Filters And Post-Mix; The Two Filters Explained; Serial Vs. Parallel; A Note If You Do Not Like The Filter Knob Sweep Range - Alesis Andromeda A6 Tips And Tricks Manual

section 3: filters and post-mix

3.1 the two filters explained:

One of the nice features of the Andromeda is its flexibility. Certainly the fact that the
Andromeda is a 16 voice polysynth (more than the typical polyphonic synthesizer of old)
with two filters each (most polyphonic synthesizers only had one filter) allows the
Andromeda to create some unique tones.
This is especially true with the two distinctly different filters. Filter 1 is based on the old
Oberheim synthesizers with a variable state filter (allowing for hi-pass, lo-pass, band-pass,
and band-reject (notch) outputs). The result is not really an Oberheim, with a lot of grit; this
may be because the oscillator choice was the smooth Moog Modular VCO. Instead, what you
get is a rather fluid sound, with some nice wetness. Although it is 12dB, its resonance is
particularly nice for designing techno patches, with less roughness than you expect out of
the Oberheim. Even so, it can do its share of old school Rush sounds and the like, getting
pretty gritty with the mix oscillator levels turned up.
The second filter is more based on the Moog Modular filter. This has a nice, creamy sound,
with decaying bass when the r esonance is turned on, and some nice characteristics in
filtering out pad-like sounds. It also is self-oscillating, which makes it the choice for drum
sounds.
The filters are a little bit on the " muddy" , or " liquid" side of things. This is probably due to
the nature of the VLSI design on these chips. Other synthesizers can be clearer sounding and
more dynamic. Few synthesizers have as good of a flexibility / sound balance to them,
however.

3.2 serial vs. parallel:

Mike Peake explains:
Parallel: In Filter 2 Input Mix mode, the oscillator mixer is sent into both filters and they're parallel,
and each output is available simumtaneously. Serial lowpass, hipass, or notch :
In Notch, you must set the Post Filter Mix level of either or both of Filter 1's Lowpass and / or
Highpass outputs and also bring up the level of Filter 2.
Serial bandpass: In Bandpass, no F1 level adjustments are neccessary although you can mix in the
HP and LP outputs. Again, F2 must be brought up in level.
Filter 2 off: There is another mode which is signified by these LEDs being off; it turns off the audio
input to Filter 2 completely. All of Filter 1's outputs are live and Filter 2 can be used as a sine wave
oscillator.

3.3 a note if you do not like the filter knob sweep range:

Turn the offsets lower (view filter menu, soft knob 4). V1.40 improved the range of the filter
knob by quite a bit, but there are still some times where it is great to turn the offset lower of
the patch, so the sweep is more to your likeing.
an entire section on filter tricks!