This was my very last complete Eurorack instrument, which only existed for about half a year. A 600TE touring instrument that can be easily folded (in a patched state) and then is about as big as a tenor saxophone case. It was perfect for me in terms of transport handling, however I actually wasn't happy with the very small Eurorack format (12V) itself. When I got the opportunity in 2015 to take over some Buchla Clone modules from Roman F. (the man who had developed many of those Buchla Clones), I unceremoniously parted ways with no regrets and switched to the Buchla 200 Series, which had what I k was looking for. However, I still carry a few Eurorack modules today.

Eastcoast - Westcoast

In 2012, I had decided to realize a more travel-friendly EURORACK instrument because of the easier transportation (at that time I only had the 5U MOTM format). It was only two years after I had changed from ARP instruments to the MOTM Modular format (5U 15V) after 30 years and I was very pleased with the sound. However, MOTM was not ideal for traveling. It was quite bulky and also weighty. As I figured out later, the patch cables of my MOTM alone were heavier than my whole, first Eurorack instrument, both patched and in a wooden travel case!

While my MOTM synth was designed "eastcoast" (Filter focus and ADSR with VCAs), I had designed the Eurorack synth "westcoast", i.e. a bit on the FM side, with waveshaping and LoPass Gates. I loved that. However, I suffered from the appearance of the "Frankensynth" and I felt the Mini-Pots were rather unpleasant to tweak. The change from sliders (ARP) to knobs (MOTM) was much more pleasant than I had expected, but the Eurorack format was overall too "fiddly" and too cramped for me - and then there still was this screeching optics.

In addition, I rather was on the "15V track" - that had already started with ARP: While the ARP 2600 had 15V operating voltage, the Odyssey (I got the first one in 2006) only had 12V - and it somehow sounded smaller, less powerful. I had countered that with the ARP Little Brother (an expander with a 2600 oscillator). However, I also was missing some things on the Odyssey that I used to really appreciate on my ARP 2600. So I finally ended up in the Modular formats - and the "problems" had obviously come along. I'm just trying to describe my path, and that it consistently led to Buchla. Well, I hear more and more very well sounding music - from Eurorack instruments…

New Beginning

I never left the Eurorack completely anyway - the 80 Audio to CV outputs of the Expert-Sleepers modules alone require around 100 HP and they are substantial when it comes to my work on the Hybrid-Modular. For me, the Expert Sleepers modules are the key modules for controlling the synths.

One half of my Expert-Sleepers modules lives in and on my Buchla (1.2V/Oct) and provides 32x CV and 8x Gate. It can generate 40x CV from an SPDIF stereo Audio signal - it's an ES-40 with 5 Expansion modules..

Audio to CV / CV to Audio - also for “non-programmers”

To me, the Expert-Sleepers modules are THE missing link par excellence! A modular system suddenly takes on a whole new meaning! Calibration and tuning can be automated! Sounds, if patched identically, are exactly reproducible even with the most complicated value changes - which is exactly what is otherwise simply unthinkable with such a system…

It is the perfect combination of computer and synthesizer. For “non-programmers” there is a fantastic collection of extremely useful CV plug-ins from Expert-Sleepers called “Silent Way PlugIn Suite”. DC, LFO, Step LFO, Quantizer, Trigger, CV Input, CV To OSC, CV To MIDI, AC Encoder and Voice Controller. This means that incoming CV values can also be converted into MIDI or OSC data. Thanks to the OSC compatibility, corresponding controllers, e.g. on iPhone or iPad, can be realized quite easily. All parameters also have a MIDI address. This is VERY extensive - the Voice Controller on its own has 122 parameters! Traveling modulists in particular will like the fact that the included functions allow them to leave some modules at home in the future.

CV can also be generated directly from audio interfaces (with “coupled DC” audio outputs), but has too many flaws (e.g. lack of volts). Because I needed the analog audio outputs of my audio interface for audio, I didn't even start with it. The digital transmission via SPDIF, AES or ADAT (Expert-Sleepers) also avoids a double DAAD conversion and the signal strengths, if transmitted digitally, do not have to be calibrated regularly, as it is required with CV from analog audio outputs. Finally, the convincing argument is that I get 40x CV with two digital audio channels, while only 1x CV per audio channel is possible with analog audio!

