NAD owner manual ABOUT THE M25, The Design, Powerdrive

ABOUT THE M25 THE DESIGN

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Designed specifically for home theatre and custom installation set-ups, the NAD M25 Power Amplifier delivers uncompromising performance. It combines supreme reliability, flexibility, and performance with outstanding value. Flexibility has always been an important part of NAD components. Such flexibility is particularly important in home theatre and other multi-channel systems. That’s because it is common for a multi-channel system to incorporate different brands and models of loudspeakers. Often these speakers have different levels of efficiency. The individual input level controls for the seven channels of the NAD M25 make it easy to compensate for such differences in efficiency, and achieve the ideal system balance. Ample dynamic headroom of the M25 ensures that the very wide dynamic range of modern cinema soundtracks and digital music sources will be preserved. In addition, the M25 will handle low impedance speakers with ease.

The M25 incorporates NAD’s unique Soft-Clipping circuitry in all seven channels. Any amplifier can be overdriven if it is played too loud, exceeding the maximum output power. Under such circumstances, amplifiers produce extreme high levels of distortion which, besides sounding very unpleasant, can damage your loudspeakers. The Soft Clipping circuit suppresses such distortion and minimizes the risk of damage to speakers. This is particularly important with movie soundtracks which often contain very dynamic outbursts in which, unlike music, it is difficult to hear this potentially damaging distortion. The Soft Clipping LED on the front panel illuminates when the Soft Clipping circuit is engaged. Soft Clipping can be defeated with a rear panel switch.

The 12V trigger connection on the back panel allows the amplifier to be switched from On to Stand-by and vice-versa remotely. This way, the M25 can be part of a system which can be turned on and off with a single command, easing operation. The 12V trigger also allows the amplifier to be installed in places not in easy reach.

The NAD M25 houses seven individual amplifiers, each on separate circuit board. Each amplifier channel acts as a “mono block” within the chassis. Each input connector, and set of loudspeaker output terminals, is directly connected to that channel’s circuit board. This design eliminates extra wiring and keeps signal paths short. Furthermore, this modular design increases reliability and thermal efficiency. The input circuit uses a totally new dual differential input topology that operates in true Class-A mode. The special Holmgren™ toroidal transformer has less hum and magnetic leakage than conventional toroidal transformers, but retains the usual benefits of high efficiency and high power-to-weight ratio.

Ruggedness and reliability are critical in custom-installed systems. The M25 uses a combination of fuses and non-intrusive electronic protection. This provides highly effective protection that does not effect audio performance. Each channel is protected against excess temperature, DC fault and loudspeaker short-circuit. The M25’s inherently conservative, high-voltage/high-current output stage has been designed for years of trouble-free service.

NAD was the first company to introduce a THX® Certified power amplifier. In that tradition, the M25 easily passes THX Ltd.s' stringent THX® performance requirements. As a result the NAD M25 will handle the most demanding signals with ease, and yet preserve every subtle audio detail in the most demanding THX® Ultra2™ Surround systems. THX and Ultra2 are trademarks or registered trademarks of THX Ltd. All rights reserved.

POWERDRIVE

To meet the diverse requirements of high current drive and high dynamic power, our patented PowerDrive amplifier circuit will build further on our reputation for amazingly effective power. By adding a second high-voltage rail to our well regulated high-current power supply, we get an "overdrive" that can nearly double the continuous power on a short term dynamic power basis. This is a further development and refinement of our renowned Power Envelope circuit, utilized by NAD in the 80's and 90's. PowerDrive differs from Power Envelope in that it offers greater amplifier stability and low impedance drive capability, resulting in less distortion when driving real speakers with real program material

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