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List:       rockbox-sf
Subject:    P#12568 Comment added by axismundi: iPod Classic - limit volume to +6db
From:       Rockbox <tracker () rockbox ! org>
Date:       2012-01-29 22:01:29
Message-ID: 20120129220129.26636.1851941929.swift () www ! rockbox ! org
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The following task has a new comment added:

FS#12568 - iPod Classic - limit volume to +6db
User who did this - Albert Barca (axismundi)

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I'm definitely not the specialist here, but I believe that the amplification levels \
in Rockbox are linked to the DAC+chip combo specifications. I doubt there is a \
practical way to easily detect the clipping level for each target and set that level \
to be the reference (0dB).

If the chip manufacturer follows the norm in the digital audio domain, 0dB (more \
precisely 0dBu) means 0.775V and this seems to have been the case at least with the \
CS42L55. The clipping levels will vary depending on the target, but it will not \
necessarily always be 0dBu (albeit this can probably be a good approximation). The \
whole dB subject can be discussed extensively given that in essence the dB scales \
measures the ratio between two levels, in other words it is a relative scale.

Shifting the volume scale is actually not a bad idea, it would be like having as a \
reference the dBFS (full scale) and not the dBu. Still I'm not sure that it will \
bring much benefit and most likely would not be consistent with how the volume scale \
is defined for other targets. Note also that many reputable manufacturers of audio \
equipment have products with an amplification scale that goes beyond 0dB without \
distorting.

Indeed, it is the user that decides the settings he adopts (that's the great thing \
about Rockbox), but definitely the CS42L55 does not benefit from being pushed to \
+12dB and neither do our ears.

For the ones interested, a good summary of the dB topic in audio can be found at \
http://www.jimprice.com/prosound/db.htm.

----------

More information can be found at the following URL:
http://www.rockbox.org/tracker/task/12568#comment42306


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