AUDIO DAMAGE BOOMTSCHAK (01) PDF Document

The AUDIO DAMAGE BOOMTSCHAK is an Eurorack module designed for synthesizing drum and percussion sounds. Its circuitry is completely analog and it contains a voltage-controlled oscillator (VCO), three envelope generators, a noise source, a multi-mode voltage-controlled filter (VCF), and several voltage-controlled amplifiers (VCAs). The module combines two main sound sources, an oscillator and a filtered noise generator, which are mixed together to create its output.

You can control the oscillator pitch on your AUDIO DAMAGE BOOMTSCHAK in two ways:

PITCH Knob: This knob sets the base frequency, or pitch, of the VCO. The range is from less than 10Hz up to about 1.3KHz.

PITCH INPUT Jack: You can control the frequency directly by applying a signal to this jack. The VCO responds to input voltages with the standard convention of a one-volt change producing a one-octave change in pitch, allowing you to play melodies or bass lines.

The AUDIO DAMAGE BOOMTSCHAK uses a dedicated pitch-bend envelope generator to modulate the oscillator’s pitch. This is controlled by three knobs:

BEND DEPTH: This is a bidirectional control that determines how much the envelope generator changes the VCO’s frequency. At its center position, there is no effect. Turning it clockwise causes the pitch to start sharp and bend downwards. Turning it counter-clockwise causes the pitch to bend upwards.

BEND DECAY: This knob sets the decay time of the pitch-bend envelope, controlling how long the pitch sweep lasts.

BEND SHAPE: This knob varies the shape of the pitch-bend envelope from a sharp exponential curve (fully counter-clockwise) to a linear ramp (fully clockwise).

These controls can create dramatic frequency swoops or add subtle character to the attack of the sound.

You can alter the oscillator’s tone on your AUDIO DAMAGE BOOMTSCHAK using the following controls:

WAVE Switch: Switches the VCO’s output waveform. The options are TRIANGLE (for a brighter tone) and SINE (for a clear but soft tone).

KLIK TONE: This knob changes the brightness of a short click that is added to the beginning of the sound, affecting the transient attack.

WAVESHAPER: This control adjusts a simple wave-folder that alters the shape of the VCO’s signal. Turning up the knob produces more folding, which changes the timbre of the wave.

The amplitude envelope for the oscillator on your AUDIO DAMAGE BOOMTSCHAK is controlled by the knobs in the OSCILLATOR section:

AMP DCY Switch: This switch selects between a SHORT and LONG range for the decay time.

AMP DECAY Knob: This sets the decay time of the envelope generator that controls the VCA for the VCO. This determines how long the VCO tone is heard. The decay time can range from about 1/10th of a second to about six seconds.

AMP SHAPE Knob: This varies the shape of the VCO amplitude envelope from a sharp exponential curve to a linear ramp. When rotated fully counter-clockwise, the voltage drops sharply at first. When rotated fully clockwise, the voltage decreases at a constant rate.

The NOISE/FILTER section on your AUDIO DAMAGE BOOMTSCHAK processes a white noise source through a multi-mode filter. The controls are:

FILTER FREQ Knob: Sets the frequency of the filter.

FILTER Q Knob: Sets the resonance of the filter, emphasizing the sound at the corner or center frequency. If you turn this knob up far enough, the filter will self-oscillate, creating a tone.

FILTER MODE Switch: Chooses one of three filter response modes:

LP: Low pass, which removes high frequencies.

BP: Band pass, which removes low and high frequencies but preserves a range in the middle.

HP: High pass, which removes low frequencies.

You can modulate the filter frequency on your AUDIO DAMAGE BOOMTSCHAK using internal or external sources:

MOD SOURCE Switch: This switch selects one of three internal modulation sources for the filter frequency:

AMP DCY: The amplitude envelope generator for the noise source.

BEND DCY: The pitch bend envelope generator for the VCO.

OSC: The VCO’s audio signal (post-VCA and wave shaper). This can be used as an LFO at sub-audio rates or for audio-rate modulation.

MOD DEPTH Knob: This is a bidirectional control that sets how much the selected modulation source affects the filter frequency. In the center position, there is no modulation. Turning it clockwise increases the frequency in response to the signal, and counter-clockwise decreases it.

FREQ Jack: An external control voltage can be applied to this jack to alter the filter’s frequency. Positive voltages increase the frequency, and negative voltages decrease it.

The amplitude envelope for the noise source on your AUDIO DAMAGE BOOMTSCHAK is controlled by the knobs in the NOISE/FILTER section:

AMP DCY Switch: This switch selects between a SHORT and LONG range for the decay time.

AMP DECAY Knob: This sets the decay time of the envelope generator that controls the VCA for the noise source, determining how long the noise is heard.

AMP SHAPE Knob: This varies the shape of the noise amplitude envelope from a sharp exponential curve to a linear ramp.

Yes. Plugging an external signal into the FILTER INPUT jack on your AUDIO DAMAGE BOOMTSCHAK will bypass the module’s internal noise source. The external signal will then be passed through the filter and its associated envelope generator and VCA. This allows you to use the module as a simple synthesizer voice for an external oscillator.

The final output controls on your AUDIO DAMAGE BOOMTSCHAK are:

MIX Knob: This varies the relative loudness of the VCO and the noise source. At its center position, both sources have roughly equal loudness. Rotate the knob counter-clockwise to hear more of the VCO, and rotate it clockwise to hear more noise.

MIX Jack: This jack allows you to vary the balance of the signals with an external control voltage. Positive voltages increase the level of the oscillator and decrease the level of the noise; negative voltages do the opposite.

LEVEL Knob: This sets the overall output level of the module.

You can trigger and control the dynamics of your AUDIO DAMAGE BOOMTSCHAK using a combination of a manual button and several input jacks:

MANUAL Button: Press this button to trigger the module manually. This is useful for setting up sounds or for live improvisation.

TRIGGER Jack: Apply a positive-going rectangular wave to this jack to trigger the module. A +5V signal lasting around 5msec or longer is best, but the module will trigger at lower voltages.

VELOCITY Jack: This is a control-voltage input for varying the loudness of the module. The input voltage is sampled when a trigger pulse is received. Positive voltages increase the loudness, and negative voltages decrease it.

CHOKE Jack: A positive-going rectangular pulse applied to this input will cut off (choke) the output of the module. An incoming pulse will cause all three envelope generators to cease their decay and immediately drop to zero, silencing the sound.

The AUDIO DAMAGE BOOMTSCHAK features control-voltage input jacks associated with the BEND DECAY and AMP DECAY knobs. Applying a positive voltage to these jacks increases the time it takes for the respective envelope to fade out. Applying a negative voltage decreases the time. This can be used, for example, to simulate a hi-hat by varying the sound’s decay time between short and long.