How to buy audio for bars & restaurants

It is pretty much the norm for bars and restaurants to have some form of sound system, and for a club it is pretty much the reason for being there. There are, of course, many people who don't want music while they eat and drink - Weatherspoons pubs, for example, generally make a point of not playing any music. But for those that do, what are the considerations for sound systems?

Well, the most significant is your type of customer. This will dramatically affect the specification, and you don't need to be a rocket scientist to know a small restaurant will have very different requirements to a noisy pub.

- How do I deliver content?

If you are running background music every day, then a CD player is unsuitable. They are not designed to play continuously. Multi-disc players just won't last as there is a high probability of something going wrong mechanically.

There are plenty of music servers available and these work just like large iPods, except they sometimes offer good external control facilities and the output of several channels of audio at once. This lets you play, say, jazz in one room and death metal in another, from the same unit.

While most of these use hard disks that are mechanical, they are still perfectly reliable for this kind of application.

- What's 'the cocktail-party effect'

- and is it real?

It sounds silly, but the cocktail-party effect is actually a tested, acoustic phenomenon. When people are in a loud environment they raise their voice to compensate. Unfortunately, as proved by the cocktail party experiments, people compensate by twice as much as they need to. This further increases the background noise, so others over-compensate too.

This means that your sound system may need to be loud enough to cope with sometimes very high background noise levels in order to be heard. This all depends on the atmosphere you want to create, since your sound system also becomes part of the background noise that people will try to talk over.

Background noise is something people seriously under-estimate. When you walk into your empty space on a Monday morning, the sound system will seem like it is blaring, yet the same won't be true for a busy Friday night.

- So how loud is loud?

The problem with sound levels is that they increase exponentially. This means that to make your sound system twice as loud, you actually need four times the power. As soon as you start needing to reproduce any reasonable volume, you need to specify quite powerful amplifiers. So, if you considered using a 100W amplifier and you want the system to be twice as loud, you will need a 400W amplifier. Twice as loud again, you need 1600W.

Once you start using powerful amplifiers, you need to make sure they are somewhere where they can stay cool. A hot amplifier won't work as efficiently or last as long, and may cut out in order to protect itself.

It's important to point out that domestic hi-fi amplifiers won't do the job. Most don't have the power capacity, except for the very smallest of spaces. In addition they are not designed to be used constantly, so you will find they won't last as long as a professional amplifier that is built with heavier duty components and cooling fans.

The nature of the content you are playing also affects what power you need. If the music is modern and bass-heavy, this will require more power too.

- What about noise pollution?

The problem with making things louder is that you run the risk of causing a disturbance to others or harming people's hearing.

Technically you don't have to worry about members of the public, as they are there voluntarily, but you do have a duty of care to your staff. They should not be exposed to a level above 85dB for a long period of time.

It is sensible to design staff areas, such as the bar area, to be less well covered by the sound system. This also helps people order drinks. Some venues also rotate staff to other parts of the building to reduce exposure time.

You must also not cause a disturbance to others. This isn't just loud noise. Even a dull quiet thud into an adjacent dwelling can be regarded as a nuisance. If you cause a disturbance you could end up losing your licence and receiving a substantial fine.

- What sort of equipment should I use?

Equipment in these sorts of environments is normally used by unskilled staff. It is best to keep most of the equipment away from staff in a locked room or rack. You need to be able to make the equipment tamper-proof so that the output from your sound system stays consistent.

Lots of equipment can be controlled with simple wall-mounted remote controls. These can be cheap and are less of a problem to replace if someone spills something on them. This makes operation of the system simple, as your staff won't have to worry about touching the equipment itself.

You can buy sequenced power distribution units that switch the equipment on and off in the right order, at the touch of a button. When switching a system it is important that the amplifiers switch on last so that any thumps created by other equipment powering on does not cause damage to the loudspeakers. When switching off, amplifiers go off first for the same reason.

- What about aesthetics?

For many bars and restaurants, it is not the volume that is important but the decor. The problem is that traditionally loudspeakers are big, bulky and ugly. However, in recent years much has been done to improve the situation.

Many manufacturers offer loudspeakers that have paintable finishes or custom colouring. This sometimes comes at a price premium of about 10-20 per cent and a minimum order quantity.

Loudspeakers have become much more efficient, meaning smaller speakers can produce higher volumes. Some manufacturers are making very small but powerful loudspeakers. These come at a price premium but are aesthetically pleasing to the point of nearly blending in to their surroundings completely.

- What about zones?

In a bar with more than one floor or area, it is important to split the sound system into zones. This is where you will allocate an amplifier and some loudspeakers to serve each area.

You will want to control the volume in each area to suit what is going on in there and the number of people. This is best achieved by having a local volume control in each room, so quick adjustments can be made in situ.

More complex systems will play back different sound in each room. This is easily achieved with a mixer/zoner, which are available from a number of manufacturers. You plug in each of your sources and then you can select which source goes to each output. It is common to have a couple of centralised sound sources, combined with a local sound input, such as from an iPod dock, for each zone.

- What are mixer/zoners?

These often form the heart of systems used primarily for background music and simple announcements. In their simplest form, they are analogue devices that simply switch different inputs to an appropriate output.

More sophisticated ones are available that use digital signal processing. They can mix, split, equalise and delay audio signals to many zones. Importantly, they contain audio limiters to protect your loudspeakers.

All mixer/zoners offer remote control options. Some are just a simple-source select and volume control, but others have small screens and offer external control from systems such as AMX and Crestron.

Also, these devices have a connection to allow them to mute the audio in the event of a fire alarm going off.

- How do I connect the audio kit to my TV system?

Some bars show TV on a big screen. With the football World Cup approaching, this can be a significant driver of revenue. It is normally easy to connect the output of a satellite receiver to a mixer/zoner so you can route that out of your sound system. There is a choice between the sound coming locally from the screens and filling your whole space with commentary.

One important consideration is that if the pictures are being sent to screens over IP, which may be the case in larger venues, this process might introduce an encoding delay, which will mean the sound is out of sync with the pictures. This delay is easy to correct by using a digital signal processor, which enables you to have a delay on the audio input.

- What about microphones?

On the whole, bars and restaurants don't have too much need for microphones. A mixer/zoner will have a microphone input or two to handle the odd announcement. If you find that occasional speeches are made, then a radio microphone can be plugged in too, just like any other audio input, and this is easy to accommodate.

- What about nightclubs?

In many ways, nightclubs have similar requirements to bars and restaurants. They often have several zones, perhaps a main dance area, VIP area, chill-out zone, etc. The major difference is that, especially for the main dance area, the sound levels are much higher and the sound quality expectations of your audience are higher, too.

A club will need a professionally designed sound system. Large powerful loudspeakers will be required and plenty of sub bass. Properly cooled amplifiers are needed that can cope with running at high power for extended periods of time. And you will need to have audio limiting on the inputs to prevent DJs driving the system too hard.