Improvisation XXXIII – Tat Tvam Asi

This was probably the most extensive analog modular improvisation, lots and lots of A-100-modules with no less than 241 patch cords have been used.

You may want to watch the improvisation on my Youtube channel:

Remark:To avoid cookies on this website, videos are not embedded.

Instruments used

The Doepfer A-100 is patched for 11 independent instruments:

  • Low Sequence 1 (a simple synth sound to be controlled by an analog sequencer)
  • Low Sequence 2 (similar to Low Sequence 1)
  • High Sequence (similar to the lower sequence voices, but more versatile)
  • BBD Bass (6 Karplus Strong voices, created with independent BBDs)
  • Drums HH (a Hihat)
  • Drums BD (a Bassdrum)
  • Drums SD (a Snaredrum)
  • Drone (a drone voice with fixed frequency spectrum)
  • Arpeggio (a more expressive voice than the sequencer lines, for use with an Arturia Keystep)
  • Solo (a strong solo voice, usable from bass to lead)
  • Vocoder Drums (a vocoder setup to be fed with some external drums)
  • Arturia Software Instruments

Low Sequence 1

An A-110-4 Quadrature Thru Zero VCO is sent through an A-121 Multimode VCF (the gritty old version) and an A-131 VCA. Pitch is controlled by the first of 2 A-155 Sequencers with some linear frequency modulation of the VCO by an A-143-9 VC LFO (modulation depth controlled manually as well as via VCA and an A-143-1 Complex EG). Filter and final VCA are both controlled by an A-140 ADSR which is triggered by the above mentioned Sequencer and an A-160-5 Ratcheting Controller.

Low Sequence 2

Another A-110-4 Quadrature Thru Zero VCO is used in a nearly identical setup as the Low Sequence 1 voice. However, an A-106-1 Extreme VCF is used instead of the A-121 Multimode VCF. This voice is controlled by the same A-155 Sequencer as above.

High Sequence

Here, an A-110-6 Trapezoid Thru Zero Quadrature VCO is used. In contrast to the A-110-4 (and many other Thru Zero VCOs), this VCO shows no pitch deviations even with higher amounts of linear FM used. At the moment, this is Doepfers most expensive single VCO and with some good reason as it seems. Linear FM source here is the output of the second A-110-4 QTZ VCO, sent through an A-101-1 Vactrol VCGF befor being used as a modulation source. The harsh self-oscillation capabilities of the A-101-1 add some interesting color to the linear FM. The output of the A-110-6 QTTZ VCO is then sent into an A-107 Morphing VCF (being sqitched by the second of the two A-155 Sequencers used) and finally into an A-132-3 VCA. The latter two are controlled by an A-142 VC Decay, the A-101-1 is controlled by a second A-142 VC Decay. Both A-142s decay times are controlled by the A-155 Sequencer and triggered by a second A-160-5 Ratcheting Controller (which gets its trigger from ther A-155).

BBD Bass

Since BBDs are usually not too good in tracking their pitch by a control voltage, I used 6 different devices for 6 different fixed pitches. For the Karplus Strong synthesis, a short voltage impulse from an A-142-4 Quad Decay is sent into the audio input of each A-188-1 BBD. With a reasonalby high (but not too high) resonance setting of the BBD, a plucked string alike sond is created. For filtering the internal circuit noises of the BBDs, each one sents its audio output through an individually adjusted A-108 48dB VCF. The BBDs are “played” by triggering the individual decay generators with an A-157 Trigger Sequencer.

Drums HH

This is a simple sound: The “6 Osc Out” from an A-117 Digital Noise is sent into an A-123-2 Highpass Filter (24 dB HP) and then into an A-124 Wasp Filter (ca. 90% LP). Finally the sound is shaped by an A-132-4 VCA, controlled by an A-141-2 Voltage Controlled ADSR. The ADSR is triggered and controlled by an A-157 Trigger Sequencer with a dedicated trigger track switching from the short “closed HH” to a longer “open HH”.

Drums BD

This voice uses the marvellous self oscillating of the A-111-5 Mini Synth Voice filter. The synth output is refined with an A-103 18dB Lowpass VCF, triggering is done by the above mentioned A-157 Trigger Sequencer.

Drums SD

For the snare, two noise sources were used. An A-117 Digital Noise (noise out) is sent into the lowpass input of an A-106-1 Extreme Filter, the “colored” output of an A-118 Noise is sent into the highpass input of the same filter. Final shaping by an A-132-4 VCA. Both A-106-1 VCF and the VCA are controlled by an A-140 ADSR, being triggered by the A-157 Trigger Sequencer.


