Improving a classic? When Dacre Stoker (Bram Stoker's great-grandnephew) and Ian Holt set out to cowrite Dracula the Un-Dead, they didn't want to improve upon a legendary classic. They meant to create the definitive sequel. A predatory glut of unauthorized movies and books in the early wake of a US court's denial to honour Bram Stoker's copyright had left Stoker's widow then the family estate in financial straits and emotional disgust. To right those wrongs, their book would work with the actual source: Bram's collected hand-written notes. They'd tie up loose ends, answer remaining questions, then advance the narrative honouring Stoker's legacy. If we apply the same method to the Classic Preamp, going back to the source means Nagra's PL-P, 1997's original very first consumer product "designed initially as a high-quality battery-powered vacuum tube preamplifier for vinyl records". Of its eight tubes, one 12AT7 and 12AX7 were assigned to the phono stage, two 12AT7 and four 12AX7 handled the line stage. A-weighted SN/R was 100dB, bandwidth 22Hz-60kHz +0/-1dB and output impedance 60Ω. By 2001, the simplified PL-L omitted the phono stage and battery supply, was down to today's 2 x 12AX7 and 1 x 12AT7 and already offered 4:1 RCA/XLR inputs. The Jazz superceded it in 2012 with 10Hz-50kHz (+0/-0.5dB) bandwidth, >112dB of dynamic range and output impedance of 50Ω based on the same tube complement. The Jazz also became the first consumer Nagra to abandon the pro-derived convention of locating its i/o on the left/right cheeks. Instead it relocated the lot to the rear where all hifi competitors have theirs. Honouring legacy whilst modernizing for continued relevance is very tricky business indeed.

From our mini survey, we learnt how Nagra's core tube linestage circuit bowed in 2001 with the PL-L; how through the Jazz and Classic successors, its complement of three dual triodes remained unchanged whilst specifications continued to push the envelope; how the headphone output skipped two models after the PL-P only to reappear in the Classic. We also noted the lengthy 11-year run of the PL-L as though example perhaps of arch-conservative possibly glacial Swiss management, plus getting it right the first time; and the comparatively short 4-year rein of the Jazz introduced in the same year that Nagra Audio reorganized under new ownership.

This warranted a few questions. Getting correct answers mandated going back to my source: Nagra's manager of global sales, Matthieu Latour, himself a descendant of not a famous Irish but French family; and not of authors but winemakers. After all, tying up loose ends with a sprawling narrative is tricky business, too.

Once Matthieu returned from the January CES show in Las Vegas where Nagra's two active exhibits had cleaned up amongst 'best of show' mentions in sundry blogs and publications, I asked certain obvious things. Published photos of the Classic show more far bigger capacitors (custom-made by SCR) than Jazz. That begged for comments. The headphone circuit wanted more details plus common power specs into 30/100/300/600Ω. With the main circuit's core specs pushed further, potential buyers might be curious how it was done. To honour Nagra's team spirit whereby no product ever is the result of just one individual, I asked for the names of those who'd handled the Classic's mechanical, software, layout and assorted other design aspects. From Jazz ownership, I knew that the 0/12dB gain toggle manipulates negative feedback. No-gain mode applies more. The presence of small-signal triodes and NFB thus isn't mutually exclusive as one might believe from assorted SET propaganda. Especially with tubes, feedback is essential to obtain low output impedance when not using output transformers.

In the emerging Classic lineup, there are no tubes except for this preamp. Meanwhile it's valves in the HD DAC, forthcoming HD preamp, 300i, 300P and VPA. The pyramid monos and later MSA were always based on solid state. So are the high-power HD Amps; and for obvious reason. With their expanding portfolio, Nagra of 2017 have more tube and transistor models. That the latter remain informed by their historical love of glowing bits shows in this quote from the Classic DAC descriptions: "...a 9-Fet design topology [to] emulate the sound of a tube providing a particularly warm and musical sound". With the Classic Preamp, even otherwise transistor systems benefit from an injection of pure tube virtues without introducing any arcane tube bias rituals or strategic load matching. These tubes will never drive a wildly variable speaker impedance with back EMF. All the Classic Preamp tubes see is the stable input impedance of whatever amp follows it. Even headphones aren't driven tube-direct but with a solid-state current buffer behind the valves. That combines tube tonality and staging with the low impedance, low noise and drive of transistors.

From Jim Saxon's CES 2017 coverage for "...recently, something has happened at Nagra. For the first time, their equipment revealed the tiny inflections, the filigrees and fractals—the texture—that gives reproduced sound a hint of reality. The difference between the dCS/Wilson/D'Agostino room and the Nagra/Wilson demonstration was the silence of the loudspeakers on Nagra electronics. It was as if the Alexx towers were on silent display and the music just arose at the front of the room. In two decades of covering the CES, I have never heard a system where the speakers weren't there. Though Nagra's technology is now available for a king's ransom, one hopes it will eventually trickle down." That trickle-down is the Classic range. And Mr. Saxon took keen note of the gains in Nagra's resolution and astonishingly low noise floors whilst using tubes in their D/A converter and preamp of the Las Vegas system.
To be continued...

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