Basic Live Sound Reinforcement

A Practical Guide for Starting Live Audio

Raven Biederman, Penny Pattison

• Publisher: Routledge
• Year: 2013
• ISBN:
  9781136126055
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Acoustical Engineering
• Index: Technology & Engineering

Access and interpret manufacturer spec information, find shortcuts for plotting measure and test equations, and learn how to begin your journey towards becoming a live sound professional. Land and perform your first live sound gigs with this guide that gives you just the right amount of information. Don't get bogged down in details intended for complex and expensive equipment and Madison Square Garden-sized venues. Basic Live Sound Reinforcement is a handbook for audio engineers and live sound enthusiasts performing in small venues from one-mike coffee shops to clubs. With their combined years of teaching and writing experience, the authors provide you with a thorough foundation of the theoretical and the practical, offering more advanced beginners a complete overview of the industry, the gear, and the art of mixing, while making sure to remain accessible to those just starting out.

Part 1

Introducing Live Sound

To begin at the beginning we need to answer a few fundamental questions and establish some basic definitions to build upon. To that end, Chapter 1 begins with the question “What is live sound?”, and builds a basic answer to this fundamental question by discussing when and how we use live sound reinforcement and, more importantly, why we use it.

Next, in Chapters 2 and 3 we look at the live sound industry, including topics such as the types of businesses and clients that hire live sound employees, the difference between employment status and freelance work, and examples of typical opportunities for entry-level live sound workers. Many live sound beginners start with a limited understanding of the industry, and even those with more background often start with some misconceptions and holes in their knowledge.

Though we revisit our discussion of the live sound industry in the last section to discuss topics aimed at students about to begin work or intern in the field as is most common, we also feel it’s important to start with an overview of the live sound industry as soon as as possible. Knowing the different types of opportunities and hurdles they may encounter can help live sound students choose wisely when faced with initial choices such as the kind of training to seek out, what internship to apply for, and even where to move after finishing training, all of which can influence the choices available to them later on. Even those who are making the most basic choices, like whether they really want to begin studying live sound at all, are better equipped to make the best choice for themselves if it is an informed choice.

Chapter 1

What Is Live Sound?

The P.A. System

Installed vs. Portable P.A.

Personal P.A.

Band P.A.

Touring/Stadium Sound

What Do We Use Live Sound for?

Public Announcements

Direct Public Address

Performance

Common Knowledge about Live Sound

Common Knowledge: Use as Directed

Looking for Assumptions

What the Pros Know that the Rest of Us Don’t

Exploring the Limits of Loud

Coincidentally Loud

A Meditation on Live Sound

What is Good Sound?

1. Good Sound is Tailored to the Application

2. Good Sound is Clear and Intelligible

3. Good Sound is Balanced and Natural

4. Good Sound is Evenly Dispersed

What Live Sound Isn’t

Live sound reinforcement is a process in which an operator uses audio technology to enhance and redistribute selected sounds. Natural sound is the unprocessed sound that comes directly from an instrument or human vocal chords. Live sound is what results anytime natural sound is captured and turned into an electric signal by the microphones of a P.A. system, to be processed and enhanced in the system before it is finally converted back into sound at the loudspeakers and re-distributed to the intended audience throughout a location.

Of course this brief description can hardly begin to define live sound reinforcement, when entire books are required to fully explain the process. Rather than try to define live sound reinforcement right away, we will use this chapter to see if we can come to a more complete understanding of what is created by the reinforcement process, the live sound the audience hears. To do this, we can start by examining the P.A. system used to create it, the types of situations where it is used, and the audience it is created for. By looking at the situations we use live sound reinforcement for, we have a better chance to accurately define why we use it, and by extension will be more able to answer the question posed in the title of this chapter; “What is live sound?” While it will take many chapters to explore all the component parts of the P.A. system, for the task at hand we only need to look at some of the broad general categories of P.A. systems.

The P.A. System

The P.A. system encompasses all the equipment, starting with the microphones and ending with the loudspeakers, that is used to convert selected natural sounds into the enhanced live sound that is heard by the audience. The P.A. system comes in many sizes and levels of complexity, and the size of any P.A, as well as the amount of work involved in setting it up and running it, will be determined by the amount of power and features required to process sound for the specific event and venue that P.A. is used for. A venue is the place where a live sound event occurs, and most venues will have a specific type of event or limited range of events that will typically occur there. There are some “all-purpose” venues, but more commonly the events held at any venue will be limited by logistical limitations imposed by the size, shape, and location of the venue, or simply by custom. Either way these parameters usually also serve to limit the kinds of P.A. used in that venue.

Installed vs. Portable P.A.

Many venues that focus on throwing regular live sound events will invest in an installed P.A. system, or fixed installation. These systems are designed and installed by a consultant who tailors the components and placement of the system to the exact needs and capacity of the venue. The advantages to these systems are that precision equipment can be used to analyze the room and calibrate the system in a way only possible with installed sound. Once tuned the ideal settings for components the operator doesn’t need to access in order to run the system can be permanently set and the components can be tucked away in storage shelves or even hidden within architectural elements. This keeps delicate equipment and controls safely hidden away from the audience, keeps cords and cables off the floor where they could pose a tripping hazard to all, and has the added benefit of saving space. Some installation companies also offer varying degrees of service; the best may even promise 24/7 on-call service and a guarantee to always have parts on hand. The main disadvantage of fixed installations is the considerably greater cost of these systems, as well as the relative inflexibility that occurs with lack of portability.

While installed systems have some advantages in being tailored to the venue, there are a variety of types and sizes P.A.s can come in, and the flexibility and scalability afforded to users of portable P.A.s means they can tailor the P.A. used to each application it is used for. This makes portable systems the preferred choice of most sound engineers and regardless of size and features, P.A. systems that are not installed are considered to be transportable from one venue location to another and categorized as portable P.A. systems. Naturally some systems are more portable than others, and some manufacturers and vendors have P.A. lineups specifically built for extra easy portability, with features like handles and wheels built into all gear in that line. The following three examples of portable P.A.s exemplify the diverse range of size and complexity that can be found in these systems, from the smallest personal P.A.s, to the massive touring systems used for stadium events.

Personal P.A.

The smallest systems are referred to as personal P.A.s and range from those that are hardly larger than personal listening devices to those that are just bigger than a brief case or small carry-on travel valet. The tiniest come with clip-on or headset microphones that plug into speakers small enough they can be clipped to the user’s belt. These tiny systems are tailored to applications where a system powerful enough to address audiences of more than a dozen people or reach distances beyond 6 to 10 feet would be too powerful and less portable than is needed. An example of a typical application calling for such a system includes a tour guide leading a cluster of people through a museum. In situations like this some amplification is useful since the audience reaches just far enough beyond conversational range that a speaker must project their voice to be heard. This is tiring to do over an eight-hour shift, and difficult to do at a consistent and precise level that is just loud enough to reach the audience, but not so loud as to disturb others beyond that range. In allowing the speaker to easily carry a system than can boost their volume just enough to reach everyone in their audience but maintain a level low enough to avoid disturbing other people in the general area, limited power personal P.A. systems are a perfect tool for this type of use. These systems are also useful for educators, especially for those teaching the hearing impaired.

The larger of these systems are still very compact, containing just the amount of power needed for venues where the user will be speaking or performing for people in a space around the size of an average coffee shop. Such situations include a poetry reading at a coffee shop or an author’s book reading and signing in an area about the same size within a larger space such as a large book store or a university commons. Consisting of a microphone, a cord, and a speaker enclosure with a handle at the top for easy carrying, these systems are easy to lift and will fit in the trunk of a small car. Set up is plug and play with few controls beyond turning the system on and setting the volume knob; to prepare to use them the operator only needs to connect the two components with a cord and to plug into a power source. These small systems are also the perfect size for applications like Pub Quiz or similar games, being powerful enough to allow everyone participating to hear, but not so powerful that the sound produced will necessarily intrude on patrons in other areas of the bar.

Band P.A.

