Ableton Forum

Setup live as shown in this picture.

There is a Utility set to invert on both returns. Make sure you set all the send and mix levels as shown.



Now start the clip. You should here nothing at all because of the various inverted signals canceling each other out.

Now adjust the sends like this.



In theory it should be just the same as before, but instead you get a "high pass filtered" version of the track, like you get with a very short, single shot delay.

Have a general play around with the various send levels to get a picture of what is going on here. Here's a diagram to make it clearer.



If you can't be bothered to set it up just look at the level meters in the two pictures, and tust me, both returns are set up the same way.

I think this shows that there is a problem with synchronisation of signals in the summing process.

n

No, it all works as it should

The reason is, that every _feedback_ within a digital system needs to introduce a one sample delay.

Sending a signal from a track to a return is not a feedback
Sending a signal from a return to a return is a feedback
(because you could also send a signal to a return and from there to another return and from there back to the original return....)

I also stumbled accross this a while ago and needed a while to get the problem.

You can check my statement by delaying the return with 0.02ms ( at 44.1 kHz ) using the track delay from the PDC.

Robert Henke
Ableton

Thanks for the explanation Robert,

but I'm still confused as to why sending from A to B is different from sendiing from B to A. As far as I can see the two settings are logically identical

... (thinks) ... (plays with software) ... (thinks some more) ...

Oh I see , it cleverly only applies the delay when routing form left to right - it doesn't need to do it in the other direction because a feedback loop must always involve routing in both directions! Very Clever!

But I think the wrong direction was chosen to apply the delay in. My natural tendancy is to chain effects left to right with feedback loops going from right to left, but I'm happy now I understand what is happening and how to avoid it.

n