Cardas Parsec Digital, digital coaxial cable
Between a CD player and a digital-to-analog converter, the coaxial connection carries data, but how it carries that data matters: a cable with varying impedance distorts the signal edges and makes the receiver’s job harder. The entry-level model in the Cardas digital cable range, the Parsec Digital replaces the former High Speed Data with a more flexible jacket, better-made connectors and a construction derived from the analog Parsec range.
A 75-ohm impedance maintained from end to end
The coaxial S/PDIF standard specifies a 75-ohm impedance for the source output, the converter input and the cable connecting them. When these three values match, the signal passes from one device to the other without bouncing back; when they differ, some of the energy is reflected at the ends and blurs the transitions between digital signal states. The bits still arrive, but the precise timing of each transition becomes less distinct, and it is this timing uncertainty, or jitter, that the converter must then absorb. In the Parsec Digital, the 75-ohm impedance results directly from the cable’s geometry, namely the conductor’s diameter and its distance from the shielding through the chosen insulating materials. The actual benefit also depends on the converter: a model with an effective reclocking stage is less sensitive to the quality of the connection than a simpler receiver.
Six-nines copper with individually enameled strands
The central conductor is grade 1 oxygen-free copper with 99.9999% purity, the same copper used in Parsec interconnect cables. It consists of strands individually coated with clear SPN enamel, following the Litz wire principle: insulated from one another, the strands do not exchange current, and the enamel protects the copper from oxidation throughout the cable’s life. The strand diameters follow golden ratio proportions, an approach developed by George Cardas and found throughout the brand’s production, and the layers are wound in a cross-field geometry, with each layer wound in the opposite direction to the previous one to limit the conductor’s natural resonances. PTFE insulation, the material known as Teflon and valued for its low losses, surrounds the assembly.
Double shielding held at a distance by air tubes
Around the insulation, low-density polyurethane air tubes are held together by FEP tape, a fluoropolymer similar to PTFE. These tubes keep the shielding at a uniform distance from the conductor, and this stable distance determines the impedance along the entire length; air, one of the best insulators available, also reduces the amount of solid material in contact with the signal. The shielding combines two layers: an aluminized polyester film that covers the entire circumference and blocks high-frequency interference, and a tinned copper spiral that ensures ground continuity. The dark green outer jacket, more flexible than that of the High Speed Data, shares the color of the other Parsec cables. The cable remains lightweight and bends easily, making it easier to route behind furniture without putting strain on the devices’ RCA sockets. This flexibility has a logical trade-off: a very tight bend or crushing locally changes the gap between conductor and shielding, and therefore the impedance, so it is better to guide the cable through gentle curves rather than bend it sharply.
GRMO connectors in rhodium-plated eutectic brass
The ends are fitted with Cardas GRMO RCA connectors whose bodies are made from eutectic brass, a non-magnetic alloy that melts and solidifies at a single temperature, without an intermediate phase, giving it a homogeneous structure. These bodies receive an undercoat of silver, an excellent conductor, followed by rhodium plating. A very hard metal, rhodium resists wear from repeated connections and corrosion, whereas silver alone would eventually tarnish; its bulk conductivity is lower than that of silver or gold, but as a thin layer it maintains excellent contact that does not deteriorate over time. The gold-plated brass shell protects the connector and provides a good grip without forming part of the signal path. The cable is terminated by hand at the Cardas workshop in Bandon, Oregon.
The devices connected by the Parsec Digital
Most CD players, transports and network players feature a digital coaxial output, and the corresponding input is found on converters, integrated amplifiers with a digital section and many home theater amplifiers. The Parsec Digital carries stereo PCM up to 24-bit/192 kHz, depending on what the devices support, as well as compressed Dolby Digital and DTS 5.1 streams; lossless cinema formats (Dolby TrueHD, DTS-HD Master Audio) and full-resolution Dolby Atmos require an HDMI connection. Compared with a Toslink optical connection, coaxial supports higher sampling rates on many devices, with optical often limited to 96 kHz. However, it electrically connects the grounds of the two devices, whereas optical fiber isolates them: when hum is caused by a ground loop, optical retains an advantage. For devices equipped with BNC sockets, the Parsec Digital is also available in a BNC version and a mixed RCA-to-BNC version.
