today designed for home use. With a minimum of 160 continuous watts per channel, all channels driven simultaneously, from 20Hz to 20kHz at rated distortion of 0.03%, the M25 easily delivers lifelike sound levels even in large home theatre rooms. It handily meets THX�s most stringent certification level, Ultra 2.

Unlike most surround sound receivers (NAD�s own receivers are a rare exception) that only rate power with 1 or 2 channels running, or use very short term measurements, the M25 can deliver its full rated power continuously for hours on end. Custom designed heat sinks and thermostatically regulated variable speed fans keep things cool under the most severe operating conditions. A unique fan circuit that tracks signal level, actually shuts down the fans during quiet passages to prevent any mechanical noise from interfering with the program material.

But it�s not just the quantity of power that is important, it is also the quality of power that determines whether you can hear just a fiddle sound, or the unique character of a Stradivarius violin.

SOPHISTICATED CIRCUITRY

The M25 is comprised of 7 individual �Monoblock� amplifier channels. Each channel uses a balanced junction FET input stage resulting in exceptionally low levels of noise and distortion. NAD employs a unique electronic ground isolation circuit to prevent ground loop noise in the system � a common problem in complex multi-channel systems. This circuit offers high input impedance for negligible loading on source components which results in less noise and distortion in the real world.

A fully complementary differential class A voltage amp with a push pull cascode output stage, provides ample current to drive the triple emitter-follower output stage. This circuit topology offers very low distortion combined with high current capability.

NAD�s PowerDrive� circuitry measures each channel�s dynamic impedance individually and computes the optimum power supply voltage required to drive the output stage for maximum power and efficiency. PowerDrive permits high dynamic power and low impedance drive capability, while maintaining ultra low (<0.03%) levels of distortion. The M25 also incorporates NAD�s acclaimed switchable �Soft Clipping� circuit. Each channel has individual over current, DC, infrasonic and ultrasonic overload sensing and protection for complete reliability under even the most severe operating conditions.

MASSIVE POWER SUPPLY

The M25 utilizes NAD�s proven Holmgren Toroidal transformer design, in a massive size, to create a power supply that offers very well regulated voltage, and truly massive amounts of current. The Holmgren transformer design utilizes proprietary low leakage field technology which is very low in both electrical noise (stray field) and physical noise (buzz).

Multiple 100,000 uF, 100V low ESR capacitors ensure a clean DC voltage supply for very low noise and truly explosive dynamics. Ultra low impedance copper buss bars are used exclusively throughout for power delivery and grounding.

DETAIL ENGINEERING

It is the many small details that differentiate a really great amplifier from a merely adequate one. Buffered low impedance level controls allow system fine tuning without the distortion typical of most level control circuits. Custom designed gold plated speaker binding posts offer multiple connector options, while maintaining a large, corrosion- free, low impedance contact area. Input jacks are also custom designed for maximum performance. Even the feet that support the M25 are engineered to filter out vibration and provide maximum performance.

PUTTING IT ALL TOGETHER

The highly developed, yet elegantly simple circuitry of the M25, is matched with a brute force power supply to create one of the most powerful Home Theatre amplifiers on the market today. Yet all this power is balanced by a liquid and transparent sonic signature that is subtlety nuanced and insightful. The M25 simply adds another dimension to surround sound that must be heard to be believed.

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