This video is a good example of how easy it is - especially with the Silent Way plug-ins - to send, edit and receive CV:

I am also enthusiastic about the Intellijel Planar modules, which I primarily use as a vector mixer for audio on the Buchla. The two outputs of the Intellijel Planar modules run into the Dual VCA and by using the ADDAC FootControl I control one VCA of the Dual VCA module via the Volume Pedal.

The Eurorack has such important and great modules - in fact, no matter what format you're at home in, the easiest solution to a problem is often obtained with Eurorack modules. The “Trigger/Gate to Buchla Pulse” module (above) from Synovatron is a perfect example of such a solution. Sadly, Synovatron has ceased to exist in 2021.

MIDI to CV

Another example: the ARP Little Brother requires 15V triggers - and the Kenton “Modular Solo” MIDI to CV interface can provide them (Pgm 27). In this case, it was also important to add an audio amplifier in order to compensate the differences in volume between ARP (line) and the Eurorack format (+12dB)...

My Kenton Modular Solo Editor

Because I didn't like the handling of the Kenton Modular Solo module at all, I've programmed an Editor - and I can't understand why there are no editors for the Kenton interfaces so far. The settings on the module are truly unpleasant to work with and you will need the manual with the list of parameters, as the abbreviations for the parameter names, which run through quickly, are almost impossible to read (and to understand). Especially in comparison with the Expert Sleepers ES 40 (Audio to CV), the Kenton module also has some disadvantages for my applications. Worth mentioning are the “enormous” depth of 8 cm and the rather weak LFO, which is rich in waveforms but only has a small tredecimal interval, which is a limitation, especially with S&H. The module is therefore primarily suitable for more subtle modulation. The limitation seems to have to do with the fact that the aux outputs do not work in 16 bit (like the “main” CV output): Aux 1 + 2 work in 12 bit and Aux 3 + 4 only in 10 bit. This means that the aux CVs are not suitable for all tasks (e.g. pitch CV). The module therefore seems to me to be designed primarily for the requirements of pop music - “experimental” electronics tend to require maximum current and resolution for all CV outputs.

Nevertheless, the Kenton Modular Solo module offers some advantages that are almost unique selling points for MIDI to CV modules: V/oct, Hz/V or 1.2V/oct for the pitches, three different gate current levels (5V, 10V and a little over 11V), which can be set not only as a Gate or V-Trigger, but also as an S-Trigger. It should therefore be possible to control virtually all historical synthesizers. The 67 parameters of the Kenton Modular Solo can be seen in the image of my Editor.

As a little extra, I added the option of saving the programs to and reading them from a hard disk to my Editor - after all, it is an editor and that also asks for a “library”. The module has 32 program slots and the programs can also be recalled using MIDI program change commands (without the Editor). Most users will probably save slight changes, e.g. of the pitch bend range, the LFO settings, etc., as a preset and recall them via MIDI PGM Change. However, if, for example, LFO Waveform, Speed or Portamento Rate needs to be changed spontaneously or via controllers (in real time) while playing, SysEx is the way to go.

The MIDI settings of the Editor can be saved and are automatically loaded when the Editor is opened.

MIDI->CV vs. Audio->CV

For people working with MAX like me, however, the Audio to CV modules by Expert-Sleepers are unrivaled for controlling modular synths - and I consider SPDIF to be the most practical solution. They work in pico- instead of milliseconds, offer the full voltage spectrum on all outputs and 12 bit [4096 steps] resolution instead of 7 bit MIDI [128 steps].

Behringer Kobol - also to be used as a Eurorack module

Behringer has a neat concept in its product range: small, clone-like “reincarnations” of old synthesizers designed as stand-alone instrument expanders (without keyboards) whose front panels and electronics can be unscrewed and used as a Eurorack module. Some of these “clones” are already available, e.g. MiniMoog, Pro-800, Pro-1, Wasp, Cat, Solina String Ensemble and others.

