It's been made clear to me more than once just how privileged I am to receive the actual production version of the long-awaited darTZeel NHB-18NS pre-amplifier for review before anyone else. However obscure Switzerland's darTZeel may seem, it's now a global player in the extreme high end. And the pressure for the scoop review of their first pre-amp ramped up by a factor of 10 immediately after their NHB-108 power amplifier won a brace of awards from our friends across the Pond at Stereophile.
• Read more audiophile stereo preamp reviews from brands like Audio Research, Classé, Mark Levinson, Krell, Linn, Naim and dozens others.
• Follow AudiophileReview.com for blog posts and opinion on the world of audiophile preamps including passive preamps, solid state preamps, tube preamps and more.
• Read Audiophile Power amp reviews here.
According to the distributor, there was a queue of reviewers dying to get their hands on it, they had to fend them off with fears of the sorts of repercussions that follow bruised egos, why Kessler?, yadayadayada. So I suppose my offer to sleep with Serge and Her- no, that's a lie: I earned the privilege because I bothered to fly to Geneva, hang out with the pair, learn about the product and prove my worthiness. The latter might even be due to sharing a common taste in music with Hervé Delétraz.
Must've worked, because I've just spent a couple of weeks with the little beauty. No kidding: I do feel privileged. Yup, it's that good. And it' so fresh that it doesn't even have a blank name plaque in the upper right-hand corner; that awaits the engraving of the name of the eventual owner.
And having heard the power amp on numerous occasions, I can confirm that - unlike other situations where one part of a pre/power package preceded another, and Part 2 was a let-down - the darTZeel boys followed their debut with a perfect sequel. Think Godfather 2, The Two Towers or Attack of the Clones. Well, maybe not the Attack of the Clones. But you get the drift.
As with the power amplifier, darTZeel opted for direct paths and 'heightened minimalism' if such a phrase isn't borderline oxymoronic. As Hervé put it, 'Our dedicated circuits are reduced to their most basic form. As before, there is no application of any overall negative feedback. Because of this approach, the delicate, small audio signals amplified by the NHB-18NS only pass through seven silicon junctions, from input to output. And that includes the 13dB full discrete gain stage. And for the phono stage, we only add six junctions, for a maximum additional boost of 66dB, or 77dB in total.' Their minimalist circuits are currently 'patent pending.'
Despite the company's designers suffering an affection for the hideously coloured Rehdéko loudspeakers, they insist that the darTZeel goal is for untrammelled, pure and open sound. Amplifying the low level signals are discrete devices, or matched transistors embedded in dedicated integrated circuits. Hervé again: 'No operational amplifiers are used in the entire signal path. As in the NHB-108, all components used in the NHB-18NS preamplifier, with no exceptions whatsoever, are based on the finest products being produced by leading-edge industries at the present moment.'
This is where you start to get whiffs of the Swissness, which requires a brief aside about the 'Made in Switzerland' philosophy. First devised, adopted and safely guarded by the watch industry, that coveted identification of birthright is as closely protected as French wine's or cheese's 'apellation contrôlée', or olive oil's IOOC. darTZeel uses as many Swiss suppliers as possible, partly because the company jingoistically (but rightly) believes that the Swiss are the best at manufacturing anything made from metals, including electronic components, and partly so that darTZeel could become the only audio company to earn the coveted Swiss Label Certificat, attesting to its Helvetian purity.
Those of you who don't share, say, my obsession with Alpa cameras, watches and Nagra tape decks might wonder about the fuss, but - away from ultra-nationalistic Germans and Brits who refuse to believe that anyone could make things as well as they could - any form of proof that your wares are as Swiss as William Tell is akin to the Good Housekeeping Seal of Approval and an Appointment by the Queen all rolled into one.
So darTZeel has taken the best ingredients, and formulated a topology that includes the following strictures:
There are absolutely no contact or switches nor relay of any kind for source selection, all in the interests of absolute transparency. darTZeel prefers, instead of routing signals through a selector box, to provide each input with its own dedicated gain stage, enabled or disabled according to the user's choice. The signal is then directly routed to the volume control module.
In the NHB-18NS, the volume control module completely avoids the use of any potentiometer, stepped attenuator or analogue switch array in the signal path. According to Hervé, 'The sound signal is attenuated in a fully passive way, within a continuous range of close to 96dB in 192 steps of 0.5dB, in full analogue mode, without the use of any VCA or other active component.
'Both of these breakthroughs constitute a big step in the right direction: no harm to the signal. As mentioned above, this new design is patent pending. As soon as the patents are confirmed, darTZeel will be pleased to describe in detail how such signal treatment is possible.'
More Swissness: they adore secrecy. Just ask anyone who banks with them.
Further in keeping with the NHB-108 power amplifier, the NHB-18NS uses only small amounts of local negative feedback at the inputs, with one small, symmetrical loop of local negative feedback in the voltage gain stages. The output stages are open loop, and free of all negative feedback.
Within the 440x170x335mm (WHD) chassis is a modular frame, with every stage on a subassembly more like a computer or multi-channel A/V amp than a stereo preamp. Because of this, the unit might one day be customisable to a degree; at present, though, its modularity shows that the unit was designed from the outset to resist obsolescence.
Unusually, the company employs its own preferred, proprietary 50-ohm 'darT' outputs and 'Zeel' inputs with BNC connectors, alongside more conventional connections. As shipped and reviewed, the unit features a mix of six inputs covering phono, RCA/BNC and balanced XLR. As standard, these include a phono MM/MC input with gain from 30-66dB, a single 'full-floating' XLR input and four RCA/BNC 50 ohm Zeel inputs. Outputs consist of one XLR full floating output, three BNC 50 ohm darT outputs, ready for tri-amping, with optional built-in passive filters, a pair of RCA outputs and a pair of fixed RCA record outputs.
Read more about the darTZeel NHB-18NS on Page 2.
Completing the package, and for many the most important part, is a feature shared by darTZeel's compatriots at Nagra: a battery power supply. Because the NHB-18NS is an 'authentic dual mono preamplifier, from input to output, with separate grounds for left and right channels,' each channel is battery-powered by its own battery bank, offering up to 15 hours of playing time on a full charge. Every input and output is treated to a 'very sophisticated, regulated and dedicated supply, ensuring the lowest power supply impedance possible.' And it's basically set-and-forget: automatic functioning allows full battery operation when listening, with the charging mode activated when the preamp is switched off. As Hervé puts it, 'Hum is gone forever, and there is no need to worry about knowing if batteries need to be charged or not.'