Although this is a most impossible to answer in general way without knowing more about the specifics of the space and type of performance, the answer depends on two factors; a) how big an area do you need to cover, and b) how loud do you want it to be?

a) If you look at the speaker specs, you will see a coverage quoted in degrees both horizontal and vertical. If you draw a plan of your venue, then place your speakers on it, you can use the horizontal value to see how the sound will radiate from the speaker. Be aware that this coverage applies to higher frequencies only. Bass frequencies radiate in all directions whatever speaker is used - this is why our sub-bass speakers have no quoted coverage. This will give you an idea as to whether you will need extra speakers to widen the spread or to cover any 'holes' in the coverage of your main system.

b) Some customers ask us for say a '2K system'. What they are asking for is a system that consumes 2000watts of power. An inefficient system may turn most of the 2000w into other energy such as heat rather than sound, whereas an efficient will produce more sound, and therefore be louder. Both would be a '2K system'. A more useful request would be one for a system that produces a minimum of 110dB SPL at the rear of the venue that is 16 metres long and 10 metres wide.

SPL (Sound Pressure Level), is a measurement of how loud a sound is. It is measured on a logarithmic or decibel (dB) scale. 110dB equates to rock music.

Now, most experienced sound designers and operators will be familiar with a range of speakers and given a room size and type, and details of the sort of performance, will be able to suggest a speaker system. It is, however, possible to calculate the required SPL from the speaker specifications in the following way.

Take the figure for the speakers maximum SPL. For a Renkus-Heinz CE153 this is 134dB and is measured 1 metre away from the speaker. Now we require a figure of 110dB 16 metres away, and as you would imagine, the further away we are from the speaker, the quieter it sounds - in fact, for every doubling in distance, we loose roughly 6dB. So, if it is 134dB at 1m, at 2m it is 128dB, 4m it is 122, 8m 116dB, and 110dB at 16m. Therefore over its given 60 degree coverage, this one speaker will be loud enough. For a room 10m wide, you would need 2 speakers to cover the area.