Kraftzwerg

General
The KRAFTZWERG module is the Euro-rack compatible version of our semi-modular analogue synthesizer of the same name. It fits into any standard Eurorack frame with 3 rack units in height and can be used as part of a modular synthesis-system. The module works as a complete monophonic synthesizer with powerful options that can be expanded and controlled through CV-inputs of other signal sources and modulators like analogue sequencers. On the other hand, it is also possible to use the module’s different sections independently in combination with other modules.

DUAL LFO
To the left, you will find two LFOs. These low frequency oscillators are mainly used for sound modulations, like e.g. pitch, filter or pulse width. The two sections are independent and offer three waveforms each and a CV-input with attenuator. The frequency ranges from approximately 100 Hz to 10 s and can be significantly expanded with a matching control- voltage. Positive or negative voltage can increase the maximum value (or decrease the minimum value) by a factor of 30.

Each LFO has its own reset-input (negative slope) to reset the waveform start. By adjusting the speed and using a separate reset-signal to this jack, a LFO can be synchronized to a sequencer.
LFO 1 (above) offers three waveform shapes: descending saw tooth, triangle and square. LFO 2 (below) offers: ascending saw tooth, triangle and Sample & Hold. The maximum output voltage is ± five volts.
The oscillators’ outputs (not the RM-output) are routed into the following mixer that offers four controls: Level1...3 (for OSC1...3) and Noise for the internal noise generator. The summed signal is internally routed to the VCF and available at Out.
The CV-inputs of both LFOs are internally connected. With unpatched inputs, LFO1 controls the speed of LFO2 and vice versa, the attenuation controls set the intensity/depth for the modulation by the other LFO.

TRIPLE VCO
Three voltage-controlled oscillators are next. These are controlled by a common Key-CV- signal from the A-100 system bus to CV1. This CV-signal conforms to the one volt/octave standard and is meant to be used for typical overall pitch-control by a keyboard or sequencer.

This section also includes digital ring-modulation of OSC1 and OSC2. It is available on the separate output RingOut. The ring modulation sound is dependent on the selected waveforms and the pitch-difference between the oscillators.
The oscillators can also be synchronized internally or externally. With internal sync, OSC3 acts as master. Depending on the position of the Sync switch, either OSC1 or both, OSC1 and OSC2, act as slaves. Inputs CV4 and CV5 allow the synchronized oscillators to be modulated by envelope signals. Any external signal at the Sync In input will replace OSC3 as sync- master. It is usually necessary to apply a square signal here. Other waveforms will not deliver a sufficient master-signal in most cases.

24 dB VCF
The mixer output is internally routed into In2 of the voltage-controlled low pass-filter with 24 dB/octave slope. In1 allows adding another signal. The filter’s frequency is set by the Cutoff control. CV CUT controls the amount of influence ADSR1 takes on the cutoff-frequency. With an external signal connected to CV Cut, this control acts as an attenuator. CV2/Key selects whether the cutoff-frequency follows the pitch of the system-bus (key-tracking). CV2 input can also be used to control Cutoff, depending on the setting of the CV2/Key control that acts as attenuator.
Emphasis (resonance) controls the filter’s bandwidth to pronounce the cutoff-frequency. At high values, the filter starts to self-oscillate and generates a sinus-like signal without any oscillator input. The pitch of this sound is defined by the cutoff-frequency and can be controlled by the inputs as described above. Voltage control for Emphasis is also available via CV EMP with attenuation control. The filter-output is routed back to the input In1. The resulting feedback is controlled by In1. The feedback will also affect emphasis. Connect a cable into In1 to disconnect the feedback path.

VCA
The final signal-processing-stage is the voltage-controlled amplifier (VCA). Gain allows adjusting the amount of amplification and therefore the volume of the sound – but only in combination with a control voltage, like ADSR2 (internally connected). With settings above five, the input signal will reach the output even with no control voltage being present. This allows prelistening to sounds without keyboard control. Using this function, the KRAFTZWERG module can also be used as a filter-box without the need of being under sequencer control. A specialty: CV2 offers an additional attenuation control for amplification gain. This jack is only active if a control voltage is present at CV1. A practical use is creating a tremolo effect that is only active if a sound is played.

DUAL ADSR
There are two envelope generators available. ADSR1 and ADSR2 offer controls for Attack, Hold, Decay and Sustain-level. When the key is released or the gate-signal is stopped, Release sets the time for fade out. ADSR 1/2 are both triggered by Gate1 input. ADSR2 can be separately triggered by Gate2. The default envelope shape character is exponential for both envelopes. The 1 ° 2 switch allows setting either ADSR1 and/or ADSR2 for a linear character.

Multiples
The KRAFTZWERG module offers two separate Multiples, one offering three, the other offering four jacks. Use these Multiples to distribute audio-, CV- or gate-signals to more than a single destination.