Everything you need to know about PA systems and live sound.
Music terminology is a daunting thing and as you get ever deeper into the topic, it always seems like there’s more and more to be learning. Even for seasoned musicians, the lexicon of live sound and PA speakers can be utterly baffling, whether the engineer is asking you to plug the TS into the DI or asking what you want in your traps.
Whether you’re a musician making their first foray into live performances, or you’re working the show yourself as an engineer or assistant, these terms will more than likely come up at one point or another. Even if you’re just helping out your friend’s band at a DIY show, understanding these terms can help make sure everything goes smoothly.
We’ve seen our fair share of shows in our twenty-year career playing live and we’ve made plenty of mistakes in that time too, so allow our embarrassment to work to your advantage with these common PA terms and their meanings.
Before we get into the wider world of live sound terminology, we need to make sure that we’re all on the same page by discussing some key PA system components that will be mentioned a lot throughout the rest of this guide. By fleshing out these common terms we can ensure everyone knows where they stand, whether you’re a beginner or a veteran.
Speakers (Loudspeakers)
The crux of any PA system, the speakers are what deliver the sound and they come in various shapes and sizes. The two main distinctions are that some require their own power, we call these active speakers, whereas others get their power from a power amp or mixing desk with a built-in power amp. These are called passive speakers.
Mixers
The mixer is where the magic happens. All the microphones on stage get plugged into the mixer before being sent to the speakers for the audience to listen to. A separate feed goes out to the on-stage speakers, typically called monitors for the band to hear. You can also apply effects here like compression, EQ, gating, reverb, and delay. As with speakers you get powered mixers, which drive passive speakers, and passive mixers which work with active or powered speakers. A mixer can also be referred to as a Mixing Desk, Console, or sometimes Soundboard.
Microphones
Mics are what deliver the sound from the stage to the mixer before going out to speakers. Typically we use dynamic microphones as live vocal mics thanks to their excellent noise rejection, but sometimes there can be the use of condenser microphones when it comes to drums and guitar amps.
Amplifiers
Not to be confused with your guitar amp, a power amplifier amplifies a signal and drives your speakers. A lot of smaller mixers now come with power amps built in, but for larger shows, venues will have a separate power amplifier to ensure there’s enough volume to fill the room or drive a lot of speakers in more complex systems.
Now that we have the basics out of the way, let's get to the more in-depth terms and colloquialisms you’ll come across when playing live or working at a live venue. There’s a lot, so we’ve arranged them in alphabetical order to make things easier for you to search.
AUX
A term also found in recording studios, an AUX is part of the channel strip and allows you to send signals to effects like reverb and delay which can be external units or built into the mixer.
Array System
An array system is what you’ll typically find in a larger, more modern PA setup. There are two main types, line arrays, and column arrays. Line arrays have pairs of speakers stacked vertically in a curve; you’ll see them at large venues where they need to cover an audience vertically, for example, if you have a balcony. Column arrays are single speakers stacked vertically and are usually found in smaller venues where the audience is just on one level, offering better horizontal coverage.
Balanced
The term balanced refers to the type of cable used. This kind of cable uses two conductors, carrying a duplicate of the original signal in order to cancel out any noise picked up along the run. Both XLR and TRS cables used for microphones and stereo instruments are balanced, whereas TS cables, like those used for electric guitars or mono instruments, are unbalanced.
Band-Pass Filter
A band-pass filter rolls off any frequencies outside the ones you target on an EQ. For example, that megaphone or telephone sound you get on vocals is usually down to the use of a band-pass filter.
Cabinet
Cabinet is an overarching term for the enclosure that contains speakers and can apply to pretty much any variety of speakers in the music industry. You’ll often hear them referred to as ‘cabs’ and this includes guitar cabinets as well.
Channel Strip
The channel strip is the main part of the console or mixing desk. It typically features a preamp and EQ and in some cases a noise gate and compressor. A Channel strip will also typically have AUX sends for routing effects like delay and reverb. Each channel will usually have a dedicated fader for adjusting the level.
Clipping
Clipping refers to a signal that provides more voltage than the input can handle. On most mixers and consoles this is denoted by red LEDs and you’ll find the same thing in your DAW too. It’s called clipping because the top and bottom of the waveform get ‘clipped’ off. It may not always provide an audible effect, but it’s the bane of engineers everywhere.
Compression
Another familiar term in the wider music lexicon, compression is the act of making loud things quieter and quiet things louder. By evening out the dynamic range of an instrument, we gain more control over it at the mixing desk, preventing having to ride the faders. Works great on vocals.
