DARTZEEL NHB-18NS PREAMPLIFIER REVIEW PART ONE

One of the personal favorites that this extremely busy year has to offer is darTZeel NHB-18NS. darTZeel is certainly one of the Swiss high-end audio companies that are surrounded by a mystical aura from their creator Hervé Delétraz. Delétraz's unconventional concepts and wit are reflected in all his creations, and NHB-18NS comes with a huge dose of humor and details such as (volume Pleasure Control control ), (on/off Power Nose switch ), (input selector Enjoyment Source), (input selector), climaxed power-off notification, etc. NHB stands for "Never Heard Before, and the NS means "No Switch".

darTZeel NHB-18NS closely follows the original concept of the NHB-108 model, which was introduced in New York in 2002. 

The feedback from those who heard it was enormous and caused quite a stir in the industry and among the audiophiles and music lovers. 

Although it took Delétraz more than 16 years to create this first instrument, he had a crystal clear vision from the beginning. The basic concept, condensed into a worldwide patent, was an amplifier without global negative feedback, no switch or contact in the signal path, and the implementation of only one pair of output transistors. All this was packed into the signal chassis amplifier!

Later, Delétraz's restless mind began to think about the fool bloodied darTZeel preamplifier that would best fit the philosophy of the NHB-108 model one.

At the very least, each preamplifier must be able to select its input source and control the output level with volume control.

Delétraz had the idea to implement the famous LDR (Light Dependent Resistors), the naturally sensitive light components that were well known in the 1960s. Those of you who follow the pro audio industry know some of the legendary dynamics compressors that still use LDRs for their inherent quality of smooth response.

So why was this not investigated earlier? In the ultimate, most puritanical way of handling amplification or source switching, this approach is not commercially feasible because these components are very non-linear and it takes an enormous amount of time and yet resources to get the same specified components from the large batch. 

In 2003, Delétraz finally succeeded in building a prototype of a preamplifier that uses homemade LDR/LED assemblies with near-perfect linearity over a dynamic range of 100 dB, with an accuracy of better than 0.2 dB over the entire range and a level difference between channels in the range of 0.15 dB at each level. 

This system, unique in its kind, was extremely difficult in mass production because several additional components had to be added and fine-tuned for each assembly.

It was then decided to use these assemblies in "lighted /switched off" mode and to create a kind of optical volume scale for each channel.

Here too, based on the experience gained from the patents applied for when the model NHB108 was marketed, the audio circuits were adopted and adapted to the functions required by the NHB-18NS, namely the processing of smaller signals.

Based on this successful venture, the official real darTZeel DNA preamplifier was introduced next year. 

The power supplies of this exceptional preamplifier are also all pure analog and linear and are powered by a battery set specially developed by darTZeel and manufactured by one of the leading manufacturers in this field, but more about this you can read later on. 

HIGHLIGHTS

To better understand how the latest darTZeel NHB-18NS differs from the previous version and what sets apart the all-new preamp from the past iterations, here are the highlights and break down of the new features. 

  • New battery technology. From lead acid gel to LiFePO4 (Lithium Iron Phosphate), we definitely solved all reliability problems related to battery performance.
  • New external power supply, in a much sexier housing, with increased current charge capacity, for speeding up charging time and keeping the housing cooler.
  • New phono stage, 8th generation: MC only for dramatically lower residual noise, close to the limit of physical thermionic junction noise. Increased gain of up to 72 dB. All parameters adjustable by an onboard microprocessor, allowing for no relays in the signal path and no more need for soldering (filling in) jumper pads. New 2 poles rumble filter, allowing for smooth barely audible, minimal phase shift transition, yet diminishing subsonic woofer cone displacement by a factor of three.
  • New XLR inputs and outputs; previous ones were transformer coupled. New ones are active, increasing bandwidth and eliminating phase shift problems inherent to transformers.
  • New Pleasure Control encoder with magnetic detents, for enhanced pleasure/feeling.
  • New display – previous version had no display at all – for an indication of volume control and many added feature settings, for unprecedented usage flexibility.
  • New IR receiver, for better remote control reception (no more need to literally beam onto preamp's front plate).

All previous NHB-18NS owners can upgrade their earlier version, to the new, latest existing one, as it is the case for all the NHB series.

