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Coaxial digital audio (S/PDIF) cables run multichannel digital audio signals between home theater devices such as Blu-Ray players and A/V receivers, and support a wide variety of audio signal formats.�� The basic specification of a digital audio cable is straightforward: 75 ohm characteristic impedance, with coaxial geometry, terminated with RCA connectors at each end.�� The Blue Jeans Cable digital audio cable, made with Belden 1694A cable and Canare RCA connectors in our shop in Seattle, Washington, combines quality components with quality manufacturing.

The best 75 ohm coaxial cables on the market are made by Belden Wire and Cable (not to be confused with the similarly-named, but unrelated, consumer brand Belkin) for serial digital (SDI) video connections.�� These cable stocks have a usable bandwidth hundreds of times the bandwidth of a S/PDIF signal, and exceptional impedance stability -- that is to say, they stay within a tight tolerance of 75 ohms and do not suffer significant return loss.�� We use Belden 1694A for our digital audio cable; it has an 18 AWG solid-copper center conductor and a heavy 95% coverage tinned copper braid shield over a two-sided, fold-shorted, 100% coverage foil shield layer for top shield performance -- better than quad-shield.�� The cable is rated CMR, which allows it to be installed in walls or in risers in National Electrical Code jurisdictions.

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The original RCA connector design is a pretty simple affair,�� created in the 1940s for analog audio.�� While it is the standard connector type for coaxial digital audio, its electrical characteristics are less than ideal for digital signals with sharp rise times, because it's inherently not impedance-matched to 75 ohm cable, and it doesn't have the best grip characteristics.�� For these reasons we use Canare's RCAP connector, a three-piece crimp RCA plug that gives the best possible impedance match to 75 ohm cable, and that incorporates a clever concentric leaf-spring ground contact (see photo, left) to allow a strong positive engagement with the RCA jack, but without the overly-tight grip that can result from "turbine-style" RCA plugs seen on a lot of high-end cabling.�� These plugs are gold-plated -- not on the exterior body for show, but where it counts, on the pin and ground contact surfaces.
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These cables are assembled in our own Seattle cable assembly workshop.�� We maintain a stable workforce -- our employees have been working here for an average of over five years (due, we hope, to this being a good place to work!) -- and so have ample experience in careful, correct assembly practice.�� We use the very best precision cable stripping and crimping equipment, from Schleuniger in Switzerland, to ensure precise dimensional control and mechanical stability of our cables.�� Are these products over-engineered?�� Yes, they are; our commitment to quality means that when you use our cables, you never have to worry about whether the cable is the cause of some problem or underperformance in your home theater system.������ ��������������
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