by Gary Malick
ATUS Classroom Services Technical Supervisor
Most of the questions we receive here at Classroom Services about audio systems and signals can be broken down into three categories:
XLR - A type of audio connector featuring three leads: two for the signal and one for overall system grounding. A secure connector often found on high quality audio and video equipment. Most often used for microphones.
1 & 2 - XLR female plugs 3 - XLR male plug
1 - XLR male jack 2 - XLR female jack 3 - mounting plate
RCA Connectors - a type of connector most often used with line level audio signals and composite video, also known as Phono plugs.
1 - 6 various types of RCA male plugs
Mini (3.5mm) - a connector used for both microphone and line level audio, can be stereo or mono. Quite ubiquitous with computer audio as well.
Mini male stereo plug (note two black insulator rings)
Mini male mono plug (note one black insulator ring)
Mini jacks (as seen on computers)
¼" Phone plugs - An older style connector used with head phones and some microphones, also seen on professional sound gear for line level inputs.
1 & 2 - mono phone plugs (note one insulator ring)
3 & 4 - stereo phone plugs (note two insulator rings)
In order for a microphone to function it needs to be used as part of a complete sound system which includes a pre-amp or mixer, an amplifier, a speaker and all of the associated cables. So when you call Classroom Services and ask for a microphone be sure you let us know exactly what parts of the system you need.
Microphones are delicate devices designed to detect very slight changes in air pressure (sound waves). To ensure the best performance please treat them with the utmost care. Never tap or thump a microphone to check it, just speak into it with your normal voice.
For more detailed information on microphones please check
Condenser Microphones - These microphones have internal amplifiers which need either battery or external (phantom) power provided through the microphone cable from a mixer or special phantom power supply. These microphones are normally more sensitive and smaller than dynamic type microphones.
Dynamic Microphones - A type of microphone that uses magnetism to turn sound waves into electricity. These do not require batteries. They tend to be slightly larger and more rugged.
Lapel/Lavalier Microphones - These used to be two separate types of microphones , one that would clip on to your lapel and one that would hang by a strap around your neck. The terms are interchangeable these days. These mics are very small, can be wired or wireless and have various pick up patterns. When wearing these mics try to keep them as close as you can to your mouth.
Wireless Microphones - Most mics use a cable to connect them directly to the sound system or recording device, some mics utilize a wireless radio link to provide that connection and are referred to as wireless mics. Basically any microphone can be made wireless; handheld, lapel, omni, uni etc. The wireless mic is called the transmitter, it is battery operated. There is also a receiver that connects to the sound system or recording device, this receiver can be battery or AC powered. For further details on wireless microphones see www.lectrosonics.com/wg/wg2000.pdf
Pick up patterns - The sensitivity of the microphone as to which direction the sound is coming from. Some of the different types are listed below.
Omni-directional - Mic picks up sound equally in all directions; it does not matter which way the mic is pointed.
Uni-directional (or Cardioid) - Mic picks up sound coming from one direction more than another, usually from the front. As sound approaches from angles more to the rear, sound pick up is diminished. The term cardioid from the latin word for heart is used because the diagram of the pick up pattern is in the shape of a heart. You will also see the term Hyper-cardioiod or super-cardioid when the mic has a very narrow pattern.
In the audio world there are basically 4 different signal levels. They are defined below. Please see notes after last definition.
You cannot mix signal levels; that is, even if the physical shape and size of a connector looks the same or fits a connection, the electrical characteristics of the signals each type carries are different. For example, you can't plug a microphone input into a line input on a VCR or take a line output and try to drive speakers with it. Nor does using an adaptor change the signal level. Using a XLR to RCA adaptor does not change the signal level of a microphone -- a preamplifier does that.
Component video - Color television systems start with three channels of information: red, green, and blue (RGB). In the process of translating these channels to a single composite video signal, they are often first converted to Y, R-Y, and B-Y. Both 3-channel systems, RGB and Y, R-Y, B-Y, are component video signals. They are the components that eventually make up the composite video signal. Higher quality program production is possible if the elements are assembled in the component domain. This type of signal is usually found on DVD players using RCA jacks.
