Many of you wanted to know more insights about the darTZeel NHB-18NS. Here is a short story by Hervé Delétraz… “When the NHB-108 model one was first introduced in 2002 in New York, the concept of an amplifier without a global negative feedback, no switch or contact in the signal path, using a single pair of output transistors while offering 230 watts under 4 ohms, all condensed into a worldwide patent, the audiophile community was rather amazed, and the following years only reinforced this first impression. That being said, although it took 16 years to make this first instrument, things were quite clear in my head, although innovative as a commercial concept, no other brand has been able to bring all these ingredients together in one single chassis to date.”
And that is when the questions arose as to how I could make a preamplifier whose philosophy would be closest to that of his older brother, the NHB-108 model one.
At a minimum, any preamplifier must be able to select its input source and manage the output level using a volume control.
This involves a good number of contacts, switches, relays, or any other kind of link that implies that the signal path will be affected by some kind of electrical “break” every time it has to pass through a pair of contacts.
And in the event that contacts are replaced by semiconductor volume adjustment systems, the signal should pass through a matrix of semiconductor junctions, which is also not the best approach to “zero contact”.
So, I came up with the idea of using naturally sensitive light components, the famous Light Dependent Resistors (LDRs). This component was well known in the 1960s, and is still used in professional audio, especially in dynamic compressors, for their intrinsic quality of smooth response.
In pure high-end audio use, i.e. to switch input sources, or to manage the dynamic range of a volume control system, no one had done so, because of the non-linearity of this type of component, and the high disparity between each component of the same batch.
In 2003, I managed to build a prototype preamplifier that used home-made LDR/LED assemblies, with near-perfect linearity over a dynamic range of 100 dB, with accuracy better than 0.2 dB over the entire range, and a level difference between channels in the range of 0.15 dB, at any level. We introduced it during T.H.E. 2004 in Las Vegas, at St-Tropez hotel.
This system, unique in its kind, was extremely difficult to mass-produce, as several ancillary components had to be added and finely adjusted for each assembly.
It was then decided to use these assemblies in “lighted/off” mode, and to create a kind of optical volume scale for each channel.
The official and final version is a bit more complex than that, and the software part to manage the whole thing is even more sophisticated.
The result is there: a transparency of the musical signal unmatched, even by today standards. The sources are also selected by LDRs, which then allows to preserve the purity of the electrical signal from end to end.
Once this “philosophical necessity” of avoiding contacts in the signal path was resolved, I thought it was possible to go further.
Here too, based on the experience of patents filed during the commercialization of the NHB108 model one, the audio circuits have been taken over and adapted to the functions required by the NHB-18NS, namely the processing of smaller signals.
And from that point, we have gone even further in developing our famous phono stage, which we are proud to present the 8th generation in the current NHB-18NS.
Also, the power supplies of this exceptional preamplifier are all purely analog and linear, and entrusted to a pack of batteries specially developed by us and manufactured by one of the leaders in this field.
After more than 3 years of preliminary laboratory testing, the final choice was LiFePO4 chemistry, which offers the highest number of operating cycles, while having a very high level of safety, as these batteries cannot catch fire in the event of a short circuit.
Battery power provides outstanding operating quality, completely disconnected from the electrical grid. Indeed, when the battery mode – this is the default mode – is activated, an optical link (there too) controls relays on the transformer located in the external power supply unit, physically disconnecting any electrical link from the wall socket.
In order to maximize the use of the two instruments, the NHB-108 and the NHB-18NS, I imagined, as early as 1999, a transmission line system which is impedance matched. Nothing revolutionary in this concept because already used in telecommunications for decades, but nevertheless never applied to audio reproduction.
This method of matching the impedance from end to end, i.e. the source, the cable itself, and the receiver, allows the electrical signal to be transported without any temporal or frequency alteration, this for frequency ranges far exceeding the capabilities of the entire animal kingdom.
For those who doubt, I wrote an article on the subject in 1999, published in 2001, which describes well what is really going on in an electrical cable.
The NHB-18NS preamplifier still contains a few small details that would take too long to list here, plus other things we prefer to keep for ourselves…
What to remember is not what you have just read, but simply the unparalleled musical pleasure that we hope to share with you when you listen to music through our instruments.
Small final note, for those who do not know …
NHB means “Never Heard Before, and the NS means “No Switch”