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Ground unit

Nordost QTR |№ 4|
QKORE6

Manufacturer: NORDOST CORPORATION
Prices (in Poland): 22 249 PLN

Contact: NORDOST
93 Bartzak Dr.
Holliston, MA 01746 | USA


www.nordost.com

MADE IN USA

Provided for test by: NORDOST


Review

Text: Wojciech Pacuła
Images: Nordost | Wojciech Pacuła
Translation: Marek Dyba

No 196

September 1, 2020

NORDOST is a company founded in 1991 by Joe Reynolds. It specializes in the production of connection cables, and their first designs were developed for the needs of the space industry. In addition to cables, the company also offers QRT series products that are used for powering audio devices and eliminating RF noise and electromagnetic interference. This is the 4th part of the article devoted to them.

uantum Resonant Technology, QRT for short, is a group of NORDOST products that are designed to eliminate or correct RFI and EMF interference that audio devices are exposed to. Some of them are related to the power supply, and some work with the devices themselves. Each of these elements uses a slightly different technique, previously used in the military and medical industries.

The article you are reading is the fourth one in which we describe their operation and influence on the sound of the "High Fidelity" reference system. First, we looked at a device called QPoint, which the manufacturer dubbed "Resonance Synchronizer". I used it then under my SACD player, and as a result of this experience, I felt a need for a comprehensive study of this issue.

The test in question began with a joint listening session - mine and Alex Brady, who in Nordost trains sellers and is responsible for all the shows in Europe. For our second meeting, he brought products that are to ultimately create the QRT SYSTEM:

  • Resonance Synchronizer QPoint (x6) – price: 3390 PLN/pc.,
  • Linear Power Supply QSource – price: 11 129 PLN,
  • DC Cables QSource (for powering QPoints) – price: 1599 PLN/pc.,
  • Ground Unit QKore6 – price: 22 249 PLN (+ 1599 PLN for each cable),
  • Ground Wires QLine – price: 1399 PLN/pc.,
  • AC Distribution QBase8 Mark II (+ power cable) – price: 8549 PLN.

| Ground

For electricians, 'ground' or 'mass' is the reference point in an electrical circuit where voltages are measured; by default its electric potential is '0'. But it is also the point where the devices housings are connected to. It is part of the protection system because in the event of a system failure and the appearance of voltage on the housing, it is shorted to the ground, which activates the fuses and disconnects the voltage.

However, connecting the device to the ground has more advantages - for example, it minimizes electrostatic charges and equalizes the electrical potentials of individual devices in the audio system. Since in house appliances ground is often used to transmit signals, usually in the form of a shielding, this means that equalizing currents flow through it, distorting the useful signal. In studio devices, proper grounding is one of the most important elements of the equipment. As for home audio systems, producers and music lovers from Japan are particularly sensitive to this problem - it is no coincidence that we can find a ground terminal in almost every audio product from this country.

The most popular reference point is "grounding rod", a large iron object buried outside a window. This is not an ideal choice as the electrical transition between devices and the proper ground never equals 0 Ω. Therefore, in modern audio systems so-called "artificial mass", i.e. a product that is connected only to audio components are often used.

| Artificial ground

Both the QPoint and its power supply, not to mention the cables, are products that many experienced engineers may have doubts about. And rightly so - it is a technique used in high-end military and medical systems, and therefore requires special knowledge. Nordost has adapted this technique to audio needs.

While the noise generator itself, which causes the signal to be less distorted, can somehow be understood, why changing the power supply for the better changes the sound so clearly - this is something I do not fully understand either. I suspect that it is about both the generator itself and the fact that switching power supplies “produce” a lot of high-frequency noise, which is fed into the mains and affects other audio devices. But I am not sure. And why does changing the cables powering QPoint influences the sound - I truly have no idea. But I can hear that it does.

Against this background, the QKore seems to be a perfectly ordinary product. Two or three years ago it would have been placed on the same shelf with QPoints, but in a very short time a lot has changed in the minds of both engineers and music lovers. Today, artificial mass, because that's what it is all about, seems to be a "legalized" element of the audio system.

Products of this type are very popular in audio. They are offered by the following companies: Entreq, Verictum , Asura, Acoustic Revive and CAD. We also wrote about it in a guide article entitled FINE-TUNING | 2 |. It's time for electronics from February 2019 |№ 191| (read HERE).

The so-called "artificial mass" (ground filter) is most often a mixture of minerals and powdered ferromagnetic, piezoelectric and other materials, often in combination with metal bars. It usually looks like a large power supply unit, but the only connections in it are - usually - the speaker terminals. These are used to connect grounds of audio components using short cables.

| QKORE6

Nordost also offers an artificial mass, a device called QKore. This is, let me say it right away, the best-built device of this type on the market. It features a perfectly prepared aluminum housing. Its rear panel features high quality gold-plated WBT speaker terminals. This device is designed to allow user to connect up to six devices. Moreover, this device has been developed in-house by Nordost, based on their own research. The company offers three versions of the device: QKore with ground only for the power strip, QKore3 with three outputs and QKore6 with six of them - and we test the latter.

QKore6 features two separate sections: "primary" and "secondary". To the former one we connect the elements on the "primary" side of the signal track, ie those „before" the devices. These are, most often, power strips and conditioners. The socket intended for them is clearly marked. On the "secondary" side, we connect audio devices, such as preamplifiers, signal sources and amplifiers. In QKore6 there are three sockets for low-power devices and two for power amplifiers, also for two monoblocks.

The diagram in the manual shows the correct sequence of connection: preamplifier, signal source, others, two monoblocks and QBase (or any other AC power strip). On the component side, the mass should be connected to appropriate terminals, located in strategic places of the housing, with connected ground terminals from various sections of the device.

However, many devices do not have them, but this is not the end of the world. Electric ground is present on any output and input - XLR, RCA, BNC, LAN and even USB. It is not an optimal solution, but it is acceptable. In the instruction I referred to, it reads:

The QKore Wire cable should be connected to any of the preamplifier’s inputs or outputs and to any speaker jack on the QKore. However, the result may be different depending on which of the preamplifier’s sockets the cable is connected to, so the user should experimentally establish which socket works best in his system.

The QKore Wire mentioned in this section are cables that connect the artificial mass and devices. It could be done with any thick wire, but as a result of Nordost's tests, it turned out that the sound of the system is also influenced by the quality and type of grounding cable. Weird? - Not really. After all, it is a piece of wire that acts as an antenna - so it should be protected against RF noise. Moreover, the quality of the conductor itself also matters.

That is why QKore Wire are high-class cables with mechanically tuned vibrations - it is one of the Nordost techniques, thanks to which the cable does not suffer from “microphonic” effect; which is a triboelectric distortion. The design also features a patented technique called Micro Mono-Filament, meaning that the conductor is wrapped with a band of FEP dielectric, creating a kind of "tube" with air inside - and air is one of the best insulators. The conductor itself is a silver plated OFC wire ("solid-core") of a 6N (99.9999%) purity, and the plugs are gold-plated BFA "bananas".

The set includes two cables (both banana to banana and banana to RCA), for each additional one you will have to pay PLN 1599 or PLN 1799 for a 2-meter section, depending on the termination. For each additional meter, the price is PLN 670.

| SOUND

How we listened to it | The QKore listening session had to be divided into several stages. On the one hand, I wanted to hear how it affects individual components of the system separately, and on the other, how it can be used to "build" the sound step by step, adding individual devices one by one:

|1| Power distributor Acoustic Revive RST-4EU Absolute: is one of the few products from Japan that does not feature a ground terminal. So I fixed the spade-terminated cable under one of the screws securing the top plate; after finishing the test, I will move it to the bottom, under the foot. It is worth connecting it as close as possible to the EIC socket, because this is where the protective wire is connected.

