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Rockbox mail archiveSubject: Re: Optimum Audio LevelsRe: Optimum Audio Levels
From: BlueChip <cs_bluechip_at_webtribe.net>
Date: Thu, 03 Jun 2004 20:24:13 +0100 At 20:05 03/06/04, you wrote: >The next question that arises is what is considered a "normal" level for >recording an mp3 file. >Around here we use about 18dB below full scale. That is, if a wav file >were to be recorded until it ran out of bits the '0' level would be 18dB >below that. That would give 18 dB of headroom to avoid clipping. Some use -24. > >I have test equipment that can measure the output of the Archos V2 on a >scope or with an audio precision test set. I just need some "standard" >test file. I can make a file with Audacity. > >I guess that making a file with Audacity recorded at as close to 100% as >possible and measuring that would be a place to start. I would have guessed that a sine wave form at 1KHz would probably be the most appropriate choice - but I am reaching the end of my knowledge and moving gently into speculation now. >I'll try to do that and post the results. > >Stu > >At 07:17 PM 6/3/2004 +0100, you wrote: > > >>>Some definition of 0dB and +12 and _ 60 is necessary. dB by its >>>definition is a relative scale. 0 is usually what we are referring >>>everything else to. The last letter in dBv dBu dBm etc gives a clue. >>> >>>So if you use dBv 0dB is 1 volt coming out of the headphone jack. dBm >>>would be around .7 V >>> >>>That is what is so nice about standards. There are so many to choose from. >>>Stu >> >>Yes, dB ...what a totally useless term. >> >>Sadly I have a hoard of Micronas documentation and don't recall reading >>anything that gives any more information about this than that found on >>page 45 of the Datasheet which can be found on the Rockbox docs page. >> >>I don't recall which doc contained the gem that "0dB" produced "Line >>Level Output", but as it concurred with two real life tests it seems >>acedemic really. >> >>I believe the last test was performed by comparing the output of the >>jukebox with that of the "line level output of my car cd player" >>...perhaps this guy (steve was it?) could offer something more helpful. >> >>My guess is dBv, as I understand the most common definition of Line Level >>to be "1V peak to peak". >> >>You seem to be quite knowledgeable ...do you own or have access to a scope? >> >>As for the reference sound level - I'm guessing that'll be some internal >>DAC thing. >> >>For now, I am content to ride with the official MAS docs ...but if they >>are wrong, and it wouldn't surprise me, then we can tweak the code >>quickly enough. >> >>> > ============================================ >>> > What is the VOLUME range you use most often? >>> > ============================================ >>> >>>Sorry to chime in late -- just catching up today. I use: >>> >>>55 - 62 with headphones in bed at night >>>72 - 75 with headphones during the day when it's fairly quiet around >>>82+ when it's noisy around, and in the car through cassette adapter. >>> >>>Hope this helps! >>>Leslie >> >>Added - thanks ;) >>...More good news :) >> >>>Sorry to contribute late. Headphones as low as 45% when going to sleep. (I >>>couldn't use the original Archos at all for this purpose because the volume >>>didn't go low enough!!). >>>Matt >> >>I've added your vote to the graph as 45..54 >> >>Rockbox 45% = 127*45/100 = 57MAS -58dB >> >>The algorithm I've settled on goes down to -61dB with accuracy, so >>...<phew> ;) >> >>I'm amazed that the original Archos scale only ran from Rockbox 50%...92% >>- there aren't 100 discreet steps between those numbers - LOL >> >>Thanks all, >> >>BlueChip >>_______________________________________________ >>http://cool.haxx.se/mailman/listinfo/rockbox >> >> >> >> >>-- >>Incoming mail is certified Virus Free. >>Checked by AVG Anti-Virus (http://www.grisoft.com). >>Version: 7.0.245 / Virus Database: 263.0.0 - Release Date: 6/2/2004 > > >Stuart Engelke >WMCA WWDJ NY >201-298-2108 > >_______________________________________________ >http://cool.haxx.se/mailman/listinfo/rockbox _______________________________________________ http://cool.haxx.se/mailman/listinfo/rockbox Received on 2004-06-03 Page template was last modified "Tue Sep 7 00:00:02 2021" The Rockbox Crew -- Privacy Policy |