Dave smith instruments DSM03 User Manual

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

lter 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 lter cutoff frequency, and resonance. Attack and Decay parame­ters 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 lter provides full, 24-bit, 96 kHz resolution.

DECAYATTA CK

TRIGGER

ENVELOPE

NOISE

FREQ RES

+

IN OUT

LPF

FB

DELAY

FEEDBACK AMOUNT

Sets the amount of audio signal

to pass to the tuned feedback path

LOW-PASS FILTER FREQ

Sets the low-pass cutoff frequency

Triggers noise output when
input voltage exceeds 1.5v

Sets the attack time for the output level

of noise when using Trigger In

DSM03 Front Panel

-5v to +5v

-10v to +10v

TRIGGER IN

0 to +10v

ATTACK

AUDIO INPUT

-2.5v to +2.5v

AUDIO OUTPUT

-2.5v to +2.5v

FEEDBACK

DSM03

Amount

LPF Freq Resonance

Attack Decay

Input

Output

Trigger In

Fbk Amt

LPF Freq

Tuning

Tuning

Resonance

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

FB AMOUNT

DSM03 Circuit Diagram

TUNING

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

lter is in the feedback path, it is important to adjust the lter settings for best results.
In other words, the lter 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 ltering it if desired). Experiment with the Tuning

parameter to vary the effect in subtle and not-so-subtle ways.

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To use the DSM03 as a signal processor:

1. Connect an audio signal to the DSM03’s audio input jack.

2. Connect the DSM03’s audio output to a mixer or other module that provides audio output.

3. Adjust the tuning parameter manually or connect a control voltage to its voltage control input
to modulate it.

4. Adjust the lpf freq and resonance parameters manually or connect a control voltage to their
voltage control inputs to apply additional processing to the sound.

DSM03 Specications

IN/OUT

• Feedback Amount CV: -5V to +5V

• Tuning CV: -5V to +5V

• LPF Freq CV: -10V to +10V

• Resonance CV: -5V to +5V

Tone Generation

You can also use the DSM03 as a tone generator through its Karplus-Strong plucked
string synthesis capabilities. In classic Karplus-Strong synthesis, a short excitation
waveform (white noise) is generated. This excitation is output and fed back into a
delay line. The output of the delay line is fed through a lter (the low-pass lter).
The lter characteristics determine the harmonic structure of the decaying tone. The
ltered output is mixed back into the output and fed back into the delay line.

To use the DSM03 as a tone generator:

1. Connect a control voltage signal of 1.6V or greater to the DSM03’s trigger in jack.

2. Connect the DSM03’s audio output to a mixer or other module that provides audio output.

3. Adjust the attack and decay parameters to shape the envelope of the generated sound.

4. Adjust the tuning parameter manually or connect a control voltage to its voltage control input
to modulate it.

5. Adjust the lpf freq and resonance parameters manually or connect a control voltage to their
voltage control inputs to shape the harmonic content of the generated sound.

• Audio In: -2.5V to +2.5V

• Audio Out: -2.5V to +2.5V

• Audio Trigger In: 0 to +10V

POWER

• Internal power connector (ribbon cable included)

CURRENT DRAW (5V or 12V operation set by jumper)

Using 5V power supply:

• +5V = 200 mA

• +12V = 10mA

• -12V = 20mA

Using 12V supply only:

• +12V = 210mA

• -12V = 20mA

PHYSICAL SPECS

• 1.99″ W x 5.06″ H (50.5 mm x 128.5 mm)

• Width: 10 HP

• Depth (measured from back of panel with power cable installed): 1.54″ (39 mm)

INCLUDED

• Mounting screws

• Ribbon cable for power connection

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