AUTO/FORCE MODE

AUTO The mode is the main and preferred operating mode but can be switched between AUTO and FORCE mode at any time in the menu. The FORCE mode charges the battery until it is full, and then the preamplifier returns to the AUTO mode.

Normally the FORCE mode won't be needed.  AUTO mode does only what its name suggests: it runs on battery until it is completely discharged, then the charging process starts, and as soon as it is charged, the preamplifier goes back into battery discharge mode.

The word "FORCE" was deliberately used to indicate that charging was initiated, although this was not necessary. Do note, that daily use of this mode may ultimately affect battery life.

For example, if friends are expected for a listening session in the late afternoon, turn the preamplifier on in the morning and around, say, noon, switch it to Force. The unit will be ready with a full battery charge when they arrive.

For everyday listening, AUTO mode AUTOmatically handles everything.

As in the previous version of preamplifier the AUTO mode starts charging the battery after switching off with the Power Nose knob. 

When the preamplifier is switched off, the LED turns yellow, and at 85% of charge it turns green, and then when it is fully charged it goes off.

The preamplifier works all the time, even during the charging process. The central LED will be red and indicates the charging process. Then the battery acts as an "energy buffer" or as an "uninterruptible power supply through the line", as found in computers. But the darTZeel follows the highest possible path. It is not about waiting for the end of the charge. You can just listen to music and enjoy it whenever you want. 

When charging is active, the sound quality is a bit condensed, but not very much because the battery "damping/buffering" effect is quite effective. The dirtier the AC, the greater the improvement in battery operation!

In battery mode, an optocoupler receives a signal from the internal MCU and lifts all contacts coming from the power supply transformer. In this mode, the preamplifier works exactly as if the AC plug is disconnected. One of the many little things that make the darTZeel preamplifier so different and better sounding.

It is recommended to leave the external power supply always on. 24/7. only when the preamplifier is moved or switch off during a heavy thunderstorm, it is "wise" to switch it off completely. In such a case, first, switch off the power supply and then the preamplifier. The message "SLEEP" will appear and this will prevent the battery from being totally discharged. 

If you leave the external power supply always on after switching off the preamplifier (as recommended) and after charging the battery (central LED off), the battery charge level will remain for several months.

If you want to maximize playing time, the display brightness should be at the 40% level. This is also adjustable in the menu (balance button). Alternatively (in the menu) the fade time can be set to either 5, 10, or 15 seconds. This not only prolongs the playing time but also gives the sound performance a final touch. As in F1, the last few percent that could play a role in the ultimate high-end audio setup. 

If the charging process has started automatically and you want to return to the battery, the preamplifier must be switched off and on again. The advantage is that the battery can be charged for an additional few hours.

It is worth mentioning that the charging time is about half as long as the discharging time, when the preamp is off. When on, charging time is longer about equal to discharging time, say around 10 hours.

Thanks to LiFePO4 chemistry, batteries can perform about 3000 full charge cycles with 85% of the original charge capacity remaining. When FORCE charging is required (from 70 to 100%,) 30% of a cycle is performed. If FORCE charging is not activated, 70 to 80% of the cycle will be performed the next time. 

The official battery life is 8 hours with the backlight set to 60%. I have even experienced up to 11 hours in line mode with the illumination off. It can even be delayed up to 12 hours with all the optimum settings. When the phono stage is activated, the real world playing time is about 9 hours.

THE ART OF GAIN 

The NHB-18NS works with LEDs and LDRs arranged in pairs. By illuminating the LDRs with the LEDs a kind of "zero contact switch" is made possible, because the LDRs are really Light Dependent Resistor Actually, LDR is made of a kind of semiconductor. However, there is no semiconductor junction, as it is the case in a diode or a transistor. So the resistance is actually purely resistive, just like a passive potentiometer in which the wiper would be actioned by light.

The NHB-18NS has about 100 devices for volume control, but also for balance and input selection.

On paper, it is quite simple, but not so if you want to make sure they work properly. Sophisticated in-house software controls all this in the smoothest possible way.

