darTZeel NHB-18NS preamplifier and NHB‑108 Model Two power amplifier

Solid-state power amplifiers,
Solid-state preamplifiers
DarTZeel NHB-18NS,
DarTZeel NHB‑108 Model Two
darTZeel NHB-18NS preamplifier and NHB‑108 Model Two power amplifier

Regardless of how much high-end audio you have heard, when you experience something exceptional, the music lets you know all about it. It might all start with a small spark of revelation. But it will grow, and I’ve read many people say that it is like hearing a piece of music for the first time. I get that entirely and have been lucky enough to experience that same feeling several times (but not many more) over a long period of listening and writing about audio equipment. When it happens, it typically leaves a hunger for more and more of whatever a particular system is dishing up. This awakening and re-alignment of musical perspectives are truly wonderfully addictive.

Hervé Delétraz is the man, and he designs and manufactures the small darTZeel range high in the Swiss Alps. He runs a CNC facility, making custom metalwork for specialised applications and companies who need components of the very highest quality and precision. Music is his passion and darTZeel is his expression of that love. Listening to his amplifiers, I think he hears music in the same way that I do. As a name in the audio world, the company has always seemed somewhat elusive to me. It’s one of those products that I have heard much about but have only managed to hear for a very brief listen over the years. So, you can imagine how quickly I jumped at the chance to review this darTZeel pre/power in its latest form; I didn’t need asking twice. Two months down the line and I am still genuinely staggered at how good it is.

Hervé’s expensive machinery comes in handy here. The construction of both the pre and power amplifiers is exacting and distinctive, right down to the red casing with gold front and rear panels.  Internally, things are just as impressive and beautiful. On the subject of the darTZeel aesthetic I have to say that some visitors found the pair somewhat ‘bling’, but I think that is because they are unusual and undoubtedly bold. I love the look, not least because it is backed up by such a memorable performance.

The front panel of the NHB-18NS preamplifier is simplicity itself. A pair of lightly-weighted knobs fitted with rubber O-rings control both the inputs and the volume level settings. The latter is referred to as a Pleasure Control while the input choice becomes the Enjoyment Source and on the darTZeel one does not select an input but rather ‘enables’ it. NS stands for ‘No Switch’, as the preamp doesn’t use switches or relays. There are over 1,200 electronic parts in the preamplifier, and the signal path has come in for exceptional attention. There are merely seven transistors from input to output to keep the signal pure. The optional phono stage – not supplied in the test unit – has just six transistors: this is purist circuit design par excellence.

The volume dial is a continually-rotating design, and though details of its operation are scant, it seems clear that it works through the cunning and contactless use of light. It exudes a quality feel, supported by the wonderfully uncomplicated remote. Finished in matching red, it feels hewn from a solid billet of aluminium and can turn the volume up and down or mute it, and that’s about it. It is however very slippery, and I couldn’t find any rubbery ‘blobs’ in the box to prevent the remote from disappearing down the edge of the sofa. I would add discrete micro feet to keep it in place.

Power up the pre and the word ‘Foreplay’ appears in the window on the top right of the fascia and when you switch it off, ‘Climaxed’ appears. Yes, it is a bit cheesy at first, but you don’t notice it after a couple of times, and it’s just a touch of light-heartedness from Hervé. Somehow it sits rather well with the colour and other design details of the amplifiers. It didn’t bother me in the slightest when listening to the darTZeel duo, and it adds much-needed character in an increasingly corporate audio landscape.

Most importantly, the NHB-18NS is battery-powered. The separate box through which that battery connects to the mains is a recharging unit that maintains power to the preamplifier and sets it into recharge mode when the batteries are running low. A fully charged NHB-18NS will run for eight hours before the cells need recharging and then it will run direct from the mains while this takes place. Twin modes are available. ‘Auto’ is battery mode, and this is how the unit should be powered when listening. ‘BTM’ is Battery Through Mode which kicks in when the charge gets too low and before full battery mode restores. Detailed monitoring of battery condition ensures that you will always get the best available sound quality, dependent on battery condition. When the pre is running from the mains, there is a slight drop in class, but the low impedance nature of the full battery condition is always preferable. The state of the battery is verifiable through the LEDs on the front panel. If this sounds in any way complicated, it isn’t. In use, you plug it in and go as everything is completely automatic and silent. The batteries themselves are Lithium Ion Phosphate and underwent a full three years of testing before Hervé was happy to include them in his preamplifier. I have used battery-powered preamplifiers before over the years, and my memory is that they were a bit of a pain for debatable gain. Not here though, as their implementation is superb, though they do need some running-in to achieve their full duration and lowest output impedance. In its manual, darTZeel suggests fifty to one hundred cycles.

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