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AV Education on MHT

Cables and Connectors – A Glossary of Terms
Written by Jeremy R. Kipnis
December 2005

Introduction
Although many people don’t really think about it, cables and the connectors on each end are actually components in your audio or video system. Without them, there would be almost no way to get a signal from one source component to another or to a display. Clearly, the quality of this cable and associated connectors are of the greatest importance to a system’s ultimate quality and transparency. Yet, few audio or videophiles really know the terminology or the history involved with this complex mechanism for coaxing a signal to go down a wire or fiber while adding as little distortion as possible.

POWER CABLES
Power Cables carry a 60-cycle medium to high-voltage 13,800 volt (11 kV in the U.K.) single-phase alternating current to a transformer near a home or business. From there, it is stepped down to create the 100-240 volt mains voltage usable by your audio and video components. They are made of 10-gauge solid core aluminum wire, bundled and shielded together into sizes sufficient to carry the required current. Most local A/C is delivered over a bundle of 48 – 64 of these conductors.

Power Cords connect the 100-240 volt A/C mains voltage (usually 15 – 30 amperes) to each component. American, Canadian and Japanese power cords are usually bulkier than A/C mains cables found in the rest of the world, due to their higher current requirements (110 V compared to 230 V). Beginning in the early ‘90s, various audio cable manufacturers began to offer an ever-widening array of specialty power cords for audio and video products that featured a detachable IEC connector, to be sold alongside their speaker wires and interconnects. Many of these designs have proven to make a difference in performance, but despite having A/C power available for over 110 years, very little science exists to support this claim.

IEC Connectors (60320 C13) (also known as an IBM Plug for its use on their earliest computers) are featured on the appliance side of an A/C power cord. It mates to an IEC socket (60320 C14), which is chassis-mounted to the source component. They feature three pins, with hot and neutral flanking the ground in the center. Although quite common today on audio and video components, captive power cords remain the norm for most A/V products.

Power Plugs are the male-featured interface that connects to an A/C mains wall socket. They are usually made of brass, plated with tin or nickel. They feature a live contact, a neutral contact and an optional earth ground, making up the common two- and three-pin configurations in common use.

Power Sockets, also known as a Duplex Receptacle when presented as a pair of outlets, are the female counterparts for power plugs and are found in both two- and three-contact versions. While usually made of brass with various platings, hospital and audiophile-grade products can feature polished phosphor brass components and utilize exotic metals such as 24k gold and/or platinum. Building codes throughout the world now require three contact earth-grounded Duplex Receptacles as standard.

Single Phase power is used in most households, with all current (117 V in the U.S. and Canada, 100 V in Japan and 230 V elsewhere) delivered via the live (or “hot”) contact. The neutral contact should ideally carry no voltage or current if a plugged-in component or device is functioning properly.

Balanced Power (split-phase) is a special case in which the single-phase mains power is split, so that exactly half the voltage is present on the hot contact and the other half is carried on the neutral contact. If executed to a very high degree of accuracy (as done by the Equitech Company), the resulting Common Mode Noise Rejection cancels out any noise that is common to both conductors. Measurably lower distortion of the A/C mains signal results in improved performance and perceived playback accuracy. In this case, the third earth pin ground is necessary to define the null point or 0 V for the CMNR to be 100 percent effective.

Next topic, Signal Cables...

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