Somone at work is doing an indie. He came to me asking a question about why the levels of his stereo audio files were dropping when he made mono and then panned one channel to the middle. He brought in some files for me to look at. I could see what the problem was & begen running through my head about ways to fix it.
After going around & about over the possibilities, a little dim bulb glowed waaaay back in the recesses. There was something there about a lesson I once learned about panning to the middle and a level drop that was/is built into pan controls of audio gear. A quick Google search later and I ran onto this site:
In particular, this was the part that I was trying to wrest from the archives of my head:
When a signal is panned centrally, exactly the same signal will be output on both the left and right audio channels. If you were to pan this signal from the extreme left channel through the centre and then onto the extreme right channel, it will sound as if the level rises as it passes through the centre. To overcome this, mixer designers engineer the panning law to introduce a 3dB level drop at the centre, relative to the edges (left and right extremes). If you were to sum the left and right channels in a mono situation, the centre gain would result in a 6dB rise, so attenuating by that amount became a must in the broadcast industry as mono compatibility is always a prime issue.
This whole interweb/series of tubes is Teh Cool.