Speaker response question...

[brokenwindow]

I have a pair of sattelites and subwoofer that has a response of 80Hz-20kHz. When I use an eq and a/b between having a lowcut at 80 hz and not having any cut..I notice a big difference in the bass response. Meaning that the eq with no lowcut is definetly bassier and deeper.

is the specs on my speakers wrong? Or am I missing something?
I shouldn't be able to hear any difference in the two if my speakers can't produce anything below 80 right?

Thanks for any replies...

 

[barefoot]

The low frequency cutoff of a speaker is normally specified as the frequency where the sound pressure level falls to -3dB (70.7% the amplitude) of the nominal level. When you use an EQ to cut the frequencies below the -3dB point you are cutting frequencies that the speaker is still capable of reproducing.

The low frequencies roll off more of less quickly depending on the speaker design. Closed box speakers roll off at about -12dB/octave (25% the amplitude for every halving of the frequency) below the -3dB cutoff. Ported speakers roll off at -24dB/octave. For a given -3dB limit a closed box speaker will have more bass response than a ported box. However, for a given woofer a ported design will generally yield a lower -3dB point.

Since a closed box system has a shallower roll off your EQ experiment will have a more dramatic affect on these types of speakers.

I've attached some graphs to illustrate these points.

barefoot

 

[brokenwindow]

ok.....that makes sense..

Thanks a lot for clearing that up...been wondering that for a long time..