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  • Genesis
    started a topic SOMO II sound volume wobbling

    SOMO II sound volume wobbling

    Hello All
    I'm working with a somo II module and an arduino board.
    I've built my own library and the datasheet is very light. some command execution time would be welcome because some delays must be added between commands to have a good working system (the busy line works only when playing) and I had to use a scope with module answer enabled to understand the problem ("CRC error" from the module because two commands were received too fast like "continuous play" + "folder and track" )
    but my problem is not there.
    I have some troubles with the files playback volume.
    I have tried to use wav files, mp3 files, different bitrates (11K up to 48KHz), mono, stereo, different bit dephts (8 to 16bits) but I have the same trouble.
    some files are well played with the same volume and the volume change for some others.
    the files are ok and tested on the computer before to copy them on the µSD card
    the board:

    the board is powered at 5v@3A with 1K on Tx/Rx lines with the arduino nano 5v board. the speaker is 8 ohms one and it's not the thermal protection of the audio amp.
    here is a link on a video.carefully listen the messages at 14, 55 seconds and 1 min 12s.
    http://www.dailymotion.com/video/k3Tr9nTKEcGwyxahu2C
    the volume is variying but not for the other files. this file is playing well on my computer.
    there's some bug?
    greetings.
    Last edited by Genesis; 3rd March 2015, 06:37 PM.

  • Genesis
    replied
    ok Doff
    One here is REV1.
    I will check the other one this evening at home but it was ordered a month ago. edit: yes it's a REV2
    but both have the problem.
    Last edited by Genesis; 17th March 2015, 06:55 PM.

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  • Doff
    replied
    It should be written on the SOMO-II PCB, backside. "Rev 1" or "Rev 2", etc.

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  • Genesis
    replied
    Hello Doff. Where can I find this info?
    Click image for larger version

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  • Doff
    replied
    Hi Genesis,

    What SOMO-II hardware revision do you have?


    Regards.

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  • Genesis
    replied
    any ideas?

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  • Genesis
    replied
    listen carefully the attached file.
    http://www.harpelaser.com/files/ardu...ssue/Vocal.mp3

    it was a recording made with my samsung phone.
    the module is playing two files in continuous mode.
    the "acces autorisé" words and an fx door sound used as "separator".
    they are played 8 times
    as you can ear the module doesn't play exactly the same sound.
    the first loop is not good
    the second one is near correct
    the third not
    the fourth near correct
    the loop 5 is not good
    and the 3 lasts are good
    the 7 is perfect.
    strange thing uuuh?
    Last edited by Genesis; 8th March 2015, 03:25 AM.

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  • Genesis
    replied
    And here is a comparison to fit with the soundforge timeline (file is 1.062s long) between the two blue cursors (dt=1.060s)
    Click image for larger version

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    the first 50ms of the wave are compressed! it's the little glitch. so the volume for this part is low as described for this issue.

    The voice say near the same word in french as the one above.
    "activé" for the one above and "acces" for this one.

    The file was duplicated in wav and mp3, normalized, mono, stereo with exactly same results.
    note: 24bits depht wave file doesn't work
    Last edited by Genesis; 7th March 2015, 10:38 PM.

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  • Genesis
    replied
    here is another test with only one file on the sdcard.
    iit's another one saying "acces autorisé".
    and here is the comparison:
    the original one from soundforge
    Click image for larger version

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    and the measured signal
    Click image for larger version

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    Attached Files

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  • Genesis
    replied
    and here the comparison between the original wave opened under soundforge and the measured envelope: Click image for larger version

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    As you can see something is missing. I don't know why but the wave file is troncated. If that can help to find why.
    greetings
    Franck
    Last edited by Genesis; 7th March 2015, 08:49 PM.

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  • Genesis
    replied
    Thanks Doff for your test.The volume go down when the french word "activé" is played. we can heard more "acTIVE" where "ac" is missing
    I've taken the time this morning to make measures.

    About my system the SDcard contain near 1395 files in 31 directories and never over 255 files in each (perhaps it makes the difference but I can test with only one file).
    now here is the original wave file opened under soundforge. to get an idea of the envelope
    Click image for larger version

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    and here is what I've measured at the output in parallel of the speaker with my scope (differential measure beetwin channel 1 and channel 2 ac coupled + math operation to avoid audio amplifier short circuit to ground)
    Click image for larger version

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    and here is a zoom of the last part where I found the volume very low:
    Click image for larger version

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    Last edited by Genesis; 7th March 2015, 09:06 PM.

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  • Doff
    replied
    Hi Genesis,

    I tested the mp3 file the link of which you posted above. I didn't notice anything wrong with the playback volume. That was my perception at least. My setup was far simpler however.

    Click image for larger version

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    I used a small 8-ohm speaker. The serial commands were sent thru a 4D USB programming cable. See attached photo.

    Regards.

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  • Genesis
    replied
    If I have free time this weekend I will try more tests and measure the output with a scope

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  • James_4DSystems
    replied
    hmm, maybe try lowering the gain/volume of the file and compensating by increasing the volume of the module?

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  • Genesis
    replied
    Thank you for the file James.
    I have two modules and I have tried on both of them with same results unfortunately.
    the strange thing is that it's not sonstant. not on each file. like random.
    you know it's like an automatic gain control decreasing the gain when it detect a peak. with compression of the signal
    Last edited by Genesis; 5th March 2015, 04:50 AM.

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