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Bussing Aux tracks - Cumulative Volume Boost...?


posthorn1

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I've created a basic Mix Bus...I've got Aux tracks 1-8 with all OUTPUTS set to "Bus 1." I've got Aux track 9 with INPUT set to "Bus 1" and outputs to "Output 1-2."

 

I'm not sure why Aux 9 (the Bus) has levels so much higher than any of the Auxes 1-8. Those original tracks are peaking in the bottom third of the meters while the Bus is getting into the red. I don't have any Effect or other setting that would boost the levels on Aux 9.

 

I'm pretty new to mixing. Is there some kind of cumulative volume for many tracks bussed together? Doesn't make sense to me.

 

I thought there might be a "Bus 1" object somewhere that was boosting the level, but the term "Bus" appears to just be a kind of invisible route between Channel Strips, but I really don't know. For example, there's nothing called "Bus" anywhere in the environment.

 

Can anyone enlighten me on this?

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I'm not sure why Aux 9 (the Bus) has levels so much higher than any of the Auxes 1-8.

Because you're summing 8 audio signals into one. The sum is bigger than each one of the original 8 signals.

 

Is there some kind of cumulative volume for many tracks bussed together?

Yes, exactly.

 

Doesn't make sense to me.

Why not? Would you expect to be able to sum as many signals as you want and the sum is still the same level?

 

If you have one violin playing in a room, you've got a certain level of sound. If you now have 8 violins playing in the same room, do you expect to have the same level of sound? Or do you expect to get a louder sound? If you answered "a louder sound" then you'd be right, and the same applies when summing in a mixer.

 

Hope that helps?

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Thanks. That clears it up, I guess. I believe you that this is a natural acoustical phenomenon, but I've never thought of 8 violins being 8 times louder than 1. In my specific case I'm finding that I have to drop the bus by 5db to make it roughly match where the original tracks are. I can do that...
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I've never thought of 8 violins being 8 times louder than 1.

Really? That's how orchestrators think: the first time the melody is exposed, we need it to be intimate? Have a single violin playing it. Now the third time that melody plays you want to create a big bang, a big eye-tearing effect, really moving, etc...? Have all 22 violins in the orchestra play that same melody in unison.

 

Ok maybe that helps if you think of:

- One person talking at a normal level in one large room.

- 1,000 persons talking at a normal level in that same room.

- 1,000,000 persons talking at a normal level in that same room.

 

Can you hear the sound level rise as you have more and more people in the room?

 

In my specific case I'm finding that I have to drop the bus by 5db to make it roughly match where the original tracks are.

Yes, nothing surprising, just keep in mind the math is a bit more complex than simply 1 + 1 = 2 so in your case it's 5 dB, next time it may be 8 dB, or 2 dB, depending on the audio signals you're summing.

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