Filter sfplay~ soundfiles to 5 - 200Hz for a ButtKicker LFE
I'm a visual artist who's using Max for several years to make my own interactive works, installations and visuals. Now I'm stepping in the world of filtering sound and there's a lot of terminology I don't understand.
For a theatre show I programmed a patch which will control the lights (dmx), visuals (syphon to a MadMapper 3 screen output), sound (-scapes music and narrator) by a simple user interface so the theater group (mentally disabled) can use the patch for their tour.
The audience will take place on a so called Sensefloor (made out of a lot of these Buttkickers http://www.thebuttkicker.com/lfe ).
These operate between 5 and 200 Hz. There's a thunderstorm in the show and I'd like to filter the thunderstorm audio so I can only send and amplify the frequencies on which the ButtKickers operate on. At first low amplitudes for the beginning of the storm which will intensify when the storm gets more intense.
I've looked into bfff~ , cascade~ , filterdesign~ and more but to be honest I don't understand from the terminology what those specific filters do. Can some one point me out to lets say one object who will do the trick for me?
Thanks in advance!
You may need just a simple lowpass filter (BTW, in lores~ helpfile you'll find the settings you need), since 5Hz is an extremely low frequency, IMHO you needn't worry about filtering lower frequencies.
Instead, if you want to filter also low frequencies, you'll need to concatenate a hipass filter to cut all frequencies below 5Hz(your cutoff frequency) and a lowpass filter to cut all frequencies above 200Hz
The most intuitive way is using filtergraph~ and biquad~ :
Thanks a lot!
I knew it would be straight forward simple thing to do. Have to dive into the world of MSP a bit more in future :)
Also, check out cross~. It's a crossover filter.
If you need a really steep filter, check out filterdesign~ with cascade~. (I'd recommend just stealing from one of the help patches.) The higher the order, the steeper the potential roll off per octave. (Cascade~ is a stack of biquad filters routed in series)