The QED Performance USB A-B Graphite sits in the middle of QED's three-tier USB cable range, above the entry-level Connect USB and below the Reference USB A-B. Where the Connect provides a solid foundation with 99.99% OFC conductors and basic shielding, the Performance Graphite adds triple electromagnetic screening and isolated power and data conductors to address the specific demands of high-resolution digital audio transmission.
Construction
Signal conductors are 99.999% oxygen-free copper in a 7/0.127mm, 26AWG twisted-pair configuration, insulated with low-density polyethylene (LDPE) for its favourable dielectric properties. The power and ground conductors are heavier-gauge 7/0.2mm, 22AWG OFC with PVC insulation, run separately from the data pair to prevent power-line noise from contaminating the audio signal.
Shielding is applied in three layers: an aluminium Mylar wrap around all four conductors, followed by a 90% coverage braid of five-nines copper. This triple electromagnetic screening is designed to reject external interference that could introduce timing errors into the data stream. The outer jacket is a flexible pearlescent graphite PVC.
Performance
QED specifies the Performance USB A-B at a typical jitter figure of 21 picoseconds RMS — a meaningful reduction over unshielded or single-screened cables. The cable meets and exceeds the USB 2.0 specification, supporting HD audio DAC applications up to 24-bit/192kHz. Characteristic impedance is controlled at 90Ω ±15Ω, with delay skew held below 100ps/m and attenuation measured at 5.8dB at 400MHz.
For comparison, the step-up Reference USB A-B achieves 12ps RMS jitter through the addition of an integral zinc-manganese floating ferrite jacket and fully electrically isolated power conductors — technologies that justify its higher price point.
Application
The Performance USB A-B Graphite is intended for connecting a computer, laptop, or network storage device to a USB DAC or headphone amplifier with a Type-B input. The 24k gold plated, shielded connectors ensure a reliable, low-resistance connection at both ends.
