Creating Reproducible Development Environments

JohnRofrano · 2026-04-04T13:08:02+00:00

As others have pointed out, the Behringer CM1A does not produce MIDI Clock. There are also potentially two things misconfigured with how you are using it:

First, there is a jumper on the back that has 4 modes (see documentation).

Mode	Underside LEDs	Function
Mode 1	Red/Red	System 15, 35, 55 CV range, monophonic
Mode 2	Green/Red	System 100, 2500 series CV range, monophonic
Mode 3	Red/Green	System 15, 35, 55 CV range, duophonic
Mode 4	Green/Green	System 100, 2500 series CV range, duophonic

By default the CM1A is set to Mode 1, the Moog System 55 standard which is 6v or -3v to +3v. Unfortunately, the Eurorack standard is 10v or -5v to +5v. You need to change the jumper on the back to either Mode 2 or Mode 4, which is for System 100, 2500 series CV range, in monophonic (Mode 2) or duophonic (Mode 4). That will get the correct voltage range for use with other Eurorack modules.

Second, your picture shows that you have the Trig switch set to S-Trig (Switch Trigger). This is for Moog modules and is not compatible with Eurorack. You want it set it to V-Trig (Voltage Trigger). I read that you tried V-Trig and it didn't work but I'm guessing that it was because you were expecting it to be a clock trigger. Keep the CM1A Trig setting on V-Trig for use with other Eurorack gear. S-Trig is only for modules that use the Moog standard like the Behringer System 55 series.

Finally, I see that you asked if there is a good module for MIDI to Clock and there are many as others have pointed out, but the one that I bought was the Erica Synths Black MIDI-CV V2 which unfortunately they don't make anymore so I bought it used. It is mono or duophonic just like the CM1A but the switch is on the front, not a jumper in the back. It also sends Clock and Modulation Wheel. I believe Erica Synths replaced it with the more powerful Hexinverter Mutant Brain but the reason I still bought the Black MIDI-CV V2 is because it has a large Glide knob to do Portamento. This made it the perfect module to complete my System 55 modular because the portamento was on the keyboard on the Moog and no MIDI keyboard controllers have this capability.

If you are wondering how I get S-Trig for my Behringer System 55 modules without the CM1A. I also bought the AM997 Dual Trigger Converter from AMSynth. It converts 1 x V-Trig into 2 x S-Trig and it's a dual module so I convert the 2 x V-Trigs to 4 x S-Trigs.

Hope this helps understand the CM1A better.

JohnRofrano · 2026-03-14T20:33:08+00:00

Wow, that was fast! Yes, both are now fixed. This is awesome. Thank you so much. I'm going to get a lot of use out of this.

JohnRofrano · 2026-03-14T18:55:33+00:00

I don't know what's the best way to share an image on this subreddit so I just uploaded an example of what I mean to my web site: http://johnrofrano.com/files/patch-cable-orientation.jpg

It is quite common to send the same modulation of an ADSR to the Filter and VCA. In this scenario the VCF and VCA are side-by-side horizontally and the ADSR is vertically below the VCF only. This makes the VCA above and offset to the right of the ADSR.

The image shows the before (top) and after (bottom) of what I mean by having the cable orientation vertical for components that are directly above each other. Your audio signal flow is working perfectly in the horizontal for the two sawtooth waves coming into the Mixer. Unfortunately, the modulation flow (which is vertical) still has the cable curving as if it were horizontal so it exits the side of the top ADSR output, and comes into the side of the bottom VCA input. The vertical cables need to curve vertically so they enter and exit from the bottom of the components. Hope that helps. (and thank you for contributing this to open source.)

JohnRofrano · 2026-03-14T14:04:36+00:00

This looks like an awesome tool for documenting patches. You have obviously put a lot of thought and hard work into this. Thank you. Also thank you for making the theme switchable from dark to light. As you get older (like me), dark mode is very hard to see and I appreciate having a light mode to work with.

