QED Performance XT25 Oxygen Free Copper Speaker Cable Per Metre Unterminated
We are authorised QED Partners, so you can be assured of a genuine product, backed by excellent customer service and, as always with QED, a lifetime guarantee.
The QED speaker cable story began in 1973, with the launch of the world's first specialist speaker cables, QED 42 and 79 strand, now household names in the audio industry. Building on this longstanding British speaker cable heritage, QED embarked on an exhaustive research program into cable parameters which began in 1995 and continues into 2017 with the release of "The Sound of Science", a 40 page White Paper distilling the research published since 1973 by QED.
These reports set out the "top down" design-principles that have resulted most recently in the development of QED XT25 loudspeaker cable - the new class leading standard in budget to mid-range speaker cables.
What are the features which make this cable so special?
X-Tube technology first came to prominence in 2005 with the launch of the world renowned Silver Anniversary XT, the most highly regarded mid-range cable in the world, winning the What Hi-Fi Product of the Year three years in a row. These design principles also grace the multiple award winning XT25 speaker cable.
As frequency increases, electrons flow more and more towards the periphery of a conductor so that if the frequency is high enough only a very thin layer (or skin) on the outside of the conductor is used. This "skin depth" varies for different materials at a fixed frequency and in copper it means that if a conductor has larger than 0.66 mm² cross-sectional area not all of that area is available for an analogue music signal to use. In SAXT the "skin effect" problem was effectively eliminated by the use of X-Tube Technology which works by placing all of the conducting material around a central hollow insulating rod. However, for a.c. signals, changing magnetic fields generated by the flow of current set up eddy currents in nearby conductors which force current to flow only in areas furthest away from conductors carrying current in the same direction and vice versa.
This "proximity effect" has a detrimental influence on current distribution in a speaker cable even if it utilises X-Tube Technology. With XT25 QED tackle the proximity effect and the skin effect by combining their existing Aircore and X-Tube Technologies into a new X-Tube variation. By forming the conductors into a tube-like shape with a hollow centre, current densities at higher frequencies are maintained because the electric field which contributes towards the skin effect acts towards the centre of the conductor from where the conductive material has been removed. At the same time instead of using a braided structure a ring of conductors is formed into separate bundles with only a loose electrical association which are then twisted into a 90 mm lay so that no single conductor bundle remains on the inside or outside of the cable (and therefore prey to the proximity effect) for long enough for it to become an audible problem. This geometry promotes a more consistent signal distribution making for a more accurate musical reproduction.
Low DC Resistance
QED recognise that low d.c. resistance of the loudspeaker cable is of paramount importance for high-fidelity signal transfer. This is because the speaker presents a frequency dependent load to the amplifier of which the cable forms a variable proportion. If resistance is allowed to be too large then audible changes to the frequency response characteristics of the loudspeaker will be introduced which cannot be corrected for by the amplifier's negative feedback loop. In order to provide a marked improvement over similarly priced cables in both their own and their competitors' ranges without increasing the overall size and flexibility of the cable substantially, the cross-sectional area (CSA) of XT25 has been enlarged to 2.5mm2 of 99.999% oxygen-free copper. This instantly gives the new cable a low d.c. resistance and therefore a more accurate musical delivery.
Low-Loss Dielectric
It is not generally appreciated that the electrical signals moving at or near the speed of light in a wire do so via the medium of electromagnetic (EM) waveforms which exist within the dielectric which surrounds the conductors as well as within the conductors themselves. The movement of electrons along the conductor merely facilitates generation of the EM waveform as their "drift velocity" is only a few centimetres per second. It is therefore important to ensure that the dielectric material used to insulate and protect the central conductors of the speaker cable is of a type which "permits" the establishment of EM waveforms without appreciable loss. Dielectric losses are directly proportional to the "permittivity" of the material used and as this a measure of each material relative to that in a vacuum it should be as close to unity as possible. Like its predecessors, XT25 uses a specially formulated low-density polyethylene (LDPE) dielectric which at 1.69 has the lowest relative permittivity practically available.
QED research has shown that low capacitance cables are generally preferred in listening tests over high capacitance counterparts and this is usually because low-loss dielectrics have been utilised. The use of LDPE and careful control of conductor spacing results in a cable with a very low capacitance per meter and a dissipation factor (loss tangent) of 0.0001 at 10 kHz.
What is the result of all these techniques?
The graph below shows how the dc resistance of XT25 remains effectively unchanged across the entire audible frequency band when compared to a conventional cable of the same cross-sectional area. Combined with the sonic advantages of a low loss dielectric the improvements in current distribution place the new cable in a class well above cables with a less sophisticated geometry.
So, unless you invest in XT25 with QED X-Tube technology you can be losing a lot of the performance of your expensive loudspeakers.
What makes XT25 unique?
1. Award winning heritage guaranteed
All QED cables are designed using the top down principle. XT25 represents the core musical performance trickled down from our money-no-object Supremus cable in a more affordable package. QED has won more What Hi-fi? Awards than any other single brand and with XT25 this heritage is delivered at a sensible price. Unlike most other manufacturers, QED offer an unlimited lifetime guarantee which means that if your cable ever fails to deliver to its full potential during its lifetime we will replace it free of charge.
