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Subject: Re: dB volume

Re: dB volume

From: BlueChip <>
Date: Fri, 19 Mar 2004 21:04:15 +0000

>>I would also prefer a dB display going from -something dB to 0dB.
>So are you recommending that Rockbox report the +12dB point as 0dB? Or
>did you want Rockbox changed so that the highest value of 0dB is what we
>call 93% now?

These are all the same:
# Archos 100%
# Rockbox 92%
# MAS 0dB

Archos puts the max vol at "0dB" so that digital distortion is not a risk.

Rockbox puts the max vol at "12dB" so that quiet tracks/poor recordings can
be cranked up to an audible level.

>I'm confused about all of this. A decibel is a logarithmic expression of
>the ratio between two signal power, voltage, or current levels. Assuming
>that P2 and P1 are power in watts, the decibel rating can be calculated as:
>dB = 10 log10 (P2 / P1)
>I understand that the wattage can be measured at the headphone output, but
>how is it measured internally?
>Note: Decibels can be calculated in terms of the effective voltage if the
>load impedance remains constant: dB = 20 log10 (V2 / V1). Since the
>headphones vary wildly in impedence, that calculation is out the window.
> > I don't think this is so unusual - all the modern amplifiers /
> > receivers (including mine) show volume in dB.
>While typical mid-fi consumer products do that, high-end audio components
>and professional products generally do not:
> opulence.html
> Fred Maxwell

Received on 2004-03-19

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