Focal Profile 918 Speaker System Manufacturers Comment
I would like to thank Mr. Fred Manteghian for a wonderful and thorough review of the Focal Profile system.
I see that there was a couple of questions marks floating over the reviewer's head when he discovered the "Subsonic filter" function of the Profile SW908 subwoofer. It is true that a subwoofer's goal is to reproduce subsonic frequencies, and at first glance, it would look a little odd to cut the lowest of that very precious lower bass.
There are a couple of different reasons why Focal offers such a function. First, this filter can be very practical when the subwoofer is placed in a small room or if the walls of the room are thin or not very rigid. The room may generate an excessive sound level in the lower bass or even cause saturation. Vibration and unpleasant resonances can then occur. The subsonic filter can progressively eliminate this annoyance and maintain a clean and strong bass performance.
The second reason is that in some cases, room acoustics does not allow really low bass to be reproduced; you'll see the subwoofer working but barely any audible sound will be heard (although your light fixtures might be in epileptic shock!). Here's what happens when you cut those lower notes: the subwoofer will stop trying to reproduce frequencies that the room can't handle and will rather get a lot more headroom and power to work in the upper bass frequencies. This trick will mainly be used in movies, often in combination with the "boost" function which applies a +3dB boost to the "40Hz-magic-gut-wrenching-frequency". Normally, boosting +3dB to that frequency would tax the subwoofer amplifier a lot and affect the entire bass reproduction. However, by combining the "subsonic filter" and the "boost" function, you'll have an extremely tight response combined with some amazing dynamics.
Daniel Jacques, president
Audio Plus Services (U.S importer of Focal)