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Noise problem with PCM4204EVM

Hussain Taher
Prodigy 30 points
Other Parts Discussed in Thread: PCM4204EVM, PCM4204

We ordered PCM4204EVM. We try to convert a DSD signal into a PCM signal. DSD signal is generated by a SACD player. After conversion to PCM, we move into the Serial Port out to SPDIF. We can hear the music but there is a noise from above.

We tried several configurations but we still have the same noise problem.

Here is a block diagram that shows how we proceeded.

Best regards.

  • 0
    TI__Genius 16270 points

    Hussain,

    Can you please attach a schematic and FFT's?  What sampling frequency is the PCM data output as well?

  • 0 in reply to Patrick Galvin
    Prodigy 30 points

    Patrick,

    The DSD is generated by a SACD player. We directly enter on port J7 with the correct data.

    We don't use the onboard DSDTEST.

    We use the Master Clock from the SACD with 22.5792MHz


    Here is the configuration we use:

    SW1

    FS0   HI

    FS1   LO

    FS2   LO

    S/M   LO

    FMT0 LO

    FMT1 LO

    FMT2 HI

    HPFD LO

    SUB   LO

    /DSDTEST HI

     

    SW3

    MONO34 LO

    MONO12 LO

    FMT1      HI

    FMT0      LO

    CLK0      HI

    CLK1      HI

    /DIT        LO

     

    SW5

    OSC1  LO

    OSC2  LO

    /EXT    LO


    We just want convert the DSD to PCM and be able to hear it on AES OUTPUTS. We can hear the music when the SACD is play but we always have noise on it. 

    When we click PAUSE on the SACD we only hear the noise. 

    Best regards.

    H.Taher

  • 0 in reply to Patrick Galvin
    Prodigy 30 points

    Here is 2 photos of the connectic.

  • 0 in reply to Patrick Galvin
    Prodigy 10 points

    Dear Patrick,

    Thank you for your help.

    We want to be able to convert DSD -> PCM using the onchip decimation filter.

    Our DSD source is a SACD player witht a DSD_BCK of 2.8224MHz and we take the front right and front left channels (stereo).

    The PCM4204 is configurated like this:

    Dual rate (64xFs input DSD data and 384xFs Fscki)  (FS2=1, FS1=0, FS0=0)

    Input mode selected (S/M=0, FMT2=0, FMT1=1, FMT0=1)

    The other bits are configurated like this:

    (HPFD=0, SUB=0, /DSDTEST=0) (To enable U2 for the conversion)

    We made some modifications on the PCM4204EVM board in order to be able to convert the DSD signals from the SACD player to the PCM4204 converter (U2) and use the onbaord transmitter interface:

    • Oscillator of 16.9344MHz (384xFs) placed instead of 22.5792MHz
    • U14 and U15 buffers have been removed and we connect directly the data form DSD-PCM Port to the transmitter U14

    We post a picture of the custom made PCM4204 for your understandling.

    At the S/PDIF output we hear the music and the sound is OK, but it is parasited by a big noise (a glitch every 15.06Hz).

    Hereunder I place a picture for you to understandling:

    I place also a FFT of the made on the recorded noise signal.

     

    Is this a problem with the digital filter and the clocks?
    Does the problem happen because the Fscki is not directly derivated by the SACD clock?
    (in DSD input mode configuration the PCM4204 is not able to take the 22.5792MHz from the SACD player.