Pan Law and mono output

Cubase
1

Could anyone enlighten me with regard to the following:

I’m mostly working with mono signals in Cubase 7 (speech) and tried to make sure, my master meter is indicating correct levels. Here’s what I did:

  • I put a sine wave -12 dB test signal on a mono audio track
  • I set Pan Law to 0db
  • now both level meters from the track and the master show correct -12 db level
  • I bounce the file via the Master Output Channel and tick “mono downmix” in the Audio Engine Output dialogue
  • The resulting bounced file has a level of -6 dB

Of course I could adjust the Pan Law to -6dB, but then again my master meter will not show correct levels anymore.

Thanks for your hints and suggestions,
Thomas

2

Put the pan law back to -3dB.

Then your mono sum will be correct.

Think about it. A 0dBFS signal sent to the master bus with 3dB pan law, when set to centre will drop 3dB on the meters.
But it’s playing from both speakers so it needs this drop to sound equal in loudness as the signal panned hard right or left, which will show 0dBFS

When downmixed to mono, the left and right are summed and would show a 6dB increase as you have found out.

3

Thanks for your reply and explanation! That works out fine!
However, the channel meters and master/control room meter now show 3dB less, that’s -15dB.
Isn’t there a way to adjust this or do I always keep in mind to read my level meters +3dB when working for a monophonic production?

4

That is correct, a signal sent to the master bus at -12dBFS will show -15dBFS when panned centre because of the -3dB pan law. This is as it should be.

Try panning the channel hard left or right, it will then show -12dBFS on the master meters.

When summing to mono you will get the correct level of -12dBFS regardless of pan setting.

If you pan a sound from hard left to centre with a -3dB pan law you will notice the sound level via speakers stays constant. With the pan law set to 0dB you will notice the sound gets louder as you pan from hard left to centre.
This increase in volume is due to the fact that two speakers playing the same sound at the same level sounds louder. The same thing happens if you mathematically sum two identical sine waves, the result is an increase of amplitude.
Hence the pan law, this compensates for the summing and increase of signal.

Remember a Stereo Bus consists of two channels, a Left and a Right, i.e the master bus. This needs to be taken into account. You are adding two channels together when summing to mono!

with the pan law set to -3dB just use the master meters as the correct level.

Of course the exact implementation of pan laws and the pros and cons are more complex that this, but for general use cubases -3dB pan law is fine imo.

5

Thanks so much, I really appreciate your detailed explanations!

6

No probs, it can be confusing when confronted by this for the first time.