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 See customer reviews of FutureShop.co.uk
QED X-Tube XT-400 Speaker Cable
SKU: C-XT400/50

Average Customer Rating
(8 Reviews)
Usually dispatched within: 24 Hours
Warranty: Lifetime UK Warranty
FREE UK DELIVERY: For Orders Over £99
Price - Custom Options:
(Need HELP with ordering? Click here)
NEXT DAY DELIVERY (If ordered before 4.30pm Mon to Fri)

The flagship Aircore™ cable. Silver Plated Oxygen Free Copper tubular conductor geometry. For use in the finest hi-fi and home theatre systems.

X-TUBE™ with Aircore™ technology is a genuine breakthrough in loudspeaker cable design. This cable range delivers many of the attributes of our world-renowned Genesis Silver Spiral cables - superb transparency, dynamics and control - in a more compact cable format.

X-TUBE™ is designed to be the natural upgrade for anyone using QED’s Silver Anniversary speaker cables or those simply wanting the best performance for their hi-fi or home theatre system.

The construction of these cables is uniquely QED: multiple Silver Plated conductors surrounding a polyethylene core, precise spiral geometry within the transparent outer jacket and excellent shielding. A truly balanced design that has been universally praised by the world’s specialist press as a true high-end performer.

"the XT400 delivers - in spades. Detail resolution is wonderful and this cable reveals the finer points of complex tunes at even low volumes." What Hi-Fi Sound and Vision April 2003

The QED XTUBE XT400 Anniversary connects your Amplifier to your speakers.


  • QED X-Tube XT-400 Speaker Cable

  • Please note, you need to enter a quantity of 2 for a pair

  • Massive 2 x 4mm2 conductor crosssectional area

  • 99.999% Silver Plated Oxygen Free Copper stranded braid conductors

  • Compact figure ‘8’ construction

  • Polyethylene AirCore™

  • Copper Mylar conductive wrap

  • PTFE tape wrap, PVC outer jacket.

  • Dimensions 12.7 x 6mm.

  • Terminal connectors - Optional. Choice of AIRLOC Banana or AIRLOC Spade terminal plugs

  • Lifetime UK Warranty



One of the big problems as cable conductor size increases, is how to keep the inductance low. This is vital to reduce cable losses and prevent inaccuracies in the signal transfer process, i.e. distortion.

The normal way to do this is to use a number of individually insulated conductors within the cable construction. This method is utilised to great effect in the design of our Genesis Silver Spiral loudspeaker cables. However, this results in a product that has a very high quality sound performance, but is expensive to manufacture and can be difficult to terminate.

To take advantage of this design ethos, but in a more conventional format, X-TUBE forms the conductor in the shape of a tube with an inner aircore. This has the same effect as using multiple insulated conductors and ensures that high frequencies are transmitted cleanly, with the added benefit of ease of termination. This unique tubular conductor geometry also provides lower flux density within the conductors, which gives improved transparency to the sound.


1.) At low frequencies both X-TUBE™ and conventional stranded/solid core speaker cable convey signals in a linear way. This is represented by the uniform green colour of the strands shown in the two diagrams above.

2.) At higher frequencies X-TUBE retains a near-linear signal transfer, whereas the conventional stranded/solid core cable fails to efficiently conduct higher frequencies uniformly across the entire conductor area. The diagram shows excess current density at the periphery (designated in red) and rapidly deteriorating current density (green through to white) towards the centre of the conductor.

The effect of this is to reduce the actual cross-sectional area of the cable at 15kHz to less than 75% of that at low frequencies. The result is induced distortion and a compromise in the performance of the cable.

X-TUBE with Aircore™ technology exhibits much lower self-inductance and is therefore less affected by this problem. The use of an innovative Polyethylene aircore enables a reduction in loop inductance to levels only usually achievable by using more costly and difficult to terminate cables.


We can terminate your cable with QED's superb 24 Carat gold plated AIRLOC termination plugs. AIRLOC is QED's specialised loudspeaker termination method and offers the very best termination with QED speaker cables. This is a solder-free, airtight fusion between the cable and plug and offers optimum signal transfer, excellent signal quality and perfect long-term performance.


We are pleased to offer a free cable burn-in service for this cable when purchased through us. The Nordost VIDAR cable burn-in machine combines three different functions all in one operation:

  • It neutralises charges that build up around the cables and the insulation

  • It provides a very wide band and deep conditioning into the conductor core, which produces changes in the way signals pass through the metal.

  • It ultrasonically conditions the surface of the conductors.

  • The VIDAR uses a proprietary combination of composite and complex signals to condition the cables. Parts of the signal oscillate at ultra-low frequencies, while other parts are in ultra-high ranges which extend beyond the range of video frequencies. The signal bounces in a ping-ping ball-like fashion from one end of the cable to the other. During the burn-in process, ultra-low frequencies penetrate deep into the core of the cable. The ultra-high frequencies zip along the surface. This method of signal transmission a set up beat harmonics, or heterodynes, between the two complex waveforms. In the digital domain, this would be referred to as aliasing products. These beat frequencies penetrate all layers of the cable.

    The design of the circuitry also has a unique feature which drives electrons above the conductor into the dielectric (or insulation) area. The VIDAR not only sends ping pong signals along the cable, it also sends a similar signal from the centre core to the outer shield in the case of interconnect cables. This function neutralises the electrical charges discussed above.

    So what does that all mean to me?
    The end result of conditioning cables with the Nordost VIDAR is improved sound staging, increased detail, and an overall more musical presentation.




    Simply select the length of cable, the type of plug and the termination required (one end or both ends) from the drop-down menus above and click on the 'Buy' button to add the item to your basket. Your cable will be dispatched within 24 hours subject to Future Shop Terms & Conditions.


    When AIRLOC Forte plugs are fitted to a cable they are subjected to such high pressure they undergo a process called 'cold welding' which transforms the plug and cable into one solid piece of metal.

    The graph below shows that when full pressure is reached, resistance is at a minimum. In addition, because all the air has been removed, there will be no degradation of sonic performance caused by oxidisation of the contact area, for the whole lifetime of your cable.

    NEW QED AIRLOC Forte plugs enable optimum performance and maintain signal integrity between amplifier and speaker.

    QED speaker cables only use 99.999% oxygen free copper, in many cases enhanced by silver plating.

    In Order to maintain channel tonal balance and minimise speaker cable resistance you should make sure your cables are of equal length.


Retail Price: £27.77
Our Price: £25.00
You Save: £2.77 (10%)
Availability: In Stock
QED X-Tube XT-400 Speaker Cable
Product Reviews for QED X-Tube XT-400 Speaker Cable
SKU: C-XT400/50

Average Customer Rating: 5 out of 5 stars.
Based On 7 of 7 reviews.
Product Reviewed: QED X-Tube XT-400 Speaker Cable
Submitted By: Jason Campbell on
Wow! These cables sound fantastic. Everything is so clear. I would like to thank Adam and Gary for such great support and service. Plus 3 and a half to four days to get to New Zealand. That's quick. Will be ordering more from Futureshop. Great stuff.

Rating: 5 of 5 Stars!  5 out of 5 stars.
Product Reviewed: QED X-Tube XT-400 Speaker Cable
Submitted By: Martin Verhoef on
I have bought several cables at futureshop and can say I am very happy with this webshop. The price is twice as cheap as in the Netherlands and also the shipping is very fast and reliable, even faster as in the Netherlands. They keep you informed about the shipment from their shop to your home, so you know exactly where the order is at the moment. About this speaker cable I only can tell I am very happy with it. The cable looks and sounds just great, with lot's of details in mid and high and a very steady bass. I would recommend this cable and futureshop to everybody, it is without any doubt one of the best webshops I know. Also the information on the website is very clear and if you have questions they are happy to help you. Keep up the good work!

