TAS5558: Cant regulate Subwoofer Volume

Hi,

By writing Reg D8 = 00 00 00 48, the digital gain is set as 0dB;

By writing Reg D8 = 00 00 00 48, the digital gain is set as -25.25dB;

Each code step stands for 0.25dB. I would recommend you to change the code and check the output level to see if the relationship is correct. 

Thanks!

Regards,

Sam

Hi Sam, thanks for quick response

"By writing Reg D8 = 00 00 00 48, the digital gain is set as -25.25dB" some write failure here?

i know the steps, with Master Voume D9 this works as it should but not with D8. LFE CHAN is completely muted if other valuable is set than 0x48

Hi,

Could you try to read the volume setting registers back after a writing operation? Just make sure they are written correctly.

BTW, the woofer mainly response in the low frequency range. The perceivable loudness with the same output power could be much lower than 1kHz~4kHz range sounds. So I would recommend to check the output level by an oscilloscope or multimeter rather than listening.  

Thanks!

Regards,

Sam

LFE output is zero, writing to 0xD8 is correct, maybe its because i switched some channels ? E.G. i switched channel 7 and 8

Hi,

Looks like you used the input mixer to switch the channel 7 and 8, then it should not cause any issue. D8 register is still controlling the channel 8 volume.

Do you have any equipment to measure the output level in volt or in dBFS? You can use a AUX0025 passive filter or a simple LC filter(like 10uH+1uF) and simple measure the audio output. Please check the output level or gain with different D8 volume setting, and check if it is changing as expected.

"By writing Reg D8 = 00 00 00 48, the digital gain is set as -25.25dB" some write failure here?" -- Sorry for the typo, it should be D8 = 00 00 00 AD, volume =-25.25dB.

Thanks!

Regards,

Sam

Output is always zero if i try oher variables than 0x48

Hi Rene,

It's quite strange to have 0 output with any other volume...

Have you read back the register value after a writing operation to the volume register? And have you tried if the master volume register 0xD9 works?

Usually these 32-bit registers needs a consistent 4-bytes I2C writing with repeated start.

Thanks!

Regards,

Sam

Hi SAM, i dont use I2C repeated start command. Master Volume D9 is working fine. The AMP Proto is running since month without problems. Only D8 Volume changeing dosnt work. On D9 i have 30 Volume Steps and on D8 i have only 10 Volume Steps.. maybe this is the problem?

Regards

Hi Rene,

Thanks for providing the background.D0~D9 volume control registers have all the same gain vs. index relationship. 

If the it remains no output with any volume code except D8 = 00 00 00 48, then it's more like the I2C writing operation related. You may try to read back the register values to check if it's written successfully.

Is it possible for you to simply try to copy the good working code D9 to D8 as they have similar index?

Thanks!

Regards,

Sam

Hi Sam, i have checked twice the code its absolutely the same. D9 master Volume control works as it should. I use my own software I2C which actually dont have the capability to read from I2C.

On program start D8 is initialized with 00 00 00 48. Then if i try to write 00 00 00 AD, SUB out is completely muted. And if i write 00 00 00 48 again its full volume again - strange

Hi Rene,

Probably you can try some intermediate volume codes and monitored the output level change. Thanks!