Other Parts Discussed in Thread: TAS5733, TAS5733L, TAS5805
We are developing a product using the TAS5733 and would like to use AGL 4 (full band AGL after Vol 1 and Vol 2 blocks) for limiting volume at high levels in order to prevent clipping as described briefly on page 18 of the datasheet. However it seems that whenever the volume reaches the attack threshold value (the "T" parameter, register 0x44) the audio just becomes severely distorted. With the default settings for the AGL, distortion occurs at relatively low volumes and increasing T allows for higher volumes to be achieved before the distortion occurs. It seems as if the AGL stage itself is causing the distortion as soon as it becomes active. The distortion actually sounds much more severe than what would occur from regular clipping alone.
The following register settings are set during initialisation:
reg 0x1B := 0x00 (osc trim)
reg 0x05 := 0x42 (shutdown)
reg 0x25 := 0x01132045 (set D = +CH1, C = -CH1, B = -CH2, A = +CH2)
reg 0x06 := 0x03 (soft muting)
reg 0x07 := 0x00C0 (master volume 0dB)
reg 0x50 := 0x0F700010 (use L CH EQ coefficients for R CH)
reg 0x46 := 0x00000028 (turn on AGL 4 (full band AGL), leave AGLs 1..3 (multi-band AGLs) off)
...
reg 0x05 := 0x02
reg 0x06 := 0x00
Registers 0x08 and 0x09 are used for controlling volume and balance. All 11 biquads on the input are configured for a gain of 1 (b0 = 0x00800000, all other coefficients = 0). The sample rate is 48kHz.
As previously mentioned, programming register 0x44 allows higher volumes to be achieved before the distortion occurs. Setting register 0x45 for very long attack and release times did not seem to make any difference. The alpha and omega parameters are insufficiently explained in the documentation to know how to program these settings but one would expect the default parameters to produce a good result in most cases.
Please offer assistance.
