User Manual

Table Of Contents
DR. OCTO REX LOOP PLAYER
(RECORD+REASON)
711
The Filter Section
Filters are used for shaping the overall timbre of all REX files in all 8 Loop Slots. The filter in Dr. Octo Rex is a multi-
mode filter with five filter modes.
D Activate or deactivate the filter completely by clicking the Filter On button.
The filter is active when the button is lit.
Mode
With this selector you can set the filter to operate as one of five different types of filter. These are as follows:
•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 the frequencies below and above through.
High-Pass (HP12)
A highpass filter is the opposite of a lowpass filter, cutting out lower frequencies and letting high frequencies pass.
The HP filter slope has a 12 dB/Octave roll-off.
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.
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 fil-
ter.
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.
Filter Frequency
The Filter Frequency parameter (often referred to as “cutoff”) determines which area of the frequency spectrum the
filter will operate in. For a lowpass filter, the frequency parameter could be described as governing the “opening” and
“closing” of the filter. If the Filter Freq is set to zero, none or only the very lowest frequencies are heard, if set to max-
imum, all frequencies in the waveform are heard. Gradually changing the Filter Frequency produces the classic syn-
thesizer filter “sweep” sound.
! Note that the Filter Frequency parameter is usually controlled by the Filter Envelope (see “Filter Envelope”) as
well. Changing the Filter Frequency with the Freq slider may therefore not produce the expected result.