Version 1 Filters
Terminology
The Transfer function  Poles or
Decibels?
The relationship between what goes into a filter at one end and what comes
out at the other is known as the 'Transfer function'. This is commonly
described in terms of decibels per octave, and occasionally as a number of
'poles'. The decibel per octave terminology refers to the amount of
reduction in gain of the signal as the frequency rises by an octave. As an
attenuation of 6 decibels (db) is the equivalent of a halving of the gain,
filter transfer functions are referred to in units of 6db/octave.
This can also be referred to in terms of 'Poles' where one pole is
equivalent to a transfer function of 6db/octave. Hence a 2 pole filter is
the same as a 12db/octave filter, a 4 pole the same as a 24db/octave filter,
and so on.
Filter types.
The most common types of filter are:
Low Pass  Higher frequencies are attenuated whilst lower ones are allowed
to pass through 'untouched'.
High Pass  Low frequencies are attenuated whilst high ones are allowed
through untouched.
Band Pass  Both low and High frequencies are attenuated, leaving just a
'band' in the middle to pass through unaffected.
Band Reject  also known as a Notch Filter  the opposite of a Band Pass
filter  the high and low frequencies are unaffected, whilst the central
frequencies are attenuated.
Comb Filter  This attenuates a number of separate bands of frequencies and
can be envisaged like a comb viewed from the side. Although not found in
version 1 of the modular, there is a Comb Filter in version
2.
The controls
Cut Off  Each filter has a Cut Off control. This determines the
frequency at which the filter starts to take effect  in a Low pass filter,
for example, it determines the frequency above which the filter will start
to attenuate the signal. To be completely accurate, the Cut Off frequency is
the frequency at which the signal is already accentuated by 3db.
Resonance  Each filter also has a control for Resonance. Filters don't just
attenuate the frequencies defined by the Cut Off control  they also boost
certain frequencies around the Cut off point, and this is referred to as
resonance. The resonance control alters the amount of accentuation that is
given to the signal around the cut off point.
Setting the Resonance at it's maximum point can easily result in what is
known as selfoscillation  a point at which the resonance of the filter
starts to feedback on itself. This can create some powerful tones which have
very little to do with the signal that is being fed into the filter, and an
awful lot to do with the nature of the filter itself. When a filter self
oscillates, it may be possible to 'play' the filter as if it were actually
an Oscillator itself.
Modulation  All of the filters have a number of Modulation inputs which can
be used to dynamically control the Cut Off frequency of the filter. A few of
the filters also have a ResMod control, which can be used to modulate the
Resonance of the Filter.
2Pole Multi Mode 

12 db/Octave filter with 3 Cutoff frequency modulation inputs and a choice of Low, High or Band pass filter outputs.  
2Pole Multi Mode 2  
Bug fixed version of the above  Cutoff Zipper noise is suppressed and Modulation works even if Cutoff is turned all the way down.  
4Pole High Pass  
24db/Octave High Pass filter. 3 mod inputs for Cutoff modulation.  
4Pole Low Pass  
24db/Octave Low Pass filter. 3 mod inputs for Cutoff modulation.  
4Pole Low Pass V  
A 'vintage' version of the above, in which the level of the original signal remains unchanged, regardless of the Resonance setting. 3 mod inputs for Cutoff modulation.  
4Pole Low Pass V  ResMod 

As above, but with a Modulation input for the Resonance amount, and only 2 Mod ins for the Cutoff frequency.  
8Pole Band Pass  
Attenuates the high and low frequencies, letting a central band through untouched  Cut Off determines the central frequency around which the Band is determined. 3 Mod inputs for Cutoff frequency.  
18dB Low Pass  
18db/Octave Low Pass filter. 3 mod inputs for Cutoff modulation.  
Uknow Low Pass  
12db/Octave Low Pass filter as used in the Pulsar Uknow 007 synth, which is modelled on the highly popular Juno 106. The filters are very closely modelled on the original.  
Uknow Low Pass  ResMod  
As above, but with a Modulation input for the Filter Resonance.  
Uknow Low Pass/High Pass  ResMod  
As above, but with an additional (nonresonant) High Pass filter. The Resonance knob and all modulation inputs control resonance for the lowpass filter only. There is a separate control for the Cut off of the High Pass filter. 

Fixed Filter Bank  
Filter with 11 separate bands with cut/boost controls for each frequency band, and a seperate gain control for the whole filter. You'll find this in the 'Effects' folder, not the Filters, for some reason. 
Samples
One day, one day...