F-em User Guide
5.7 Filter 1 and 2
On this page, you find the filter and drive controls. To open this page,
click on the F1 or F2 selection field in the left section. Each Layer
features 2 filters with drive.
As for the Operators, the Filters features hardwired modulations
sources as a Cutoff LFO, a Level LFO, a Cutoff Envelope and Level
Scaling and finally a Level Envelope.
A filter is used in synthesizers to attenuate or emphasize certain
frequency ranges of a source signal. Most filter types consist of a pass
and a stop band, some have two pass or two stop bands. The pass
band is the frequency range where the input signal can pass (almost)
unaffected, the stop band is the frequency range that is attenuated,
sometimes fully. F-em offers various Filter types abbreviated LP, BP, HP
or BS, followed by a number denoting the slope in decibel per octave.
F-em offers two filter stages that are arranged in serial wiring.
The
Copy/Paste
buttons lets you copy all
settings from this envelope and paste it to
any other, regardless of its Layer.
•
Filter On/Off
: Click on this button, to activate/deactivate the
corresponding Filter module.
•
Filter Type
: Click on the pop-up menu to select the desired
filter type. Note that there are no Band Pass or Band Stop
types for 6 dB. A 6 dB filter consists of one so-called pole,
which can‘t be split in half. LP = A low pass filter lets low
frequencies pass and attenuates high frequencies. It is the most
common filter type found in all synthesizers with subtractive
synthesis. BP = A band pass filter lets frequencies around its
center frequency pass and attenuates frequencies further away
from it. HP = A high pass filter lets high frequencies pass and
attenuates low frequencies. BS = A band stop filter, also known
as a band reject or notch filter, attenuates frequencies around
31
✎
To hear the effect of a filter and the drive parameter, you need to
route an operator/noise generator/sample oscillator signal
through the corresponding filter. This needs to be done in the FM
Matrix.