Component video jacks found on DVD player
Composite Video - An all-in-one video signal comprised of the luma (black & white), chroma (color), blanking pulses, sync pulses and color burst. This is the signal found on the yellow jack on the back of most VCRs and DVD players. The connector most used for this signal is the RCA.
Composite video jack
DV Mini tape - All of the digital video camcorders owned by ATUS record video and audio on a Mini DV tape. The cassettes measure 2.6 x 1.9 x 0.5 inches (L x W x H), while the tape itself is only .25 inches thick. A Mini DV tape that is 65 meters long can hold an incredible 11GB of data, or 80 minutes of digital video.
DV mini tape cassette
The small size of DV minitapes has helped camcorder manufacturers reduce the size of their video cameras significantly. Some consumer cameras that use DV minitapes are smaller than the size of your hand. Because DV mini tapes store data digitally, the footage can be exported directly to a computer using a Firewire (IEEE 1394) cable. If you want to record video and edit it on your computer, avoid the SVHS and Hi-8 options and be sure to get a camera that uses DV mini tape.
Firewire - Also known as i-link, 1394 or IEEE-1394 is the fastest and highest quality way to transfer your video. A data communication standard used with digital camcorders,the IEEE 1394 is the standard for transferring digital video and audio signals at a very high rate of speed and quality. This puts broadcast quality video footage directly into your computer or DV (digital video) editing system. FireWire supports data transfer rates of 100 to 400 Mbps.
Four pin firewire jack
Four pin firewire plug
Six pin firewire plug
NTSC - National Television Standards Committee - the television standard for North America and parts of South America having 525 lines/60 Hz (60 Hz refresh), two fields per frame and 30 frames per second.
PAL - Phase Alternate Line - the TV standard used in most European countries, South Africa and Australia. PAL uses a 625-line, 50-field composite color transmission system. It is a television standard in which the phase of the color carrier is alternated from line to line. This alternation helps cancel out phase errors. For this reason the hue control is not needed on a PAL TV set.
RCA Connectors - connectors that are used with both audio and video signals such as composite video, line level audio and component video. Also referred to as phono plugs.
RCA connectors used with line level audio are often red and white (stereo)
RCA connector used with composite video
RGB & RGBHV - A five-wire signal where the red, green, and blue video signals, as well as the horizontal and vertical sync signals are each on their own conductor. This is the most common output of a computer video card, often referred to as VGA, and also the most common input for LCD projectors.
Male VGA connector
S-Video - actually two separate video signals that pass through the same connector. One of the signals is the color information (abbreviated C for Chroma) and the other is the black and white and brightness information (abbreviated Y or sometimes called Luminance).
If you look at the S video connector there are 4 connectors inside, as opposed to the composite video connector which has only two. In composite the color (Chroma or C) and black and white ( Luminance or Y) are mixed and passed on the same wire, whereas a S video signal keeps the Chroma and luma separate which in turn requires more wires.
Please note these types of connectors are delicate and can get damaged very easily.
Male S-video plug
Female S-video jack
VHS - Video Home System. The 1/2" videocassette format originated and developed by JVC and adopted by a number of different manufacturers. Not compatible with the Beta format, which also uses 1/2" tape but differs electronically.
VHS tape cartridge
S-VHS - A high bandwidth recording system used for the VHS format, increases the resolution and picture quality. It is not the same as S-Video. S-VHS is interchangeable with standard VHS and uses the same cables and connectors.
VHS-C - A Video recording format that uses the same size tape as standard VHS but the tape housing or cassette is smaller. The tape can be played in a standard VHS VCR if an adaptor cartridge is used.
For everything you ever wanted to know about audio technologies see
More exhaustive glossaries can be found at
If you have questions about media terminology, please contact Gary Malick, ATUS Classroom Services Technical Supervisor, 650-4934.
Rev. May 2005