Mis à jour le 26 February 2019.
This week we?re reviewing the NAD C388. NAD has been rethinking its approach to amplification in a big way. The Canadian brand is in the process of replacing its iconic Class AB amplification technology with hybrid Class D amplification. Baptized PowerDrive, NAD’s new generation of amplification technology was already integrated into its compact streaming amplifiers (NAD D3020 and NAD D7050) and BlueSound multiroom amplifiers. From this point forward, the entire Classic range (NAD C338, NAD C368 and NAD C388) is inheriting NAD’s new digital amplification modules. A complete 180.
NAD C388: presentation
The NAD C388 amplifier generates up to 2×150 Watts across the entire audio spectrum. This powerful hi-fi stereo amplifier has been designed to handle complex impedance loads and make any speaker sing, from compact models to floorstanders with multiple, large-diameter drivers. Equipped with digital inputs handling Hi-Res Audio (24 bits / 192 kHz) as well as a wireless Bluetooth apt-X receiver and analog stereo inputs?of which is an MM phono preamp?the NAD C388 boasts a modular design (MDC, Modular Design Conception). Several add-on cards will soon be made available, bringing with them features such as HDMI inputs and outputs and a BluOS network controller.
NAD C388: functions
The NAD C388 amplifier is equipped with tone controls for lows and highs as well as an RCA stereo pre-out output to which an additional power amp or active subwoofer may be connected. The pre-out output also functions in wideband mode (when connected to a power amp) and offers an active low-pass filter function with a cut-off frequency of 300 Hz. IR connectors (which receive signals from remote controls) and a trigger (for powering the amplifier on and off automatically and for sources equipped with trigger connections) are also available. An RS-232 connector allows the user to integrate the amplifier into a home automation system. Meanwhile, the amplifier?s USB type A connector enables updates to be made to the NAD C388?s microprogram, and two sets of speaker terminals, of which two pairs can be used simultaneously (for a combined impedance of 8 Ohms), are available.
NAD C388: Hypex UcD power amplifier modules
NAD’s PowerDrive technology makes use of the latest UcD (Universal Class D) amplifier modules from the Dutch manufacturer Hypex Electronics. Aside from their very high output capacity, these amplifier modules benefit from the rare advantage of being totally unaffected by speaker impedance (electrical resistance). This means that variations in impedance (across frequencies) will not affect the NAD C388?s performance. The most commendable result: the sound is totally free of coloration. This is a crucial point. Moreover, audio distortion is brought down to 0.009% at full power?ten times less than a traditional Class D amplifier. But the most important factor is the NAD C388?s approach to processing incoming audio signals.
NAD C388: the concept behind the power DAC
To thoroughly understand what makes the NAD C388 exceptional, it?s important to consider the standard working principles of an integrated amplifier. In a classic layout, the amplification stage applies a fixed amount of gain to signals (analog) transmitted by the preamp. The volume potentiometer, positioned at the end of the preamplification circuit, serves to lower (significantly) the analog signal received from the line inputs or internal DAC (if present). This damages the quality of the signal. In the NAD C388?s circuits, the incoming signal’which is essentially digital’ is simply not lowered. Let?s recap: a digital audio signal is sent to the NAD C388, and instead of being converted by a traditional DAC, power modulation is carried out directly and the signal is converted into audible sounds at the very end of the circuit by a low-pass filter (simultaneously eliminating the very high frequencies which are full of digital noise). These are the operations which make the NAD C388 a power DAC, in essence. Analog signals generated by analog sources (turntable, CD player) are, for their part, digitized.
NAD C388: design
Radical changes have been made in this area as well, as the assortment of buttons which usually adorn the brand’s amplifiers has disappeared. All that remains is an input selector and arrows allowing the user to navigate through the menus of the NAD C388?s LCD display (this, too, is a new feature for a NAD integrated hi-fi amplifier), in addition to a volume potentiometer.
NAD C388: test conditions and listening impressions
We tested the standard version of the NAD C388 (without the optional cards). We listened to several pairs of speakers, including the Focal Aria 906 and Klipsch Heresy III. For cables, we used the NorStone Skye MC and Viard Audio Silver HD12. Our test called upon the amplifier?s digital S/PDIF inputs (with a Raspberry Pi2/Volumio serving as a source, and USB transfer to the S/PDIF entrusted to an Encore mDSD). We used a Sony NW-ZX100 portable audio player (apt-X compatible) to test the amplifier?s Bluetooth function.
Setting up the NAD C388 was absolutely straightforward. Relatively compact (12 cm high), the amplifier is easy to handle, even if it weighs in at 12 kg. We won’t keep you in suspense: the NAD C388 amplifier is truly a phenomenon. NAD is not exaggerating when it claims that improvements made to Class D amplifiers have allowed this technology to surpass Class AB technology in terms of performance (the latter being warm, but also a huge energy consumer and not free of distortion).
From the first notes, the C388?s character makes a striking impression: completely serene and balanced sound which shines in the lows with just enough articulation to avoid becoming intrusive, and without the least bit of projection in the mids and highs, even with the volume turned up very high.
With the Klipsch Heresy III?speakers not known for warming up to brawny class D amplifiers?the NAD C388 doles out generous helpings of softness, even when processing over-compressed electronic music. The listening experience is relaxing, with men’s and women’s voices always finding their rightful place. A judicious distribution of mids and highs contributes to a highly complimentary layering of the sound stage. The result is reassuring and we didn’t hesitate to play tracks which had previously left us unimpressed. Better yet, we could easily crank up the volume. The NAD C388 is a stalwart of soft power: as volume levels increase, the amplifier?s sensitivity is boosted and the sound stage is widened.
Lows: full and deep, with rarely-seen tightness; well-articulated regardless of the speaker used (12? drivers included)
Mids: balanced with flavorful timbres
Highs: neither too bright nor too dry, with incredible precision for hours of fatigue-free listening
NAD C388: conclusions
If you?ve been looking for a powerful amplifier capable of driving speakers which sometimes seem unbalanced, aggressive or sluggish, the NAD C388 is perhaps the miracle you?ve been waiting for. This amplifier benefits from all the qualities of the most powerful models: impeccable timing, smooth and well-articulated lows, judiciously distributed mids for a deep and realistic sound stage, and highs which are perfectly integrated into the other two registers. In our opinion, this model is a perfect candidate for driving the most demanding Focal speakers, as well as for flattering the compression chambers of tweeters and other titanium dome models which may sometimes seem a bit turbulent. We would be remiss not to mention that the NAD C388 comes in a more modestly priced version, the NAD C368 (2 x 80 W). The NAD C338 (2 x 50 W), with its Google Cast and Spotify Connect streaming functions, also offers some serious advantages. Bravo all around.