Hybrid DigitalTM Purifi EigentaktTM Amplifier

Purifi is a Danish technology company where some of the leading developers in the Hi-Fi industry pursue the goal of identifying and eliminating the last remaining weaknesses in digital amplifier technology. The current state of their work resulted in the Purifi EigentaktTM amplifier, which NAD was the first company to license and, until now, exclusively used in the BluOS streaming amplifier M33.
The Purifi EigentaktTM technology impresses with extremely low intermodulation distortion, a particularly low total harmonic distortion across the entire frequency range and the complete power bandwidth – only 0.00017% at 100 watts output power! – as well as minimal self-noise. Since the amplifier's distortions are lower than the self-noise of today's measuring devices, Purifi first had to develop new measurement methods to be able to substantiate and document the progress.
Pivotal to the development of EigentaktTM technology was the realization that a memory effect occurs in the components of the amplifier's output filter. This phenomenon, called hysteresis, evidently leads to the well-known sonic degradation of conventional digital amplifiers. By modifying the output stage and using the clever algorithms of EigentaktTM technology, Purifi succeeded in reducing hysteresis effects by more than 75 dB. Another advantage of EigentaktTM power amplifiers is that they are absolutely insensitive to changing speaker loads. Their extremely low output impedance also leads to a very high damping factor, which results in an absolutely clean and controlled bass reproduction.

Balanced Signal Transmission

In recording studios and professional sound reinforcement technology, balanced signal transmission has literally been standard practice for many years. It transmits audio signals not via a single conductor, but via two, which – even over longer cable runs – keeps possible interference out. In addition to gold-plated RCA jacks, the M28 features balanced XLR inputs, ensuring interference-free signal input without noise or interference.

Key Features

HybridDigitalTM Purifi EigentaktTM Amplifier
Continuous output power (2 channels driven): 220 W into 8, 400 W into 4 ohms
Continuous output power (all channels driven): 200 W into 8, 340 W into 4 ohms
Impulse power: 280 W into 8 ohms (all channels driven), 560 W into 4 ohms (one channel driven)
Balanced XLR inputs
Gold-plated RCA inputs
12 V trigger input
Auto power-on
Ground terminal
Separate power cord

Enormous Power Reserves

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

PowerDriveTM ensures large dynamic peaks

NAD's PowerDriveTM circuit ensures that an amplifier has sufficient power reserves even during extreme impulse peaks to reproduce music signals with their full dynamics. If necessary, the power supply briefly provides very high current reserves, so that almost double the output power can be mobilized for impulse peaks.

Continuous power output, two channels driven
220 W (at rated THD 20 Hz – 20 kHz, into 8 Ω)
400 W (at rated THD 20 Hz – 20 kHz, into 4 Ω)

Continuous power output, all channels driven
200 W (at rated THD 20 Hz – 20 kHz, into 8 Ω)
340 W (at rated THD 20 Hz – 20 kHz, into 4 Ω)

Peak power output
280 watts into 8 Ω (all channels driven)
560 watts into 4 Ω (one channel driven)

Total harmonic distortion (THD)
< 0.003 % (250 mW to 400 W, 20 Hz – 20 kHz)

Signal-to-noise ratio
650 W (one channel driven)

Signal-to-noise ratio, A-weighted
102 dB (A-weighted, 1 W output, XLR input)
97 dB (A-weighted, 1 W output, RCA input)
124 dB (A-weighted, rated output, XLR input)
120 dB (A-weighted, rated output, RCA input)

Damping factor
750 (into 8 Ω, 50 Hz and 1 kHz)

Input sensitivity
1.3 V (at rated output)

Input impedance
47 kΩ (XLR input)

Input impedance (R and C)
23 kΩ (RCA input)

Frequency response
±0.1 dB (20 Hz – 20 kHz), -3 dB (3 Hz – 60 kHz)

Time to standby without input signal
≤30 minutes

Standby power consumption
<0.5 W

Dimensions (W x H x D)
435 x 156 x 380 mm

Carton weight
21.2 kg

*Dimensions include feet, protruding controls and terminals

DALI GmbH
Berliner Ring 89, 64625 Bensheim, DE
support@nadelectronics.com
https://www.nadelectronics.com