PATCH #2: "Lead MS20 Style"
Earlier this year, Doepfer announced its new Basic System 3 (BS3), the latest in its line of complete, pre-configured Eurorack systems aimed at beginners, experts, explorers and purists alike.
To accompany the system, Doepfer — in collaboration with Stromkult — has designed a comprehensive Patchbook with fourteen different patch ideas for the BS3. Every patch comes with custom-made patch diagrams and a step-by-step-patching manual, making it easy for anyone to recreate and play with these patches.
While the patches were specifically designed for the BS3 and its configuration, most of the patches revolve around basic "building block" modules such as VCOs, VCFs, VCAs, mixers, envelope and LFOs and thus should be able to be recreated on a variety of systems — above all, we hope these patches may inspire you!
You can download the full PDF of the patchbook with all of the patches here (link goes to Google Drive).
Every individual patch is divided into an introductory overview of the patch, a section for the audio path, a section for the control voltage path and a final "play the patch" section with ideas on how the patch could be further tweaked and iterated upon.
PATCH OVERVIEW
This is a very simple lead patch with slightly metallic and percussive qualities inspired by the venerable MS-20 synthesizer from the 70’s. It makes use of amplitude modulation (AM) and serial lowpass and highpass filters. If you feed it with a steady 16th note sequence it can sound quite “techno”!
AUDIO PATH
The A-110-1 VCOs are tuned to a musical interval, the first being a C and the second a G an octave above.
The saw wave from the first oscillator goes to the audio input of the A-132-3 DVCA. Its “CV In” receives a sine wave from the second oscillator, which means that the volume (amplitude) of the first oscillator is modulated by the second oscillator at audio rate. This is called amplitude modulation (AM), which can add a lot of noisy and inharmonic overtones to the sound. You can adjust the depth of the modulation using the “CV” knob. In this patch example, the modulation is turned all the way up to create a very rich sound. The tuning relationship between the oscillators affects the character of the AM modulation.
The output of the A-132-3 is fed to input 1 of the A-138 mixer. We also send the saw wave output of the second oscillator and white noise from the A-118-1 noise generator to the A-138. The AM modulated signal connected to the first input forms the core of the sound, while the saw wave and noise are added to further beef up the sound.
The signal is then filtered using the A-108. We choose the classic 24db lowpass output and send it to our second filter, the A-121-2, which will act as a highpass filter by taking the highpass output. That way, the two filters will process the sound serially, one after the other.
The last stage of the signal path is the A-131 VCA, before the sound is fed to our headphones or speakers.
CONTROL VOLTAGE PATH
As usual, we patch our keyboard/sequencer CV into the A-180-2 to distribute it to different destinations. We make use of a handy little trick here: we send one of the outputs from the first row of multiples into the second row below, in order to get more than three copies of the CV source (this patch requires four).
We send it to both oscillators via their “CV1” input (scaled to 1volt per octave), so that the sound follows along in pitch when we play. We also send it to the “CV2” input of the A-108 and to the “FCV2” input of the A-121-2, which will result in filter key tracking. This means the cutoff will change depending on the notes played.
Finally, we connect the keyboard/sequencer gate signal to the “gate” input of the A-140-1 ADSR to trigger it on key presses. One of its outputs is sent to the “CV1” input of the A-131 in order to control the volume contour of the sound. The other output goes to the “CV3” input of the A-108 filter.
PLAY THE PATCH
The patch becomes more percussive, even drum-like, if you shorten the A-140-1 envelope controls.
By changing the tuning of the oscillators, you can radically modify the character of the sound, since amplitude modulation is a nonlinear process that depends on the relation between the two oscillators.
As already stated, you can tune the amount of AM modulation using the “CV” knob on the A-132-3.
In this patch example, the highpass filtering on the A-121-2 VCF is fairly subtle, but by turning up the resonance (“Q”) and playing with the cutoff frequency (“Frq”) you can make it a lot more drastic! Increasing the resonance (“Emph.”) of the A-108 adds further growl and grit to the patch.
Both filters in this patch can be overdriven by raising the input gain, giving you a lot of different saturation and distortion tones! The output level of the mixer also has an effect since it is feeding
into the filters.