Trace Arithmetic summing issues

[Dmanstarr]

When I add a trace of midrange to a trace of tweeter that are crossed, I get exactly what I would expect in the summing relative to how well the curves match (LR4). About 3db up at the xvr pt with the remainder about an octave away staying the same as they were. Same with a MB LP combined with Mr HP.

For some reason with sub to midbass summing in the trace arithmetic section, it seems to discount the midbass contribution to the sum for the most part (or something). I’ve tried multiple sub and midbass traces. In some cases, the sum is only an exact copy of the midbass trace with no sub at all.

In the photo, the bright green is what I would expect the sum to be, the forest green is the sum I get.

 

[John Mulcahy]

The sub time alignment is probably incorrect. Best posting an mdat for more detail.

 

[Dmanstarr]

Would the trace summing tool incorporate alignment if measured with multiple RTA measurements averaged?

Also, there was a negative offset added to the sub data only. Would that cause this behavior? I thought once the offset was “added to data” it was the same as if the measurement was recorded at that same level. Is that wrong?

 

[John Mulcahy]

Would the trace summing tool incorporate alignment if measured with multiple RTA measurements averaged?

There isn't really any point in summing RTA measurements. They are magnitude only so the result won't be representative of summing actual responses.

I thought once the offset was “added to data” it was the same as if the measurement was recorded at that same level.

It is.

 

[Dmanstarr]

Got it. But I’m still wondering what went wrong for when I attempt this with sweeps. When I had the sub at original measured level, the sum looked normal (granted with the sub portion at higher level), after I saved -6db offset to sub’s data, it did the above. You indicate it’s not the offset, but that is all I changed. Both were RTA measurements.

I’ll see if I can post mdats.

 

[Dmanstarr]

There isn't really any point in summing RTA measurements. They are magnitude only so the result won't be representative of summing actual responses.


It is.

Hmm. Maybe a glitch. When I reopened the measurements (the sub still had the -6db offset I “permanently “added), now they sum as expected. For now I will just avoid offsets and get things recorded at the desired level before attempting summing. And only bother with summing when I have phase data in the measurments. Thanks again!