The NAD C298 embodies the culmination of nearly fifty years of amplification expertise, integrating Purifi Eigentakt technology into a discreet chassis that favors substance over appearance. This power amplifier marks a technological turning point for the British brand, delivering performance that defies established conventions in this price range.
Uncompromising Technical Design
The C298 breaks away from traditional amplifier architectures. At its core are Eigentakt modules, developed by the Danish company Purifi under the direction of Bruno Putzeys and Lars Risbo, two leading figures in modern digital amplification. This self-clocking technology (Eigentakt literally means “self-clock” in German) represents the most significant evolution of class D since the introduction of Hypex NCore modules.
The C298’s architecture is based on a NAD-designed switching power supply, specifically optimized for these modules. This generously dimensioned power supply delivers 185 continuous watts per channel into 8 ohms, with impressive dynamic reserves reaching 570 watts during musical transients. The damping factor above 800 demonstrates exemplary control over speaker cones, ensuring precise reproduction even with complex loads.
The internal layout reveals meticulous attention to detail. The input stages, developed specifically by NAD, incorporate ultra-low-noise buffer amplifiers that preserve signal integrity regardless of source impedance. This approach differs from generic implementations and allows the C298 to accommodate a wide variety of preamplifiers without sonic degradation.
Versatility and Flexibility of Use
The rear panel of the C298 features connectivity designed to adapt to any usage scenario. Balanced XLR inputs sit alongside traditional unbalanced RCA inputs, each selectable via a dedicated switch. This dual connectivity allows integration into both professional and home systems, with a 56 kΩ input impedance that ensures a negligible load for any preamplifier.
The variable gain control is a particularly appreciated feature. Adjustable from 8.5 dB to 28.5 dB in stereo mode, it allows precise matching of input level to other components in the chain. This function is essential when combining multiple amplifiers or in active multi-amp systems. RCA line outputs allow daisy-chaining to other amplifiers or adding subwoofers, turning the C298 into a true nerve center for complex systems.
The auto-sensing function deserves special mention. Its adjustable threshold enables automatic power-on upon receiving a signal, allowing the amplifier to be installed in a closed cabinet or at a distance from sources. The 12V trigger inputs and outputs further enhance automation possibilities, integrating seamlessly into modern home automation setups.
Bridge Mode: Monumental Power
The bridging capability radically transforms the C298. A simple switch on the rear converts the stereo amplifier into a monoblock delivering 620 continuous watts into 8 ohms, with dynamic peaks reaching 1000 watts. However, this configuration requires certain precautions: NAD uses a specific topology where the signal is taken between the left positive terminal and the right negative terminal, an unusual but necessary setup to optimize the power supply load.
This particular architecture prohibits certain connections, notably subwoofers with a common ground or switching systems sharing a ground reference. The lightning symbols visible on the terminals serve as a reminder of this technical peculiarity. In return, this configuration offers channel separation greater than 100 dB at 1 kHz and maintains linear response even with complex loads.
Using two C298s in monoblock configuration is the ultimate expression of this architecture. Each amplifier then has its entire current reserve for a single channel, eliminating any interaction between channels. This setup is particularly suitable for demanding speakers or high-level listening, where absolute control of transients becomes critical.
Industrial Design and Construction
The C298’s aesthetics reflect NAD’s philosophy: functionality before ornamentation. The stamped steel chassis may seem spartan compared to high-end designs, but this simplicity conceals rigorous construction. Weighing 11.2 kg, the amplifier remains substantial for a class D device, a testament to the generously sized power supply and integrated heatsink.
The front panel is limited to the essentials: a power button and two status LEDs. This deliberate simplicity eliminates any visual distraction, focusing attention on the device’s primary function. The startup process follows a precise sequence: after activating the main switch on the rear, pressing the front button triggers a relay after a few seconds, with the LED changing from orange to blue to indicate the amplifier is ready.
The dimensions of 435 × 120 × 390 mm adhere to the standard hi-fi format, making integration into any audio furniture easy. The ventilation slots, strategically positioned above a single heatsink, optimize natural convection. Despite the efficiency of class D, NAD has provided substantial heat dissipation, ensuring long-term reliability even under intensive use.
Measurable Performance and Subjective Qualities
The C298’s technical specifications are impressive in their consistency. The frequency response maintains linearity of ±0.2 dB from 20 Hz to 20 kHz, with extension to -3 dB at 60 kHz. This bandwidth, unusual for an amplifier in this range, ensures linear phase throughout the audible spectrum. The signal-to-noise ratio exceeds 120 dB A-weighted, placing the noise floor well below the threshold of perception even in the most resolving systems.
Total harmonic distortion, below 0.005% from 1 to 185 watts, remains constant regardless of load impedance. This stability sets Eigentakt modules apart from previous generations of class D, whose performance varied significantly depending on the load. The peak output current above 25 amperes into 1 ohm demonstrates current capabilities comparable to the most robust traditional amplifiers.
Dynamics are the immediate highlight: transients are reproduced with remarkable speed and lack of compression. The low frequencies particularly benefit from this architecture, with articulation and definition rivaling the best class AB designs. The midrange retains exemplary neutrality, with no apparent coloration, while the treble offers a natural extension free from the harshness sometimes associated with class D.
Frequently Asked Questions
Can the C298 drive difficult speakers such as electrostatic panels?
With its damping factor above 800 and its ability to deliver over 25 amperes peak, the C298 is perfectly suited to complex loads. Its power nearly doubles into 4 ohms (340 watts) and it remains stable even into 2 ohms (570 watts dynamic), essential characteristics for electrostatic or planar magnetic speakers.
What is the difference between Eigentakt modules and other class D technologies?
Eigentakt modules use a sophisticated feedback loop that compensates for nonlinearities in real time. This self-adaptive approach virtually eliminates intermodulation distortion, the main flaw of early class D generations. The result is transparency comparable to the best analog electronics.
Is the variable gain transparent or does it degrade the signal?
The variable gain circuit uses precision components that maintain signal integrity. In fixed position (28.6 dB), the circuit is bypassed, offering the most direct path. The variable mode is essential for balancing multiple amplifiers or adapting the level to modern sources, which often have very high output voltage.
Is the C298 suitable for active bi-amplification?
NAD engineers advise against bi-amping with class D amplifiers in general. These topologies deliver most of their power in the bass, leaving little reserve for the mid-high range in a bi-amped setup. Bridge mode on a single C298 or using two C298s as monoblocks are better alternatives.
How does the C298 compare to NAD’s Masters models?
The C298 shares the same Eigentakt modules as the M33 and M28 from the Masters series, but differs in its power supply and input circuits, which are optimized differently. The Masters series offers more luxurious construction and additional features, but the fundamental amplification performance remains comparable, demonstrating NAD’s commitment to democratizing high-fidelity audio.