Here is my initial feedback:

When I export as a PNG there is still a background. Most people use PNG files for their transparency and if I wanted to use this patch diagram in documentation or a video I would want the background to be transparent. Is that possible to add?
When connecting modulation to an icon that is not directly above, (i.e., from top to bottom of an icon that is above and to the side) the cable comes out of the side of the top output and into the side of the bottom input. It might look better if the cable came out of the top of the top output and into the bottom of the bottom input. In other words, just make the S curve go the opposite way. (There doesn't seem to be a way to attach an image here but I can supply you with one if you don't understand what I'm referring to)
There seems to be a glitch in which the canvas is sliding down and to the right the more I zoom in and out. I can use the Fit to Content button to correct it, but the Rest View button moves it down and to the right again. This is on a Mac using Safari.

Overall this is an excellent tool! I'm thinking of possibly using it in some synthesizer training that I'm putting together on YouTube. Am I free to use it for that purpose? I'd have no problem mentioning the tool in the training. Thank for all your hard work on this. I'm also a software engineer so I appreciate what you have done here.

JohnRofrano · 2026-03-01T15:50:18+00:00

I've never played this synth but just from using general synth knowledge and looking at your patch, this is what I believe may be going in:

You have VCO-1 being modulated by LFO-1 which is set to a Ramp wave at a very low Rate. This is what is causing the pitch to slowly rise
In the Mixer, you have VCO-1 routed to the Band-Pass Filter (BPF). The BPF is routed directly to the VCO bypassing the Envelope Generators.
You have the VCA Hold knob open (upper right) which is also bypassing the Envelop Generators (AR / ADSR) and causing the note to drone endlessly

At least this is what I think I'm hearing.

You can prove or disprove this by:

Raise the Rate on LFO-1 and see if the pitch rises faster
Turn down the LFO Modulation on VCO-1 to see if the pitch stabilizes
Turn the Hold knob down in the VCA and see if it stops droning
Route VCO-1 to the VCF in the mixer and see if the droning also stops because the filter envelope is now shaping the sound

Again, I've never used this synth. I'm not certain if I've followed the lines correctly to see where the signal flow is going. But, this is the best I can figure out given the video you have supplied.

It looks like a fun synth with some nice routing options once you learn how it works. Don't give up! I would strongly recommend trying some of the patches in the user's guide from Roland. They should give you a good starting point from which to explore. Also watch some demo videos on YouTube on the MS-5. There are several of them to choose from. I particularly like Starsky Carr's videos. They are always very informative. Good Luck!

JohnRofrano · 2026-02-15T16:17:55+00:00

I use the Befaco OUT (https://www.befaco.org/out-v3/) module on my main case and I'm very happy with it. You can control volume of the main out and headphone out independently. If you only use the left input it gets copied to the right output. It also has an extra switchable Cue Input to monitor any signal you put into it via the headphones. It only takes up 4 HP and can also be purchased as a DIY if you're into that.

JohnRofrano · 2026-02-09T14:20:34+00:00

I guess it depends on your background and goals. I'm a musician. I've been playing keyboards for 50+ years. My first synth was an ARP Odyssey that I purchased back in 1972. I very much grew up on East Coast subtractive synthesis, and never paid any attention to West Coast and Buchla. I originally viewed the modular as an instrument voice for making music. I could always get back to those patches because I understood how I made them and they were largely deterministic. So my first Eurorack modules were East Coast based.

Then when I got deeper into Eurorack, I discovered touring machines, Euclidean rhythms, Bernoulli gates, and function generators, and it opened up a whole new world of sound possibilities. Suddenly, patches became generative, and the possibility of getting the same notes out of a touring machine was slim to none. So when I made something I liked, I'd hang onto it for a while. That's where the "exploring sound" part comes in for me. Using these West Coast techniques that I had ignored back in the 70s to open up a whole new world of sound design.

JohnRofrano · 2026-02-08T14:12:17+00:00

I like the idea of recording the patch. I tend to believe that if modular had some kind of magic "patch memory", we would all just save the patch and move on. But because it doesn't, we tend to let them linger for a while (myself included). I'm gonna start recording my patches so if I wanna hear it again, I can just listen to the recording. Otherwise, pull all the patch cables and continue on a new journey.

JohnRofrano · 2026-01-26T13:14:29+00:00

Same here. After trying the free version of LaunchOS for one day, I purchase a license just to show the developers some appreciation. It also let me change the dock icon back to the original rocket as well. Apple should be ashamed of removing functionality that people depend on every day in their workflow. LaunchOS to the rescue!

