[Walt]

Randy Yates wrote:

Walt writes:

[...]
For example, if the original stereo recording has three singers at
equal volume panned hard left, hard right, and hard center, summing
to mono will make the guy in the center 3 db louder than the other
two.

Shouldn't he have been 3 dB softer to begin with (in the stereo mix)?

Yes and no. In order to sound like they're all three at the same level,
the center guy would be -3db in the left channel and -3db in the right
channel.

Say for the sake of the argument that guys on the outside are recorded
at a signal level of 0 dbu (.775 volts), that would mean the guy in the
center is -3dbu or 0.54837 volts. Do a mono sum and the guys on the
outside are still at .775 volts but the guy in the middle is now at
1.09674 volts, or 3db louder.

This little anomaly comes about because loudness as we perceive it is
proportional to the *square* of the voltage. It's called "center
channel buildup" and has been around for as long as we've been doing stereo.


//Walt