|2| SACD player Ayon Audio CD035 HF Edition: also this device does not have a dedicated ground terminal. I tried three different cables with it - with BNC, LAN and USB terminations - it sounded best when connected via a BNC cable.

|3| Preamplifier Ayon Audio Spheris III: also no ground output. In addition, you can choose whether the mass of the system is independent of the chassis, or whether it is connected to it - it is worth trying which one works better in particular system, I connected the QKore6 to one of the RCA inputs.

|4| Soulution 710 power amplifier: no ground socket, so I connected it to the XLR input; however, in the future I will try a different input - the amplifier is equipped with LAN sockets for system communication.

|5| Phonostage RCM Audio Sensor Prelude IC, combined with the CS Port TAT2 turntable: phono preamplifiers do feature ground terminals, so the matter was simple - the banana-banana cable (BFA-BFA).

Anything else one might do? This is not the end of possible improvements. The QKore can be placed on proprietary anti-vibration feet called Sort Kone. The rubber feet have to be unscrewed and two of the three new feet are inserted in their place - a separate recess has been milled for the third foot. Amazing, but it really works - I attended some presentations during several shows and they made a huge impression on me every time. So, in the future, I will give it another try...

| Albums

⸤ Aquavoice, Silence, Zoharum ZOHAR 168-2, Master CD-R (2018); ⸤ Art Pepper, Art Pepper Meets the Rhythm Section, Contemporary Records/JVC VICJ-42524, K2 CD (1957/2006)
⸤ Bob Dylan, The Freewheelin', Columbia/Mobile Fidelity UDSACD 2081, „Special Limited Edition | № 3085", SACD/CD (1963/2012)
⸤ Duke Ellington, Duke Ellington Live!, Nippon Phonogram | EmArcy 842071-2, CD (1989)
⸤ Elvis Presley, Elvis is Back!, RCA/BMG Japan BVCM-37088, „Living Stereo”, CD (1960/2002).
⸤ Jean-Michel Jarre & Gesaffelstein, Conquistador, The Vinyl Factory VF183, 45 RMP | 180 g LP (2015); ⸤ Jun Fukumachi, Jun Fukumachi at Steinway, Toshiba Records LF-95001, „Pro-Use Direct Cutting Series”, 180 g LP
⸤ Miles Davis, The Musings of Miles, Prestige/Analogue Productions AJAZ 7007, „Top 100 Jazz | 45 RPM | Limited Edition #0706”, 2 x 180 g, 45 RPM LP (1955/?)
⸤ Portishead, Dummy, Go! Disc Limited/Universal Music Company [Japan] UICY-20164, SHM-CD (1994/2011)

|1| Power distributor

Connecting the ground to the power strip is felt as a calming of the sound and increased resolution. The difference is quite big, not to say significant. Similarly to the QPoints before, the sound of my system without the “help” of the Nordost products is completely satisfactory and I like it. I like listening to the music on it. What's more, after some time without the QKore artificial mass attached to the strip, I liked it again.

But the comparison of "with" and "without" is not favorable for the latter - the sound is a bit more matte, a bit more dull and a bit less addictive. Listening to music with the QKore plugged into the Acoustic Revive strip for a longer time makes us “switch” to this new level. It's not something you can't live without, but also while having it in the system, I wondered how I could have had lived without it before?

It was audible both with electronic music by Aquavoice, with lo-fi music, i.e. Portishead, but also with fancy productions from Contemporary Records, such as Art Pepper Meets the Rhythm Section in the Japanese K2 version. The changes that I noticed in the presentation when I plugged the QKore to the power strip made the music more exciting, more dynamic, more "here and now". And yet it seemed calmer, better arranged, with a "blacker background" behind the instruments.

|2| SACD player

After connecting the SACD player to the QKore, I already knew that the changes this product introduces to the sound consist in "cleaning" the sound. However, unlike what we are used to in audio, it does not mean brightening and delivering more detailed sound. It's all about higher resolution. Much higher.

