REw impulse align centre cant get to 0 is it ATR delay

[warek]

Hi all

I am using REW 5.30 on Windows 10 computer.

I am trying to align speakers in a home cinema system and trying to align left mains with right mains and centre. I have taken individual sweeps and then using overlays and impulse peaks.
I tried using left mains as acoustic timing reference , but as I am also moving the left speaker trying to align it with right mains and keep the same distance measurement for left and right mains in the AVR at 3.25 metres.
Therefore I decided to use the centre speaker as the acoustic timing reference when aligning right and left at 0 in overlays impulse. I thought that first I should align the centre speaker to zero using centre as ATR. I cant get to O. I measure it early by 308mm. I reduce centre distance by 30 cm in AVR. Remeasure and then compare the overlays impulse of the two centres. The centre impulse basically stays in the same position. It is 308 mm early.
Now I notice that in the REW measure menu, the ATR shows a timing offset of 308 mm. I have not done anything with this timing offset. Do I need to set this back to 0 in some other menu ?

Thanks for any assistance and have a good day

Kevin

 

[sm52]

The central channel as a zero point is correct. Once you measure it, click Actions, Estimate IR delay, Shift and update timing offset. After this, the peak of the central channel impulse moves to zero time. After this, measure the remaining channels without using Estimate IR delay. Then you will see all the impulse peaks in the overlays window, and you can easily determine the time differences between them.

 

[warek]

The central channel as a zero point is correct. Once you measure it, click Actions, Estimate IR delay, Shift and update timing offset. After this, the peak of the central channel impulse moves to zero time. After this, measure the remaining channels without using Estimate IR delay. Then you will see all the impulse peaks in the overlays window, and you can easily determine the time differences between them.

sm52

Thank you, it working now.
It is a very powerful program, I find anything but the basic features take a long time to understand.

Regards