2. X-Tube Technology....but with a twist
In loudspeaker cables high pitched sounds are forced to travel towards the outside of the conductor and so are able to use less and less of the available cross-sectional area as the pitch increases. This is called the "Skin Effect". It means that for high frequencies the resistance of the cable appears to be much higher than it does for lower pitched sounds. Eddy currents in one conductor can affect the current flowing in an adjacent conductor so that currents flowing in the same direction move away from each other. This "Proximity Effect" also increases resistance as frequency increases. These phenomena have a detrimental effect on the fidelity of the sound you hear. The XT25 variation of QED X-Tu Insulation LDPE jacket with 100% coverage of Aluminium Mylar tape wrap Plugs and spades QED Airloc Forte banana plugsbe Technology solves these problems by creating a hollow tubular conductor geometry out of individual conductor bunches through which each frequency can pass with equal ease when compared to traditional solid or stranded conductors.
3. Low-Loss Dielectric
Music signals in a loudspeaker cable move back and forth many times every second. The insulating material used to separate the send and return conductors from each other (the dielectric) has to be charged and discharged every time. Not all of the energy stored in the dielectric during each charge cycle is completely returned during each discharge cycle which has a detrimental effect on the fidelity of the sound you hear. That's why at QED we use low-loss dielectric materials such as Polyethylene (PE) or Teflon (PTFE) in preference to cheaper PVC alternatives found in inferior unbranded cables.
4. 99.999% Oxygen-Free Copper
Speaker cables need to have a large current carrying capacity. If the electrical resistance of the cable is too large, part of the music signal will be lost, causing a detrimental effect on the fidelity of the sound you hear. To stop this from happening we make the resistance of our speaker cables as small as possible. We do this by using the largest practical cross-sectional area of copper within the size constraints of each cable. In order to squeeze the last drop of performance from the conductors we make sure that there are no impurities in the copper which would defeat the object of making them so large. That's why we use 99.999% oxygen-free copper exclusively.
5. Just Listen
Unique proprietary technology and trademarked geometries plus our award winning heritage all combine to create audible sonic improvements when compared to other loudspeaker cables.
Cross sectional diagram
This listing is for this cable per metre unterminated. Maximum length of 50m drum.
when paid before 4pm
About Us
Formed in 2005, Digitalis Audio is a well established professional business based in Romford, Essex.
We work closely with many major manufacturers including Audio-Technica, Edifier, Audiolab, Wharfedale, Dali, Mission, Kanto, Blue Aura, Pioneer, QED, Onkyo.and so many others.
As our eBay feedbacks testify, we are totally dedicated to amazing customer service, with over fifteen years trading on eBay, as well as other online platforms, including our own website.
We always put you as the customer first so in the unlikely event that you have a problem our dedicated support team are here to help in any way. Basically, our top priority is customer satisfaction and we strive to make your buying experience a fantastic one.Should you require further information or advice, please do not hesitate to contact our Romford team.
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Terms
TERMS AND CONDITIONS
The following terms and conditions apply to all purchases of items from Digitalis Audio.
Sale of Goods
By placing an order with Digitalis Audio (referred to as us/we/our) you (the customer) are accepting these terms and conditions. These conditions do not affect your statutory rights.
Your order confirmation is proof of purchase . Please ensure you keep this in a safe place as this will also be your guarantee on the following terms: Should any goods develop a fault simply return within 30 days of purchase (complete with original packaging and accessories) and you will be offered the choice of either an exchange or full refund. Any faults developed after this time must be reported to us via eBay messaging prior to return, please do not just return. Obviously we cannot provide a guarantee in respect of any misuse e.g. if you drop the unit, misuse or excessive wear and tear e.g. commercial use. Please note the guarantee will be invalidated if repairs are done other than by us or our authorised agents.
You have the right to terminate the contract between us without penalty within 7 days from the date we accept your order. In the event of termination we will gladly refund to you all sums paid to us once you have, at your expense, returned any goods that we have despatched to you, providing they are unused and still sealed in the original packaging. Termination of contract shall be without prejudice to the rights and duties of either you or us accrued prior to termination.
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Title in the goods will pass on delivery. Should you return the goods pursuant to conditions set out under these terms and conditions, then title in the goods shall revert to us when you return the goods to us.
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Many of the goods we sell are of a technical nature and unfortunately it is not practical to publish detailed specifications of all the goods and keep specifications 100% up to date. All drawings, descriptive matter, specifications and advertising on our website are for the sole purpose of giving approximate descriptions of the goods. However, if your goods do not conform to the specification displayed on the website relating to such goods at the date of purchase, we will arrange for collection of the goods from you and you will be entitled to receive a refund on production of the proof of purchase (sale receipt).
As you can appreciate, we shall not be liable to you for any failure or delay in performance of our contract if it is due to an event beyond our reasonable control, including, without limitation, acts of God, war, industrial dispute, fire, flood, tempest and national emergencies and if so delayed we shall be entitled to a reasonable extension of time for performing such obligations.
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Returns
All new items are naturally covered against faults by a minimum manufacturer guarantee of 12 months, usually more.
We will happily accept the return of your purchase under the following circumstances.
Goods may be returned within 60 working days of the date they were received by you. We offer a full refund for units purchased as long as they are in an as new unopened condition and complete with packaging / accessories. Any refund would exclude delivery and collection charges incurred by us or you if the unit is unwanted.
Should the unit arrive faulty or damaged in transit we must be advised within two working days and will happily exchange it, once collected by us, for a replacement unit or issue you with a full refund or credit as soon as possible.
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