Preamp / Amp NAGRA CLASSIC PRE & AMP

Coincidentally, as we write these lines, Nagra is presenting its brand new converter, the Classic DAC II, at the Munich High-End. The Romanel-sur-Lausanne manufacturer indicates that it has been equipped with the NADM digital engine (Nagra Audio Digital Module) common to the DAC X HD and Tube DAC, in order to offer a more accessible, nevertheless efficient version. The Classic DAC II supports all current high-resolution formats such as DSD256 (4x) and DXD.

With this converter with class A output stages, Nagra aims wider than its natural clientele by specifying that the Classic DAC II is suitable for all those who have a large CD library, the designers having taken care of compliance with the Red Book defined by Sony and Philips in 1980. To them, Nagra promises that the Classic DAC II will reveal “the striking potential of this always dynamic format”.

Classic generation 2015

But, for now, let’s review our Classic with the Amp and Preamp ensemble whose technical biases give a fairly clear indication of the musical direction pursued, somewhere between efficiency and the search for truth.

Honor to the Classic Amp launched on the market in 2015. This amp is part of Nagra’s line of power stages which starts with the MPA (1998), and continues with the PMA (2005) and MSA (2009). Compared to the latter, the power increases significantly, going from 2×60 W to 2×100 W at 8 Ω, the first watts in class A, from a single pair of power MOSFET transistors. This simplicity of design plays a large part in the musicality and respect for the integrity of the signal. As a prerequisite, a drastic sorting of these military grade transistors, measured and sorted by hand prior to assembly. Another salient point, the power supply, essential to follow the differences in dynamics in musical mode and compensate for the sudden variations in impedance of most speakers in the bass. A 400 VA toroidal transformer powers rectifiers and six chemical capacitors totaling 141,000 μF per channel (!). In parallel, a power factor corrector (PFC) circuit ensures that the current is always in phase with the voltage, without interference peaks or distortion.

The input stages are accessible in symmetrical or asymmetrical mode with a choice of sensitivity (1V or 2V) and the possibility of bridger the two channels to obtain a mono block of 200 W at 8 Ω. Like all Nagra, the Classic Amp carries a two-needle modulometer and a start key with position Mute and automatic input signal detection.

A layout found on the front of the Classic Preamp presented the following year, accompanied by a motorized volume (ALPS potentiometer) and an encoder wheel providing access to menus whose parameters are displayed on a screen LCD.

The Classic Preamp is also part of a lineage going from PL-P (1997) to PL-L (2001) then to Nagra Jazz (2012); in common, a tube architecture that one would hardly guess, as the Classic Preamp, the latest to date, turns out to be silent and straight. Operating silence is a point on which the designers of the Classic Preamp have focused their attention, aware of the importance of this parameter from both a subjective and objective point of view. As a result, the Signal/Noise ratio changes from 105 dB for the Nagra Jazz to 125 dB for the Classic Preamp!

The Classic Preamp gain can be chosen either unity or 12 dB (4x). Although the general layout of the preamp is the same since the PL-P (double 12AX7/ECC83 triode in class A anode follower assembly at input, half 12AT7/ECC81 triode in class A cathode follower assembly at output), each generation pushes more performance, by the choice of components, their location and their current source. Equipped with an internal power supply with external option (Nagra MPS), the Classic Preamp only contains polypropylene capacities, both in connection and for filtering the power supplies. Chemicals banned.

Equipped with XLR but also RCA inputs and outputs, it can optionally accommodate balun transformers custom made and has a headphone amp on 6.35 mm jack borrowed from the Nagra HD DAC. In this generation, the connectors are classically found at the back. And like the Classic Amp, its anodized aluminum chassis isolates it from electromagnetic noise while the 14 mm front panel marks the finish.

Highly recommended, the VFS L insulating bases, made up of aluminum plates separated by Alpha-gel balls, act positively by absorbing vibrations, particularly those coming from speakers transmitted by air.

Main observation when listening to our Focal Spectral 40th: a feeling of calm, linearity and aeration brought to its incandescence. If the source delivers a significant level like, for example, the Soulnote S-3 DAC/player with X-3 clock in this file, we will prioritize the Classic Preamp with unity gain to further gain in openness and subtlety.

The mix of triode tubes as preamp and simple push-pull MOSFET as amp comes close to a theoretical ideal in terms of sound reproduction. Unhindered signal pathing, advanced linearity, minimal distortion, noise reduction, spectral richness and respected phase: what more could you ask for?

Illustration with the Ensemble vocal de Lausanne directed by Michel Corboz in the In Paradise of Requiem by Fauré (Mirare): this one settles in majesty in our auditorium, making each desk breathe and exist the metaphysical tension which governs this work of singular intensity. Same emotion with the Blattwerk Quintett in a transcription of My Mother Goose by Ravel (Schweizer Fonogramm): the timbres of the wind instruments are reproduced with rare sensitivity. Classic Swiss delight !

PPI : Classic Preamp : 17 250 €.

Classic Amp : 15 950 €.

Bases VFS L : 2150 €.

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