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Rockbox mail archiveSubject: Re: dB volumeRe: dB volume
From: Fred Maxwell <rockbox_at_anti-spam.org>
Date: Fri, 19 Mar 2004 15:08:31 -0500 Uwe Freese wrote: > 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? 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: http://www.adcom.com/preamplifiers/gfp750.htm http://www.atma-sphere.com/products/mp3.html http://www.legendaudio.com/prod02.htm http://www.ys-audio.com/symphonies.htm www.metaxas.com/pages/products/ opulence.html http://www.tascam.com/images/popups/TASCAM_AV452Front_Rear.jpg Regards, Fred Maxwell _______________________________________________ http://cool.haxx.se/mailman/listinfo/rockbox Received on 2004-03-19 Page template was last modified "Tue Sep 7 00:00:02 2021" The Rockbox Crew -- Privacy Policy |