27 FIRST STEPS
Routing
Here’s that “Routing” parameter mentioned earlier – twist the
VALUE 1 knob to see the various options...
So far you have used the filters either in series (the output of fil-
ter 1 is sent to the input of filter 2) or in isolation (by setting
extreme FILTER BALANCE values). Here is a list of all four rout-
ing options – you might like to look up the word “Pole” in the
glossary:
> Serial 4: The filters are routed in series, with two poles each
(12dB per octave). This adds up to a total of four poles (i.e.
24dB per octave) if FILTER BALANCE is dead centre (0).
> Serial 6: The filters are routed in series. Filter 1 has four poles
(24dB per octave) and filter 2 has two poles. This adds up to a
total of six poles i.e. 36dB per octave if FILTER BALANCE is
dead centre (+0).
> Parallel 4: The filters are routed in parallel, with two poles
each.
> Split Mode: The filters are also routed in parallel, with two
poles each. Unlike the Parallel 4 mode, each filter processes a
different set of sources: Oscillator 1 and the sub-oscillator are
routed to filter 1, whereas oscillator 2, its FM signal and noise
are routed to filter 2. The ring modulator (see “RING MODU-
LATOR” on page 137) is disabled.
To step through filter routings without having to open the menu,
hold down SHIFT and press the Filter 2 button (labelled FILT2).
Cutoff Link
When set to “Off”, the CUTOFF knobs are independent of each
other. CUTOFF controls filter 1, CUTOFF 2 controls filter 2.
When Cutoff Link is set to “On”, the CUTOFF knob can control
both filters at the same time – CUTOFF 2 becomes an offset i.e.
it determines how much lower or higher filter 2 is than filter 1.
Note that Cutoff Link is normally left on (as it is in most pro-
grams, including ROM-A126 and ROM-A127).
About Saturation
The term “Filter Saturation” was originally coined to describe
the effect caused by pushing the input of a filter beyond its nat-
ural limits. Jan Hammer’s work on “Birds of Fire” (Mahavishnu
Orchestra) is a classic example but, depending on your age
and/or musical tastes, you might be more familiar with the sear-
ing techno “bass lines” and various other distorted synthesizer
sounds used in more recent music.
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