When the DRC is enabled and is aggressive enough, the protection rarely initializes and does not dominate the overall color of the sound. However, pushing the speaker output to its limits to achieve a high SPL is ideal. If the speaker response at high volumes cannot achieve the level of the reference device in a certain band with or without the DRC enabled, try to increase the excursion and temperature protection priority for that band.

Remaining aware of the resonant frequency (Fs) and the electrical resistance (Re) acquired during characterization is always important. Find these parameters on the characterization data tile in the Audio Processing → Smart Amp pages of the PPC3. The high-pass filter cutoff for nominal loudness tuning determines the low cutoff frequency of the low-band protection. The user can set the cutoff frequency of the mid-band protection to either include or exclude the resonant frequency. TI recommends to set the mid-band frequency 100 Hz above Fs for matching purposes.

Users typically note that the most excursion occurs in the low band, especially if the low-band cutoff is set to include Fs. As the speaker characterization excursion response in the Figure 2-10 shows, the high band does not have much excursion; therefore, the user can set the low band with a higher priority than the high band. Try 3, 2, and 1 as low-, mid-, high-excursion priorities to see if it increases the low-end response. Likewise, the speaker temperature is dominated by the mid and high bands. Try 1, 2, and 3 as the low-, mid-, and high-thermal priorities. Set the low-band excursion and thermal speed to 10 / (mid-band frequency).

For instance, if the mid-band frequency is 1000 Hz, set the low-band speeds to 100 ms. Likewise, set the mid-band speeds to 10 / (mid-band frequency). Be sure to check whether these settings have any effect on the pink-noise response matching in a negative way.

Figure 2-10 Modeled Excursion From Characterization