Introduction
Whether it's a concert, a conference, a wedding, or a trade show, sound is much more than just background noise. It is a central pillar of the experience you offer your guests. Imagine a wedding ceremony where the vows cannot be heard, a concert where the instruments are drowned out in a shapeless din, or a conference where the speakers are inaudible. Frustrating, isn't it? Good sound allows for clear message transmission, maintains audience attention, creates an immersive atmosphere, and most importantly, ensures the smooth flow of the event.
Summary:
- Understanding the basics
- Essential Elements
- Wiring and Connectivity
- Sound capture
- The role of the technical team
- The acoustics and venue management
- On-stage monitoring management
- Audio processing and effects
- FAQ
Understanding the basics of sound reinforcement
What is a sound system?
A sound system, is the set of technical equipment that allows the broadcasting of an audio signal to an audience. It generally includes sources (microphones, audio players), processing elements (mixing console, effects processors), amplifiers and output devices (speakers, subwoofers).
For a system to work well, it must be coherent. This means that all elements must be compatible in terms of signal level, impedance, power, and of course, connectivity (XLR, jack, RCA...). The choice of system depends on the venue (indoor or outdoor), the number of participants, and the type of sound (speech, live music, broadcasting), and the duration of the event. There is no universal solution: an outdoor rock concert will not require the same setup as a corporate seminar or a children's show.
Key Concepts
To understand the basics, one must know a few essential concepts. The decibel (dB) is the unit of measurement for sound level. Prolonged exposure above 85 dB can become harmful to hearing. This is why hearing protection is also discussed in event settings, especially for technicians, musicians, or children.
The power of speakers, expressed in watts (W), does not necessarily mean that the sound will be "better" or "louder." It mainly indicates the speaker's ability to deliver sound without distortion.
Acoustics is influenced by materials (concrete walls, wooden ceilings, curtains...). A reverberant room amplifies sounds and causes reverberation, which can blur understanding. Conversely, a highly absorbent space gives a feeling of sound dampening.
The directivity of speakers, their placement, and adjustments on the mixing console allow for compensation of these effects to provide clear, balanced, and immersive sound.
The enemies of good sound
If you have ever heard a shrill whistle coming from a microphone during a conference, you have experienced feedback. It is a form of acoustic feedback due to sound returning between the microphone and the speaker. It is unpleasant, aggressive, and above all... avoidable. Feedback can also occur in the form of humming, unwanted vibrations, or double voices (echo). These phenomena are caused by issues with placement, gain level, or poorly adjusted equalization.
To avoid them, microphones should be positioned far from the front speakers, directional or cardioid microphones should be used, gain, EQ, and anti-feedback filters should be properly adjusted, and it is important to avoid having multiple open microphones at the same time and to use suitable processors or limiters.
Essential Elements
Speakers are the pillars of any sound system. They convert the electrical signal into sound waves and broadcast the sound to the audience. There are several types: active (with built-in amplifier) or passive (requiring an external amplifier). The choice depends on the nature of the event, the venue, and the budget.
Subwoofers are specialized in reproducing low frequencies. They are essential for any musical or festive event where one wants to physically feel the vibrations of the bass.
The ideal is to have a homogeneous distribution between the front speakers, which project sound forward, and the monitors, which provide monitoring for the performers or musicians. Directivity plays a crucial role here: the speakers must be oriented and positioned to evenly cover the area, without leaving any "acoustic holes."
Amplifiers and their role
Amplifiers are the engine of the system. They take the signal from the mixing console and boost it to a level that is strong enough for passive speakers. It is essential to match the amplifier's power to that of the speakers. Note: the power expressed in watts is not the only criteria. Impedance, component quality, thermal dissipation, and signal stability must also be considered. Nowadays, many systems use active speakers, which already incorporate amplification, which simplifies installation and reduces the risks of misconfiguration.
The amplification must also take into account the power supply: check the power strips, extension cords, wiring and the safety of connections to avoid failures or incidents.
Mixing tables, consoles, and FOH control
The mixing table or audio console is the brain of the sound system. This is where all sound sources (microphones, instruments, computers) are connected, adjusted, processed, and sent to the speakers or monitors. There are analog consoles (simpler and intuitive) and digital ones (compact, versatile, with scene memory, built-in effects, etc). The choice depends on the complexity level of the event and the technician's skills.
Each input channel can be adjusted for volume (fader), input gain, equalization (EQ) to correct frequencies, effects (FX) like reverb, delay, or compression, panning (stereo left/right), and routing to the front, monitors, recording, etc.
