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.
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 XT40 speaker cable and XT25.
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.