3 filter section, Filter controls, Power – FXpansion DCAM Synth Squad Operation Manual User Manual

Page 15: Cutoff and res (resonance), Drive, Mode, Direct modulation, Filter section

2:3 Filter section

Filter cutoff

direct mod: Key

Filter cutoff

direct mod: LFO

Filter cutoff

direct mod: Env

Filter Power

Strobe’s filter is its main source of tonal variation,
especially when modulated. While there are direct
modulation routings to the cutoff from the keyboard
pitch, LFO and Mod Envelope, the filter’s controls
can be modulated with the TransMod system for
really creative and varied effects.
Strobe’s filter is based on an OTA (operation
transconductance amplifier) cascaded core, with a
diode clipper in the feedback section. The diodes
are slightly mismatched, leading to the characteristic
growl of a real analog filter.

Filter controls

Power

The

Power button switches the filter on or off. When

the button is disabled, the audio from the oscillator passes through the filter unaffected.

Cutoff & Res (Resonance)

The

Cutoff control determines the cutoff frequency of Strobe’s filter.

The

Res control adds emphasis around the cutoff frequency, giving a warm, resonant sound to the osc tone. At extreme

Res settings, the filter self-oscillates.
The cutoff can be modulated from the keyboard, LFO and Mod Envelope using the dedicated controls.
The control is adjusted in semitones, allowing you to tune the self-oscillating filter just like an oscillator. Setting the
keytracking depth control to maximum allows you to ‘play’ the filter musically from the keyboard.

Drive

The

Drive control increases the gain of the signal going into the filter. This overloads the filter’s components, drastically

changing its sound and character.
Note that the effective resonance is reduced as you turn up the Drive control.

Mode

A large variety of filter modes are available by adjusting the

Mode control.

Note that filters denoted as ‘T’ feature 2 or more filters with an octave between the frequency of each. The first filter in the
name is at the cutoff frequency, with subsequent filters each an octave higher than the last. The only exceptions are the
last 2 filter modes - see the table below. Graphical plots of the filter responses can be found in Appendix 2.
In other combination filters, all filters act at the cutoff frequency.

L2, L4, B2, B4, H2, H4

2-pole (12 dB/oct.) & 4-pole (24 dB/oct.) Low-pass, Band-pass & High-pass filters

2-pole Peak filter

NP2

1-pole Notch and 2-pole Peak filters

N2P2 T

2-pole Notch and 2-pole Peak filters, an octave apart

N2L2 T

2-pole Notch and 2-pole Low-pass filters, an octave apart

N2H1L1 T

2-pole Notch, 1-pole High-pass and 1-pole Low-pass filters, each an octave apart

P2N2 T

2-pole Peak and 2-pole Notch filters, an octave apart

H2N2 T

2-pole High-pass and 2-pole Notch filters, an octave apart

H1L1N2 T

1-pole High-pass, 1-pole Low-pass and 2-pole Notch filters, each an octave apart

N2P2N2 T

2-pole Notch, 2-pole Peak and 2-pole Notch filters, each an octave apart

2-pole notch filter

4-pole notch filter

N2L2

2-pole Notch and 2-pole Low-pass filters

H2N2

2-pole High-pass and 2-pole Notch filters

H1N2L1

1-pole High-pass, 2-pole Notch and 1-pole Low-pass, each an octave apart

N2N2A T

2-pole Notch with 2-pole Notch an octave higher than the cutoff frequency

N2N2B T

2-pole Notch with 2-pole Notch an octave lower than the cutoff frequency

Direct modulation

The filter section contains dedicated controls for setting modulation depth of the filter

Cutoff by 3 modulation sources:

• Keytracking
• LFO
• Mod Envelope