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My Modular-Synthesizer

There are several modular synthesizer formats which have different sizes and operating voltages. Most formats however can be mixed among themselves, since today the Control Voltage (CV) is primarily 10V pk-pk audio and +5V for Gate and envelopes. Of course different operating voltages require the appropriate PSUs.

I decided for MOTM as main format, due to special functions however frequently several formats meet in larger modular systems. In my instrument some eurorack modules are active in particular in the connection with the computer (see below).

Since the way to a modular synth and the planning was not half bad i decided to do this little documentation. My selection is focussed on analog modules (there are digital modules too). I realize the digital signal processing with Max/MSP just as Sequencers, LFO's, Quantizers, Dividers, MIDI-Clock etc.. This saves about the same quantity of modules which is already used as hardware.

The modules that i use are from Synthtech (USA), the MOTM-home and from Oakley Sound Systems, the leading developer in the UK. My Oakley modules have been assembled by Paul Darlow - Krisp1, a very fine manufactor of this format in the UK. Two modules are from Catgirl Synth, the Burst Generator (a Gate/Trigger/Clock module) and the CGS Digital Noise Module. The three cases contain 3x VCO, 2x VC-LFO, Sample/Slew, Noise/LPF/HPF, Digital Noise, Triple Lag, OTA VC-LPF, Triple Resonance Filter, Diode Superladder-Filter, 2x RM, 2x ADSR, 2x Triple VCA, 2x MultMixer, Multiples, Envelope Follower/Gate Extractor, Dual VC-Router, WaveWarper, SubOctave Multplexer, Comparator, Burst-Generator, Phaser and Overdrive.

The Larry Hendry prototype #1 of the MOTM 850-Pedal-Interface (it is for 2 pedals) applies a special kick to my instrument (right picture). I connected two Yamaha FC9 - switched to CV and without PSUs. Just perfect!

The Eurorack modules (orange and silver) are Expert Sleepers ES-1, ES-2 und ES-3-modules (Audio to CV / CV to Audio), a A-198 (Ribbon-Controller) and the spring reverb module A-199 from Doepfer. My Eurorack modules in this case are powered also with 15V and will share the 3U frame with the MIDI-Switch-Matrix from Hinton Instruments. The remaining devices are an Art CleanBox - for unbalancing and conditioning audiosignals from the computer to the synthesizer and the Kenton Pro 2000 MK II MIDI to CV Interface.

Connoisseurs may have noticed that some typical modules, like Quantizer, Clock Divider and other function-modules, to be missing. These, like further LFO's, Envelopes and naturally all digital signal processing I program with Max/MSP (see below).

More about the modules and functions soon.

P o w e r

From the beginning the somewhat fragile situation with the OEM-MOTM-PSUs, offered by Synthtech and Oakley, had irritated me, since they are not very effective, although quite large and not even cheap. Through the matrix development I had the luck to meet with Graham Hinton of Hinton Instruments who suggested building new power supplies for my setup.

The Hinton PSUs are fully specified with large toroidal transformers, are outstandingly built and customised for my needs. The PSU (right)) is envisaged for the matrix and my 10U case and supplies besides the +/-15V additionally +5V. The distribution card also offers Eurorack connectors besides MOTM.

The big PSU (left) operates up to 20 MOTM modules (at present 19 modules are in the filled case). Although much larger, the PSU is mounted “invisibly" in the 2' inches void of the case. Thus permits 3U (MOTM) more surface on the front side - which is 10% of the entire surface of a 15U Case and 15% of a 10U case.

Together with the PSUs I also exchanged the distribution cards and connector-cables: instead of the MTA- now Molex connectors are used. Six additional eurorack connectors are provided on the right distribution card.

Here is the PSU from above as it is assembled behind a 3U frame in the 10U case. It is designated for the MIDI-Matrix and a few Eurorack modules (ExpertSleepers "Audio to CV", "CV to Audio" and a Joystick-module).

The EuroRack modules are fed with 15V instead of 12V. This cannot be done with all Eurorack modules and must be checked before.

C o n t r o l

MIDI to CV

The Kenton Pro 2000 MK II offers many features such as 2 independent CV and Gate outs, 6x Aux Out, 2 LFO´s with 9 waveforms, Sync Portamento, Volt/Octave, Hz/Volt, !,2 Volt/Oct, Clock and Sync24 - a real asset and for sure one of the best MIDI to CV interfaces you can find - particularly in questions of reliability.

The very good idea to assemble the MIDI and 1/4 Jacks as adapters into the rack-ears i spotted first on this photo of Larry Hendry. The Kenton Pro 2000 only has Mini-Jacks on the rear and when it is used inside a case the CV-cables are hidden. This way it's ideal with a modular since everything is on the front!

