MFB KRAFTZWERG Owner's Manual

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.
The KRAFTZWERG module can be used alone, even without the need to use any patch
cords. The classic routing VCO-VCF-VCA as well as most popular modulations is internally
prewired. Small labeling below the input jacks will indicate any existing prewiring with its
destination.
Set-up and connections
The KRAFTZWERG module is fully compatible to Doepfer's A-100 modular system - in
size, bus-power and CV/Gate voltage. Connect the 16-pin cable to a corresponded 16-pin jack
on the Doepfer mainframe bus or the (MFB)-MIDI/CV circuit board. Supply voltage needs to
be +/- 12 volts, 5-volt connections are not required. The wattage is +/- 250/100 mA, the
module size 60 TE (Teileinheiten) = 300 mm.
ATTENTION: Please, check for correct polarity! The colored side of the connector-cable
needs to point downwards, so that the cable is not twisted.
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 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.
At CV1, all three oscillators receive the same CV-voltage, meaning the same pitch. For
individual oscillator-pitch-control, it is necessary to use the front CV inputs 1-3. This will
decouple the other oscillators from CV1.
CV-inputs 1-3 and audio-outputs 1-3 are each interconnected. This means that a CV-signal
applied to CV1 will also control OSC2 and OSC3 as long as these are not individually
patched. If, for example, input CV3 is patched, OSC3 is decoupled from the voltage applied
to CV1, while OSC2 is still under combined control with OSC1.
The output-logic is comparable: Out3 carries all three oscillators' signals. With Out1 or Out2
patched, these signals are subtracted from Out3. To avoid internal clipping, the summing
signal is slightly reduced in level compared to the individual output of OSC3 at Out3.
All oscillators are globally tuned by the Tune control. Detuning of around +/- one octave (in
reference to OSC1) is available for OSC2 and OSC3 via Interval2 and Interval3. Each
oscillator offers three waveforms, selectable by Wave1...3 switches. The choices are triangle,
square and saw tooth. The square symmetry (pulse width) of OSC1 and OSC2 is adjustable
via CV4 and CV5 inputs. Each oscillator's register is set with the Octave1...3 switches.
Additional CV-inputs, e.g. for vibrato or creation of a pitch-envelope, are available through
CV4...6. Depending on the setting of the corresponding switches, pitch (OSC1...3) or pulse-
width (PW1+2) or all three oscillators are modulated. These inputs accept control voltage up
to +/- five volts.
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.
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.