hybrid digital^TM Purifi own beat^TM amplifier

Purifi is a Danish technology company where some of the leading developers in the hi-fi industry are pursuing the goal of identifying and eliminating the last remaining weaknesses in digital amplifier technology. The current status of their work resulted in the Purifi self-beat^TM-Amplifier that NAD is the first company to manufacture under license and used exclusively in the M33 BluOS streaming amplifier.

The Purifi own clock^TM Technology convinces in terms of measurement with extremely low intermodulation distortion, a particularly low distortion factor across the entire frequency response and the entire power bandwidth - only 0,00017% at 100 watts of output power! – as well as a minimal self-noise. Since the distortion of the amplifier is lower than the inherent noise of the measuring devices used today, Purifi first had to develop new measuring methods in order to be able to prove and document the progress.

Pioneering for the development of the self-clock^TM Technology was the realization that a memory effect occurs in the components in the output filter of the amplifier. This phenomenon, called hysteresis, obviously leads to the well-known loss of sound of conventional digital amplifiers. By modifying the output stage and the clever algorithms of the self-clock^TMtechnology, Purifi managed to reduce the hysteresis effects by more than 75 dB. Another advantage of self-clock^TM Power amps is that they are absolutely insensitive to changing speaker loads. Their extremely low output impedance also leads to a very high damping factor, which is reflected in absolutely clean and controlled bass reproduction.

Balanced signal transmission

In recording studios and in professional sound reinforcement technology, symmetrical signal transmission has been part of good sound in the truest sense of the word for many years. It transmits the audio signals not via a single but via two conductors, which means that possible interference is excluded, even over longer cable runs. In addition to gold-plated cinch sockets, the M28 also has balanced XLR inputs, which ensure interference-free signal feeding without noise or interference.

Enormous power reserves

As the most powerful NAD power amplifier of all time, the M28 mobilizes an enormous pulse power of 560 W (4 ohms, one channel driven). Even when all channels are in operation at the same time, the power amplifier still has a respectable 7 x 280 watts of peak power - enough reserves to reproduce complex dynamic peaks in film soundtracks and music recordings without any loss of sound. The official continuous output power is 7 x 200 watts into 8 and 7 x 340 watts into 4 ohms.

PowerDrive^TM ensures large dynamic peaks

NAD's PowerDrive^TM Circuitry ensures that an amplifier has sufficient power reserves, even in the case of extreme pulse peaks, to be able to reproduce the music signals in their full dynamics. If required, the power pack provides very high current reserves for a short time, so that almost twice the output power can be mobilized for pulse peaks.