Calibrating Monitoring Levels / Digital Clipping

over-man · 12th January 2007, 10:02 PM

Yesterday I attempted to calibrate my monitoring levels as described by Bob Katz in "Mastering Audio." I setup pink noise at -20dbs RMS in Logic, routed the signal through my Lightbridge to HD24XR, sending analog outs 1-2 into the Stereo Insert of a Yamaha MG32 to bypass unneccessary circuitry on the board.

I used a decibel meter, c weighted, to mark the master fader position that produced 83 db SPL at my listening position, then -2, -4, etc.

Here is the question portion: When I play CDs or mp3s from iTunes, I should leave the volume fader in iTunes all the way up, correct? This way I have a solid reference that shows me how loud CDs have been mastered. With the fader at 0, classical CDs are at a comfortable listening level, mainly hovering around the 83-85 db mark, with peaks of 92 and lows around 70. Very dynamic! Other modern rock CDs force me to turn the fader down to -6 or so, showing me they have been mastered very loudly.

A few CDs constantly light up the red clipping meters on my XR. Does this mean these CDs are literally clipping over and over? Or is there something in my chain that is adversely affecting my results? Its nice to have a solid reference, something that is fixed, but I just want to be sure I really understand whats going on here. Thanks guys.

over-man · 13th January 2007, 06:15 AM

The trend I observed is pretty clear after an afternoon of listening to random tunes in my library. Jazz cds hardly ever clip, although some do occassionaly, and most of my rock and hip-hop cds clip from a little to most of the time in extreme cases.

On some of the cds I can hear what sounds like digital distortion, but in many of the others I don't. Why? Do I have something calibrated improperly or would the digital clipping be worse with lesser DA convertors?

Monsterlab · 13th January 2007, 06:22 AM

somethings wrong with your math.......especially if you can HEAR the clipping....

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12th January 2007, 10:02 PM	#1
over-man Gear maniac Join Date: Oct 2006 Location: Dallas, TX Posts: 206	Calibrating Monitoring Levels / Digital Clipping Yesterday I attempted to calibrate my monitoring levels as described by Bob Katz in "Mastering Audio." I setup pink noise at -20dbs RMS in Logic, routed the signal through my Lightbridge to HD24XR, sending analog outs 1-2 into the Stereo Insert of a Yamaha MG32 to bypass unneccessary circuitry on the board. I used a decibel meter, c weighted, to mark the master fader position that produced 83 db SPL at my listening position, then -2, -4, etc. Here is the question portion: When I play CDs or mp3s from iTunes, I should leave the volume fader in iTunes all the way up, correct? This way I have a solid reference that shows me how loud CDs have been mastered. With the fader at 0, classical CDs are at a comfortable listening level, mainly hovering around the 83-85 db mark, with peaks of 92 and lows around 70. Very dynamic! Other modern rock CDs force me to turn the fader down to -6 or so, showing me they have been mastered very loudly. A few CDs constantly light up the red clipping meters on my XR. Does this mean these CDs are literally clipping over and over? Or is there something in my chain that is adversely affecting my results? Its nice to have a solid reference, something that is fixed, but I just want to be sure I really understand whats going on here. Thanks guys.

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13th January 2007, 06:15 AM	#2
over-man Gear maniac Join Date: Oct 2006 Location: Dallas, TX Posts: 206	The trend I observed is pretty clear after an afternoon of listening to random tunes in my library. Jazz cds hardly ever clip, although some do occassionaly, and most of my rock and hip-hop cds clip from a little to most of the time in extreme cases. On some of the cds I can hear what sounds like digital distortion, but in many of the others I don't. Why? Do I have something calibrated improperly or would the digital clipping be worse with lesser DA convertors?

13th January 2007, 06:22 AM	#3
Monsterlab Gear nut Join Date: Oct 2005 Posts: 143	somethings wrong with your math.......especially if you can HEAR the clipping....