DSLO said:
If the volume goes up to +16.5, all I have to say is holy s**t! Thanks for the reply. I'll never push it to that level, but it's nice to know that you can. Whatever happened to the 0 to 10 (or 100) level on the volume control? Where do they derive that -94 (or whatever) to +16.5 scale?
Good question (and a common one).
The scale is irrelevant and receivers vary as to how the volume control is calibrated; ie how much the level increases with a given movement in the volume knob. Even if two receivers use the same numbers (eg. -80 to +16) you cannot directly compare their output unless they are both calibrated to the same level. In other words, if they both have been calibrated to 85dB SPL output when the volume control reads 0dB, then you could conclude that moving the volume control to +1 on both would increase the SPL by 1dB.
The two scales are known as absolute (eg. 0-80) and relative (eg. -80 - +10). The relative scale is preferred because it closely mimics the way digital audio levels are defined. 0dB is 'max' and everything below it is relative to that. It's not perfectly analogous to digital audio, however, because you can't exceed 0dB for digital audio. 0dB on a receiver is just the accepted point to use for calibration - you make the receiver output your desired SPL at 0 on the volume scale and everything else is relative to that.
So for example, calibrating to Dolby Reference Level you would get 85dB SPL when the volume control is at 0dB (assuming you use a -20dB input tone). That gives you 105dB peak at the listening position. If you then had the volume knob on -10, you would be listening 10dB below reference level. You can do the same thing if your receiver uses the absolute scale.
Onkyo receiver manuals say that 82 on the absolute scale corresponds to 0 on the relative scale, but as I said they are only directly comparable after you calibrate so that the receiver is outputting a known SPL level at that volume knob setting.
