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DSM03 Feedback Module
Thank you for purchasing the DSM03 Feedback Module. At the heart of this module
is a tuned feedback line for audio processing; a 4-pole resonant, digital low-pass
filter for tone shaping; and a triggerable noise source for Karplus-Strong-type
plucked string synthesis.
The DSM03 is a 10HP wide, Eurorack-format device. Interconnections are made
using 3.5 mm phone jacks and allow voltage control of feedback amount, feedback
tuning, low-pass filter cutoff frequency, and resonance. Attack and Decay parame-
ters control the triggered noise envelope. The module provides one audio input, one
audio output, and a trigger input for the internal noise source. The signal path of the
digital filter provides full, 24-bit, 96 kHz resolution.
Input
Output
Fbk Amt
LPF Freq
Tuning
Resonance
Trigger In
Amount
DSM03
FEEDBACK
Tuning
LPF Freq
Resonance
Attack
Decay
FEEDBACK AMOUNT
-5v to +5v
Sets the amount of audio signal
to pass to the tuned feedback path
FEEDBACK TUNING
-5v to +5v
Sets the delay time for the
tuned feedback from 8Hz to 64kHz
RESONANCE
-5v to +5v
Sets the amount of resonance applied
to the low-pass filter cutoff
DECAY
Sets the decay time for the output level
of noise when using Trigger In
VOLTAGE CONTROL INPUTS
8mm input jacks for voltage control of
Feedback Amount, Tuning
LPF Frequency, and Resonance
LOW-PASS FILTER FREQ
-10v to +10v
Sets the low-pass cutoff frequency
TRIGGER IN
0 to +10v
Triggers noise output when
input voltage exceeds 1.5v
ATTACK
Sets the attack time for the output level
of noise when using Trigger In
AUDIO INPUT
-2.5v to +2.5v
AUDIO OUTPUT
-2.5v to +2.5v
DSM03 Front Panel
ENVELOPE
NOISE
LPF
FB
DELAY
TRIGGER
IN
OUT
FB AMOUNT
TUNING
DECAY
ATTACK
+
FREQ
RES
DSM03 Circuit Diagram
About Tuned Feedback
The DSM03 Feedback Module’s tuned feedback delay has a 9-octave range, which is
most noticeable when it oscillates. The tuned feedback loop will track reasonably well
at 1V/octave over a 3-4 octave range via control voltage (CV). Because the low-pass
filter is in the feedback path, it is important to adjust the filter settings for best results.
In other words, the filter settings will affect tracking accuracy. Setting the
lpf
freq
knob
to 12 o’clock is a good starting point. When an audio signal is passed through the input,
the feedback tends to lock to frequencies of the input signal. So, a pitched audio input
will result in closer feedback tracking, while non-pitched audio will give less predictable
results.
Using the DSM03
The DSM03 has many uses, including as a signal processor and as a tone generator.
Signal Processing
You can create a broad variety of effects with the DSM03 by processing an audio signal
though the tuned feedback path (and filtering it if desired). Experiment with the Tuning
parameter to vary the effect in subtle and not-so-subtle ways.