# REW measurement question



## Hakka (Sep 10, 2006)

I have been equalizing my subs with REW over the last couple of days. One thing I am unclear on and have been unable to find in the help file is how to go about re-testing the sub after filters have been applied.

I started by testing the un eq'd sub, I then applied the auto filters, and tweaked them manually while watching the corrected response graph. I then ran the sweep again, my sub response was a lot better, but the corrected graph is now all over the place, REW has applied the filters to a signal that already has the filters, if that makes any sense. I tried disabling all the filters in REW boefore running the sweep again but I get the same result. 

What am I missing here??

Thanks.


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## brucek (Apr 11, 2006)

> how to go about re-testing the sub after filters have been applied.


Uncheck the filters in REW when you want to do a new mesurement after you've entered filters into the BFD.









brucek


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## Hakka (Sep 10, 2006)

Hmm...tried that, as soon as I reactivate a filter to tweak it the corrected graph goes out of whack.

Lets say I am using 1 filter at 50hz with a 10db cut, and have a freq response that is flat once this filter has been applied. I uncheck that filter and run the sweep, the measured and corrected graphs are identical, until I enable that filter to tweak it, which then moves the corrected graph down by 10db at 50hz relative to the measured graph.

Thanks.


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## brucek (Apr 11, 2006)

> Hmm...tried that, as soon as I reactivate a filter to tweak it the corrected graph goes out of whack.


Well sure, because the signal you just measured with REW is a new equalized response after entering the filters that REW recommended. If you enable the same filters now in REW it will be like filtering twice.

If you want to manually add a new filter in REW to modify the equalized result you can. 

Or you can slightly tweak the existing filters in the BFD and use REW to quickly measure the results.

brucek


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## Hakka (Sep 10, 2006)

brucek said:


> Well sure, because the signal you just measured with REW is a new equalized response after entering the filters that REW recommended. If you enable the same filters now in REW it will be like filtering twice.
> 
> If you want to manually add a new filter in REW to modify the equalized result you can.
> 
> ...



Thats what I've been doing, I thought I might have been doing it wrong but I guess not. Thanks for your help Bruce.


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