No Filter works on ADAU1701

Hey Everyone,

I've spent more than one day in trying to solve this problem. Looking forward for your advice:

I'm developing a 2-ways battery powered monitor loudspeaker containing a ADAU1701. The Setup includes some functions controlled by GPIO-Pins. As I had struggles setting up the correct crossover I removed all but the basic features from my program. So basically I'm trying to merge both stereo signals into one and later seperate for a woofer and a tweeter at a 2 kHz point. Later I'd like to add an EQ.


No filter seems to work. Whatever Filter I set, I can't notice any difference. When I download the programm to EEProm there will not be any output on any DAC, that has a filter in the signal path before. When I use the "link compile download" I have an output, but any filter settings I adjust won't have any effect.

I attach a very basic setup I'm trying to get to work right now:

I appreciate any help!

  • 0
    •  Super User 
    on Dec 22, 2020 4:25 PM

         Hello Peter,

         Sorry to hear you're experiencing these issues -- it must be frustrating!

         I duplicated your project and found what appeared to be the exact same condition -- the volume controls worked fine but there was full-range sound coming from both of my headphone drivers.  Then I discovered that my headphones weren't fully plugged into the ADAU1701MINIZ eval board all the way, so that each earpiece received (L+R).  With that problem resolved, the project worked as intended. Though not likely, is is possible that your connections between your -1701 board and your power amps have been compromised somehow, so it wouldn't hurt to check these one more time.

         What hardware are you running -- a new custom pcb, an eval board, or one of the third-party (like Sure DSP) boards?  If the latter, perhaps you can also find some assistance from a forum dedicated to the particular hardware.  If the former, could there be a solder bridge between the two DAC outputs (they're adjacent on the IC).  Since your EEPROM isn't working as well, there could be a problem with your board and/or a third-party USBi (if any) not downloading the project as designed -- only that such issues usually cause no sound at all, or else awful white noise.  Finally, is your project using SigmaStudio's default register settings and such?  If you wish you could zip up and attach your project, I can run it here and see if it works any differently than the one I made from your screenshot.  SigmaStudio screenshots unfortunately don't show everything in their underlying projects, so it always helps to attach projects unless some proprietary work is involved.

         Best regards,


  • Hey Bob and thank you very much for your super fast reply!

    I took your response as an inspiration to rebuild the project myself. Since I started the project some months ago and spent hours and hours in troubleshooting, I always used to copy the project file and change it. As you said, it was frustrating! The solution was incredibly easy now: I started a new project file and put the exact same filters as before: It works! I can put any kind of filter, EQ, crossover and so on.