As in some cases before, I use my A-143-4 Quad VCLFO as a source for drone sounds. The module can work in VCO mode and generates some interesting effects when the four oscillator frequencies are close enough to get their circuits “hooked” to each other (some kind of unintentional synchronisation). The sum output (square waves) is sent into an A-199 Spring Reverb with an A-189-1 VC Bit Modifier in its feedback loop. The reverb output is then sent into an A-106-5 SEM VCF and then into an A-127 Triple Resonance Filter. Ther is some slight modulation of tthe SEM filter by the external drum track (via the envelope follower of the A-119 External Input).


This one is to be played with an Arturia Keystep keyboard, which is set in arpeggiator mode and controls everything with its CV and trigger outputs. We have three A-110 VCOs, mixed with an A-138 Mixer and sent into an A-101-6 Opto VCF configured as an allpass filter. An A-146 LFO controls the VCF. After this, we go into an A-102 Diode VCF as the main filter. The A-102 really has a beautifully pungent and sparkling sound. The A-102 is controlled by an A-149-1 Quantized Random Generator, by the control voltage from the Arturia and by an A-140 ADSR. Finally, there is an A-132-2 VCA, being controlled by the same A-140 ADSR.


The solo voice was set up to be played by a Native Intruments Komplete Kontrol keyboard (layered with a virtual Arturia CS80 synthesizer) or by a Doepfer LMK2+keyboard (with key split between the A-100 and the Arturia CS80 and both layered with an Arturia DX7). Again, three VCOs are used, this time three A-111-1 Highend VCOs for their increased scalability. After mixing with an A-138 Mixer, we use an A-120 Ladder VCF with its classic and slightly distorted sound. For better interaction with the CS80, the filter output is then sent into an A-114 Ring Modulator with an A-147 VC LFO as second input. Original filter output and ring modulator output are then both sent into an A-134-2 Voltage Controlled Crossfader and then into an A-101-3 12-Stage Phaser with an A-143-9 VC QLFO as modulation source. Finally we go into an A-132-2 VCA. VCA and A-120 filter are both controlled by an A-140 ADSR. Speed of both the ringmodulator and the phaser LFO is controlled manually by the modulation wheel (Komplete Kontrtol or LMK2+) as well as the crossfading between ringmodulated and direct sound.

Vocoder Drums

Within Doepfers Vocoder Subsystem, the A-129/5 Voiced/Unvoiced is used as the main entry point. As “speech” input, a drum track from the DAW sequencer is used (Toontrack). The “voiced” signal is created by three A-110 VCOs with frequencies controlled by the same keyboards as the “Solo” voice mentioned above. The “unvoiced” signal (usually used for hissing and plopping speech components) is simply white noise from an A-118 Noise Generator. Vocoder Analysis of the “speech” input and Vocoder Synthesis (i.e. filtering of the voiced and unvoiced signals) was separated by a complete set of 3 A-129/3 Vocoder Slew Generators.

Arturia Software Instruments

Polyphony is not a strength of analog modular systems although within reach since e.g. Doepfer introduced his polyphonic A-100 modules. However, I always preferred software with a decent controller keyboard when I needed something polyphonic. Poly sounds never need that kind of complexity as monophonic ones but rather a good set of controlling means like pressure/velocity and aftertouch sensitivity, handwheels, footswitches etc.

Here, I’m using some software keyboards from Arturia, namely the B3V, a really stunning Hammond emulation, the CS80V (just lacking a keyboard with polyphonic aftertouch) and the DX7V.

DAW, Mastering, Video processing

First preparations of Tat Tvam Asi began in August 2019 with a handfull of patch cords. At the end of this process, 241 patch cords were in use and I stared at a something not only more complex than anything I did before on this instrument, but also on, well, 241 patch cords. How should I remember which module is used in which sub-patch and is connected with which other (distant) modules?

So I tried to write down some sketches of all the “instruments” and their components and connections. No fancy tool, just a little Excel spreadsheet (download as pdf file).

In addition to that, I exchanged some of the grey rotary knobs with colored ones: blue ones for oscillator frequency controls, red ones for filter cutoff frequency controls and yellow ones for any bipolar attenuators. This helped to qickly identify the key controls of each module…

As usual since a couple of years, recording and mixdown was done with Ableton Live (Suite 10.1.6). The recording session was a live improvisation. Audio and Midi signals were recorded on 26 simultaneous tracks.

After mixdown, some mastering was done with Adobe Audition: a slight multiband compression and normalization.

Live video was taken with a Canon EOS 5D MkV and a Panasonic HDC-SD707 with some additional takes by the panasonic camcorder. Video mixdown with Adobe Premiere Pro.

That’s it. Several months of “labour of love”.Hope, you enjoyed it!