A band performing an average bar will need a bigger system to be able to capture the input of each performer on stage and to distribute the sound throughout the multiple areas and/or larger spaces typical of these venues. Unlike personal P.A. systems, band P.A.s are complete systems, capable of using all the components covered in Part 3 of this book, though each will be configured differently according to the specific requirements of the events and venue they are used at. Band P.A.s can be scaled up or down and provide sound for performances at venues ranging from small to midsized to large. Because they are complete systems, scaling them up or down can be achieved merely by adding to or subtracting from the number and/or capabilities of the P.A.’s components, without requiring any qualitative change in the way the system is set up and operated. Flexible enough to process sound for nearly any type of live sound situation, in just about any kind of venue, band P.A.s are the quintessential live reinforcement P.A.s and the benchmark against which all other sound systems can be compared and described according to differences or similarities.

The smallest systems in this category are simplified to make them easier to use, and compact enough to fit in the trunk and passenger seats of the average car. The average band P.A.s, however, are large enough to require some planning and assistance to transport. More than one person will usually be involved with the process, and at least one live sound pro is required to help with setting up and operating the system. Generally, a truck or van will be required to transport the P.A., even those used at small venues, especially if one of the bands is transporting it together with their backline equipment, which refers to all the instruments, pedals/effects, and instrument amplifiers that a band uses to create the sounds that the P.A. then captures, processes, and distributes. Back-line equipment is nearly always owned or provided by the band and is not considered part of the live sound reinforcement system itself.

Band P.A.s are not limited to use in small venues and can be scaled up to process sound at all kinds of events and in venues of nearly any size. Mid-sized or large band P.A.s, may need anywhere from one to half a dozen or more large trucks to be transported, requiring proportionally more support personal to set up and run. These powerful P.A.s are more appropriate for events with audiences numbering in the thousands. They are more impressive than their small venue counterparts but not so different as to qualify as a separate class of P.A. altogether, as the next P.A. systems we will look at do.

Touring/Stadium Sound

On the extremely large end of the spectrum, the average P.A. system used for large stadium tours or festival events requires dozens of semi-trucks to transport, and an army of personnel to pack, move, and set up the system. P.A. systems as massive and elaborate as the sound systems used on large stadium tours/world-class festivals are sometimes set apart from run-of-the-mill large P.A.s by being referred to as tour sound systems or stadium sound reinforcement systems. While these titles sound like they are attempts to set these systems apart from the lowly P.A., these systems are still P.A.s, but on a monstrous scale. On a basic level, scale is essentially all that sets them apart; they contain the same components as the large P.A. systems used at other venues, but these systems are pumped up so that there are more of each type of component and everything is larger.

At the same time, the difference in scale has reached a point where a closer inspection reveals the reality that in order to perform the same function on such a different scale, these systems have evolved beyond simply being the biggest of P.A.s. The logistics of providing live sound on this scale has meant that over time perfecting these systems required them to evolve differently. Despite the many similarities, everything from design parameters for the overall system and component parts, to procedures for setup and operation has diverged slightly from those for any other type of P.A. One might argue that somewhere along the line the scale tipped and tour sound systems have become qualitatively different than other P.A.s, even if they are still related.

To sum things up metaphorically, at some point the differences added up so that instead of being just a bigger breed of P.A. like a Great Dane is a bigger breed of dog, tour systems are now different enough to qualify as a related but entirely unique species, like a wolf is to a coyote or dog. Whether one agrees they have become distinct enough to be the big bad wolf, or thinks they are just the big dogs of the industry, there is no disagreeing that they are the giants of live sound reinforcement. When all set up, top-tier tour sound is beyond impressively large; it is truly awesome and exponentially larger than any other type of sound system on the planet.

What Do We Use Live Sound for?

The initials P.A. stand for “public address,” which sums up what the P.A. is used for. No matter how trivial or important the content, we use live sound to convey a message to the audience, and how a particular P.A. is set up and used depends on the type of message we want to communicate and the environments typically employed for each type of communication. Almost all live sound applications, for all their variety, are e...