5.1-channel, 6.1-channel, and 7.1-channel inputs

These preamp-level analog inputs can be found on the back panels of some home theater receivers. A 5.1 input features jacks for 6 channels: left front, right front, center channel, left surround, right surround, and subwoofer (sometimes called "LFE" or "Low-Frequency Effects"). Because the LFE channel carries a limited range of frequencies, it's the ".1" in 5.1. A 6.1 input features the same jacks as a 5.1 input, but adds a back surround jack; a 7.1 input adds two back surround jacks.
Any of these multichannel inputs allow you to hook up a separate 5.1-channel surround sound (Dolby® Digital, DTS®) decoder, such as those built into some DVD players. You can also use these inputs with newer, cutting-edge 5.1-channel music sources like DVD-Audio and SACD players. The extra jack(s) in 6.1 and 7.1 inputs have no current functionality unless you happen to be using a separate surround preamplifier with 6.1 or 7.1 processing — the main function of these extra jacks on a home theater receiver is to keep you ready for future gear and future surround formats.

5-way binding post speaker terminals

5-way binding posts are a versatile type of terminal used for amplified, speaker-level signals, usually found on higher-quality speakers and receivers. This kind of terminal accepts 5 kinds of speaker wire connections: bare speaker wire, pin connectors, spade connectors, banana plugs, and dual banana plugs. Some binding post connectors aren't considered "5-way," because they don't accommodate every one of these connection types. Each speaker (or each output channel on a receiver) uses a pair of binding posts for a single connection: one for the positive speaker lead (usually red), and one for the negative lead (usually black).

75-ohm coaxial jack / plug

Sometimes called an "RF input," this kind of jack is commonly used for hooking up antennas, cable boxes, VCRs, TVs, etc. A 75-ohm coaxial cable can carry video and stereo audio information simultaneously. RF cable connectors (often called "F-type" connectors) either screw onto the 75-ohm jack, or just push on to connect. There are different types of coaxial cable. Standard coaxial cable is stamped "RG-59"; higher-quality "RG-6" cable features better shielding, and exhibits less high-frequency loss over longer runs. (For connecting DBS satellite systems, it's essential to use RG-6 cable to correctly pass the entirety of the digital signal.)

Analog audio minijacks

Most portable CD players, MD recorders, and computer sound cards use minijacks for their analog audio inputs and outputs. Portable players usually output sound via a single headphone minijack. Portable recorders usually add 2 additional minijacks: a line input and a microphone input. PC sound cards typically have at least 1 minijack line output; some also have a separate headphone minijack output. Like portable recorders, most sound cards also feature minijacks for line input and mic input (these permit you to record sound directly to your hard disk drive).

Most minijack connections are stereo; that is, they pass both a left and a right audio channel. However, some minijack connections (such as microphone inputs) pass just a single mono audio channel.

How we remember is stereo has 2 "lines" n the jack and mono has 1 "line."

Coaxial digital jack

This type of jack is used for the digital audio inputs and/or outputs on A/V components such as receivers, CD players, DVD players, and more. Coaxial digital jacks are also sometimes found on higher-end PC soundcards for digital audio input and output. Coaxial digital inputs and outputs use standard RCA-type jacks (so coaxial digital cables are terminated with standard RCA connectors). But the cable itself is specially designed to handle the much wider frequency bandwidth of digital signals.

Component video jacks

This 3-cable connection allows the chrominance (color) and luminance (brightness) portions of a video signal to be processed separately. S-video works similarly, but component video improves color accuracy further by splitting the chrominance signal into two portions. Component video connections are found on most DVD players and HDTV tuners, and on a growing number of TVs and A/V receivers. However, this type of connection can vary in bandwidth from unit to unit. To pass progressive-scan DVD signals without noticeable softening of the picture, a component video connection should have bandwidth of 12 MHz or higher; passing HDTV signals without softening requires bandwidth of 30MHz or higher. If you are only slightly shy of the required bandwidth for the signal you're viewing and your TV is 36" or less, the picture softening may be extremely subtle, or even unnoticeable.

Composite video jack / plug

A composite video input or output uses a single standard RCA-style jack to pass video signals. This type of connection combines chrominance and luminance information, sending it along a single cable. Though capable of delivering a high-quality picture, composite video is not as accurate as either S-video or component video, both of which provide separate paths for chrominance and luminance. Commonly found on A/V components like DVD players, VCRs, TVs, DBS systems, etc., composite video jacks are often grouped with corresponding stereo audio jacks (the composite video jack is usually yellow). Though they use standard RCA-type connectors, composite video cables are specially designed to maximize video signal transfer.

DVI (Digital Visual Interface) jack

DVI is a multi-pin connection used for passing standard-definition and high-definition digital video signals, found on HDTV tuners, a growing number of DVD players, HDTV-ready televisions, and some computer displays. DVI connections transfer video signals in pure digital form, which is especially beneficial if you're using a "fixed-pixel" display (like a plasma, LCD, or DLP TV). Signals are encrypted with HDCP (High-bandwidth Digital Content Protection) to prevent recording. There are actually two types of DVI connections. DVI-D, which is the type of DVI connection found on most home video gear, carries digital-only signals. DVI-I, used with some computer video cards, is capable of passing both digital and analog video signals. Some TVs feature DVI-I inputs for greater hookup flexibility.

Ethernet card

The most popular form of Network Interface Card (NIC) available, Ethernet cards allow PCs to interface with one another over home networks and broadband Internet connections. The very popular 10/100 Base-T Ethernet card — now a standard inclusion on many new PCs — allows transmission speeds of either 10 Mbps (megabits per second) or 100 Mbps, automatically self-adjusting to the proper speed for the type of connection being made. With this flexibility, Ethernet cards are capable of a particularly wide variety of connection options.

Game/MIDI port

MIDI stands for Musical Instruments Digital Interface. The MIDI protocol lets PCs and electronic musical instruments (like digital keyboards and sequencers) share performance data with each other. Today, another very popular use for this port type is as a joystick interface for many PC games. (Also called game ports.) Musical instruments use a different type of jack for MIDI connections. To connect a MIDI-capable instrument and PC, you'll need a special adapter cable.

i.LINK port

i.LINK, also known as IEEE 1394 or FireWire™, is an extremely fast (up to 400 megabits per second), two-way digital connection used between computers and peripherals like digital camcorders. It is used in digital camcorders because it is one of the few connections capable of quickly transferring full-motion video. Most consumer video equipment uses 4-pin i.LINK ports and connectors, but some peripherals employ a 6-pin i.LINK configuration.

Mini-optical jack

This type of jack is commonly used for the digital audio input and output of portable audio devices. A mini-optical jack is the same shape and size as a standard analog audio minijack. This allows portable MiniDisc recorders to use a single input jack that accepts both mini-optical connectors and standard analog audio minijacks. The MD portable detects whether you're making a digital or an analog connection based on the type of cable you're using, and automatically selects the appropriate recording mode.

Optical digital jack (Toslink)

This type of jack is commonly used for the digital audio inputs and outputs on home A/V components such as receivers, CD players, full-sized MD recording decks, DVD players, and more. Also, some higher-end PC sound cards offer digital input and output using Toslink jacks. Toslink jacks and connectors usually come with protective caps which need to be removed before connections are made.

Parallel port

The parallel port is one of the oldest PC-peripheral connection technologies still in existence. As such, it's significantly slower than many of the connection types that have followed in its wake — particularly USB and i.LINK — and its popularity has declined correspondingly. The parallel port most often takes a 25-pin connector, and in years past was very commonly used to connect printers and other external devices to PCs. Today, many new PCs (but almost no peripherals) offer parallel ports, although adapters are available for people wishing to connect a newer device to an older computer via a parallel port.

PCI slot

PCI is an acronym for Peripheral Component Interconnect. As the name implies, this is a slot that allows you to connect various peripheral devices to your PC, such as ethernet cards, sound cards, and TV tuner cards. The slots themselves can only be accessed by opening your computer's case, so they're not designed to support the frequent peripheral-swapping you can do with connection technologies like USB and i.LINK.

