Overview QED Reference High Resolution USB Cable (AB)
QED presents the improved and updated cable - Reference High Resolution USB with a thinner and more flexible profile, and with improved performance.
Reference High Resolution USB is the result of extensive research into cable design, which began in 1995, recently detailed in the updated Genesis report. This report sets out the design principles to which QED adheres and which result in the development of a range of cables that represent the best expression of sound through uncompromising science. Each QED cable in the range is based on the top model, and although they may be influenced by price, size, ease of use, each maintains the original basic characteristics of that model. This also gives the basic cable a sonic advantage over competitors with a similar price. Reference High Resolution USB has the latest QED technologies and represents the pinnacle of understanding this complex application.
Impedance Controlled Data Lane
QED Reference High Resolution USB uses 99.999% oxygen-free copper conductors, 24 AWG, and has polyethylene foam dielectric, uniformly bonded to an aluminum/mylar sheath. This arrangement is similar to that used on high performance QED HDMI cables and is not normally used on USB cables. Because the impedance of the data band is kept strictly within the defined limits of 90 Ohm +/- 5%, with a rise time of only 100 ps for a 3m cable, it exceeds the specification given by the USB 2.0 standard by more than half; therefore, the synchronization error or the added jamming are minimized.
Ultra-low Jitter geometry
When measured using an analyzer at the correct data rate for high-bandwidth USB 2.0, the cable exhibits 50% less jitter than a comparable cable without a ferrite jacket. This shows, in conclusion, that the combined technologies of impedance-controlled data bands, insulated electrical conductors and ferrite jackets have the effect of halving the jamming induced in the digital transfer between source and receiver.
Clean Path Audio™ technology
Many audio enthusiasts say that using USB power cables that carry charging currents and power noise along with isochronous audio data streaming can have an adverse effect on sound quality. One solution is to remove the power cables, but this deviates from the USB specification and can cause inconvenience, especially if the DACs require USB power. Instead, QED Reference tapes are electrically isolated by using a double-layer shield, comprising a 100% aluminum/mylar shell.
High resolution sound
Although the highest resolution audio stream of 24/192 kHz or more (such as DSD) is well beyond the permitted data capacities of the USB 2.0 standard, synchronization errors caused by attenuation, propagation delays and characteristic impedance mismatches will result in increased jamming in the isochronous data flow. Depending on the reception capacity of the equipment, this jamming can produce audible problems with the digital audio signal. Basically, jamming causes signal distortions. This is due to the interaction of the required frequency with the jamming frequency. The distortion is similar to the version of intermodulation distortion, or THD, present in many amplifiers. Therefore, the QED Reference High Resolution USB is suitable for Hi-Res sound applications due to its unrivaled superior performance.
Ferrite Insulation™ technology
QED Reference High Resolution USB has a unique jacket, made of Zn/Mn. Using a proprietary process, QED was able to distribute this RF absorbing material evenly throughout the cable via an impregnated inner "jacket". It can absorb internally and externally generated high frequency noise signals. It works to produce a much quieter electrical environment inside and around the cable, so that jamming in the audio data stream is reduced to a minimum.