Rating: 5 of 5 Stars!  5 out of 5 stars.
Product Reviewed: QED X-Tube XT-400 Speaker Cable
Submitted By: Akos Galacz on
I really enjoy having this cable for one month now! I purchased stunning performance and made a nice improvement with XT-400. Detailed low frequencies, vivid mid and sophisticated high frequencies. Never heard details appeared while listening to my 15 year old CDs. Delivery was quick. I got answers for my questions in no time, thanks to Adam. Dealing was a pleasure with Futureshop for me. Thank you! Akos from Hungary!

Rating: 5 of 5 Stars!  5 out of 5 stars.
Product Reviewed: QED X-Tube XT-400 Speaker Cable
Submitted By: Stephen Shepherd on
im a little late writing this review,but better late than never! great service and delivery,i was previously using silver anniversary xt before upgrading to the xt400,for anyone thinking of upgrading i can say with confidence do it,the xt400 is a massive improvement on the silver anniversary xt,none of the brightness of the cheaper cable,good even tonal balance,and good timing and integration and a far more musical cable,i used this cable with a roksan kandy amp and i was impressed with the massive improvements this speaker cable added to my system,far more detail,greater voice expression,this cable really let the amp perform to its full potential,revealing detail that i had never heard before,good value cable and a very good mid range upgrade.

Rating: 5 of 5 Stars!  5 out of 5 stars.
Product Reviewed: QED X-Tube XT-400 Speaker Cable
Submitted By: eric huizinga on
dispatched on monday arrived on wednesday, i've dealt with slower Dutch internet shops. Very nice speaker cables and 40 % cheaper than buying them in Holland. Absolutely to be recommended. E.Huizinga the Netherlands.

Rating: 5 of 5 Stars!  5 out of 5 stars.
Product Reviewed: QED X-Tube XT-400 Speaker Cable
Submitted By: jean marc bonnet on
Parfait! excellent produit vendu moitié moins cher qu'en france avec uniquement 4 jours de délai entre la commande et la livraison.

Rating: 5 of 5 Stars!  5 out of 5 stars.
Product Reviewed: QED X-Tube XT-400 Speaker Cable
Submitted By: Cyril Damestoy on
Oh my god... excellent cable, impressive upgrade from my Ecosse CS4.4!!! I'm living in Belgium and I received this cable 3 working days after my order, very quick delivery, special thanks to Adam ^^ I use 2x XT400 cable per front speaker (bi-amplification) and 1 XT400 for the center speaker (B&W 804S and HTM3S, surround are 805S with Silver Anniversary XT, electronic is Rotel RSP1098 and RMB1077, sources are Marantz SA15S1, DV6001 and Panasonic BD10A). What's best now? Stronger and cleaner low frequencies, very deep bass, detailed medium more than in the past, very analytic high medium and tembles but not too brilliant, no, very well balanced , at the end a very large bandwitch with high level of dynamic, details, and timbres. Plenty of new informations are now accessible with my system that was not poor in the past but now really optimized, using the XT400 from QED is like removing a curtain between my speakers and me. I also get a larger stereo and multichannel area, the sound spacialization is better, 3D deep effect vertically and horizontally. For sure this upgrade was a very good idea! I've also tested at the same price leve, the Ecosse MS2.3, MIT AVT3 cables and I feel better with the QED cable on my system (well in my system I assume that this may not be the same result with other components). This is a great upgrade for my system for sure, and I think I'll discover new subtleties in the next days! Thank you Futureshop for the excellent service and advice. The ailock banana plugs are very well mounted, and connexion with my system is strong and optimal. Airlock is a must-to-have accessory! Don't hesitate too much between XT350 or 400, go directly to the 400 it's not so much expensive and you'll not ask you the question in the future ''maybe I had to choose the 400 instead of the 250'' ;o) Cyril from Belgium.

Rating: 5 of 5 Stars!  5 out of 5 stars.
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