ADAU1452 + CS42488 output noise
Hello,
I need your advice and help.
I have 4 DSP pair boards - ADAU1452 + CS42488.
All programmed successfully with fs = 192 KHz . Project is simple DSP 3 way crossover.
The problem is permanent noise with all the boards without input signal or on low volume with connected source signal on all outputs.
Tested it with small desktop stereo speakers on each outputs and 3 way big audio system - always on all outputs there is noise.
( so there is no ground loops or similar ... )
Crossover is working fine with input signal, but when there is no signal ( stop the player ) --> you can hear the noise.
Is it possible that fs = 192 KHz for CS42488 is making this noise ? ( post 549 for example - just now saw the post ) ...
Can you direct me where to dig ... or to put somewhere check box labeled "no noise" .. ?
Best regards,
Emil
DIYAUDIO post 558 with all pictures and SigmaStudio project
www.diyaudio.com/.../page-28
Audio Signal Processors
adau1452
hardware
SigmaDSP Audio Processors
ADAU1452 + CS42488 output noise
Hello Emil,
I have noticed a couple of things in your project.
1) The sample rate setting isn't correct, you set the CG1 to output 48KHz and you are using CG1's rate as start pulse which makes the DSP's sample rate to be 48KHz and your serial ports are all set for 48KHz. The sample rate at the top of sigma studio is for a software sample rate which will used for calculating filter coefficients, compressor curves, etc. basically anything that needs timing in the DSP code will get its timing reference from sigma studio sample rate and it will NOT set the actual sample rate of the DSP.
2) If your sample rate is 192KHz, then you can't run TDM8. The serial ports are limited to maximum of 24.576MHz clock. So, you can only do TDM4 with 192KHz. If you reduce the bit depth to 16bits/ch instead of 32 bits/ch, then it's possible to have TDM8 at 192KHz.
BCLK = 8*16*192KHz = 24.576MHz
So, if you wish to run the project at 192kHz, then you will have to make the below changes.
set the start pulse (DSP sample rate) to be 192KHz like below.
set the serial ports to be 192KHz like below.
Also consider the limitation of serial port clock of maximum 24.576MHz and either reduce the sample rate or channels or bit depth. Because you can't exceed 24.576MHz BCLK.
Just set the port to TDM4 and make the above-mentioned clock changes and see if you still get noises.
Regards,
Harish
Hi Harish,
Thank you for your fast respond !
Will try your suggestions on my hardware.
Have a nice day,
Emil
Hi Harish,,
The problem was PSU - I tried 2 SMPS - even 3A variant - but it doesn't work --> noise..
Now I am using transformer ... :) - no noise ..
May I ask to check my project for 96 KHz setting ( too complicated for me ) - all forum user suggest 96 KHz for that DSP PCB
Project is attached in post 572 - https://www.diyaudio.com/community/threads/low-cost-adau1452-china-board.309680/page-29
If all tabs on hardware configuration are ok... I hope to try it.
Have a nice day,
Emil
Hello Emil,
I had a look at the project attached in the above-mentioned link.
Your CG1 is set for 48KHz and start pulse is set for 2x CG1's out (2xBase_fs) which is correct. It will make the DSP run at 96KHz, so you are fine here.
But you have to do the same in the serial port sections as well, it's not set for 96KHz, it's still at 48KHz. Refer the picture below and make it 2*fs, then everything will run at 96KHz in your project.
Regards,
Harish
Hi Harish,
Thank You again for your help ! Will use 2*fs in Serial Ports configurations.
BR,
Emil
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