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DIY PA | Tannoy

As installation contractors of PA / Tannoy and Background Music (BGM) systems, we have a wide range of experience against all types of commercial environments and customer installations. We consider many smaller, basic and traditional Public Address (PA) / 'Tannoy' and / or Background Music (BGM) applications to be DIY capable by electrically knowledgeable tradesman and end user customers.

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Basic Design and System Specification

Note: Use as a guide only traditionally commercial audio applications - assumes basic technical knowledge.

Deisgn Specification:

What audio application do I want from my system?
You may have some specific thoughts or requirements. Most basic traditional applications are designed for making voice announcements, for producing background music (BGM) or a combination of both of these (there are some notable differences).

What size mixer/smplifier do I need?
Your amplifier will provide the basis of power delivery from the system inputs, and out to the speakers. In 'size' terms, amplifiers are sold with a power rating, specified in watts. You should correlate the power requirements of the amplifier directly to the power demands of the speakers which are also specified in watts.

TIP: To avoid loading stress to the amplifier and to ensure product longevity, allow for a margin of 'headroom' capacity when specifying your amplifier size. Always refer to specific manufacturer requirements. Our advice is to allow for at least 25% headroom capacity for voice PA / announcement applications and at least 50% for BGM / radio applications.

What 'Inputs' will you require to you system?
Your application requirements will likely dictate your inputs (eg. if your system only requires voice announcements, then you are likely to want a microphone/s). If your application is for BGM or Radio, then you will need to consider input capability of the mixer / amplifier as well as the associated input source (ie. radio tuner, music player). You can of course combine these applications.

How many speakers do I need?
The most frequently asked question we receive. Every project is different, all will have their specific requirements and challenges.

- Work out your coverage plan (where you want / don't want coverage)
- Assess the environmental impact and acoustic challenges (eg. ambient noise levels, scale and volume spaces, construction and ceiling heights).
- Is the application background music or radio? (these applications generally require a higher density of speakers).
- Locations. Strategically position speakers for maximum coverage and audio quality benefit.
- Smaller rooms / areas will obviously need smaller and less powerful speakers, but not necessarily less of them. For example, in an office we wouldn't look to use a single large speaker (this would work, but be very disruptive), we would look to deploy a number of speakers that would afford a generally low and localised output and volume level.

TIP: We all know the result of a single, large speaker, poorly positioned... "what?" Allowing for a good number of speakers, strategically located, means that we can keep the overall levels down, whilst providing quality coverage and output intelligibility.

What type/s of speakers do I need?
Commercial audio systems are fundamentally different to stage, performance and typical home audio systems (see foreground and background audio). For most installed commercial audio systems, the amplifier output is a high voltage (up to 100volts in the UK) to afford efficient long distance audio transmission over relatively small cable sizes. Commercial audio speakers have line transformers built in to them to step down the voltage. It is therefore very important that you attach the correct speaker type to the system. The speaker design is really up to you, the installation surface, location and of course the aesthetics. Consider also the environment, specialist speakers may be required (eg. weather-proof, anti-vandal, ATEX).

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Installation Guide:

Equipment Location?
Consider the location of the main system equipment. Cables to the speakers will need to be installed from this location, is there cable containment to use? is there easy access to and from this location to install cables? If you intend to input radio to the system is there external access to install the aerial, perhaps select a location with an external wall.

Speaker Volume Settings and / 'tappings'
Commercial audio speakers are line driven from integrated transformers. The secondary side of these transformers usually have selectable 'tappings' (eg. a 6watt ceiling speaker might have tappings for 6, 3, 1.5 and 0.75 watts). Using these tappings, you can set individual speaker volume level output, ie. higher tapping for noisy areas, lower for quiet areas.
PA / Tannoy Speaker Cable Size
What type of speaker cable should I use?
Amplifier output to speakers can run at up to 100volts in the UK. We would therefore always recommend using a double insulated cable, installed within cable containment or locations to protect it from mechanical damage.

What size of speaker cable should I use?
The size of speaker cable is determined by the power output and the distances to the speakers (see chart opposite).

How do I connect the speakers?Speaker Wiring Diagram
Commercial audio speakers are wired connected in parallel (see diagram opposite).

Volume Levels and Controls
The mixer / amplifier controls the power delivery to the speakers. It will likely have multiple input levels control and a single output control (master). By adjusting an individual input (eg a mic input) you can alter the volume level associated with this input (ie. microphone announcements are louder or quieter, but other inputs remain unchanged). The amplifier will also have a 'master' levels control which adjusts all volume levels. Remember you also have the speaker transformer 'tappings' to control the levels of individual speakers.

TIP: You can install a volume attenuator controller to provide for further individual volume control to one or many speakers.

Audio Zones or 'All Calls'
Most commercial audio systems simply present output to all of the speakers (ie. the announcament or music goes to all speakers, we call this an 'all calls' system). It is possible though to configure and design a system to create audio 'zones' so that you can control output to individual speaker groups (this could be to separate office areas from the factory or even segmenting the system into separate floors or different buildings. Zone design and configuration can be complicated - for this reason, we view multi-zone commercial audio designs (PA/Tannoy or BGM) as beyond the scope of a basic system, and would recommend your contact with us to discuss further.


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