QED Supremus Zr loudspeaker cable
When The Ear was offered one of the first samples of the new flagship QED Supremus Zr loudspeaker cable, we couldn’t resist. I personally was very keen to see what this British cable pioneer could do with this “no compromise” newcomer.
Owned by Armour Home since 2004, cables and accessories specialist QED was founded in 1973 and celebrated its 50th anniversary last year. In 1976, it introduced its 79-strand cable, which was I believe the first commercially available specialist speaker cable on the market. QED cables are designed in the UK and while some are still manufactured here, most, including the Supremus Zr, are made under strict quality control in Taiwan.
Way back when retailers would make up speaker cables to suit customer’s systems, usually with something like Radiospares 20 amp stranded copper cable that they bought on a big reel. QED can rightly consider itself a pioneer in specialist loudspeaker cables, and once Linn and Naim introduced theirs, the floodgates were well and truly open for the trickle of of high-end cables that would become the torrent that floods the market today.
The global audio cable market is now estimated to be worth around $830 million and is expected to keep on growing, with projections suggesting it will top $1 billion by 2031. High-end cables obviously do not account for the lion’s share of that figure, but industry experts suggest that they may represent around 10% of it. That is still a substantial figure and the way the market has burgeoned with a plethora of high-end brands is evidence of the continuing growth that sector is enjoying, and that consumers are more receptive than ever to the message that cables make a significant difference in every part of a hi-fi system.
Give me some skin
Is that subheading a hint that congratulations are in order for the new flagship cable? Well, you’ll have to keep reading to find out, but what it does refer to is one of the main design criteria at the heart of the Supremus Zr, Aircore technology. This aims to minimise the impact of what is known as the ‘skin effect’. This is a phenomenon that affects cables of all sorts, in which high-frequency analogue musical signals tend to travel along the outside off the conductor. It is caused by eddy currents within the conductor set up by the alternating magnetic field. As frequency increases, these currents get larger and push the main current further towards the periphery of the wire.
In the Supremus Zr QED has aimed to minimise the skin effect while still providing a cross-sectional area overall of 6.2sq mm to achieve the large current carrying capacity required.
How? Well, QED realised that for a frequency response of up to 20kHz, each individual strand had to be less than 0.92mm. In the Supremus Zr, QED opted for a diameter of 0.7mm for the 16 strands used for each positive and negative wire. These conductors are individually insulated and arranged around a hollow, foamed polyethylene core. As they are all joined together at the end of the cable, they act as if they were a single conductor. Their 0.7mm diameter reduces the skin effect in each conductor, while arranging them in a ring around the hollow core is said to reduce the skin effect in the whole conductor.
The individual conductors are silver-plated, 99.999% oxygen-free copper and these are cold-welded under high pressure to 4mm plugs, which, QED says, effectively makes the conductors and the plug become one piece. They also remove all the air so that there can be no oxidisation or deterioration in connection. The barrels and boots of the plugs are made from zirconia and are said to be not only electrically inert, but also highly resistant to scratches and wear. The pins are beryllium copper, rhodium-plated to make the connecting surface very smooth, which increases the contact area and reduces resistance. The plugs also have a locking design that makes the pins expand inside the terminals for a more secure fit.
Other features worth mentioning are the cryogenic treatment of the conductors in the cable, which is said to improve the uniformity of their internal crystalline structure, which in turn improves sound quality. And finally, QED has arranged the positive and negative wires in a spiral to help protect against the ‘proximity effect’. When conductors that are placed side by side, the magnetic field generated in one cable by the current flow can generate currents in the neighbouring conductor and cause resistance to rise within the audio band. The conductors in the Supremus Zr are twisted around each other, rather than running parallel.
One direction?
I was supplied with a 2m stereo set of the Supremus Zr. Despite its impressively large diameter, it is reasonably flexible and the fact that the plugs lock in place ensures that the weight of the cables can’t pull the plugs out of the speaker binding posts.
