Talon Tech Tip: The Basics of a Public Address System

NOTE: Much of my writing published here has taken a broad look at the industry and with a fairly philosophical tone. Other posts have been super geeky and designed for industry technical peers. This one is a very basic intro to an AV topic. If you have much experience in the technical side of production, you probably already know this, but if you’re less confident in your understanding of audio technology, or are just getting started in the events industry, you might check it out. I break down the very basic building blocks of a Public Address system. If it’s not your jam, feel free to gloss over. Even if this isn’t your cup of tea, I hope you’ll come back to see my future writings - I’ll be jumping between tech-heavy and more general postings.

The Basics of a Public Address System

I recently received a message from a long-time client asking for help understanding how to amplify voices at a socially-distanced, outdoor event. They knew they because their very small audience was all separated from each other and from the presenters that they needed microphones for their event, but were unsure how all the pieces worked together. This article came out of offering one client some basic help understanding how the pieces of an event sound system (often called a “Public Address” or “PA” system) fit together.

In general the basic components of a public address system are the microphone(s), the mixer, the amplifier, and the speakers. Sometimes one or more of these components are combined in all-in-one units.

Microphones

In terms of microphones, a very common live sound microphone (in fact probably the most popular / famous mic in the world) is the Shure SM58. A microphone is a transducer that takes the physical sounds of your voice (or a musical instrument) and turns it into electrical energy, which is carried over a wire to the rest of the system.

Wireless microphones have two more parts - the transmitter, and the receiver. The transmitter has the microphone element attached to it, and that picks up the sound from the person speaking, and the transmitter converts the electrical energy from the mic element into radio waves. The receiver turns those radio waves back into an electrical signal that connects to your mixer. You can think of a wireless microphone transmitter as a tiny radio station, to which the receiver is “listening.”

Wireless microphone transmitters typically come in either a Hand-Held form factor, which can be held or placed into a stand, or a “Body Pack” form factor that is designed to be clipped to the belt and used with a lapel microphone or a headset microphone.

Because wireless microphones use radio frequency to transmit sound, they offer different "channels" which adjust the frequency each mic is using. The transmitter and the receiver need to be on the same channel to work, just like you have to have your car radio on the correct frequency to hear your favorite FM station. If another microphone, or a local TV station, or a walkie talkie, or any other device uses an overlapping frequency, the mic will get radio interference, causing dropouts or unpleasant noises. There is a whole science to frequency coordination, but a great start is to use the “scan frequencies” function on your microphone system to find available channels in your area.

Many new wireless microphones use digital encoding to provide high-quality audio over minimal radio bandwidth, but the basic principles above still apply.

Mixers

The next component of the sound system is the mixer. Mixers take multiple audio signals and “mix” them together, allowing the operator to change the relative volumes of the inputs and adjust aspects of the sound from each one.

Mixers can come with as few as 2 up to 70+ inputs, and come in various feature sets. To use 4 microphones with one PA you would need a mixer with 4 microphone inputs, and to mix an arena rock concert, you probably need a much bigger mixer.

Small, low channel-count mixers are usually analog devices that manipulate the sound with physical electronic components. Larger, higher-channel count mixers are often digital, encoding the audio into a digital signal and using digital signal processing to manipulate and mix the signals. This approach gives a great deal of control over the audio when working with complex systems.

Amplifier and Speakers

The mixer connects to the amplifier, which raises the amplitude of the audio signal high enough to physically move the speaker drivers, and then to the speakers, which are transducers that physically reproduce the electrical signals as sound waves.

Some mixers have built in amps (amplified or “powered” mixers) and some speakers have built in amplifiers (“active” or “powered” speakers). Depending on the configuration, you may be able to connect your mixer directly to your speakers, because the amplifier is built into one or the other.

NOTE: You should not cannot connect the output of an amplifier or amplified mixer to the input of a powered or active speaker - make sure you are connecting the appropriate kind of equipment.

There are also many all-in-one PA systems, some with batteries, that have built in wireless mics, mixers, and amplifiers. These are super useful for small events and events in unique or challenging locations that may not have available electrical power. Note that most will only work with a limited number of inputs and may have somewhat limited output power due to the limitations of the battery.

Connecting it All Together

Once you have all the components, you can connect them together. You will use several different kinds of cables to connect your system together. Make sure components are all connected while they are powered off, and then when you power them on, turn them on in the direction of signal flow. That is, Sources, then Mixer, then Amps. When powering down, turn off the power in the opposite order - Amps, then Mixer, then Sources. This helps avoid unwanted pops and noises that can occur during power up and down.

For most events, your AV provider will be using a fairly complex sound and video system, with multiple types of speakers, electronic mixing and routing controls and several trained operators, but even the biggest audio rigs for arena rock tours are combinations of these basic parts.

So now you have the basics of a PA system.

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Tim Kerbavaz (he/him) is the founder and Technical Director of Talon Entertainment Audio Visual as well as a freelance Technical Producer with over a decade in corporate event production after an early career in live music production management. As both a live event technology professional and a creative geek, Tim serves as an event technology sherpa, guiding clients through production and technology decision making and delivering events to production bliss.

7 Questions About Event AV Your Team Needs to Ask

When you plan an event, make sure you and your boss are asking these questions before you sign on the line. If you are the boss, then make sure you pay attention.

So you’re planning a meeting. You’ve got a venue picked out, you’ve got your speakers lined up, and you (and/or your boss) are ready to sign off on your plan.

But Wait! What about your Audio/Visual plan? Have you thought about your AV needs? Who your suppliers are going to be? Make sure you and your team think about these questions before you sign off on your event.

1. Do you have your AV needs documented? Make sure you know what you need AV wise, and that you arrange in advance to make sure it’s all ready for your event. Whether you provide the AV yourself, or you hire a company to do it for you, make sure you make a plan and stick to it to avoid last minute surprises.

2. Are you comfortable setting up yourself? If you are, then you’re all set. If not, do you need to call Steve from IT to set something up? Or is Anita from Accounting your Go-To setup wiz? No matter who you have doing the setup, make sure you know in advance who that will be and you schedule them to be there.

3. Do you need to bring in a professional? Remember both Steve from IT and Anita from accounting have a full-time job. Does taking your skilled employees away from their desk really make the most sense? Sure, if it’s just hooking up a laptop in the boardroom, it’s no problem, but if you’re taking them away for a long period of time, doesn’t it make sense to hire a professional?

4. Does your Venue provide AV support? When you’re looking at off-site meetings in Hotels and conference centers, find out what’s included in your rental. Does the room come with drop-down projection screens? Do you have to pay extra for the projector? Does a lectern and riser come with the rental, or does that cost extra? Do you have to arrange with the AV team separately, or is there a default setup? Will a technician be in the room the whole time? Will there even be a tech onsite? How much does that all cost?

5. Is in-house AV your best option? The answer to this is often no. Did you know that at most hotel properties, the in-house AV is not done by the hotel, but by a 3rd party company that pays to be the prefered provider? These companies often pay a 40-50% commission on the rates you pay back to the hotel. They also don’t usually travel to other locations, and have different crews for each property, so you’ll have different technicians at every event you do. They may be a great value and are certainly a great onsite resource, but they may not be your best choice, which brings us to #6:

6. Did you red-line exclusivity agreements in your venue contract? Given that they get 40% back from the in-house AV vendor, venues often have exclusivity clauses in their contracts which will require you to use the onsite provider. These can almost always be negotiated off the contract - the hotel salespeople are in the business of selling meeting rooms and guest rooms. While they like the AV kickback, it’s almost never a deal breaker for them, but it should be one for you. This doesn't rule out using the in-house AV, in fact they may be a great option, but if you redline the exclusivity clause, you have the option to use whoever you want, and the in-house has to be more competitive.

7. This is the most important question - Did you schedule time for your own breaks? You, your staff, Steve, Anita, and your AV crew all need to eat, rest, and use the restroom. Did you build in breaks for self-care, and schedule coverage for your positions while you’re gone? Your boss needs you in one piece, and you need your staff and crew in tip-top shape. Take care of yourself, eat, and don’t forget to drink water!

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Microphone Tips from the Pros

Are you confident about using microphones at your events? Here are some microphone tips from the pros.

“Is this thing on?”

I can’t count how many times I’ve heard someone announce this uncertainty into a live microphone to a room full of attentive listeners.

Microphones: Using one should be simple, but event attendees and presenters are often confused when you hand them a mic. Where do I hold it? Where do I set it down? And the eternal question, "IS THIS THING ON?!"

Hopefully this blog post will help clear up some basic misconceptions about microphones, and help make you a microphone pro.

How Do I Hold a Microphone?

Hand Held Microphone

Hold the microphone in front of you, pointed at your mouth, about 3-5 inches from your face, and about an inch below your mouth. You want to talk into the microphone, so it can pick up your voice loud and clear, but you don’t want to breathe directly into the mic to avoid heavy breathing and the annoying plosives - the popping sound when you say “P” and “B” sounds with a puff of air. We’ll cover those pesky on-off switches a bit later.

Gooseneck Microphone - Lectern or Panel Discussion

Again, make sure the mic is about 3-5 inches away and about an inch below your mouth. Try not to turn your head too far away from the mic as you reference your slides or look around the room - you still need the mic to pick up your voice to be heard by your audience. Don’t talk too far away from the mic, but also don’t talk right on top of the mic. If you’re up too close to the mic, you may hear distortion and clipping from the mic being overpowered by your voice, especially on plosive sounds. If you hear distortion, back off the mic a bit.

Lavalier Microphone

If you’re using a lavalier microphone (the kind that clips onto your shirt), make sure it’s high up and centered on your chest, so that it picks up your voice over the room noise. You want to make sure that it can still hear your voice if you turn your head and that you won’t suddenly change volume as you move. If you wear it on one side, put it on the side you’ll turn towards to face the screen.

Headset Microphone

If you’re using a headset or an “earset” (a headset that clips to only one ear), make sure you position the mic element so that it’s just off to the side of your mouth, so that you don’t get breath noise or plosives, but still close enough to hear you well. Make sure the headset or earset is securely attached to your head, and, if appropriate, clip or tape the cable to your shirt so that it doesn’t pull on the mic.

With any wireless body-worn mic, make sure you clip the mic transmitter pack (called a “belt pack” or a “body pack”) to your belt or put it in a pocket, taking care not to pull on or put strain on the microphone cable.

What is that awful squealing noise?

Feedback - we’ve all been to a meeting where the microphone squeals and screams, making the whole room cover their ears and wince.

Feedback occurs when the microphone picks up the sound from the speakers more than the sound of the person speaking. This can occur because the mic volume is too high, because the person with the mic walks in front of the speakers, or because the microphone is being held in such a way that it picks up too much room noise.

The basic rules are these:

• Don’t point the mic at the speakers.

• Make sure the person speaking is louder to the mic than the amplified signal.

• Don’t cover the mic with your hand.

That last rule is a bit counter-intuitive - you would think that covering the mic would make the feedback go away, but in fact it can make feedback worse. Most microphones used at events are directional - they pick up sound in front of them, and reject sound in back of them. If you put your hand over the top of the mic, or cover part of the windscreen “rapper-style,” you can turn a directional mic into an ominidirectional mic - one that picks up sound from any direction. This is a great way to make feedback happen; unless you want feedback, don’t cover the mic.

If you need to make a comment off-mic or walk in front of a speaker, mute your mic instead of covering it.

On/Off

Wireless Mics

All wireless microphones have a switch of some kind, but every brand of mic is different, so the mics at your event may have a slightly different interface. But no matter the brand, there will be a switch labeled “Power” or “On/Off”. If it’s a toggle switch, flick it on. If it’s a push button, press and hold for about 3 seconds until the screen and lights turn on.

Most mics take between 1 and 3 seconds to power on, so turn the unit on, and wait a few seconds before you talk.

On mics with a push button, a long press and hold usually turns the unit on and off. Often, a short press mutes and unmutes the microphone. On these models, the light is often green to indicate “on” and red or amber to indicate “mute”. On models with only one color of light, there is usually a small text indicator on the LCD screen on the mic transmitter to indicate mute status.

If there’s a sound operator in the room, he or she may ask you to leave the mic transmitter on all the time and allow him or her to unmute the mic remotely when you begin your presentation and mute it for you when you come offstage. If you turn off your mic manually, the operator won’t be able to remotely turn it on again, so make sure you leave the transmitter on and unmuted if that’s what the technician asked when they gave you the mic.

Gooseneck Mics

If you’re using a gooseneck mic at a panel discussion or lectern, there may be a push to talk button. Many of these mics are Push-On-Push-Off, meaning you push the button once and let go to turn it on, and push again and let go to turn off after you’re done using the mic. If that’s the case, make sure you turn off your mic after you speak to avoid picking up rustling paper or any side comments you make. Often these mics will have a light on the mic or the base to indicate the mic is on.

If the mic is Push-and-Hold to talk, press the button and keep it pressed as long as you are speaking, then release the button when you’re done talking.

Off to the meeting

I’ve covered the major types of microphones you’ll encounter at events, so with this guide under your belt, you should be ready for your next meeting.

Just remember the basics - the mic has to pick up your voice, and avoid picking up the sound in the room. Avoid plosives and feedback with proper mic placement, and take note of your on-off switches.

Now you’re a microphone pro!

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© 2019 Talon Entertainment - All Rights Reserved

Cover image via Depositphotos - Halfpoint

You want how many microphones?

“You want how many microphones?”

I’ve found myself asking clients that question on many occasions. Big board meeting. National membership meeting. Round-table committee discussion. Meetings where there are 30 to 100 people who all need to be able to hear and be heard.

I’ll be honest -- you cannot have 50 microphones live at once in one meeting room without digital processing and expect to not have feedback. There’s no way one sound technician can manually keep track of who’s speaking and who’s up next and keep it all going smoothly. It’s not going to be pretty. And think of how many cables you’d need!

Luckily there’s a solution that lets everyone have a mic, prevents feedback, and keeps technicians from ripping their hair out.

It’s called an Audio Discussion System, or alternately known as a “Congress” or push-to-talk system.

A push-to-talk system in use at a business meeting.

A Discussion System can come in multiple styles and feature sets, from installed systems with voting, speaking order tracking, translation, and video displays (as is used at the United Nations), to wireless systems with multiple zones, to simpler portable systems with basic push-to-talk microphones and fewer frills.

All of these systems offer simple wiring, as most allow the mics to daisy-chain around the table. They also have a central processor that both limits the number of simultaneous mics that are turned on as that processes and adjusts the audio on the fly, preventing feedback and excessive room noise in recordings and conference calls.

Each mic unit has a push to talk button on the mic base, and in many of these systems the base contains a small speaker, allowing all the participants to hear each other clearly without external speakers, and all can all be plugged into external sound systems for reinforcement, conferencing, or recording.

These systems provide a solution for events where everyone needs to be heard. They are typically used with audiences seated around a U-shape or hollow square table arrangement, with all the participants around the room facing in, or with rows of delegates in classroom style or tiered seating all facing a central dais or head table. They can be used with one mic station per seat, or spaced between alternating seats, with one mic for every 2 people.

We typically recommend that no more than two people share a discussion mic, because the bases are daisy-chained together. With a wire running in each direction, it’s best that they not be picked up and moved so the cables from the other units won’t be pulled too much.

If you are planning a large board meeting, or you’d like a large group to be able to have a round table discussion, with or without an off-site teleconference, a multi-mic discussion system is a solution worth exploring. We carry a range of these systems, and we’d be love to chat about your event. We’re in California, but if you’re curious about how these systems work, feel free to drop me a line no matter where you are -- I love to geek out about AV technology, especially if it helps folks find solutions to their event technology problems.

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