The FOH (Front of House) refers to the main control room, often located in the center of the venue or at the back. This is where the sound is controlled live during the event. A good control room should have a direct view of the stage, be protected from external noise, and have reliable access to power and all wiring (via snake or multicore).
Wiring and Connectivity
Types of Cables
Wiring is as vital as the speakers or the mixing console. A faulty cable can cause unwanted noise, signal loss, or even a failure during a live performance. The most commonly used audio cables are:
- XLR: a three-pin balanced connector, ideal for microphones and professional signals. It helps limit interference over long distances.
- Jack (6.35 mm or 3.5 mm): often used for instruments or monitor returns, but more sensitive to interference.
- DMX: used for lighting signals, it can sometimes be confused with audio, so be careful!
- Multipair (snake): allows grouping multiple audio lines into a single cable to the control room, essential for complex installations.
Proper wiring should also be labeled, organized, and secured to the ground (gaffer tape, anti-slip mats, cable pathways). Never underestimate the importance of extension cords, power strips, and electrical protections.
Importance of Patch, Snake, and Direct Box (DI)
The patch is the connection plan for the equipment. It indicates where each signal enters and exits the system. The snake (or multipair) is essential to avoid miles of disorganized cables. It centralizes all stage signals to the control room, with an interface often called a stage box. The DI box (or direct box) allows for adapting the signal of an instrument (often unbalanced and strong) to a balanced microphone signal, which is more stable and noise-free. It is widely used for guitars, keyboards, computers, etc.
Electrical safety
A good sound also means good power! The electrical supply is the foundation of any technical setup. It is important to ensure that each element has a dedicated, protected outlet suitable for its consumption. It is strongly recommended to use power strips with protection, uninterruptible power supplies for sensitive equipment, and to distribute the load across multiple lines to avoid overheating.
Outdoors, or in the case of a remote site, an appropriate generator should be used, with a power margin of at least 30%. Be mindful of the generator's noise; it should be placed far away and long, but quality, extension cords should be planned. Trust a qualified technician, follow current standards, and never improvise with electricity.
Sound capture
Microphone
There are two main families: dynamic microphones and condenser microphones. Dynamic microphones are robust and less sensitive to ambient noise. Dynamic microphones are robust, less sensitive to ambient noise, and do not require electrical power. They are perfect for noisy environments, live concerts, or outdoor speeches. Their resistance to feedback makes them a common choice on stage. Condenser microphones offer a wider and more accurate frequency response. They capture more details and subtleties, but are more sensitive to background noise. They require a power supply called phantom power (+48V), usually provided by the mixing console. These microphones are ideal for recording, acoustic concerts, soft vocals, or string instruments. It is therefore important to match the type of microphone to the use. A singer in a rock setting will need a dynamic microphone, while a filmed speech in a subdued setting will benefit from a condenser microphone.
When and how to use them?
Wireless microphones (HF) offer great freedom of movement, essential for speakers on the go, actors, or stage performers. They come in several formats:
- Lavalier microphone: discreet, attached to the jacket or shirt. Ideal for conferences, TV shows, weddings.
- Headset microphone: stable, attached around the head. Perfect for sports presenters, guides, or performers.
- Handheld wireless microphone: similar to a classic microphone but wireless. Versatile and practical.
The role of the technical team
Who does what?
A well-sounded event relies on teamwork. Everyone has their role and responsibilities:
- The sound engineer: he is the technical conductor. He defines the needs, prepares the technical sheet, chooses the equipment, makes adjustments, controls the balance, and supervises the entire broadcast. He is the one who guarantees the overall sound quality.
- The sound technician: he assists the engineer, installs the equipment, cables, tests, monitors, and responds to technical issues. He knows every element of the installation and ensures the safety of the wiring and power supply.
- The stage manager: he is the link between the artists, the organizers, and the technicians. He coordinates interventions, manages the schedule, the technical rider, the technical sheet, and ensures that everything goes as planned.
The importance of soundcheck and balancing
Before each event, it is crucial to conduct a soundcheck or a balance (adjustments of instruments and vocals). This step allows for detecting problems, setting levels, adjusting monitors, and preparing the event in real conditions. Typical steps of the soundcheck:
- Testing each microphone (checking wiring, level, effect)
- Testing instruments (DI, microphone, amplifier level)
- Adjusting stage monitors according to musicians' preferences
- Calibrating front-of-house volumes
- Checking overall consistency and adjusting the mix
The acoustics and venue management
Reverberation, directivity, and sound coverage
Each venue has its acoustic characteristics. An empty gym resonates a lot, while a theater with curtains absorbs sound. This is why sound must be adapted to the context. The goal is to provide each listener with a coherent, clear, and balanced experience, regardless of their location in the room.