Phono (turntable) input

When a turntable plays a vinyl record, it produces an audio signal that's considerably different from the standard line-level signal output by CD players, tape decks, and other components. Not only is the phono signal much lower in voltage, but the process of vinyl mastering involves applying a special equalization curve that cuts low frequencies and boosts highs. (This prevents the "overcutting" of grooves, and minimizes noise.) Many receivers feature a specialized phono input intended for turntables only. The signal coming from this input is sent to a dedicated preamp circuit which applies inverse equalization and boosts the signal up to the standard line level — resulting in proper sound from your turntable. (Keep in mind that feeding an ordinary line-level signal into your receiver's phono input will probably result in horrific distortion, and could actually damage your amplifier and speakers!) Receivers with a phono input also feature a ground screw for connecting your turntable's ground wire. (Neglecting this connection can result in an audible hum from your system.) If your receiver or preamplifier doesn't have a specialized phono input, you can use an in-line phono preamp, which allows you to connect your turntable any regular line-level input.

PS/2 keyboard port

The keyboard port used by virtually all Windows®-based PCs, employing a 6-pin configuration. Many CD mega changers with memory for disc and song titles now feature their own PS/2 jack — this allows you to plug in a keyboard for speedy naming of your CDs. Additionally, some PC-friendly peripherals Y-jack into your PS/2 port as a source of power.

RGB (D-sub 15-pin) jack / plug

Found on some HDTV-ready TVs and HDTV tuner boxes, RGB connections are used for transferring video signals, including high-definition content. As implied by its name, RGB sends the red, green, and blue components of the video signal along separate paths. Though RGB connections can take a number of forms, one that's increasingly common on TVs and set-top boxes is the D-sub 15-pin jack. If you own a computer, D-sub 15-pin connections may look familiar — they're the same ones found on standard VGA-type computer monitors. RGB connections pass video signals in the analog domain.

RJ-11 and RJ-14 phone/modem jacks

PC modems, DBS receivers, hard disk video recorders, and other kinds of A/V gear use these jacks for sending and receiving information via a telephone line. Usually computer modems feature a second phone jack — this allows you to plug in a telephone that will be operational whenever the modem is not in use. RJ-11 jacks and connectors allow for the transmission of a single phone line; RJ-14 connections can carry two separate phone lines simultaneously. The connectors for one type will fit into the jacks of the other, but if you plug an RJ-14 cable into an RJ-11 jack, you'll lose the ability to access the second line from the computer and/or phone thus connected.

Serial (RS-232C) port

A serial port, or RS-232C port, is an interface that provides low-speed communication between your PC and attached devices (such as digital cameras, printers, and more). Because it is so slow in comparison to newer connections (like USB or i.LINK), fewer and fewer peripherals offer serial connections, and new PCs tend to provide only one serial port, if any. Serial ports most frequently take a 9-pin connector, although a number of older peripherals employ 25-pin serial ports.

Speaker wire (no connector)

Speaker wire consists of two leads, typically encased and bundled in plastic insulation — one for the positive signal, and one for the negative. Usually, speaker wire is marked (+) and (-) to help you distinguish between the two. Though it's not an ideal long-term installation method, you can connect your speakers and receiver using just the bare, stripped ends of your speaker wire. Drawbacks to this approach include: 1) Stray wire strands, if not properly twisted, could make contact with the cable's other lead, and cause a potentially harmful short circuit and 2) Bare wire ends corrode, since they're made of copper. Most speaker wire connectors, on the other hand are usually coated with a corrosion-free material, such as gold.

Speaker wire connectors

All kinds of speaker wire connectors are designed to accomplish the same job: to make solid electrical contact between your speaker wire and your gear. By using speaker wire connectors, you reduce the risk of a short circuit caused by frayed wire strands. And since speaker wire connectors usually have corrosion-free contacts, they help maintain optimum connection over the long term. There are 4 main kinds of speaker wire connectors:

• Pins. Pin connectors may either by straight or angled. They work with spring clip speaker terminals, as well as with binding posts.

• Spades. Spade connectors feature a forked piece of metal, designed to hug the collar of a 5-way binding post terminal. The spade is then secured by tightening the binding post's cap. Spade connectors give you very secure contact.

• Banana plugs. If you have binding post terminals on your speakers and/or receiver, banana plugs are a great choice. The flexible metal collar of a banana plug is slightly wider than the center hole of a binding post. It compresses to fit when you plug it in, resulting in a very solid connection. Banana plugs are extremely quick and easy to hook up.

• Double-banana plugs. The same as banana plugs, except the positive and negative banana connectors are both fixed in a molded housing that spaces them 3/4" apart. (These are even quicker and easier to connect than regular, single banana plugs — as long as the terminals on your speakers and/or receiver are true 5-way binding posts with the proper spacing.)

