|
Rockbox mail archiveSubject: (unknown charset) output level equalisation(unknown charset) output level equalisation
From: (unknown charset) ten Velde family <tenvelde_at_xtra.co.nz>
Date: Sat, 29 Nov 2003 11:59:12 +1300 I've seen a number of posts here describing settings for a sound that's close to the sound produced by a CD player. I'm trying to use the Jukebox through a PA and found that it's rather thin when all settings are on 0 or off, so decided to create a series of test tones of various frequencies and put them on the Jukebox as mp3 files, so I can adjust the settings to give me a reasonable level frequency response using the level meter on the PA mixer. I created a series of files of sine waves of one frequency each in wav format, then bulk converted them using CDex without normalisation. To check whether these tones were indeed all of the same level, I used the analising function of MP3Gain. I thought that would be the best way since I run all my files through this program to ensure a reasonably "evenness" of levels. The results of this are rather alarming: at 50Hz the level detected is 72.9 (below that it's even less, but I'm not too worried about those), the levels then rise to 98.8 at 3840Hz and drop back down again to 62.0 at 15kHz. The mp3s are encoded at 192kbps to ensure a reasonably flat response at the higher frequencies. When I load these three files into Goldwave, the levels are: 50Hz maximum 0.2500 RMS 0.1767 3840Hz maximum 0.2510 RMS 0.1767 15kHz maximum 0.2722 RMS 0.1767 which would indicate no significant variation in levels. The question is: should I use the files as they are and assume that MP3Gain would distort the real levels, or should I normalise using MP3Gain to get a true evenness of levels? Also, since I have processed all the music files through MP3Gain, and if that has "adjusted" the frequency response of these files, would I be better off to process my test tones the same way? Only one can be right, surely - and a level variation of some 40dB over the audio spectrum is rather too large to ignore. ---------- John ten Velde Received on 2003-11-29 Page template was last modified "Tue Sep 7 00:00:02 2021" The Rockbox Crew -- Privacy Policy |