This type of volume control, which was introduced in 2005, has never before been achieved elsewhere. As far as I know, the darTZeel preamplifier NHB-18NS is still the only preamplifier in the world that really has no contact in the signal path, i.e. from the inside out. And the difference is immediately audible.From the reviewer's point of view and in a general sense, the NHB-18NS is a gift of the Demigods when it comes to dealing with the individual and system gain. 

It's a chance that even the owners of the darTZeel NHB-18NS have not yet taken full advantage of the preamp's superbly adjustable internal/maximum output gain, which provides one of the most flexible and fluid, trouble-free and, most importantly, sound signature-free performances I have ever heard.

One of the less-discussed issues is the importance of properly matching the overall gain of the high-end audio system and matching the components involved, something that is much better handled in the pro audio industry with the standards in place. With high-end audio, even with the sources, we are dealing with the mind-boggling extremes. 

The NHB-18NS flexibility of the input and maximum output gain, which can be set via the menu with the balance control, offers greater adaptability than usual.

Due to the specifications, the NHB-18NS might be described as a not quite dead quiet preamplifier, as it was initially designed for the best possible sound reproduction, but in my experience so far it is far from being able to hear any noise in my reference system setup. And I take huge pride in having everything setup up at an extreme level.

The optical volume ramp system is limited by an S/N between 93-95 dB. Yeah, that sounds like an appalling affair for some bench testing... But, uh... the NHB-18NS noise level with the internal phono stage was the lowest I have ever experienced, and with the MSB Select DAC, the noise was practically non-existent. With my ears glued to the tweeter!

But to make things even more intricate, the internal reinforcements and darT to Zeel 50-ohm links connections have been optimized to work almost silently in conjunction with our NHB-108 or NHB-468. The NHB-108 is on its way to Mono and Stereo, and I will write about this special connection in the second part. The NHB-108 has - like all darTZeel power amplifier circuits - an internal gain of 26 dB. and when using the dtZ links it is even 6 dB less, so that the preamp output signal is amplified by 20 dB. Full DarTZeel connection is something I'm highly excited to evaluate!

The line gain of the NHB-18NS is well 11 dB in all sircumstances. However, it is when you pair it with a power amplifier which has 32 dB or higher gain, that you will hear some hiss. When used with the NHB-108, which has an internal gain of 26 dB, still reduced to 20 dB when connected via our dTZ links, the noise is barely audible, since 16 times less loud than with such a 32 dB gain's amp.Nevertheless, I tried the NHB-18NS with five different power amplifiers and no excessive noise was audible. So far it was actually completely noiseless operation!

In a full darTZeel configuration, the total dynamic range of each component is maximized. The accent is set at the inputs (in terms of gain) where it counts most. After that, only what is needed to move the speaker cones is amplified. 

In a darTZeel system, things usually work between -10 to 0 dB gain (if you keep it realistic) and maybe 10 or 15 dB less if you use the extremely high-efficiency speakers. 

Similar to the old vintage amplifiers, the NHB-18NS would tick at 12 o'clock when the music is played at 9 o'clock. 

NHB-18NS uses a larger portion of the usable dynamic range, thus following the logic that the fully used dynamic range of 90 dB is better utilized than 120 dB, of which only the first 60 dB is active. 

The darTZeel NHB-18NS volume control ramps are designed to provide consistent performance over the entire dynamic range! They also operate in a fully passive mode between two fixed gain stages within the preamplifier. 

The music can be fully experienced at any level and with any settings, and the sound quality does not change! A rare feature alone worthy of all of the highest praise!

But, if the sonic performance alters it is probably due to the perception, which will vary depending on the absolute SPL level, as is normally the case. Especially if the music is heard at very low levels, where the Fletcher/Mundsen curve is more important. Psychoacoustics in action...

In short, darTZeel NHB-18NS was designed from the ground up to ensure that you can listen in complete confidentiality and do not pay attention to the level of value and this is something that needs to be experienced to fully comprehend!

THE WARMUP

The usual, frequent question is always, what about the warm-up time?

With darTZeel NHB-18NS it is between 10 and 20 minutes, 30 minutes for the most demanding listeners and golden ears. This is simply due to the internal components, which must achieve their optimum temperature junctions.

This is also the reason why it is not necessary to run NHB-18NS 24/7.

