What is a Low Pass Filter


I can not fin a definition that a newbie like me can understand searching Audiogon. My Subwoofer, Sonus Faber Cremona, has 2 dials in the back. One for Low Pass Filter, switchable from 38-65Hz 6 positions and one for Gain that reads min to max.

More Info:
http://www.sumikoaudio.net/sonus/prod_cremonasubwoofer.htm

Thanks in advance for any help,
David
captaincapitalism
Viridian, I do not understand your response. Let me ask you this: Why would I want to "attenuate" any frequencies? I am assuming that by "attenuate" you mean that it is modifying the signal above a certain frequency?

thanks,
David
A filter lessens (attenuates) frequencies above or below a selected cut off frequency. Loudspeakers use filters to selectively limit the frequencies sent to individual drivers. A subwoofer input could employ a low pass filter to allow only bass frequencies to be sent to the woofer cones. As the name implies, a low pass filter lets low frequencies pass through unchanged.
Otherwise, your subwoofer would also be receiving midrange signals full force, which would make it much easier to hear its location. Your ears would know that it is not blending as well as could be with your main speakers, as it should 'disappear' when set up well. And as far as a sub trying to do high frequences like cymbals, well, that's really funny to hear.

Hope this adds to your understanding.
I am told that different filters will alter the quality of the sound and that, even though a filter is screening out inappropriate frequencies, there can be a perceptable altering of the final product that you might or not not like.

This is just one adjustment in your overall system.
Is the sub on the link your subwoofer?
i hope that you didn't pay the hefty 3500$ for a subwoofer
and you don't even know what is the purpose of the low pass filter .. :p
hihi