Connecting the SACD player to the artificial ground did not bring such a clear change in dynamics as connecting a power strip to it. The player reacted to the new situation by deepening "awareness" - I do not know what else to call it. I was more aware of the music than before. Probably the point is that I got more information about it and my perception of it as an artificial event was more balanced by the fact that it sounded more like something experienced live.

Apparently, the sound was even calmer than before. In fact - everything got "deeper", so the slight pressure that the system previously put on me disappeared. If I had not compared the sound of the player "without" and "with" Nordost many times, I would not have noticed it. But that's how we learn new things. Nobody can explain what this "new" will look/sound like and until we experience it ourselves, the explanation will bo nothing more but a story.

|3| Preamplifier

The grounding system in question can be tested by listening to music with each device separately, but you can also "build" the sound by adding more devices to this network. I did so too. Having a power strip and SACD player connected to the Nordost, I connected a line preamplifier to it - through one of the RCA inputs.

This time the sound changed towards adding weight to it. The upper midrange was a bit „weaker” than before, which made Philly Joe Jones' cymbals from the Pepper disc more audible, the very long reverb accompanying Elvis's vocal from Fever, a track from the Elvis is Back! album, was more clearly audible.

After connecting the preamplifier to the artificial ground, there was no more "wow!" effect, but only because all the basic changes that this product brings to the sound were already "taken care of" by the power strip and the SACD player. The preamplifier did something else - it intensified the sound again. It saturated it a little and brought it closer. The changes concerned how the "buble" of sound is built around us, for example in the opening track for the Aquavoice album entitled Silence. After connecting the preamplifier to Nordost, it was more continuous, denser and more pleasant.

|4| Power amplifier

An interesting thing happened when I connected an amplifier to QKore6. When building changes based on the Nordost product, I assumed that the changes introduced to the sound would be similar and would become stronger. It was true, but it didn’t matter. What remained in my head after these auditions is not "big, bigger, the biggest", to recall a classic, but rather something else.

An amplifier connected to the ground, even if it is an artificial one, delivered a smoother, softer and more pleasant sound. I did not miss anything in its performance before. And yet… Now it was a much more elegant, well-ordered sound. The perspective improved a lot - it became deeper into the soundstage and also behind me. When in the first track on the Silence a low, deep theme placed in front of me came, this time it was placed a bit further away from me. When the sound behind me joined it, it was placed far behind and took up a larger area, not just a small point.

The mass did as much good with the amplifier as it did with the power strip before. Perhaps because the SACD player, the preamplifier and the strip itself were grounded. Still, now it was complete. That's why Duke Ellington's concert from Newport Jazz Festival '59 sounded so nice, so cool. And I listened to regular, though released in Japan, version. It was a dense, explosive, swinging sound with perfectly arranged layers, great timbre presentation and incredible resolution. And without a hint of "detail" - just imagine it!

|5| Phonostage

The phono preamplifier left for last, could not change my opinion about the QKore. Yet it added something else to it: an attack. All previous changes led to a nicer, slightly softer sound. It's a good thing, the sound reproduction follows its own rules and it is not about showing the event "as if it were live", but about convincing us that it is so. These are two different things.

Anyway, the phono preamplifier with the QKore created an effect as if I heard an event on a stage. It slightly strengthened the attack of the sound, improved a bit of the rhythm, added credibility and - voila!, the result was completely different.

| Summary

QKore is a "parallel" product to the Audio system, same as the QPoint. It is not inserted into the signal’s track, but rather "next to" it. However, connecting all elements in our system to the artificial ground is equivalent to replacing any of its elements with a superior one. But - and here it starts to be interesting - we get more of everything that we already have in the system, not something completely new. In other words, the sound we worked for, polished and refined, will be improved, not changed.

I heard it with every single component I connected to the Nordost. I know the influence on the sound of each of the elements of my system and I know what they bring in, what they add, what they do not, what they take away. QKore made their qualities stronger, even more audible, without any negative changes. This is really great!