Because of the slightly obsolete 80s-style handling (2 rows/16 digits display and 4 buttons) i've programmed an editor which makes working with the Kenton Pro 2000 MkII much easier and offers a great overview.

The software-editor also spares the use of the internal presets of the hardware. Should i need to use another Kenton Pro 2000 MkII i'll have all presets in my software already. For clients environments it helps to avoid problems with unknown hardware since all assignments are predefined. If you're using a Kenton Pro-2000MkII please feel free to download the editor.

Current version: 1.5.3

Mac only standalone: KentonPro2000MkII Editor (9,1MB).

Mac and Windows: KentonPro2000MkII Editor (544KB) - this version requires Max Runtime.

The Kenton Pro-2000 offers many defaults however only selected parameters for MIDI controller allocations. Most parameters are attainable only over MIDI system-exclusive data strands, however the interesting features of this MIDI to CV converter are located just here. With Max the Kenton Pro-2000 can be converted easily into a real-time controller.

Some functions of the editor, like MIDI channel- or controller assignments are missing in this patch, because they are not changed during performances. Instead there are (assigned) MIDI controllers. Some functions that consist of several MIDI messages are summarized in one button - e.g. the Portmento on/off between (assigned) pedal (MIDI-controller) or legato-playing on the keyboard (Auto-Portamento). With this patch Transpose, Tuning, LFO Waveshape, LFO- and Portamento-Speed etc. - are controllable in real time. Thus the characteristic of the Kenton Pro-2000 gets more similarity with a modular Synthesizer than with a MIDI Preset Synthesizer. Now this interface saves besides some expensive modules (plus size, cables and weight). Next i plan to transfer some micro-tonal scales with assistance of the software, which shall be available as “tables” in the setup.

For a better outline the representation format of Ableton Live is quite suitable. Since I wanted to program a Live PlugIn once for a long time and Live does not transmit SysEx data originally, this was the perfect challenge!

Here is the controller for Ableton Live. Live requires a different way of thinking, because some parameters are edited over MIDI tracks and others over the “Kenton track”. Already for years the Interface of Ableton Live - in particular handling addressings fascinates me. I will continue to train imyself into the software and will surely port more PlugIns to Ableton Live.

If you like to use this (Mac only) PlugIn please write me a message.

Audio to CV und CV to Audio

CV control can also be done with the plug-in suite Silent Way - generated from the audio interfaces audio outputs. A fantastic collection of extremely useful CV-PlugIns including Silent Way- DC, LFO, Step LFO, Quantizer, Trigger, CV Input, CV To OSC, CV To MIDI, AC Encoder und Voice Controller. This means, CV values can be transformed in Midi or OSC data. Due the OSC compatibility, it should be quite simple to realize corresponding controllers on iPhone or iPad! All parameters also have a Midi address. This is VERY significant - the voice controller alone has 122 parameters! In my opinion, Silent Way has eliminated THE Missing Link! In particular, some traveling modulists will appreciate that through the functions some modules like to be left at home in the future.

Of course, these plug-ins can also be programmed with Max/MSP, but they are so good that I simply use a MSP vst-object and program only the GUI for the plug. Now i don't need to open any window for the plug, but can place it on my programs GUI. The picture shows my Max-GUI for the SW Step LFO. Now it offers some presets too.

I noticed that 18 parameters allocated in four plugins surpass the upper 14 character-limit and therefore cause problems. This incomplete transmitted and therefore doubled parameter names must be replaced by parameter index numbers. Until it is corrected in an update - Os from Expert Sleepers has been informed - here is a jpg with the appropriate parameters. For each (incomplete) name there are two addresses (L/R), so 2 numbers are behind each name.

Alternate Parameter-Index-Numbers

Although this PlugIns may be used directly from (some) DC-coupled Audio-Interface outputs - significant better results can be achieved (also with AC-coupled interface-outputs) with the Expert Sleepers modules.

ES-1 is a 8x Audio-to-CV-, ES-2-2 a 2x CV-to-Audio-, ES-3 a Adat to 8x CV and ES-4 a Spdif to CV interface-module in Eurorack-format, which supposedly works with MOTM (+/-15V) too!

Thus a modular system suddenly gets a very different meaning! The calibration and tuning can be automated. Sounds are, when identically patched, even with most complex value-changes precisely reproducible. Also, pot movements can be recorded from the synthesizer - which is exactly what normally doesn´t work with such a system ...

Since Kenton Pro2000 and ARP Odyssey have CV mini-jacks as well I'll keep the Minijack-Eurorack modules. Here the ES-1 module can be seen in a Doepfer Mini-Case which i use as my reception centre for Eurorack modules.

