darTZeel NHB-108 model one Audiophile's technical manual
darTZeel NHB-108 model one Audiophile's technical manual Page 2 of 28
TABLE OF CONTENTS 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. Introduction ................................................................................................................................................... 5 Genesis of NHB-108 ..................................................................................................................................... 5 Criteria..........................................................................................................................
darTZeel NHB-108 model one Audiophile's technical manual Page 4 of 28
darTZeel NHB-108 model one Audiophile's technical manual 1. Introduction Thank you for studying this manual, demonstrating proof of your interest in the darTZeel NHB-108 model one. First of all, please do not think for a minute that we consider audiophiles differently from music lovers. We know perfectly well that audiophiles love music too, and we are very happy with this.
later, new ICs allowed further investigation, and we built several prototypes. We quickly noted, however, that digital had some limits when pushed hard. We used a sample frequency of 500 kHz at the time, corresponding to a theoretical bandwidth close to 250 kHz, far higher than all competitors, even in the analog domain. But – alas – even with such a high sample frequency, the actual measured bandwidth was strongly dependant on the loudspeaker impedance.
4. Structural aspects It would be all too easy to compare the darTZeel NHB-108 model one and wristwatches, both being made in Switzerland. There are no springs, cogwheels, or hands in a NHB-108 model one. Here, everything is a tad… bigger. 4.1. The case modules The case of your machine is exclusively machined from AW-5754-ALMG3 alloy aluminum, offering a remarkably even surface and hardness.
frequencies, most important in terms of sound reproduction accuracy. And while on this subject, have you ever heard an amplifier singing? This can occur when the transistors of the final stages and/or the power transformers are not properly decoupled. They start to vibrate at the excitation signal frequency – in this case the music – this vibration interfering with the electrical origin of the signal.
5. The audio electronics Simplicity. The whole darTZeel NHB-108 model one electronic concept could come down to this single word. Simplicity does not mean simple, however. Purity Total cancellation or absence of harmonic distortion does not mean "purity", alas. You certainly know that most musical instruments are very rich, harmonically speaking. Thanks to these harmonics, we can distinguish between a saxophone and a flute.
Some amplifiers available on the market claim extremely low THD figures, at the very limit of instrumentation measurement, assuming this result necessarily leads to outstanding sound purity. We take this with some caution, since it recalls for us the 70-80' Japanese philosophy, by which "performance" implies "quality". We have to be fair by acknowledging that such designs can be liked and even loved by audiophiles. The world is big enough for multi musical tastes.
(3 to 5% for THD) is considered as not disturbing, even not audible in a musical context, judging by the Single Ended Triode aficionados or by all the psycho acoustical experiments conducted over the past few decades. By way of conclusion, it appears that IMD, while perhaps more disturbing than THD, remains practically harmless, provided the levels are not outrageously high. Okay. Now bring on the next suspect… 5.1.3.
If the THD and IMD produced by the amplifier are kept low enough, say lower than the audibility threshold, then no further correction will be needed, and the audio circuit can remain simple. At the start of this new century, 3 main technologies coexist in the construction of transistors, these being in chronological order: - Bipolar, in the early 1950s. Field effect, in 1962. IGBT, a mix of the previous two, in the ‘eighties. At darTZeel, we strongly believe in new technologies.
circuitry to make the best of their possibilities, and that means a longer and more complex signal path, and hence a reduced resolution. MOSFETs are also slower, in absolute terms, than bipolars, and are much harder to drive in pulse mode. Reproducing very fast transients requires a lot of instantaneous current drive, not easy for the power supply to properly feed, so temporal integrity could suffer. 5.2.3. Bipolars These have been in existence for more than fifty years. The industry knows them very well.
For once, we give the description in French, which is, after all, the very original text. A translation can be provided on special request. If you have any specific questions about this circuit, please do not hesitate to contact us at info@dartzeel.com 5.3.3. Component layout This schematic is multi patent protected In analog, especially in audio, the layout of components is of paramount importance in the signature they can print onto the musical signal.
5.4. Symmetrically balanced? The following could seem contradictory sometimes. It is mainly due to the terms "balanced" and "symmetrical", or "unbalanced" and "single ended". In French, these terms lead to even more confusion, since both "balanced" and "symmetrical" are translated by "symétrique". So, you will not feel less comfortable than our French-speaking friends. Feel free to contact us at info@dartzeel.com if you need explanations in greater depth.