However, if I were to start somewhere, it would be with a power strip - in this case, it resulted in the most significant improvement. Later in this hierarchy there would be the sound source, power amplifier and preamplifier, that's how it worked for me. The sound with the QKore is much more resolving, much more spacious and much more natural. I do not expect anything more from an audio product. And so it becomes a permanent part of the "High Fidelity" reference system.

| QRT series in „HIGH FIDELITY”

|1| Nordost QPOINT → HF | № 184 • August 2019, see HERE
|2| Alex Brady @ Nordost QPOINT x 4 → HF | № 190 • February 2020, see HERE
|3| Nordost QSOURCE • DC power supply → HF | № 191 • March 2020, see HERE

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Reference system 2020



1) Loudspeakers: HARBETH M40.1 |REVIEW|
2) Line preamplifier: AYON AUDIO Spheris III Linestage |REVIEW|
3) Super Audio CD Player: AYON AUDIO CD-35 HF Edition No. 01/50 |REVIEW|
4) Stands (loudspeakers): ACOUSTIC REVIVE (custom) |ABOUT|
5) Power amplifier: SOULUTION 710
6) Loudspeaker filter: SPEC REAL-SOUND PROCESSOR RSP-AZ9EX (prototype) |REVIEW|
7) Hi-Fi rack: FINITE ELEMENTE Pagode Edition |ABOUT|

Cables

Analog interconnect SACD Player - Line preamplifier: SILTECH Triple Crown (1 m) |ABOUT|
Analog interconnect Line preamplifier - Power amplifier: ACOUSTIC REVIVE RCA-1.0 Absolute-FM (1 m) |REVIEW|
Speaker cable: SILTECH Triple Crown (2.5 m) |ABOUT|

AC Power

Power cable | Mains Power Distribution Block - SACD Player: SILTECH Triple Crown
Power (2 m) |ARTICLE|
Power cable | Mains Power Distribution Block - Line preamplifier - ACOUSTIC REVIVE
Power Reference Triple-C (2 m) |REVIEW|
Power cable | Mains Power Distribution Block - Power amplifier - ACROLINK Mexcel 7N-PC9500 |ARTICLE|
Power cable | Power Receptacle - Mains Power Distribution Block: ACROLINK Mexcel 7N-PC9500 (2 m) |ARTICLE|
Power Receptacle: Acoustic Revive RTP-4eu ULTIMATE |REVIEW|
Anti-vibration platform under Acoustic Revive RTP-4eu ULTIMATE: Asura QUALITY RECOVERY SYSTEM Level 1 |REVIEW|
Power Supply Conditioner: Acoustic Revive RPC-1 |REVIEW|
Power Supply Conditioner: Acoustic Revive RAS-14 Triple-C |REVIEW|
Passive filter EMI/RFI: VERICTUM Block |REVIEW|

Anti-vibration

Speaker stands: ACOUSTIC REVIVE (custom)
Hi-Fi rack: FINITE ELEMENTE Pagode Edition |ABOUT|
Anti-vibration platforms: ACOUSTIC REVIVE RAF-48H |ARTICLE|

Isolators:
  • PRO AUDIO BONO Ceramic 7SN |REVIEW|
  • FRANC AUDIO ACCESSORIES Ceramic Classic
  • HARMONIX TU-666M "BeauTone" MILLION MAESTRO 20th Anniversary Edition |REVIEW|

Analogue

Phono preamplifier: Phono cartridges: Tonearm (12"): Reed 3P |REVIEW|

Clamp: PATHE WINGS Titanium PW-Ti 770 | Limited Edition

Record mats:
  • HARMONIX TU-800EX
  • PATHE WINGS

Headphones

Headphone amplifier: AYON AUDIO HA-3 |REVIEW|

Headphones: Headphone Cables: Forza AudioWorks NOIR HYBRID HPC