DE3507841A1 - Individual pre-equalisation of audio signals for loudspeaker boxes - Google Patents

Abstract

To improve the radiating characteristic of loudspeaker boxes, the audio signal supplied to them is pre-equalised in such a manner that individual radiation errors can be compensated for by this means. The characteristics necessary for the pre-equalisation are taken from a memory via a microprocessor. The memory content is determined by individual calibration. Additional corrections are possible for including the room.

Description

v T w Individual pre-distortion of audio signals for loudspeaker boxes The invention relates to the possibility that the speakers fed Pre-distortion of audio signals individually according to the preamble of claim 1.

The previous loudspeakers have no sound radiation straight frequency-amplitude curve. The dips in the frequency response curve will be caused by interference in the radiation. Some manufacturers of speaker boxes try to do this by different distances between the chassis and the baffle in the direction of the beam, again others by fixed delay elements z. B. for the midrange in the case of active boxes. However, the result is still not satisfactory. In addition, there are the frequency drops due to the different transit times of the sound into the playback room.

These disadvantages are compensated for in the method described below and the playback room is also included.

The high amplitudes of the natural resonances are fully targeted set to a non-disruptive level, which is positive for the structural dimensions of the box influenced (smaller boxes with better bass reproduction). Also the transient behavior is improved, which leads to an even more transparent sound image.

The audio signal fed to the loudspeakers is split into pure frequency components decomposed with the associated amplitudes. The coded frequency and the amplitude level are read into memory. The microprocessor searches for that frequency di necessary amplitude correction and changes the amplitude in the memory. In addition, the processor searches for the stored phase correction under the frequency. Frequency, corrected amplitude and phase correction are output and converted into analog signals. The phase correct: ursignal could be different from one high DC voltage, which are the time intervals between the individual frequencies changed during the digital-to-analog conversion.

At the end there is a frequency with corrected amplitude and corrected Phase.

With the corrected audio signal, the emission errors can now be eliminated of the loudspeaker boxes are compensated. The ones won for each individual box Parameters for amplitude and phase are stored in the memory.

For the comparison, the parameters are changed until the Box reproduces a clean square pulse and broadband emits pink noise. The memory contents should be backed up thereafter.

Additional information should also be entered in the memory that takes into account the radiation behavior of the box at the installation site.

Claims (2)

1. Individual pre-distortion of the audio signal to control the Chassis in loudspeaker boxes to reduce amplitude drops and for linearization of the amplitude curve in sound radiation is characterized in that for each loudspeaker the audio signal is broken down into frequency and amplitude according to Fourier, the amplitude is corrected according to a certain plan and converted back into an audio signal is transformed back. 2. Individual pre-deformation of the electrical signal according to claim 1, is characterized in that the audio signal broken down according to frequency and amplitude individually corrected in the phase and converted back into an audio signal will.