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  1. #1
    Junior Member
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    Picoreplayer equaliser settings

    I've enabled the equaliser option and it's working, but can someone please explain what adjustment units it uses? I want to try out some headphone equaliser settings that use the common frequency band decibel gain values, e.g. +3.0 dB or -2.2 dB, but the adjustment values in the equaliser range from 0-100 with a default value of 66 for each frequency band. How does this relate to dB values? Is there a conversion formula I can use?

    Apologies if this is answered elsewhere but I've had no luck with searches so far, however I'm sure I can't be the first person to ask this.

    Thanks.

  2. #2
    Senior Member paul-'s Avatar
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    run alsamixer and select the -equal output device. It should show you software db values.

    It's hard to do a HTML slider in db (Which is why we just do 0-100)
    piCorePlayer a small player for the Raspberry Pi in RAM.
    Homepage: https://www.picoreplayer.org

    Please donate if you like the piCorePlayer

  3. #3
    Junior Member
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    Paul - thanks for the reply but that doesn't seem to work for me. I tried with the following command,

    sudo alsamixer -D equal

    It displays the equaliser bands but the labels are in the 0-99 range with the default values showing as 66.

    I wonder if I've stumbled across the answer on this page - http://quitte.de/dsp/caps.html#Eq10 - which I *think* describes the Eq10 equaliser that ALSA is using. It shows a dB range of -48 dB to +24 db which is a 72 dB range. If I assume that each step in the 0 to 100 scale is therefore 0.72 dB that would equate to the default value of 66 being the nearest step to 0 dB (0.72 * 66 = 47.52 dB). That would seem to imply that it's a linear range but it just means the it only allows adjustments in multiples of 0.72 dB.

    Does that make sense or is there some other way to get alsamixer to show dB values?

    Thanks
    Phil

  4. #4
    Senior Member paul-'s Avatar
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    Yes, that is the correct page for the caps library.

    And it looks like the library is not reporting db back to alsa, so it's not displayed. I would think it would then be a linear control, but I'm not 100% sure.
    piCorePlayer a small player for the Raspberry Pi in RAM.
    Homepage: https://www.picoreplayer.org

    Please donate if you like the piCorePlayer

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