FILTER 8
MULTIMODE FILTER/8-PHASE OSCILLATOR
5
The final pole-mixing output is a 4-pole
bandpass response, selecting a band of
frequencies around the filter frequency. It will
resonate at 360° (equal to 0°, so no phase shift).
By plotting the voltages over time of all outputs
in self-oscillation, the 8-phase relationship
between them becomes visible. With gain
compensation enabled, all generated sine waves
will have the same amplitude. While the outputs
will sound identical on their own, having access
to phase-separated signals opens up many
advanced patching possibilities.
12 HOLD GATE INPUT AND SWITCH
The hold feature ‘freezes’ the filter core, slowing
it down to near-standstill until the hold is
released. This is useful for halting modulations, or
as a sync-like effect at audio frequencies.
By default, the feature can be manually toggled
using the toggle switch. It can also be controlled
from an external gate signal on the ‘hold’ input.
When the socket is used, the switch enables or
disables the input.
Filter 8’s hold input is uniquely designed to be
driven reliably even from weak, slow, bipolar
signals. It features Schmitt action, with a +2 V low
and +3 V high logic threshold.
13 PING INPUT
Filter 8 includes a built-in transient generator to
create ‘filter ping’ sounds. To use this feature, set
the resonance on the verge of self-oscillation.
This point is typically found just past 3 o’clock, as
indicated on the front panel.
A rising edge at the ping input, reaching above
+3 V, will ‘strike’ the filter core, creating a crisp
percussive sound. The amplitude and decay time
are set by the frequency and resonance
parameters. Each output will generate a different
ping timbre. For example, the lowpass outputs
will have a pronounced transient, useful for
synthesising kick drums. The bandpass output
will be the purest, more suitable for bongo-type
sounds.
Gain compensation should be disabled, to avoid
the outputs distorting at the transient (except for
output BB+N). The ping generator is designed to
reliably create ping tones, no matter which kind
of signal is used to drive it.
Additionally, the ping feature can be used in LF
mode to trigger multi-phase decaying sine wave
modulations.
