Time align confusion

[thothsong]

From the Help: "For meaningful results measurements that have impulse responses or phase data should be properly time aligned before they are combined."
That sentence implies to me that "Time align" should be clicked before using Trace arithmetic (other than Merge). But for traces with a common timing reference, the correct result appears to be obtained by NOT clicking Time align. So I'm confused about what that sentence is trying to say.

 

[John Mulcahy]

Being properly time aligned may mean having a common timing reference or may mean removing time delays, it depends on the operation and what you are trying to achieve.

 

[thothsong]

If I have a set of measurements with a common timing reference selected, and mistakenly click Time align, is there a one-click way to revert all the changes? Or do I have to do Zero cumulative shift on each one individually?

 

[thothsong]

Being properly time aligned may mean having a common timing reference or may mean removing time delays, it depends on the operation and what you are trying to achieve.

Adding that sentence to the Help would be helpful.

 

[John Mulcahy]

is there a one-click way to revert all the changes?

Afraid not.

 

[sm52]

John Mulcahy​

It would be nice if in REW there was a cancellation of the last action, as in many editors, by ctrl Z.

 

[thothsong]

Afraid not.

Is there a way to manually undo the changes correctly? Using Zero cumulative shift appears to be the wrong answer, as I see now that the traces start off with varying Cumulative IR shifts.

 

[John Mulcahy]

Negate the delay figure from the measurement notes and apply it as a t=0 offset.

 

[thothsong]

Thanks.