I consider the “Kobol Expander” to be exceptionally well done, with which you can create some really beautiful sounds. In contrast to the previous models, this module is also a real (externally scaled-down) clone, as the original was the RSF Expander Kobol (also without keyboard). Alongside the Kobol, there was also the “RSF Expander II”, which transformed the Kobol into a very powerful synthesizer. It offered Multiples, Lag Processor (e.g. for Portamento), LFO (with S&H), Noise Generator, Envelope Follower, RM, Voltage Processor, Gate Delay, 3 in 1 out Mixer, ADSR and a VCA. It would be fantastic if Behringer were to add the “Expander II”.

The Behringer Kobol can be played very easily via the USB input (as a desktop expander), but with the “Kenton Modular Solo” module, a few functions (which were also in the Expander II) can be added to the excellent but simple synth. The Portamento function is particularly noteworthy here, as the Kobol has no Portamento on the hardware side. Furthermore, the module offers an additional LFO, which has more waveforms and parameters than the simple LFO in the Kobol (only triangle and square). However, the Kenton LFO does not cover the entire sound spectrum, but only a small tredecime (which is a limitation, especially for the Sample&Hold application). Three additional “Aux” outputs can be routed to the existing MIDI controllers if required. So the little Kobol remains small and yet can do a little more.

The photo shows the historic RSF Expander II and I added color frames to the two unlabeled Multiples. For the functions of the Expander II you will also find corresponding Eurorack modules - even very inexpensive ones from Behringer - e.g. for Ring Mod / Noise / S&H / LFO the Behringer 150 module from the “Roland series”. The Behringer ARP 2500 module series is also very interesting, e.g. the Envelopes with Gate Delay, the Sample & Hold module or the Ring Modulator module. If the Kobol is controlled via a module (such as the Modular Solo), the step of using the Kobol as a Eurorack module is of course the obvious one.

Behringer Kobol

also has its own page on my site.

Sequencer

Sequencers had never been "my cup of tea". But I always considered the concept of the sequencer in the ARP 2500 interesting and after Behringer offered these modules, I decided to try again and make friends with a sequencer. It's a pity, however, that the "Sequential Control 1027" module only has 8 steps per row (color) - the ARP 1027 had 10 steps (musically this is a big difference, because it's easier to get out of the 4/4 pop universe). The 1027 module is easily replaced with a Max patch and a Quantizer and Microtuning can be fitted straight away. Without a Quantizer, the pitch adjustments are rather tedious because you need too much time to get the tuning correct. The Mix Sequencer is of course difficult to implement in the synth without hardware.

The most interesting results can be achieved by using at least one IN of the 1050 mixer for a position gate of the 1027 module to send a reset signal from the Out B back to the 1027 module. The first Position Gate of the 1027 may then be patched into the left input "EXT ADV" of the 1050 Mixer and thus generate a switching of the 1050 Mixer after each 8 steps. If a patch cable is then inserted into e.g. Position Gate 5 of the 1027, the Reset is first sent after 65 steps! Unfortunately ( at least "unfortunately" for me), patching the modules is very complex and time-consuming if you are looking for interesting results. However, the concept is really excellent!

Behringer's entry into the world of synthesizers is truly impressive. Especially for beginners, it offers a wide range of possibilities at extremely moderate prices.

Power

Power is no longer an issue, but 10 years ago there were only very few good Power Supplies. I still own my TipTop Zeus Studiobus with a 4.6A PSU, which I think is very good. I used to use three Studiobus boards, today just a single one.

Although I don't mind the extra-large toroidal transformers in the MOTM, I found toroidal transformers in my first Eurorack case to be very disturbing - especially because you handle around in the instrument very often (e.g. when changing modules). They also make the instrument significantly heavier. The Studiobus was a real relief.

I am also very satisfied with the small "4MS Row Power" (my power supply for the Eurorack modules in the Buchla). In the meantime I also have a "CP1A" by Behringer, which works fine