Spring clip speaker terminals
Spring clip terminals are a type of connection used for amplified, speaker-level signals, usually found on lower-priced speakers and lower- to medium-priced receivers. Spring clips accept bare speaker wire, as well as pin-type speaker wire connectors. To make the connection, just push the spring-loaded lever, insert the wire (or connector), and release. Spring clips are sometimes also referred to as "push terminals." Each speaker (or each output channel on a receiver) uses a pair of spring clips for a single connection: a red one for the positive speaker lead, and a black one for the negative lead.

Stereo RCA jacks and plugs

RCA connections are the standard means of passing analog line-level (or "preamp-level") audio signals between components. RCA jacks are commonly found on most types of A/V gear: receivers, CD players, turntables, MiniDisc recorders, cassette decks, VCRs, DVD players, and more. The audio inputs and A/V inputs found on receivers are RCA connections (though some A/V inputs may also include a different type of jack — such as S-video or component video — for the "video" portion of the signal). Usually, RCA jacks, connectors and cables are grouped in stereo pairs, with one connection for the left audio channel and one for the right. However, some components (such as many powered subwoofers) use a single mono RCA jack for audio input and/or output. (Note that a turntable's RCA jacks output a signal that's significantly different from standard line-level signals; hookup requires a specially designed phono input or an in-line phono preamp.)

S-video jack

Found on DVD players, DBS receivers, Super VHS VCRs, TVs, and other kinds of A/V gear, S-video inputs and outputs use a round, 4-pin jack to pass video signals. The "S" in S-video stands for "separate": S-video connections transmit the chrominance (color) and luminance (brightness) portions of a video signal along different paths, allowing them to be processed separately. S-video provides a sharper picture than composite video. However, component video connections yield even better performance than S-video by further dividing the chrominance portion of the video signal.

USB audio adapter

A kit that allows you to output PC audio signals from a primary USB port on your computer to an external component, such as an MD recorder or A/V receiver. Unlike the analog output of your PC's line-out jack, audio signals exported via USB are still in pristine digital form when they leave your PC. This offers you two big benefits on the sound quality front. First, you skip the low-quality digital-to-analog (D/A) conversion employed by many PC sound cards. Second, no analog audio routing or processing takes place within your computer's case, which is a hotbed of electrical activity that can easily muddy the clarity of audio signals.
If you use a USB-to-digital audio adapter, this signal is then passed on directly to the digital input of the connected component. If you're using a USB-to-analog adapter, the signal is converted to analog by a high-quality inline D/A converter before being passed on to the audio component's analog input. You can also use an analog USB adapter to connect your powered speakers for better sound quality than you'd get by plugging them into your PC card's line-out minijack.

a

b

USB port
USB (Universal Serial Bus) is a "plug and play" interface between a computer and peripherals (like audio players, digital cameras, joysticks, keyboards, and printers), which lets you plug in a device without adding an adapter card or even restarting your PC. Its speed makes it ideal for music and digital still transfer. USB 1.1, the familiar USB standard of the last several years, supports a data transfer speed of 12 Mbps (megabits per second) — significantly faster than a serial connection. Though USB 1.1 can't compete with i.LINK (which maxes out at 400 Mbps), the new USB 2.0 standard is even faster — 480 Mbps! That kind of speed makes USB 2.0 suitable for transferring demanding files like full-motion video, etc. Today, most new computers (both IBM-compatible PCs and Macs) and many peripheral devices are equipped with USB; for example, USB support is integrated into Windows® 98, 98SE, 2000, 2000SE, ME and Windows XP, as well as Mac OS 8.6 and up. USB 2.0 is not as common yet. Fortunately, all USB 2.0 devices are backwards-compatible with existing USB 1.1 devices. USB ports are expandable with the addition of hubs, which allow you to connect several peripherals simultaneously through a single USB port. Many newer PCs offer multiple USB ports, often placing one or more on the front of the case for easy access. Note however, that usually only one port is designated the primary USB port, and some peripherals will not work when plugged into secondary ports. There are three types of USB connectors. The USB Type A, connector plugs into the USB port on your computer. The USB Type B, connector plugs into a peripheral device (such as a monitor or printer). Some smaller devices like cameras and USB audio adapters feature a smaller version of the Type B jack, known as mini (Type B). These devices typically include a Type A-to-mini-USB (Type B) cable.