Compression Driver
A compression driver is the smaller part of a PA speaker that usually sits at the top. They’re used to produce the high-frequency content of sound, usually used in conjunction with a horn for producing lower frequencies. On studio monitors, these are called ‘tweeters’.
Console
Also known as the mixer or mixing desk, you’ll often hear larger PA system mixers referred to as the console.
Decibel
Decibels, denoted by 'dB' is the unit by which we measure sound. For example, normal breathing will register around 10dB, whereas 100dB will be something like the horn on your car. Decibels are usually used with another standard, so when people say dB, they usually mean dB in relation to SPL (Sound Pressure Level). You can however also measure dB as a voltage which is where you’ll find dBu or dBv, and there’s even one in relation to power, marked as dBm.
Distortion
In the world of PA, distortion is usually a bad thing. Essentially it’s when a signal is affected by receiving too much voltage, faulty components, or impedance mismatching. When it happens in your fuzz pedal it sounds great, but you don’t want any distortion in your PA or monitor system as it affects the quality of the sound.
Dynamic Range
Dynamic range is the measure of how loud a system can get before you get distortion, or how quiet it can get before you hit the noise floor. Measured in decibels the dynamic range of jazz music can be from 13dB to 23dB, whereas a full orchestra playing live can go all the way up to 90dB. Engineers often control the Dynamic Range of an instrument by adding compression at the mixing desk or console.
EQ
EQ or equalization is something we find in all of music, covering the entire spectrum of sound we can hear. In live sound, EQing is something we do to control where an instrument sits on this spectrum, for example taming an overly bassy sound with a low cut or ‘notching’ out an annoyingly harsh frequency higher up the spectrum. The idea is to use EQ to create a clear and balanced sound where every instrument can shine for the audience.
Front Of House (FOH)
Front of house, also known as FOH, refers to the position that the main engineer works in during the show. It can also be colloquially referred to as what the audience hears out the front of the stage. Usually, the mixing desk or console is placed in the optimal position for the engineer to hear everything that’s going on, placing microphones and assigning channel strips to get the best sound.
Gain
Gain is the amount of amplification applied to a sound in order to make it more audible. It’s typically measured in decibels.
Ground
The concept of ground could provide an article in itself but we’ll try and keep it simple! One of the most important concepts of ground is allowing electrical current to flow somewhere safely, i.e. not through the microphone or your instrument. It also ensures all electrical current moves in the same direction, preventing you from receiving a nasty electric shock.
Ground Loop
Disregarding our alphabetical order for a second in the interest of clarity, a ground loop is a hum that you can’t seem to get rid of in your equipment, typically caused by the system having more than one route to ground. Some devices may have a ‘chassis ground’ or a ‘signal ground’ that conflict with the existing ground in your system. This leads us nicely onto…
Ground Lift
You’ll often see ground lift switches on DI boxes and certain guitar pedals and it disconnects that device's particular Ground, allowing you to remove unwanted hum from the system.
Headroom
Headroom is how much space you have before you start getting clipping or distortion in your signal.
Hertz
Hertz is the standard measurement for audio with Hz for lower frequencies and kHz for higher frequencies.
Impedance
Impedance is a measurement that’s related to AC voltage, similar to its cousin resistance which relates to DC voltage. Although they’re both often classed as the measurement of resistance, Impedance is used for audio items like speakers, cables, tubes, and transistors because they involve a waveform, whereas straight resistance is related to DC voltage, like that of a 9V battery, because it doesn’t have a waveform associated with it.
In-Ear Monitors
Known as 'in-ears' or IEMs, in-ear monitors are small earbuds that can be connected to the PA system. They're favored in pro setups because they allow every band member to dial in their personal monitoring preferences, and allow for a much quieter stage which makes the engineer's job much easier.
Instrument Level
Instrument level refers to the signal from things like electric guitars and bass guitars. These can sometimes need a preamp but not always depending on the instrument. They generally run from 20 to -10dBV.
Line Level
Signals from a lot of gear will run at line level, like synthesizers which give a very ‘hot’ signal, meaning you don’t have to boost them with a preamp. Usually, these come in around -10 to +4dBu.
Mic Level
The lowest of instrument signal levels, mic level inputs will most likely require a preamp to boost the signal to a usable level. They run around -60 to -40dBV.
Monitor Mix
Also known as the cue mix, the monitor mix refers to the sound that musicians hear on stage. This can be from traps or floor wedges, or via in-ear monitor systems. Engineers will use a set of headphones so they can hear the monitor mix at the mixing desk or console.
Motors
The motor is the component that’s attached to the back of your PA speaker that drives the sound. When engineers use this term they’re typically referring to the components that include the front plate, magnet, voice coil, and back plate of a speaker.
