Mixing Test Tones

Cubase
1

Hi,

While trying to balance my orchestral template I bumped into something odd which I don’t understand.

Start with an empty project. Add a stereo audio track. Insert the included Test Tone Generator with the default settings (sine wave, -12db). Duplicate the track three times, for a total of four tracks playing the same test tone together.

The level I get at the output varies widely when I mute some of the tracks. Here’s what I get when each track is active (i.e. unmuted):

1       -12
1+2     -11,2
1+2+3   -7,8
1+2+3+4 -4,8

2+3+4   -5,2
3+4     -10
4       -12

1+4     -6,3
1+3+4   -7,5
1+2+4   -5,8

Also, note that when going from 1+4 to 1+2+4 I actually get a lower output level.

Could someone please explain what is happening here?

Thanks.

2

Assumption: Test tones are not exactly the same frequency, and/or the 4 tracks’ sine waves aren’t synchronized (and therefor cancel each other out in a partial or less partial way). Phase is the magic word here. If you’re interested, you should try the same experiment with white or pink noise. Also - always mention what type of reading you use at the stereo output meters. ‘Level’ and then dBs is not enough to describe it.

3

The sine test tones are the same frequency (the default one, 440 Hz). But you are right about the phase issue, because apparently the oscillators are not in sync. I tried the same test with white noise and got consistent results (-12, -6, -2,5, -0,2 for 1, 2, 3 and 4 channels respectively).

The reading I was referring to is the output meters’ Peak Meter Value (which I was resetting after each test).

What I’m trying to figure out is this: if I have four channels going into a bus all at the same fader value, and then I reduce each of the four faders by, say, 2db. Now, by resetting the four faders to their original value, by how much would I need to attenuate the bus fader in order to get the same result? What is formula for this?

Thanks!

4

Interesting to know that the test tones each live a life of their own… Before this arose, I’d assume they would all start at the same zero point and stayed in sync just from the processor clock - well, apparently not. As for the formula, it’s not rocket science, but I have to dig too deep to give you an answer off-hand :confused: