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Guide to purchasing audio/video cables
A high-quality cable should be made of copper or silver, considered two of the best conductors of electricity. Fiber-optic cables, which use light to transmit signal are considered to be the best conductors of audio signals. They have little to no electrical resistance. Any cable made of aluminum is a poor conductor and should be avoided.
Thick cables are best. The thicker the cable, the less electrical resistance, and the less the audio/video signal has to struggle to get from one end to the other. Different manufacturers use different gauges of wire for the cables that connect audio/video components. However, with speaker cable, the choice is yours. They come in all flavors, from 10-, 12-, 14- and 16-gauge speaker wire. (The lower the gauge number, the thicker the cable.)
The 75-Ohm Rule
Speaking of resistances, a very important number for video cables… 75-ohms of impedance. What is impedance? In short, it is the measurement of a cable's resistance to the flow of audio and video signals. The more resistance, the more trouble these signals have getting from one end of the cable to the other, and the worse your picture clarity and color will be. When shopping for video component or interconnect cables, always check the packaging for a nominal 75-ohms of impedance. Even some of the better cables on the market are barely pushing 75-ohms. The wires itself are compliant, but the connectors are not, so signals run into resistance at both ends of the cable. Almost always, the cables that come with your DVD, TV, or receiver will never have 75-ohms of impedance. Always look for this number when shopping for cables, especially when using them to hook-up video components. It is usually listed under 'Nominal Impedance.'
In addition to transmitting the cleanest, clearest signals, high-quality cables should also provide shielding from the rough and tumble world. Audio/video signals are constantly bombarded by other electronic and magnetic signals traveling about in nearby wires or antennas – interferences from appliances such as a microwave, cell phone, AM/FM radio, wireless LAN, etc. Look for cables that use braided copper shielding or some kind of foil shielding, or better yet, look for both.
In addition to getting quality cables, try these wiring techniques for improvements:
1. Keep the length of cables as short as possible. The shorter the distance your signal have to travel, the less resistance it sees, the better the signal.
2. Don’t wrap cables together. Binding cables may create a cleaner environment, but it can also increase the interference between the wires. If you must bind cables together, keep all power cords and signal cables separate and perpendicular.
3. Avoid sharp bends. With cheaper cables, this leads to signal loss and a ghosting effect in video cables.
4. Use better signal splitters. Poor quality signal splitters are the main source of signal loss and bad quality image. I have found that Radio Shack cable splitters are very poorly manufactured. I recommend obtaining a few from your local cable installer. They are of better quality and priced the same.
Video Cables – 75-ohms, shielded
Video cables may be the most important and sensitive cables in your system. The signals that are being passed through the cables are in the megahertz range. Regular NTSC signals run at 8-10MHz, HDTV signals operate at 35MHz. The higher the frequency of signals, the more critical it is to have a 75-ohm total impedance (wires and connectors), and adequate shielding.
Analog Audio Cables
Analog audio cables interface with high impedance components, usually over 10,000 ohms for receivers, pre-amps, and amplifiers. They operate at lower frequencies, usually from 20Hz to 20,000Hz. It is important to use twisted pair cables, for the geeks out there – CAT5, or use shielded coaxial cables. Shielded Coax cables with RCA connectors usually provide lower capacitances and better shielding than twisted pair shielded cables. However, coaxial cables tend to be more expensive, and due to its solid core wires, it will be more difficult to route through in tight places.
Digital Cables come in three flavors, coaxial, fiber-optic, and Toslink. The purpose of these cables is to pass a 44.1 - 48kHz signal from your Dolby Digital, DTS, or PCM source. When using coaxial cables, a good 75-ohm video cable will do. When running cables for longer distances (greater than 10 feet), use Toslink or fiber-optic. They are less susceptible to signal loss and interferences. It is acceptable to run optical cables parallel to power cables. When purchasing optical cables, I recommend looking for ones with a locking mechanism. Optical cable connectors are very light and flimsy, and tend to get damaged by the weight of other cables in your system.
Of course to every rule, there is an exception, and make this article a complete hypocrisy. Despite everything that’s been said in this article, speaker cables are not as important you may have been led to believe. For distances of less than 20 feet, 14- or 16-gauge speaker wire is sufficient. For longer distances, or better performance, use the larger 10- or 12-gauge speaker wire. Most high-end speakers today are internally wired with 14- to 16-gauge copper wires to begin with. What is important is the type of connectors you use with the speakers. You want to make the tightest connection to minimize contact resistance. I recommend using spade connectors or banana plugs.
Highly praised and recommended by enthusiasts. Cobalt Cable sets the standard for build quality and performance. All of their cables have a braided, black, nylon wrapping around it. Each connector is terminated with a very rigid and snug Vampire Wire banana plug connector, which Cobalt Cable regards as the best connector available. When you have one cable company praising another, you know its got to be good. All Cobalt audio/video cables adhere to the 75-ohm impedance rule. The video cables (component, composite, and S-Video) are shielded with at least 93% copper braided and 100% foil shielding. Audio cables have a double layer of at least 92% copper braiding. Their speaker cables are made of 10-gauge wire, and are pre-cut and crimped to specified lengths. Cobalt Cable can be purchased directly from the manufacturer at www.cobaltcable.com or calling them at 1-877-6-COBALT.
One of the most widely available cables on the market. They offer all kinds connectors and cables, from consumer-level to professional use. Monster Cable claims that all their cables offer 75-ohms of impedance, even when bent around corners. Their Standard® line of video cables offer 95% copper braiding and 100% foil shielding. The Standard® audio cables use 100% foil shielding. The Original and Navajo brand of cables use 12-gauge wiring and are sold by the spool so you can measure, cut, and crimp yourself. Monster Cable offers a tremendous range of products, so I recommend going to the store and checking out the specifications on the packaging. Monster Cable can be found at almost every home electronic store, Best Buy, Circuit City, Fry’s Electronics, J&R, etc.
Many privately owned home audio/home theater stores make their own line of cables, usually cheaper than what Cobalt Cable or Monster Cable has to offer, and of similar quality. BetterCables.com is a very highly regarded cable manufacturer and store. United Home Products (866-4U AUDIO) offer DH Labs Cable. Parts Express is a great online store with even better prices on DIY parts. Check the cable specifications before buying.