One thing I noticed was that there is no indication of directionality on the cable. Generally cables will sound better when the signal travels in a particular direction and most brands help the user by indicating this somewhere on the cable outer sheath or the plugs themselves. If there is no arrow, there is a generally accepted rule of thumb that any wording or writing on the cable should read from source to speaker. There is no directional arrow on the Supremus Zr, so I checked with Armour Home who said that the way the wording on the sheath reads reflects the direction in which the conductors were extruded during manufacture (which is usually the way you want the signal to run), but suggested this was not super-critical.
Nonetheless, I had to try it for myself. I tried the cables in two systems. One comprising an Audio Note TT3 turntable with Arm2/Io1/AN-S9 transformer or CDT Five CD transport and DAC 5 Special, through an Audio Note Meishu Tonmeister amp and either AN-J LX Hemp or Russell K Red120Se speakers. The other used a Melco N100 streamer and Gold Note IS10 DAC through an Accuphase E380 integrated amp and a pair of Marten Oscar Duo speakers.
Addressing the directionality question, I tried the Supremus Zr both ways. There was no doubt in my mind that it sounded better when the writing on the cable read from the source to the speaker. Drums and percussion were more sharply defined, vocals were more open and bass guitar lines were tighter and better controlled. I also felt that when oriented in that way, the rhythmic ebb and flow of the music was improved. OK, so we are not talking night-and-day, couldn’t-possibly-live-with-it-like-that differences, but for me, I left the cable oriented that way for all of my listening.
A love supremus?
First impressions of the Supremus Zr were very favourable indeed. I started with the track It Didn’t All Come True from Ben Sidran’s excellent Bop City, which is a superb recording, and the QED cable was persuasive, dynamic and detailed on drums and percussion, revealing subtlety in delicate cymbal lines as well as impact and drama on snare. Sidran’s vocals were natural, articulate and open, while fleet-fingered work on piano was nicely handled and the bass line was agile, tight, weighty and tuneful. In all, the sound was well balanced, well presented and detailed.
Switching to Linda Ronstadt’s Lo Siento Mi Vida from her Hasten Down the Wind album, the Supremus Zr handled the guitars on the opening few bars well, conveying their different sounds, while Ronstadt’s vocals were open, powerful, sensual and lacking colouration or congestion. The bass line was tight and moved well, and the cable managed to let the tremendous power of her vocals shine through without making it sound like she was shouting, even when she really went for it.
Reissued on vinyl a while back, The Dude from the legendary Quincy Jones is a timeless classic and I just had to try out the QED cable on the title track. The Supremus Zr did not disappoint, capturing the dynamics and exuberance of the track well, conveying the complexities and layers of its lush arrangement with detail and without blurring it all together. Bass lines were really tight, the horn section was powerful and detailed, while vocal articulation and balance was excellent. All in all, the track packed a solid punch and had the swagger and panache it should.
A good vocal is always a stiff test for any hi-fi and so I next tried my favourite track, So Amazing, from Luther Vandross’s superb Give Me The Reason album. The QED cable conveyed the nuances, range, subtlety and emotion of Vandross’s vocals very well, while Marcus Miller’s superb bass line was tight, deep and moved as only he can make a bass line move. Backing vocals too were well separated and defined. If a Luther vocal doesn’t send shivers down your spine, there is something very wrong, and I am pleased to say the QED cable passed that test.
Track after track, it was the same story and the Supremus Zr made a positive contribution in the systems it was tried in, bringing to the party a neutral balance, lack of artefact and good detail, delicacy and dynamics. I had a couple of similarly priced, well respected cables to serve as a benchmark, which leads me to the confident conclusion that, although hardly cheap, the Supremus Zr is an excellent performer at the price and can compete against the very best. Its neutral balance also means that it should be suitable for use in a very wide range of systems. I highly recommend you give it a try.