How Are Video Interconnects Different From Audio Interconnects?

What makes a video cable different from an audio cable? Many factors define a video cable, some of which are overlooked by wire manufacturers. The most important quality of a video cable is its characteristic impedance. Nearly all video components have an input and output impedance of 75 ohms, and it's important that a video cable maintain the same characteristic impedance for the best picture quality.

Transmitting video signals requires cable with a characteristic impedance of 75 ohms. Video requires more bandwidth than audio  a minimum of 4 million cycles per second (MHz) versus 20,000 cycles per second for audio. In the case of a line-doubled picture or other types of video processing, the bandwidth requirements can go as high as 100 MHz! Due to the non-specific impedance requirements of audio equipment, audio cables are not up to the task of conducting video information. Using audio cables in a video application will result in a loss of bandwidth, leading to a decrease the level of detail in a picture and other anomalies.

Interconnects that maintain a characteristic 75 ohm impedance from tip to tip are difficult to manufacture. One of the first considerations is the cable itself. Characteristic impedance is defined by the ratio of the center conductor diameter to the center conductor insulator diameter. This ratio must be consistent under all conditions, regardless of the twists and turns encountered in an installation. When the ratio of the cable is changed, as in the case of a "kink" in an installation, the impedance is altered and the cable's bandwidth is reduced. This variation will reduce the picture quality.

TRIBUTARIES® V1 and V2 video cables, featured in our SCV and DCV interconnects, are specifically designed to maintain the proper ratio between center conductor and insulator in virtually any installation. In order to preserve the internal geometry of the wire, multiple layers of insulators and shields are used. These layers allow the wire to move freely within the PVC jacket, preventing "kinks" from affecting the performance of the wire. For more information about the construction of V1 and V2 cables, just visit the TRIBUTARIES website or pick up our new Silver Series brochure.

The construction of a true 75 ohm video interconnect doesn't stop with the wire itself. Often overlooked, and just as critical as the wire itself, the connector impedance must be 75 ohms for maximum performance. Many interconnect manufacturers don't use 75-ohm RCA connectors, compromising the overall impedance and performance of their video cables. Our MCC75 RCA connectors used with our Silver Series video cables are true 75-ohm designs, as are all our BNC connectors. >

TRIBUTARIES SCV-C uses MCC75 TRUE 75 ohm RCA connectors

How can you tell if an RCA connector is a true 75-ohm design? As in the case of the wire discussed previously, the ratio of insulator diameter to center conductor size determines a true 75-ohm design. Just sight down the center pin and look at the insulator shielding it from the outer body of the connector. You'll notice the insulator has an unusually large diameter, much larger than the typical RCA video connector. This large diameter insulator is required for true 75-ohm performance, and can be found on the TRIBUTARIES MCC 75 true 75-ohm connectors.