IPSIS developed a line array speaker system consisting of conventional modified loudspeakers.
The system is compact and cheap compared to other high-end systems.
We can finish the system to the specification of the client to adapt the speaker to the architectural layout of every room.
Reverberant halls demanding high speech intelligibility are a classic problem in acoustics.
Acoustical treatment is often expensive and sometimes unwanted. In churches a combination of long reverberation time for organ and choral music and high speech intelligibility is preferred.
To prevent the stimulation of the reverberant field loudspeakers with high directivity are wanted. These can aim the sound exactly to the audience and not to walls and ceilings, causing reverberation.
Classic column speakers are not able to prevent lobing (off axis sound radiation), thus stimulation reverberation in a room. And horns often have insufficient directivity.
A modern approach to these problems is the line-array.
a line-array is a well designed and engineered speaker system with extremely high directivity and effectively suppressed lobing.
Polars (measurements around loudspeakers) determine the total radiation characteristic of a loudspeaker, on-axis and off-axis.
Here we present some measurements: a 4 tweeter array, speakers are spaced 20 mm; 4 tweeters spaced 10 mm, 24 tweeters spaced 1 mm and 32 tweeters spaced 1 mm.
Close spaced speakers clearly show superior radiating characteristics.
The lobe only fires to the front, while speakers with more spacing create unwanted lobing.
24 and 32 element speakers show superior behaviour to over 10.000 Hz. This is sufficient for very high speech intelligibility.
Line-arrays radiate sound shearing the heads of the public. Measurement data are contained this way; the measurement microphone is aimed at the bottom of the tweeter-array
The frequency characteristic determines the amplitudes of all frequencies.
The cumulative spectral decay (waterfall) inspects the existence of unwanted resonances in the sound.
Our line-arrays behave like normal speakers. No special amps or processors are required. In practice a simple parametric EQ suffices to adapt the array to the most difficult environments.