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Nordost QRT system Review

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Bringing the music home

The next stage involves treatment of the AC line to reduce the effects of inaccuracies in the AC waveform and EMF/RFI interference. Nordost refers to its technology for dealing with AC anomalies, as Quantum Resonant Technology (QRT). The QRT technology is incorporated in an external module (QX2/QX4), which is installed between the wall outlet providing system power and the QBASE into which the remainder of the system is plugged. One beauty of the Nordost approach is that it is modular in nature with fully complementary elements. This ensures that your initial purchase will not later become obsolete.

The same set-up structures apply to the QX2/QX4 as well as to the QBASE: siting and isolation are critical as are the power cords utilized. In practice, the power cord between the QX2/QX4 and the QBASE is more critical than the one from the wall. The substitution of an Odin power cord for a Frey 2 was quite audible. There is a switch on the rear of the QX2/QX4, which allows the user to switch off the QRT technology without interrupting power to the system.

The QRT technology is designed to address two of the most significant types of AC power line noise, namely RFI and EMF, as well as to improve the consistency and regularity of the AC waveform. It does this without limiting voltage swing or altering the impedance of the AC supply. The QX modules used in the QRT power purifiers are responsible for these effects. In theory, the greater the number of the QX modules used, the more profound the benefit. The QX4 has twice the modules of the QX2. The QX modules employ what Nordost refers to as QRT Field Generators to (in their words) “impact the system’s operating parameters by functioning at the beat frequency of its electro-magnetic energy.” While this sounds really impressive, what does it really mean and can you really hear the effects?

While I cannot claim to understand the technology involved, I can offer an anecdote. Think of these solutions as being similar to a common water filter (perhaps in an extreme scenario) you might use in your home. These filters certainly filter harmful metals, however, they can also filter out other salts and minerals, which are extremely beneficial and necessary. But what if you had a field generator around your faucet pulling out those harmful metals from your precious water, but not taking away the so-called nutrition? This would be the QRT method and advantage.

The QKOIL: QK1 and the QV2 AC Line Harmonizer

The QK1 is a load resonating coil (LRC), which generates a passive electronic field that has a beneficial effect on the AC current. Like the QV2, the QK1 is a module, which may be plugged into a spare outlet in the system, quite often an unused outlet in the QBASE. While the effect of a single QK1 is quite audible, use of at least two is recommended, as the effects are cumulative. In practice, it can have a rather pronounced effect on tonality, particularly in the midrange. It can add a bit of warmth and richness or harmonic complexity in the midrange, sharpen edge definition and image focus and improve the sense of depth while lowering the noise floor. In some applications it may have the effect of bringing the center image forward. High frequencies generally become somewhat more three-dimensional.

The QV2 is modular and may be inserted into an unused plug. The QV2 applies QRT technology directly to the AC line, introducing a carefully calculated range of harmonic frequencies to a system’s AC supply, clocked from the line frequency itself. It seems to effect immediacy and presence. The effects are most audible in the bass where it can improve pacing and make the music more relaxed.


Listening in two very different systems

While the effects of the Nordost QRT products are easily audible in any system, how we react to the changes may to some extent be a function of how our system is tuned and how well we have dealt with power line issues. For this reason, I inserted the Nordost QRT products into two very different systems: one comprised of transistor electronics and a digital front end and the other a much more expensive analogue based system using low power tube electronics to drive horn loaded speakers. The owner of the transistor-based system was initially reluctant to disturb her system, but was eventually convinced to at least try the QK1 and QV2 since they would require minimal disruption to the system configuration.



The first system was initially harmonically lean with limited depth and lacking in focus and edge definition. Given the ease of installation, we began with the insertion of a single QV2 module. The effect in terms of improved focus and depth was easily audible as was the improvement in the harmonic structure of instruments, particularly in the midrange, and the lowering of the noise floor. Insertion of a second QV2 further enhanced each of these areas. Insertion of a QK1 improved pace and seemed to make the music more relaxed.

At this point, any reluctance to install further pieces crumbled. The next change was the addition of the QB8. Initially, the sound was disappointing; however, the placement of Nordost Sort Kones underneath the QB8 completely resolved any problems. Once Sort Kones were inserted, the system’s noise floor was significantly lower, stage depth deepened, the soundstage became wider, overtones and pace improved, and there was an increase in dynamic range.

There were significant gains in all areas but particularly in the reduction of noise and increase in resolution, depth and image focus.

The owner of the system subsequently purchased a QB8 and several of the QK1 and QV2 modules and ultimately will probably add at least one QX4.