THE REMOTE 

Operating the NHB-18NS via an elegant, red anodised remote control is extremely simple. There are only three buttons you can work with, and in addition to the left and right volume buttons there is also a mute button. 

By briefly pressing both volume controls, you can access the balance setting, where the levels are set in 0.5 dB.


THE PHONO

Hervé Delétraz is an analog lover at its core. That is why the NHB-18NS feels a bit like a stand-alone phono stage, with a line preamp built around it. Add to this the fact that it is fully battery-powered (in a purely analog, linear way). The hum is simply not the key imposter. 

A lot has been written about phono amplifiers with a current source or voltage source... Many contemporary current source phono preamps claim that they are the something mostly unique and much more "modern". Delétraz begs to differ. And with a reason...

The NHB-18NS uses a truly low impedance voltage source input so that the cartridge can express itself rather than being imprinted by the electronics signature of the phono stage.

Delétraz does not regard the source phono stages as inferior. All the contrary!

Delétraz does not regard the source phono stages as inferior. The CTH-8550 from 12 years ago already used a current source phono stage because it was easier to design it for a given (high) performance level. From Delétraz's point of view, the revival of current sources and the assertion of anything new is not quite up to beat... 

The earlier darTZeel phono had a maximum output power of 77dB (66dB + 11 dB in the line stage), but the current phono stage has 83dB when the input gain is set to maximum and the volume gain is set to the full value.

The latest, 8th version of the NHB-18NS' phono stage is practically about 20 dB quieter than surface noise. This is very close to the theoretical limit of thermal junction noise, and this type of hum is generally much lower than the surface noise of the LP! The level of the residual hiss of the phono stage is much lower compared to the surface LP noise, and this is an exceptional achievement on its own. 

That is a rather bold claim, but I think that the NHB-18NS is worthy of recognition for the phono stage even before talking about the line stage. The phono stage is one of the quietest, if not the quietest phono stages that I have the luxury to evaluate so far. But not only quiet. It's a dynamic monster, that rather calls for taming then wishful hankering for more gain. 

I 'm a low output MC fanatic by default and the impact that the NHB-18NS can achieve is not even funny. It's of a completely different league. I have no problem pointing this out by feeling intimidated. It is one of the luxuries of being an independent journalist. Not to report on this kind of achievement would be wrong.

I will break down all the qualities in the second part of the review, with the respective musical references, but so far it is beyond the scope of what I could get out of my beloved records and to what extent. The level of analog front end dynamism even pushed my power mono amps into the safe mode more than once. The NHB-18NS level of gain is lethal! But in a positive way, letting the dynamic range to fully blossom.

By any means, the NHB-18NS phono stage doesn't feel evolutionary at all. It rather feels revolutionary. 

But ... Analog is the heart and soul for Delétraz, and the dedicated phono stage reflects this in the best possible way. 

All gain and loading settings for the cartridge are easily accessible on the left and right rear panel modules. Adjustments are very easy once played around once or twice, and in addition to these two settings, there is also the option of setting up the subsonic filter, as well as the Neuman EQ which removes attenuation above 50 kHz, giving more air by not altering phase in the audible spectrum.

My current inventory of MC cartridges gives me quite flexibility and grander insights into reaching a certain level of objectivity. 

NHB-18NS phono stage performed splendidly with all of the cartridges, including Zyx Ultimate ASTRO X, X-quisite CA, Top Wing Blue Dragon and Red Sparrow, Gold Note Tuscany Gold cartridge, HANA SL and ML cartridges, Etsuro Urushi Bordeaux cartridge and even Murasakino Sumile Mono cartridge, thanks to the NHB-18NS capabilities and mono switch. It was not hard to find the sweet spot with loadings. The NHB-18NS let all of the cartridges to perform unreserved, easily shown the intricate differences between these micro machines! 

THE SUMMARY

Usually, the other outpost for high-end audio media may be limited in time and space, but I am urged to write at length about something that really excites me and shakes my innermost nucleus. At the end of the day, despite everything, all I care about is the music being conveyed in its best proximity. 

With this kind of ear-catching performance device, there are always lots of follow-up emails asking me to explain in detail certain technical points, the benefits of the music reproduction, and the special advantages it offers. So I do my homework right from the start.


