# Cutoff on Sub and Front



## sonata31 (Jun 2, 2006)

Why -3db at cutoff=40Hz for the front left and -6dB at cutoff=40Hz for the sub ?

Excuse my poor english (I am French)


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## brucek (Apr 11, 2006)

> Why -3db at cutoff=40Hz for the front left and -6dB at cutoff=40Hz for the sub ?


To match the standard bass management roll-off characteristics that are normally 2nd order for high pass filtering (of the 5 main channels) and 4th order low pass for the subwoofer channel. This provides the best crossover transition.

brucek


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## JohnM (Apr 11, 2006)

This is per THX recommendations for bass management filters, the idea being that the combined effect of a main speaker's own roll-off together with the 12dB/octave roll-off of the bass management filter will give an effective roll-off that matches the 24dB/octave applied to the sub. This does raise the question of whether the target response in REW should really be 24db/octave for both, however, since this is what is aimed for as an in-room measurement. I'll think about that, may change it for the next version of REW.


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## sonata31 (Jun 2, 2006)

Ok, thank you for your responses


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