点Filter里面那个MODE钮选择！！！
低通，高通！！
多好的功能呀！！！
以下为详细介绍！！！
Filter Mode
With this selector you can set the filter to operate as one of five different
types of filter. These are as follows:
24 dB Lowpass (LP 24)
Lowpass filters lets low frequencies pass and cuts out the high frequencies.
This filter type has a fairly steep roll-off curve (24dB/Octave). Many
classic synthesizers (Minimoog/Prophet 5 etc.) used this filter type.
12 dB Lowpass (LP 12)
This type of lowpass filter is also widely used in classic analog synthesizers
(Oberheim, early Korg synths, etc.). It has a gentler slope (12 dB/Octave),
leaving more of the harmonics in the filtered sound compared to
the LP 24 filter.
Bandpass (BP 12)
A bandpass filter cuts both high and low frequencies, while midrange frequencies
are not affected. Each slope in this filter type has a 12 dB/Octave
roll-off.
High-Pass (HP12)
A highpass filter is the opposite of a lowpass filter, cutting out the lower
frequencies and letting the high frequencies pass. The HP filter slope has
a 12 dB/Octave roll-off.
Notch
A notch filter (or band reject filter) could be described as the opposite of a
bandpass filter. It cuts off frequencies in a narrow midrange band, letting