It is often written how this and that product is made by a music lover for a music lover. Even I have used this vociferation a few times, but the darTZeel NHB-18NS takes this to a whole new level. The NHB-18NS is one of the most musically appealing, if not the most enchanting preamplifiers I have come across so far. 

The sound is a nether tube as in the solid-state. The NHB-18NS seamlessly combines the two so-called juxtapositions into a seamless harmonic whole that is not bound by the usual standards. It pursues the goal of achieving the end game in its very own, extreme way. 

To describe any high-end audio component as a higher-order instrument is often considered controversial. The NHB-18NS plays in a completely different league and has dream machine qualities. It plays music in a way that is both captivating and believable. 

It's by no means cheap, but for what is out there, it's actually quite affordable. In our niche industry where prices are reaching its peak by each upcoming year, the darTZeel NHB-18NS can be seen as quite an affordable option. 

The darTZeel NHB-18NS is a work of love and Delétraz's proudest creation, with a look that clearly points at its luxurious origin and captures the essence of Made in Switzerland. 

The gold-red Iron Man alike look of the NHB-18NS offers a highly distinguished way of expressing itself in a timeless way, rather than imposing esthetics. Like the best pieces of the Swiss Haute Horlogerie, the less is more, but not less speaks out with every inch of the preamp. 

Stay tuned for the second part, in which I will conclude my impressions and touch on the core qualities of the NHB-18NS using the music references. 

Even before I summarize the second part, this is clearly a winner of the rare and prestigious Mono and Stereo Editors Choice Award. 

While many of you will look at the final part of the review with great anticipation, I have to take a close look at my finances. I can hardly imagine letting go of this extremely versatile and musically highly appealing instrument from my premises and my reference listening system. It touches my urge for technical inclinations as well as my quest for a musically satisfying instrument with all of the upper league essences.

The DarTZeel NHB-18NS still contains many finer insights, which I was not able to include in this review despite the not exactly modest writing, as well as many other things Delétraz prefers to keep to himself.

Still...  The review should give you an unabridged insight into the unique world of darTZeel and mysterious realms of the NHB-18NS preamplifier.

Stay tuned. ⧉


Matej Isak

THE PRICE

  • NHB-18NS standard (1 MC, 4 BNC/RCA, 1 XLR) Retail price CHF 40'800.00 (without VAT and import taxes and duties worldwide)

TECHNICAL SPECIFICATONS

  • Line Gain: Up to + 11 dB
  • Phono Gain: 54 to 72 dB (up to 83 dB gain at output)
  • Analog Input Impedances: Zeel BNC 50 ohms from 1Hz to 1 MHz
  • RCA line: less than 30 kohms, from 5 Hz to 50 kHz
  • XLR Line:  less than 15 kohms, from 5 Hz to 50 kHz
  • Phono MC: User select from 43 ohms up to 47K ohms
  • Line Output impedances: RCA = 75 ohms, darT BNC = 50 ohms, XLR less than 600 ohms, REC OUT less than 150 ohms
  • Frequency Response: 5 Hz - 500 kHz, +0, -1 dB
  • Rise Time: less than 0.5 µs
  • Slew Rate: More than 24 V/µs, peak-peak
  • Total Harmonic Distortion: (THD )less than 1 % from 10 Hz to 100 kHz within the output dynamic range
  • Temporal Distortion: None, at any level and load, as specified above
  • Crosstalk: Less than - 80 dB from 20Hz to 20kHz
  • Signal to noise ratio: More than 92 dB (A), Line; more than 70dB (A), Phono w/factory settings
  • Power consumption: 7 - 77 watts depending on working conditions
  • Size in mm: 440 x 335 x 170 (WxDxH). Total deep with handles : 415mm
  • Size in inches: 17.32 x 13.2 x 6.7 (WxDxH). Total deep with handles : 16.4 inches
  • Net weight: 24 kg, power supply 3 kg, total 27 kg
  • Fuse ratings: 115 volts: 1.0A (T) or slow blow
  • 230 volts: 0.5A (T) or slow blow

CONTACT

darTZeel Audio SA

2 chemin Louis-Hubert

1213 Petit-Lancy / Geneva

Switzerland


Email: dartzeel.com/en/contact/

Web: dartzeel.com/