Loudspeaker compensation

AN3340

14/24

Doc ID 18453 Rev 1

3.

Open the dedicated Speaker Tune menu by clicking “Panels” on the main menu then

click “Speaker Tune”, or alternatively by using the keyboard shortcut, F5. Figure 12

shows the ST Speaker Tune menu.

Figure 12.

ST Speaker Tune window

In the Speaker Tune menu you can program or select the options which the tool will apply to

make the compensation.

Frequency range (red arrow).

The lower limit of the frequency range should be selected according to the resonant

frequency measured in the impedance characterization. This limit should be higher

than the resonant frequency. The upper limit should be selected considering the source

and the quality of the sound or the performance of the speaker. For example, it is not

necessary to force the compensation up to 20 kHz when the audio source is a MP3 file

where the maximum frequency is around 15 kHz.

Another situation where it is undesirable to extend too much the maximum frequency is

when the speaker response is very poor in the high frequency range. In this situation

the Speaker Tune tool could force some of the biquads to compensate an over-

attenuated response thereby adding high levels of gain that can produce excessive

distortion and increase power dissipation.

The width of the frequency range becomes important when the number of biquads

available is perhaps insufficient. The best choice in this case is to focus the action in

the portion ot the frequency range where the result is going to be most effective.

Action criteria (green arrow)

The compensation can be optimized in terms of peak or area.

PEQ tuning (blue arrow)

Enabling the deep PEQ tuning option the tool applies an iterative action to optimize the

single PEQ; the effect of the filter is optimized but the execution time increases.

PEQs refinement (orange arrow)

Using the option PEQs refinement during tuning process, the tool acts recursively to

refine the PEQs already fixed when a new PEQ is applied. If this option is not used the

PEQs are applied in sequence until all available biquads are used. The execution time

is shorter than with the recursive action but the accuracy of final result is lower too.