Mult
A mult refers to a patch bay that gives you multiple copies of the same signal so you can send them to different sources, usually effects like reverb and delay. Mults are becoming a fairly old term thanks to modern mixers which allow you to do this digitally from the mixing desk or console itself.
Noise Floor
The noise floor refers to the lowest point of a system’s dynamic range. It’s where your sound is no longer audible over the inherent noise of every amplification system.
Noise Gate
A noise gate controls a signal by cutting it when it reaches a certain level. Frequently used by guitar players, a gate can prevent feedback or hum by cutting off an instrument when it’s not being played. It’s also sometimes used on drums to provide a punchier feel and can be used to control the ‘bleeding’ of other instruments into microphones.
Notch Filter
A notch filter is the opposite of a band-pass filter, allowing you to cut out a very specific frequency whilst retaining all of the other content in the signal. Usually used to cut out muddy or harsh frequencies in sounds.
Off-Axis
Off-axis is a term for microphone placement, whereby you place the microphone at an angle to the speaker cone or instrument. The idea is to capture a wider tone than pointing the microphone directly at the sound source, which we call…
On-Axis
On-axis is where a microphone is pointed directly at the center of a speaker cone, or instrument. This gives you a brighter, more direct tonality.
Ohm
Ohms are a measurement of resistance, or how hard a signal has to work to travel along a cable. The higher the ohm, the harder the signal has to work to get to its destination. You’ll frequently see these listed on the back of PA speakers and guitar cabinets.
PFL
PFL stands for Pre-Fader Listen, and you’ll find these buttons on the channel strips of your mixing desk or console. They allow the engineer to listen to incoming signals before it’s affected by the fader, to ensure that there’s no clipping and that any other effects like EQ, gating, and compression have been properly applied.
Phase
Another term that could have its own article, phase is the measurement of the cycle of a soundwave. If signals are ‘in phase’ then they’re both starting at the same time, if they’re ‘out of phase’ then they’re starting at different times. ‘Out of phase’ signals can be a big problem, as they’ll cancel each other out, resulting in a quieter overall sound.
Phantom Power
Phantom power refers to a method by which audio gear can be remotely powered. A common usage of phantom power is with condenser microphones, but it can also be used for ribbon microphones and remote mic preamps.
Plosive
Plosives are one of the biggest headaches for engineers and are caused by certain consonants when a vocalist sings. The biggest culprits are the letters ‘t’, ‘k’, and ‘p’, but they can also be caused by the letters ‘d’, ‘g’, and ‘b’.
Point Source
Point source refers to a smaller system where the speakers are two or three-way. These portable PA systems are usually found in very small venues or band rehearsal spaces.
powerCON
A powerCON is a type of cable used for power, it locks into the device which prevents you from accidentally unplugging it which can come in super handy!
Preamp
A preamp increases gain, taking a weaker signal and boosting it to line level. Preamps can come in many forms, whether it’s a clean mic preamp or a colored preamp you might use in a studio. There are also preamps in your tube amp, audio interface, guitar pedals, and loads more music gear.
Ring Out
Ringing out, or ‘tuning’ the room is a process an engineer uses to pinpoint any issues in the sound of the room. By using a signal generator that outputs white and pink noise, you can raise the volume on any of the microphones to the point where it starts to feedback and find any problematic frequencies. The engineer can then cut out any problem tones with EQ to create a ‘flat’ and balanced sound.
Sibilance
Sibilance is the ‘hissing’ sound vocalists make, typically with the letter ‘s’. Sibilants can stand out a mile in a mix, hence the invention of a de-esser. You can also reduce sibilance with EQ should you have the type of singer that’s particularly harsh on their esses.
speakON
The speakON cable is a locking cable designed by Neutrik for connecting speakers. They’re a favorite of engineers for their durability and ability to handle large amounts of power.
TRS
TRS stands for Tip, Ring, Sleeve, and are cables that are used to carry stereo signals. They can be ¼-inch or 3.5mm jacks and are often found on headphones, wireless body packs, and AUX inputs on mixing desks.
RCA
Also known as phono connectors, an RCA cable is a type of audio cable that was found on cassette decks and turntables. They’re still found on some DJ gear and compact mixers and can be useful, particularly with older gear.
Unbalanced
An Unbalanced cable is your typical TS or instrument cable. They only use a single conductor, which makes them susceptible to noise, unlike their counterparts in the balanced or TRS cable. It’s a good idea to keep unbalanced cables away from power lines and lighting cables as these can induce noise into the system.
XLR
The XLR cable is one of the most used in live sound, with its iconic three-pin design found in loads of pro-audio gear, including the best XLR mics. They’re balanced cables so reject exterior noise, although they can be used to run an unbalanced stereo connection through a single cable too.
