What are the physical limits of the optimization?

FIRmaker is not magic. It employs straight-forward laws of physics combined with high-end algorithms. Just like with any other physical process, simple limits apply:

  • FIRmaker optimization is a very fine-grained tuning of magnitude and phase of each sound sorce to control interferences between these in a positive, optimized way. At each frequency, the system should provide a minimum of three or four overlapping sources in order to achieve sufficient control of these interferences. Less overlap results in less control. 
  • High frequencies can only be optimized if the distance between the acoustical centers of the HF drivers fed from separate FIR channels is small enough. 
  • Additionally, especially at high frequencies, very accurate loudspeaker "GLL" data is necessary for good results. Each individual cabinet may differ only minimally from the one measured to produce the EASE GLL data used as a basis for optimization. 
  • Higher frequencies are also more vulnerable to air movement than lower frequencies. If too much air movement influences the sound radiation, then the actual results might be degraded at high frequencies more easily than in the low and midrange frequencies.
  • Low frequencies can only be optimized if the total array is longer than approximately one wavelength and the LF drivers sufficiently fill its full length.
  • Low frequency optimization will also require a longer tap-length of the FIR filter, causing a higher latency.
  • AFMG recommends judging the appropriate size of the array and the acceptable FIR filter length (latency) on a case-by-case basis. A limited array length might make optimization at low frequencies altogether impossible. On the other hand, many systems behave nicely at low frequencies making detailed optimization unnecessary.

Last update on 27/06/13 by Thilo Schütz.

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