How does Ardour calculate signal levels across mono/stereo channels

#1

I understand that, when you split a mono signal into L+R channels for stereo you lose volume and the resulting stereo signal is -3 db in volume.

I also understand, when you have a stereo signal with identical L and R signals and you sum those together to a mono channel the volume increases and the resulting mono channel is +3 db in volume.

But what I don’t understand is how Ardour handles mono → mono. As far as I understand there shouldn’t be any math involved. Route a mono track into a mono bus and the signals should be identical in volume.
But no matter how I connect mono to mono the signal is never correct.

In the routing grid a mono channel always comes out as L and R.
If I only connect one them to the input of a mono bus, the mono bus -3 db.

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but if I connect both to the mono bus I am +3 db.
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Is intended this way? Am I doing something wrong?
This is so weird. How do I get consistent and predictable signal levels?

#2

You’ve fallen into the trap created by language. “mono” and “stereo” are imprecise terms. What matters is “number of inputs” and “number of outputs”. Your “mono” tracks still have 2 outputs, and so they still have a panner, and so they still show the effect of the panning law.

Recommended: create tracks with 1 input and disable auto-connection so that they do not get 2 outputs. Alternatively, try disabling the panner with a right click.

4 Likes
#3

Aaaaahhh, ok thank you.
Bypassing the panner and then connecting only one of the “mono sides” actually gives me the correct signal level.