No way to use ADAU1701 Class-D amplifier

I´m really disapointed with the performance of the outputs DAC0 and DAC1. No sound at all!

I´m using the Evaluation Board UG-072. It should be easier to get a simple sound.

Do I have to set up anything?

Thanks

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  • 0
    •  Super User 
    on Aug 11, 2019 12:01 AM

         Hello,

         The UG-072 document describes the ADAU1401ABEZ evaluation board, a 6" x 6" board with many setup options / jumpers yet with no Class-D amplifier.  Its four DAC outputs have active op-amp filters with 600 ohm output impedance -- these outputs can drive an external amplifier but you'll get little or no sound with headphones.  The much smaller ADAU1701MINIZ board does include an on-board SSM2306  2-watt Class-D amplifier wired to DACs 0,1.  Its speaker outputs are available at the green terminal board.   DACs 2,3 output to a headphone jack with sufficiently low impedance to drive sensitive headphones or an external amplifier.

        Examining your screenshot, I cannot see what signal you have feeding the VCO.  I'd suggest testing with a straight sine oscillator instead -- one less thing to go wrong.  If your ADAU1401ABEZ board is new out of the box its switches and jumpers should already be set to get output from the DACs -- but if not, carefully go over the settings shown on page 3 of document UG-072.

        If you're actually using the ADAU1701MINIZ board and cannot get output from its Class-D amplifier via the two speaker outputs on its green terminal board -- the SSM2306 is off by default, you need to  enable it.  To do this, first go to Hardware Configuration / 170x/140x Register Control and set MP7 to Output GPIO:

    Then add a nonzero DC source feeding GPIO output 7, as shown below:

         Best regards,

         Bob

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  • 0
    •  Super User 
    on Aug 11, 2019 12:01 AM

         Hello,

         The UG-072 document describes the ADAU1401ABEZ evaluation board, a 6" x 6" board with many setup options / jumpers yet with no Class-D amplifier.  Its four DAC outputs have active op-amp filters with 600 ohm output impedance -- these outputs can drive an external amplifier but you'll get little or no sound with headphones.  The much smaller ADAU1701MINIZ board does include an on-board SSM2306  2-watt Class-D amplifier wired to DACs 0,1.  Its speaker outputs are available at the green terminal board.   DACs 2,3 output to a headphone jack with sufficiently low impedance to drive sensitive headphones or an external amplifier.

        Examining your screenshot, I cannot see what signal you have feeding the VCO.  I'd suggest testing with a straight sine oscillator instead -- one less thing to go wrong.  If your ADAU1401ABEZ board is new out of the box its switches and jumpers should already be set to get output from the DACs -- but if not, carefully go over the settings shown on page 3 of document UG-072.

        If you're actually using the ADAU1701MINIZ board and cannot get output from its Class-D amplifier via the two speaker outputs on its green terminal board -- the SSM2306 is off by default, you need to  enable it.  To do this, first go to Hardware Configuration / 170x/140x Register Control and set MP7 to Output GPIO:

    Then add a nonzero DC source feeding GPIO output 7, as shown below:

         Best regards,

         Bob

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