P a t c h b a y / M a t r i x

To achieve a complete connection of the synthesizer and Max/MSP, a matrix is needed - but it has to be externally switched (e.g. with MIDI). The only thing I found was the full analog matrix Switchmix of Hinton Instruments. It can process both audio and CV (AC/DC) and it also does real summing, which means that multiple inputs can be routed to any output. But the SwitchMix is not externally switchable and could be more considered as a descendant of the EMS pin-matrix. It is the control panel itself.

The company Hinton Instruments brings a lot of experiences with matrices, customized products and CV-, audio- and MIDI patching and seems to be the best address for a matrix-module.

I´ve learned a lot already only by reading the very interesting and instructive website!

An analog matrix is due to the circuitry not designed for switching all channels simultaneously, it would create noises and rumbling - therefore the offered customization doesn't bring any advantages for my purposes. The most important thing for me is the switching from the computer (because I'm looking for the connection with Max/MSP). Also the smallest possible size of the module would be much appreciated, since I do not want to switch anything on the module. If the matrix is MIDI controllable, there is a variety of controllers (eg, the Novation Launchpad) which can be used as a wonderful panel. I have discussed this and more extensively with Graham Hinton, who showed great interest and an amazing openness!

On the right side the scetch of the switchable Matrix can be seen. The existing module is 3U high and needs 2/3 of the 19' width. The patch-field is separated and can easily be exchanged against other plug-formats. Exclusively switchable over MIDI the Matrix is perfect for the Novation Launchpad or Touch-Osc on iPhone or iPad. Of course Max/MSP is perfect to write a smart dedicated software.

Also economic reasons made the decision for 8x8 relatively simple: a 16x16 matrix is 4 x 8x8, so 4 times the hardware. Just two 8x8 matrix, used well, could be more helpful for me to than a 16er matrix, since "it has not always be a square". The modules can even still be switched together via MIDI.

Both the sontroller-hardware-integration and the MIDI handling is much easier on a 8x8 (64 pads) rather than 16x16 (256 pads). Nevertheless the 16x16 Matrix isn't off the cards. For improvisation a 16x16 matrix could also be intellectual too demanding since viewing, counting and thinking would need too much time - which isn't as is well known disposable while making music.

C a s e

Through the 19-inch sizes (19 inches = 10U MOTM) and the 5 U (22.5 cm) height I opted for two cases, 15U and 10U. The main reasons were a) 15U is apprximately the size of a minimoog, b) with around 20 Modules as an average, the PSU may be "friendly" sized, c) the lower 10U case can be in a beveled position and d) easier transportation.

Thus the case remains as flat as possible, 14cm ranging from rack rails is enough depth for most MOTM modules. Should it be carried wired, the instrument must allow the lid with 6-8 cm depth. That results in a case exterior dimension of 53 x 23 x 70cm.

The price of the custom cases was comparable with the ones off the shelf. I bought my cases from LT-Cases in Bavaria.

The stand is from Ultimate and has been individually shortened. I have attached a VESA mounting bracket for preventing slippage of the instrument. This also spares a large crossbar.

D i g i t a l

I noticed that many new module developments are digital - I do not understand this, because, in my "modular" thinking, those things could rather take place in a computer system. These things I will try in part-way to implement with Max/MSP. This might probably be the biggest communication needs with the MOTM community for me.

Digital sind bei mir hauptsächlich Steuerungs-Daten. Seit Neustem habe ich nun ein iPad im Setup - damit möchte ich den Computer weiter in den Hintergrund verlegen. Mir ist es sehr wichtig, beim Spielen nicht in den Monitor schauen zu müssen. Das iPad mit TouchOsc ist ein grosser Schritt bei diesem Vorhaben.

TouchOsc Oberflächen können mit einer Software auf dem Computer frei gestaltet/angeordnet werden. Für die Gestaltung werden verschiedene Valuatoren (Fader, Button, Pot, XY) verwendet. Wertigkeiten können vom iPad zum Rechner und vom Rechner zum iPad geschickt werden. Ein Controller-Setup kann aus mehreren Seiten (Pages) bestehen, die als Tabs am Rand zu sehen sind und über eine Berührung (oder vom Computer) aufgerufen werden können.

Beim Bedienen müssen die Faderknöpfe nicht genau getroffen werden: mit der Einstellung "Relative" (alternativ zu "Absolute") reicht eine Berührung innerhalb des Faderzuges. Der Berührungspunkt wird nun als die Position des, vor der Berührung angezeigten Wertes interpretiert - so passieren keine ungewollten Werte-Sprünge. Auch werden benachbarte Fader nicht versehentlich bewegt, wenn man während der Faderbewegung auf andere Fader/Potis kommt. Sehr gut! Und Multitouch fähig. TouchOsc rocks!

Bisher habe ich Motorfader für die Steuerung gebraucht - ich bin sehr gespannt auf die Veränderungen!