I followed a somewhat different path with respect to insertion of the QRT products into my own low power, triode-based system (System 2). Initially, I inserted a single QK1 into my HB Cable Design PowerSlave Marble power distributor. At the time, I was listening to a cut from Zorba the Greek which employs a mandolin. The mandolin seemed to take on more weight and solidity; however, there was a very slight reduction of stage width. Otherwise the imaging remained unchanged. Adding a second QK1 increased the width of the stage and somewhat lowered the noise floor. Focus, particularly edge definition, improved. My amps are on a separate circuit so it was possible to try the same experiment with them. In that instance, the QK1 seemed to improve decay but otherwise was inaudible.

I went through the same sequence of insertions with the QV2 modules. In that case, the effects were subtler; however, pacing improved and the bass seemed to have more weight.

Next, I inserted a QX-4 between the wall and my HB PowerSlave Marble. The QK1 and QV2 were totally out of the system at this point. Decay was audibly better, particularly with respect to struck instruments such as triangles. The sound was addictive. The overtones of metal instruments were easier to distinguish. The sound of plucked strings was particularly well delineated.

At this point, I used the QB8, QV2 and QK1 in combination. This seemed to yield the best results, more or less cumulating the individual improvements. Decay of the strings on the mandolin was particularly well handled and there seemed to be an increase in resolution, particularly with respect to sounds very close in level to the noise floor.


To briefly summarize the contribution of each of the Nordost modules:


  • Lowers level of background noise
  • Reduces mesh noise (noise in the spaces between instruments)
  • Renders voices purer with less strain


  • Improves pace and rhythm
  • The space between instruments is cleaner/blacker
  • Reduces background noise
  • Makes it easier to differentiate between voices in a choir or individuals clapping in mass
  • Bass is cleaner with slightly more weight
  • Increase in resolution
  • Bass has slightly more weight
  • Increase in soundstage depth and air


  • Added warmth/ harmonic complexity in midrange
  • Increase in mid bass power and weight


  • Renders highs more dimensional


Final thoughts

Find a Nordost dealer who will loan you these products starting with the QBASE, and then try first the QV2, then the QK1, finally adding the QX2/4. In an audio world where it is possible to spend the cost of a small car on a pair of interconnects, these products are a real bargain.

6 Responses to Nordost QRT system Review

  1. John Oakman says:

    An excellent commentary on the various components. However don’t be too hard on the rubber feet. I have just upgraded the QB4 & 6 to Mk2 status & the improvement is one of the most remarkable improvements in musical articulation & engagement i’ve heard in years. I also use QX 2’s & 4’s, etc not to mention a complete Valhalla 1 loom. I have Sort tc’s under my source components but can’t afford them under another 6 boxes. Nordost would probably suggest i’m wasting my time by not moving the 3 sets I have to the first QX 4 & QB’s. Hey you know perhaps I should try it.
    Keep up the great work.

  2. Bill says:

    What is the internal wiring of the QX4 ?

  3. Hal says:

    I was completely stunned when I put a QB4, Qx4 and pairs of Qv2/Qk1s in my source rack a year ago with Heimdall 2 power cords on the input to the the QB4 and Qx4. My Nordost dealer recommended I start with power cords and based on the performance of the Blue Heaven loom with which I began, I too the plunge. I have never regretted spending the money and recommend the Nordost QRT solution myself.

    Based on your experience with improved decay, I suspect the power conditioning of the Nordost QRT components are enabling my Lyra Dorian to deliver a warmer mid-range with the note decay most reviewers say is missing from this generation of Lyra cartridges. In fact, I had a spooky moment the other day with my eyes closed when Nora Jones took a breath right next to me on the Painter Song from the latest Analog Production pressing of her “Come Away with Me” album. The contribution the Nordost QRT system makes to delivering this performance is greater than I ever imagined until I tried it.

  4. L. Battilana says:

    I used two Qv2 as a standalone in my system plugging them into wall outlets that had a power conditioner and the other my amp. The affect was immediate and outstanding. I agree with the reviewer and how the mids seem more pronounce and the bass seemed warm and sustained. I look forward to adding the Qbase and getting rid of my Monster MKII 3600 hts. I believe at this price point, nothing comes close to how much this improves the sound quality of your favourite songs.

  5. E.J.R. says:

    To achieve the lowest noise level of the QBase4/8, they must be connected to a secondary ground…which is logical if it can be done.

    However, if one lives in an apartment, as I do, it will be either impossible or dfficult: the only solution I might have, is to connect the QBase4 to an unused radiator terminal up from the floor as the radiater to which was attached, has been disconnected.

    Does anyone know if this will work, and how to do it? I am at a loss and buying a QBase4, without maximising it full potential, is wasteful and illogical.

  6. Bastards of Young says:

    I wonder if Nordost has any white papers that proves that this unit improves on Sonics. If you really want to improve things just buy better speakers. LOL What is the internal wiring, what engineering is behind this thing, and why specifically does this help? I mean if you live in downtown New York where you power grid is full of unwanted noise then maybe I could hear some improvements. If you in a newer home that is wired correctly and or have a dedicated circuit for your HT or Audio Gear than this is extreme overkill.

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