erm i dnt get wot type of filter it is by wot ur saying, but im assuming from the "whistle" that u speak of, that its a high pass filter as this is the one I use the most. Its very simple to use so its great for mixing. The best way of finding out is by using an effects processor and go thru the effects and see what they sound like.
I have a kaoss pad mini, and have never looked back in terms of effects. Soooo simple to use and great sounding effects and combinations that only require the touch of a ya finga, so u can be using ur other hand to fade in or woteva!