What about radio waves? What medium do they use, in the vacuum of intersidereal space? Well, write us, and we will send you the Physicist manual, as soon as we have got round to writing it… As for acoustical waves, it is a much easier phenomenon to describe, and especially understand, since it is part of our daily life. The medium can be water in the case of mermaids singing… er, sorry, when whales sing.
ended topology, and requires a higher output stage NFB to compensate. Now that you have read these simple but demonstrative explanations, do the words "full balanced" still mean "absolute superior sound" for you? All this explains our choice for using, as a matter of course, transformers of the highest quality for our XLR inputs in the version B. We said above that by very nature, music is part of a single-end world.
sion technologies use impedancematched links. So why not audio? The great advantage of impedance matched-links is their virtual absence of losses, whatever their length. For those of you who want to know everything about matching impedance in audio links, do not hesitate to contact us at info@dartzeel.com Propagation time delay is preserved in DC up to several GHz in such lines, and no other link from any make can claim this, unless perfect impedance matching is achieved. our esteemed competitors disagree.
Generally the best solution is to insert a fuse – rather a big one of its kind – between the supplies and the loads. In case of emergency, you only need to short circuit the power at the load terminals. But this is easier said than done: the sudden, huge current peak generated, well supported by the power inverter, immediately melts the fuse, shutting the load down. If the fuse is located at the input of the inverter, the entire supply system will be stopped.
6.2. Without adding any disturbance in the signal path? Yes, indeed. Supervision system 6.2.1. Current sensing Most available amplifiers, if not all, use an output current limitation circuit, protecting the output stages against any possible overload. This current limitation generally takes the form of one or more transistors that will shunt the incoming signal to ground when the current has reached a defined value. The current sensing is taken through one of the emitter resistors of the output stage.
7. Power supplies 7.1. From mains to loudspeakers More and more, audio manufacturers are insisting on the quality of the power supplies. They are quite right! After all, the electric energy fed to your loudspeakers comes from the power supply and nowhere else. The audio circuit itself is really just a sort of regulator for this energy. The better the quality of the source energy, the easier the task of modulating it into sound waves. This modulation is truly the audio signal you listen to.
- pedance, and hence the need for a greater NFB at output stage. This also induces TD. Much greater physical volume and area, limiting the high frequency response because of higher RFI sensitivity. And this list is unfortunately not exhaustive. Without special precautions, the use of speakers with nominal impedance of 4Ω or less on a single output paired stage can cause excessive dissipated heat, outside the safe working range of the output devices.
8. The sound of darTZeel It is always hard to define objectively what we perceive subjectively, isn't it? How to enjoy an excellent glass of wine, if not sharing it with friends? We could say that the darTZeel NHB-108 model one offers an outstanding temporal linearity, allowing true three-dimensional re-creation. We also could say that the bass is deeper than the Mariana Trench, with every nuance incredibly rendered.
Furthermore, in normal use, say if you sometime power OFF your machine, life span can be easily doubled, or even quadrupled. As soon as we realize that working temperature is the most long lasting factor, it becomes easier to choose components for their sonic attributes first. Another factor, even less known but very interesting, is that of sustaining bias powering. A given component, being active or passive, lasts longer if some voltage, however low it is, remains applied to its terminals.
In order to keep our word and offer full maintenance of your darTZeel NHB-108 model one, we have stocked the following items: - - - - - - - 1 fully assembled darTZeel NHB-108 model one, fully tested and in working condition, powered OFF but maintained "energized". 1 darTZeel NHB-108 model one in the form of pre-assembled and tested modules. Spare parts representing 2% - but a minimum of 5 complete sets – of all mechanical and CNC machined components.
11. Keeping an open door Well, now we have reached the end of the Audiophile's technical manual. Is it too technical? Not audiophile enough? Please do not hesitate to tell us. We will be pleased to read your complaints, and we will take them into account for future manuals. Any suggestion or criticism concerning the darTZeel NHB-108 model one, a particular manual, or any other point, can be emailed to: info@dartzeel.
12. Special adjustments 12.1. Output DC voltage drift Caution! The procedure described below can present some risk, since the darTZeel NHB-108 model one must remain powered ON. WE DECLINE ANY RESPONSIBILITY IN THE EVENT OF ELECTRIC SHOCK DUE TO INCORRECT MANIPULATION. WARNING! ONLY A QUALIFIED PERSON OR A TECHNICIAN CAN SAFELY PERFORM THIS ADJUSTMENT. When darTZeel NHB-108 model one's eyes are blinking, it means that an output DC voltage greater than ±0.6 volt is present at the terminal speaker outputs.
Voltage values are those obtained in average conditions. It is possible that they vary much less than mentioned, having less DC drift from cool to warm operation. If so, you can adjust these values a bit tighter. Conversely, it could arise that you may have to work closer to the critical 600mV, say +590mV at cold start, and -590mV at warm cruise, for example. The final goal is only to maintain outputs within the voltage range mentioned above.
