![]() When the soundtrack's average level is around the level of the tone you used, the SPL at your listening position will be around 75 dB. Let's say the music of the soundtrack suddenly gets a little louder, but not quite full scale, so the level is now -20 dB - at that point you get 75+10 = 85 dB SPL (the input signal is now 10 dB hotter than the one you used to calibrate). When it hits 0 dB, you get 75+30=105 dB SPL. As the signal gets 'hotter', its digital level gets closer to zero. When the signal hits a peak (loud music transients, explosions, etc) it will be higher than -30 dB. Thus when playing a signal with an average level of -30 dB, you get 75 dB SPL at the listening position.Īll of this is when the volume display reads 0 dB because that is the point you chose: ![]() When you played that tone, you adjusted the channel trims on the receiver until the SPL meter read 75 dB. The test tone you used has an average level of -30 dB or 30 dB below full scale. A peak occurs when the digital signal is as high as it can be and that point is known as 0 dBFS (0 dB 'Full Scale'). Remember Dolby Reference Level is 105 dB PEAK. Greenhill, you calibrated correctly to (Dolby) Reference Level. On receivers that use absolute volume display (0-80 for example), you can of course still calibrate to reference level - the reference volume will just be a positive number (mine happens to be 60). There is no magic to the 0 dB reading - it is just a point near the max range of the volume dial. If you calibrate so that 0 dB on the dial is reference level, then -15 dB is 15 dB BELOW reference level. By convention, 0 dB on the dial is used because it makes it convenient to tell the level just by looking at the screen. Reference Volume (my term) is the number on the receiver's volume dial that achieves Reference Level. If eg., you use the receiver's test tone at -30 dB, you would have to calibrate to 75 dB to achieve Dolby Reference Level because 75 + 30 = 105. The reason you calibrate to 75 dB or 85 dB is because the test tone you use to do the calibration is at either -30 dB (internal receiver tone, DVE calibration disc, THX standard) or at -20 dB (AVIA calibration disc). You calibrate the receiver to achieve that level. It is defined by Dolby as 105 dB PEAKS at the listening position for the main channels and 115 dB PEAK for the LFE channel. Reference Level has a well-defined meaning. We really need two different terms: 'reference level' and 'reference volume'. GlocksRock has it right but let me further clarify.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |