The sound system
The aim of PA systems at conferences is not the diffusion of sound at a high volume, but rather a uniform diffusion for all the participants at a moderate volume and high enough in quality to allow for several hours’ listening. In view of this, it is important to know the answers to several questions allowing the correct identification of the requirements of the conference.
- is the conference room designed for this use and is it therefore equipped with fittings to house the sound equipment?
- How many speakers will there be and where will they be? Will they be standing up? Behind a desk? Able to move about? According to these factors it will be possible to plan the use of wired or wireless microphones and how many will be needed.
- Does the room have good acoustics? Is there an echo? If there is, it will be necessary to provide switches on the microphones in case of feedback.
- Will the audience be invited to speak? If so it will be necessary to provide portable microphones carried by assistants
- Will it be necessary to provide an exterior re-transmission, for example via a link to the Internet?
- Are there going to be musical or video interludes which will need more powerful sound?
Finally, do you wish to make a recording of the conference?
If you wish to broadcast video on a giant screen during a conference, firstly you need to know what type of images you want to show. If you only want to film what is happening in the room and re-transmit it directly, the speakers can have their backs to the screen. This also applies if the speakers are silent during the projection of the recorded images. However, if the speakers are to comment on the recordings whilst they are projected, they must be in a position to see them without turning their backs to the audience. There must also be a secondary light on the speakers during their commentary if the ambient lighting of the room is dimmed during the projections. If they have a desk for their microphones, these must be placed to the side where the speakers will be standing to see the screen.
Position the screen at least 120cm above the floor so that it is sufficiently separated from the stage. Always use a screen with a width of at least one tenth of the distance to the back of the room.
There is no absolute rule for the number of lumens the projector needs. Nevertheless as a guide we recommend:
- 3000 lumens for an audience of fewer than 100 people with ambient lighting
- 4500 lumens for an audience of between 100 and 200 people with ambient lighting
- at least 6000 lumens for a projection in bright light for more than 100 people
- more than 12000 lumens for large events