Sound system design and loudspeaker directivities
Most users ask about this as CATT-Acoustic is increasingly used for designing complex sound systems. Directivity files written specifically for CATT-Acoustic (SD1 formats) are available for Philips, L-Acoustics, Duran Audio, Meyer, d&b, Peavey and Martin speakers among others.
SD1 files are speaker directivity files in a native CATT format, assuming that the directivity does not change with distance from the loudspeaker. This is not true when you are in the near field of the loudspeaker, which is important when dealing with large column and curved arrays. This is important - after all, the reason why a large column loudspeaker "beams" sound is that it has a large near field and is designed for the listener to be in that near field. Hence in 1998, CATT also developed a dynamic directivity format (SD2 using DLLs) which offers array modelling and a very general handling of directivity. SD2 offers a much higher resolution than the 10-degree "industry standard" of the time.
In CATT-Acoustic v9.1 and TUCT2, the SD2 format has now been superseded by a freely-editable CTA array format not requiring DLLs. Arrays can be made up from any point-source elements defined in SD0, SD1 or CLF files but, uniquely, can also feature line source elements, such as ribbon tweeters. For now, TUCT1 is also included with CATT v9.1 to preserve compatibility with the older SD2 source format.
CATT-Acoustic also supports the CLF (Common Loudspeaker Format). The CLF Group was formed for the purpose of defining and maintaining a single, open but safe file format that loudspeaker manufacturers could use to supply data to end users in the professional sound and acoustics community. As more acoustic and sound system design software has developed, the number of formats used for loudspeaker data has increased. The CLF Group have agreed to support a common format, making loudspeaker data easier to supply and use, and this is now supported by a wide range of loudspeaker manufacturers. More information is available on the CLF website www.clfgroup.org