The Kraftzwerg is advertised as a semi-modular version of their Synth II . At 580EU/899USD it's the cheapest fully assembled analog modular synth available . It's only about 12" wide, the picture below shows it atop my Motif workstation giving you an idea of it's size.
For those not familiar with MFB products, the construction is best described as adequate. It uses the same plastic case as the Synth II and is just a step beyond a homemade hobbyist's project. It should stand up fine for studio use, live you will want to be a bit protective of it especially the pots. The wall wart supply is 16VAC, so if you misplace it you won't be able to swap it out with some other adapters you might have on hand.
The circuitry is identical to the MFB Eurorack modules except the MIDI interface lacks the clock outputs (pitch, gate, bend and mod wheels only). While it is technically semi-modular because normaled connections allow use without patch cords, it duplicates all the patch access of the individual modules. There are only two connections not patchable: the input to the ring mod (hardwired to VCO 1 and 2 outs) and the inputs to the VCO mixer (it cannot be used for mixing anything but the VCOs). This is actually superior to most semi-modulars past and present. Missing features compared to the Synth II are program memory (doh), step sequencer (likewise), portamento/glide and external audio in. While you can patch into the filter, there is no preamplifier to boost the signal to the appropriate level. All patching uses 1/8" (3.5mm) jacks, five 18" cords are provided.
Rather than discuss every feature (see the MFB website for all the specs and the manual) I'll mention some of the more interesting highlights.
LFOs
The exciting news is that there is a CV input to modulate rate of each LFO. They will easily get into audio range for FM/AM applications. The patching is normaled so that you can use each LFO to modulate the other's rate.
VCOs
There are three following the Minimoog design MFB has used as it's inspiration. VCO 1 and 2 offer 4/8/16 foot ranges and PWM, VCO3 has 8/16/32 foot ranges but no PWM. There is one master tune and individual detunes for VCO2 and VCO3, all have ranges of about +/- 1 octave. Unlike the VCOs on many modulars, you cannot access all waveforms at once, a switch for each VCO chooses saw, triangle or square (no sine). Manual pulse width adjustment is not offered. There is an output for each VCO plus ring mod of VCOs 1&2. Each VCO has a main pitch CV input normaled to the MIDI interface plus a second for modulation with a depth control.
VCF
The filter is a 4 pole LPF modeled after the Minimoog. There are two inputs that can be mixed, one is normaled to provide a feedback path which thickens the low end while reducing resonance. There are two CVs for cutoff, one normaled to an EG the other to follow the MIDI pitch. Resonance has it's own CV input. All three have depth controls. Self resonance is easily achieved and with the tracking CV depth at 100% it will stay in reasonable tune.
VCA
The VCA has three audio inputs (one with a attenuator control). There are two CVs, one normaled to an EG. There two outputs, one with a volume knob...yes, finally a modular with a master volume control 8) The gain pot is unusual, at settings above 5 it opens the amp up without the CVs to allow droning sounds. At lower settings, it acts as a gain boost and the CVs must be used to open the amp. So the actual output level depends on the settings of three pots: gain, EG CV and output. Quirky but flexible.
EGs
There are two, one normaled to filter cutoff and one normaled to the VCA. Each is an AHDSR type, the H for hold. This keeps the EG output at a steady level between the attack and decay phases. The normal response is exponential but a switch allows setting either EG (but not both
) to linear response. The release time in particular seems rather short to me in expo mode, changing to linear response increases the time significantly.Stay tuned for some demo mp3s.
Since it is not blended in with the pitch CV you can tweak the bend range unlike some other low-cost MIDI/CV interfaces and it also can be used for bipolar modulations. The mod wheel CV varies from 0V to +5V.
which is the A an octave and sixth above the highest note on a 61 note keyboard. This is a rather bizarre map to be sure...82 notes? Keep in mind that on an analog synth pitch is not absolute as it is in MIDI, it's relative. Most analog monos are designed so the CV generated for the lowest key is 0V, that's usually a C but need not be. The lowest key on a typical 61 note MIDI keyboard is note 36, 3 octaves above the lowest MIDI note (0) so what voltage should a MIDI-CV interface put out...0V, 3V, something else (if you're wondering why anyone would need to handle MIDI notes below 36 anyway, keep in mind that the GM drum map...based on the mapping of Roland drum machines...places the kick drum at MIDI note 35.)?
I'm surprised at how much body there is to these VCOs.