AV equipment can transform a run-of-the-mill presentation into an event experience. In an era where attention spans are short, effective AV equipment can captivate and sustain audience engagement.
Understanding what is audio equipment is essential for preparing an event. This article will cover a variety of essential topics, from playback devices to signal processors.
Speakers
Speakers are the devices that convert electrical audio signals into mechanical energy which produces sound waves. They are an integral part of the entire audio system as they transmit acoustic vibrations which produce sound, whether it be music on a long road trip or a TV show during a relaxing day at home. In order to get the best sound out of speakers, it is important to know how they work and what factors influence their performance.
There are several components that make up a speaker, but two of the most important are the cone and the voice coil. The cone is what vibrates when a signal is sent to the speaker, and the size, shape, and material of the cone will determine the quality of the sound that is produced. The voice coil is an electromagnet that is attached to the cone and is driven by a current from the amplifier. When the current passes through the coil, it creates a magnetic field which can be controlled to move the cone back and forth at a specific rate in order to reproduce a particular range of frequencies.
The rated power (sometimes called the peak power) of a speaker is its maximum capacity for handling an electrical audio signal. This value is generally determined by a pink noise test and may be printed on the speaker’s packaging.
In most speaker systems that have more than one driver, there is a small network of passive electronics called a crossover that helps to direct components of the electronic audio signal to the drivers best capable of reproducing those frequencies. Typically, the drivers that can reproduce high frequencies are called tweeters, those for middle frequencies are called mid-range drivers, and those that can reproduce low frequencies are called woofers.
Microphones
Mics are transducers – they convert one type of energy (acoustical) into another (electrical). When you speak into a microphone it causes a physical response in the mic that then creates an electrical signal. This electrical signal is transferred to the audio board where it is turned into sound for your audience to hear.
There are many different types of microphones, all with their own unique characteristics based on their design and intended use. Some of these characteristics include directional properties and impedance. Most common are dynamic and condenser microphones, with a few other options specialized for certain applications.
The basic concept for these microphones is that incoming sound pressure causes a thin membrane called a diaphragm to vibrate. This vibration is then transferred to a coil of wire that moves in relation to a magnet and generates an electric current that we can measure.
There is a little more to it than that but that’s the gist of how these microphones work. The most common dynamic microphones are the ones you’re likely familiar with – they’re used in almost every setting you can imagine, from recording vocals in the studio to micing up a guitar or drum kit for live performances. They’re also very sturdy and can withstand a lot of loudness without distorting or breaking.
Lapel mics are another type of microphone that can be worn by speakers for hands-free operation. These small mics can be clipped on a speaker’s shirt, pinned to their chest with a brooch or a safety pin, or even attached to their clothing using a string or cord. Lapel mics can be either wired or wireless, with a lavalier cord that runs from the microphone to an RF transmitter in a pocket, clipped on a belt or hidden by a vest for mobile use or directly to the mixer for stationary applications.
Amplifiers
The main purpose of audio equipment is to amplify signals. Most electric devices have outputs that are too small to drive a speaker or a needle on a record player, so they need amplification before they can be heard. Almost all electronic equipment contains amplifiers, including power amps. The circuitry of these amplifiers is usually based on semiconductors such as transistors or vacuum tubes.
The first step of an amplifier is to take in a small input signal that has either electrical or magnetic components. Then it converts this into a larger output that maintains the shape of the original signal but has a higher amplitude. The amplifier can also add additional features to the signal such as equalization or mixing of different signals. The basic diagram of an amplifier is shown below.
One of the most important parts of any amplifier is the power supply. The wattage of the power supply is used to provide the energy required for signal amplification. This is commonly expressed as a percentage, and a good quality hi-fi power amplifier will have an efficiency of around 50 percent.
Another factor in determining the quality of an amplifier is its distortion. This is a measure of how closely the output waveform matches the input one. The lower the distortion, the better the quality of the amplifier.
There are many types of audio equipment available on the market today. These include microphones, speakers, headphones, mixers, and amplifiers. Having the right audio equipment will ensure that you can create the best sound possible for your next event. For example, the right microphone will help you capture the sound you want and project it to the audience. It will also minimize background noise and unwanted sounds.
Mixers
Mixers, also called consoles, are electronic devices that allow multiple input sources to be connected and controlled in one place. They can be true analog, digital, or a combination of both, and are often color-coded to help the audio engineer quickly identify different sections of the mixer.
Mixer features include a number of input jacks, usually with XLR connectors for mics and the outputs of electric instruments, and RCA or 1/4″ phone connection line inputs for other types of signal sources (such as pre-recorded music being played back on turntables or CD players). The mixer’s channel strips typically have faders (which are sliding volume controls that affect how loud each instrument is) and input gain knobs to set a desired level. Some mixers provide EQ controls that enable the user to adjust the tone quality of a signal by separately attenuating or boosting a range of frequencies.
The mixer’s main output jacks (usually XLR) connect to speakers that amplify the mix for an audience at a concert or other live event. Some mixers have pan pots that control the balance of each sound in a stereo image, such as how much is heard from the left and right speakers. Other important mixer controls include talkback controls for conversation with performers through a speaker in the stage area and headphone and headphone monitor outputs for private listening by the audio engineer.
A special section of the mixer, often in a center section flanked by banks of input channels, provides subgroup and master output fader controls. This section may also have a matrix routing system and auxiliary sends that connect to external processors and effects that affect only one or more channels.
Headphones
Headphones are small speakers designed to rest over the ears, delivering music or movie soundtracks and sound effects directly into the listener’s ear. They are also used to make phone calls, or to play video games. Headphones are available in a range of styles and prices, with a wide choice of features, from noise-canceling technology to Bluetooth wireless connectivity.
The most popular headphones feature a dynamic driver, which transforms electrical audio signals into sounds by moving a diaphragm that creates the pressure waves that our ears perceive as sound. The diaphragm is typically crafted from lightweight, high-stiffness-to-mass-ratio materials, such as polymer, carbon material, paper or cellulose. An electrical signal enters the headphone frame, and the voice coil, a light coil of wire suspended within a magnetic field, sends an electric current to deflect the diaphragm. The faster the signal deflects the diaphragm, the louder the sound.
There are also electrostatic headphones, which are much rarer. They use a thin diaphragm, usually a PET film membrane, suspended between two perforated metal plates (electrodes). The electrical sound signal applied to the electrodes changes the polarity of the electromagnetic fields, and the electrostatic force deflects the diaphragm in a continuous cycle that generates air pressure waves our ears perceive as sound. These require a special amplifier to generate the high electrical potential needed, which makes them more expensive than their dynamic counterparts.
In-ear monitors (also known as IEMs) are another form of headphones that are often utilized by musicians and audio engineers, as they offer a tailored listening experience and excellent noise isolation. The headphones are inserted into the listener’s ears, and form a tight seal that effectively blocks out external sounds, allowing them to hear a more intimate, high-fidelity, and controlled soundstage.