Reverberation can create a sense of grandeur, but it makes words difficult to understand. Therefore, it must be controlled by adjusting the EQ, choosing directional microphones, and adapting the placement of speakers.
The directivity of a speaker corresponds to its ability to direct sound in a specific direction. A wide speaker covers the sides well but can generate sound reflections. Conversely, a highly directional speaker may miss certain areas.
Sound coverage must be uniform: the audience member in the front row must hear as well as the one in the back. This sometimes involves adding delay lines (relay speakers) or playing with stereo spatialization.
On-stage monitoring management
Monitoring is the sound that artists hear on stage. It is independent of the sound sent to the audience. Well-adjusted stage monitors allow musicians and performers to clearly hear their performance and synchronize. There are two solutions, stage monitors which are placed on the ground (wedge) and oriented towards the artist and in-ear systems (in-ear headphones), this is increasingly used for professional performances, as they are more precise and isolating. Each musician can request a personalized mix: more bass here, less guitar there... This requires a console with multiple auxiliary outputs, good coordination, and sometimes a dedicated monitoring technician.
Stage plan, technical rider, and backline
The stage plan is a diagram that shows the placement of musicians, instruments, microphones, monitors, and cables. It helps prepare the setup and anticipate needs. The technical rider, on the other hand, is a document provided by the artist or the band that lists the necessary equipment, the desired settings, the stage dimensions and the patch plan. The backline refers to all the equipment made available to the artists: guitar amps, drums, keyboards, etc. which is often rented to avoid transportation.
Communication between the artists, the stage, and the FOH control room is essential. It can occur through: talkbacks, visual signals and intercoms in large configurations.
Audio processing and effects
Effect processors
Audio effects enhance raw sound. They are not decorative; they serve to make listening more pleasant, more intelligible, or more immersive. Compression reduces the gap between soft and loud sounds and allows for a consistent voice without abrupt changes. Equalization (EQ) allows for boosting or cutting certain frequencies which can make a voice clearer, a bass more present, or avoid feedback frequencies. Delay adds a slight offset or echo to create space, when used correctly these effects add depth, when misapplied they make the sound muddy, muffled, or unpleasant.
Noise gate, limiter, and sound balancing
The noise gate cuts sound below a certain threshold. It is very useful for avoiding background noise on open microphones. The limiter acts as a fuse. It prevents the signal from exceeding a certain level, protecting the speakers and the audience. It is essential in all professional installations. Sound balancing is the art of making all sources coexist: Voice, instruments, ambient music... This is done on the console, with the faders, EQs, effects, and experience. A well-balanced mix respects the artistic intention while ensuring comfortable listening without auditory fatigue.
Conclusion
Event sound engineering is a true science, at the intersection of technique, art, and logistics. A well-sounded event leaves a memorable, smooth, and pleasant impression. But for that, it's not enough to have good equipment: a competent team, rigorous planning, and constant attention to every detail are also necessary. Whether you are organizing a concert, a conference, a wedding, or a seminar, take the time to think about sound. It carries your messages, your emotions, your strong moments. And often, it makes the difference between a successful event... and an unforgettable one.
FAQ
What is the difference between an active and passive speaker?
An active speaker has a built-in amplifier and plugs directly into the mains. A passive speaker requires an external amplifier. Active speakers are easier to use, while passive speakers offer more flexibility in large installations.
What sound power is needed for an event of 100 people?
Count on about 5 to 10 watts per person indoors, so between 500 and 1000 watts RMS in total. Outdoors, this power often needs to be doubled or even tripled due to dispersion.
What are the risks of poor sound balancing?
Poor balancing causes auditory fatigue, feedback, poor intelligibility, and an unpleasant sound for the audience. It can also damage the equipment.
Can one manage the sound for a small event alone?
Yes, if one has a basic understanding of the technique and has a simple system (active speakers, microphone, basic mixing console). Otherwise, it is better to hire a service provider.
Is a special authorization required to play music in public?
Yes, it is generally necessary to declare the event to SACEM and pay copyright fees, even for a simple playlist. There are some exceptions for non-profit private events.
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