ADAU1701 DAC2&3 noise

Hello, I use ADAU1701 as crossover for loudspeakers. Its on freeDSP Classic SMD B board. Sound from DAC0&1 is OK, no noise. But DAC2&3 have unacceptable high noise. I would describe it as white noise. When I power down DAC in SigmaStudio, noise is gone.

Here are things I already tried

  •  Mutliple power supplies (switching, linear, battery)
  •  Used ADAU as tone generator to eliminate ADC, noise was on DAC2&3, DAC0&1 were clean
  •  Measured with RoomEqWizard, RTA shows DAC3(red) has 15-20dB more noise than DAC0(green)

There are many people using this board without problems, so I don't expect the board is bad, or badly designed. All SMD components were pre-assembled.

Amplifiers are class AB, have 27dB gain and I could not measure/hear their noise.

Is this ADAU1701 broken?


Best regards

Robert Slosar

[edited by: Rslosar520 at 3:27 PM (GMT 0) on 31 Jul 2019]