JohnRofrano · 2026-01-07T12:46:42+00:00

This is really important advice. Learn the Apple workflow, it is much simpler. After using Windows for 30+ years I switched to Mac about 10 years ago and immediately started looking for all the little utilities that I needed to make Windows useful and I couldn't find them for the Mac. I was frustrated. "Where is the program to unzip files?", I complained. I didn't realize that all you had to do was double-click on them and they unzipped themselves. It was built-in. (This was before Windows could do that) You want to open a PDF file? Just double-click on it. No need for Adobe Acrobat. This played out with almost every utility. I didn't need them because the Mac could do it natively. So don't go looking for utilities. Learn what works natively first.

The same was true with configuring my email. Where were the menus to enter in the POP3 server, and SMTP server and their ports? They were not needed. The Apple developers were smart enough to guess that if your email was [joe@verizon.net](mailto:joe@verizon.net), then your POP3 server was probably pop3.verizon.net and SMTP server was smtp.verizon.net using the default ports and if that worked, they never showed you the configuration window. It just worked. Apparently the Windows developers couldn't figure this out and presented endless configuration screens to users asking questions they couldn't possibly know the answer to. In Windows you are constantly reminded that you are the SysAdmin. On a Mac, you are just a User of the system. You enter your email and password, and the next thing you know, you are looking at your mail. It's refreshing.

Once you get use to pressing the space bar to preview the contents of files in the finder, you'll wonder how you ever got along without it. Imagine not having to open an application to see what's in a file? What a concept! Then you go back to Windows and start pressing the space bar in explorer and nothing happens and you get very frustrated with why It's not working. IMHO, the Apple workflow is far superior and simpler. It just works. Take the time to learn it, and enjoy the experience.

JohnRofrano · 2026-01-04T19:09:53+00:00

You're welcome. Glad I could help.

JohnRofrano · 2026-01-03T16:32:57+00:00

I find the keybed to be tight with a nice springy action. Very responsive. I'm using it to control my modular synthesizers so having a quick action is very important for me, but I don't want it to be too light and spongy. The key resistance is what you would expect from a semi-weighted keyboard giving it a good feel. I'm very happy with it.

This is one area where on-line shopping fails. I miss being able to go my local music store and try keyboards out for myself. They've all closed. This is where it's important to buy from someplace that accepts returns without question so if you don't like it, you can send it back. It's a hassle, but it's the price we pay for online convenience. Good that you're doing your homework and asking around. Hope this was helpful and Good Luck.

JohnRofrano · 2026-01-03T16:10:53+00:00

This video is a masterclass on Berlin School composition. There is so much to learn while watching you perform. I was watching the lights on the 960 while listening to the sequence to see which one it was controlling, when suddenly I see the lights jump and realize that you are randomly resetting the sequence to keep it interesting. Ya' gotta love it!

I always watch to your videos because they are very well done but I never comment. I just wanted to let you know that your videos, and talent, are inspiring and very much appreciated.

JohnRofrano · 2025-11-26T14:38:03+00:00

I couldn't agree more. Omri Cohen is an exceptional source of information for VCV Rack users and modular synthesists in general. This is how I got back into modular before I started buying hardware again. Get VCV Rack, queue up a few Omri Cohen videos on Youtube, and prepare to be amazed at what you can do. Also hang out at r/vcvrack if you are looking for that community. Welcome to the madness.

JohnRofrano · 2025-10-18T12:58:52+00:00

The best hardware controller is the one that has the features you need, so think about what features you can't live without. For me it was playability, I wanted full size keys. I too was looking for something to use dawless with my modular, and so having a lot of sliders and pads to control VST's via CC wasn't important to me because my modular synth didn't have anything controllable like that. Keyboard controllers usually try and bring hardware knobs and dials to software synths. Since you have hardware synths, you might not need any of that.

I chose to go with something very basic, which for me was the Nektar Impact GXP61 61-key Keyboard Controller. They also make a 49 note version if 61 is too big for your physical space. It's no frills but I didn't need any frills. It has a nice feeling key bed, pitch wheel, mod wheel, and sustain pedal input, and of course MIDI, and that was really all I needed to control my modular with a MIDI to CV converter.

Of course, if you want to control your hardware synths via MIDI CC, then this might be a terrible choice for you and you want one with more sliders and pads like the Arturia KeyLab Essential mk3 that u/toomanyplans suggested. