ARP 4075 LPF 36A
The
4075 Filter is a faithful recreation of the 24db low-pass filter found in
late model Arp Odysseys.
The filter topology is almost identical to the Arp 4072
filter module found in later editions of the ARP 2600
synthesizer. This version has been modified to extend the frequency range
from the original 16kHz up to 32kHz for improved fidelity.
The following
two mp3s are examples of
the 4075 as a self oscillating sine wave generator
being modulated by the Sequencer 17a and a variety
of LFOs,ADSRs and Oscillators.
Self-oscillation1.mp3
Self-oscillation2.mp3
Input
The
filter input level is adjusted using the gain control attenuator. Moderate
gain settings provide the smoothest sound but higher gain settings are better
for high resonance sounds.
1V/Oct Input
Exponential converters track
linear voltage input at 1 volt per octave. This input is primarily used for
keyboard
tracking and pitch control of filter in self-oscillation mode.
CV Input 1
Control Voltage input with attenuator
to control the depth of frequency modulation.
When the knob is centered no modulation occurs. Positioning the knob to the
left of zero inverts the incoming voltage (negative) and to the right the
voltage is non-inverted (positive).
CV Input 2
Secondary Control Voltage input with attenuator.
CV inputs are used to control the filters cutoff point.
The most common
input signal would be from an envelope generator or LFO.
Resonance Control
This knob varies the height of the resonant peak at the cutoff frequency of
the filter.
Separate Attenuator
Section
These are simple passive attenuators useful for limiting the amount of signal
being passed to a modules inputs. They are available on this module to fill
remaining space left by the filter
Specifications:
Wide-range lowpass filter with variable-height
resonant peak at cutoff frequency.
4 pole response
24db/oct cutoff slope
Range:Continuously variable from 16Hz-32kHz
Input impedance:
47K ohms
Output impedance: 1k ohms
Control Sens: 1 volt per octave