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| MAPP Online Pro | Features | Quick Start | Loudspeaker Measurements | Acoustical Information |
Acoustical FAQ (Frequently Asked Questions) Measured Arrays
| OMNI Loudspeaker | Surfaces
| Sound Field Scaling |
Frequency Response Scaling About the SPL CalibrationThe Meyer Sound loudspeakers available in MAPP Online Pro have had their maximum linear frequency weighted, slow time weighted, average SPL measured at 2 meters while being driven with pink noise at the onset of limiting. This is done by driving the loudspeaker with pink noise at a higher and higher level and watching the level of the frequency response in SIM II. Because a frequency response measures the ratio of output to input, if the loudspeaker is functioning linearly, increasing the input will cause a proportional increase in the output and the frequency response will not change. As the input level is increased you eventually reach a point where the speaker can no longer reproduce the highest peaks. Because the input increased, but the output doesn't increase, the frequency response decreases. When a loudspeaker's maximum average SPL is measured, the level of the pink noise is increased until the decrease in frequency response just begins to happen. The linear frequency weighted, slow time weighted, average SPL of that speaker is measured for that drive level. The sound level meter is then switched to Peak mode to ensure that peak to average (crest factor) of the output sound is the same as the crest factor of the input pink noise. Because the crest factor of SIM II pink noise is 12.5 dB, the Peak SPL reported by MAPP Online Pro is always 12.5 dB higher than the average. The peak level reported by a loudspeaker in MAPP Online Pro will always be lower than the peak level reported in the datasheet for that loudspeaker. The peak level reported in the datasheet is measured using a short burst of music. Meyer Sound loudspeakers can reproduce short bursts of high power while the peak limiters are engaged but before the RMS limiters engage. For this reason the peak level for music reported in the datasheet will always be higher than the peak level for pink noise which is reported by MAPP Online Pro. MAPP Online Pro has been calibrated such that a virtual microphone placed 2 meters from a virtual speaker set to a Relative Level of 0dB will report the same average and peak SPL as the actual loudspeaker when driven with pink noise at the onset of limiting. The OMNI source and SPHERE source have been set arbitrarily to produce 94dB at one meter. |
SUPPORT RESOURCES RELATED PAPERS MAPP: Predicted & Curvilinear arrays Low Frequency DOWNLOADS: Zipped Archive with JM-1P Project Files For questions or more info: |
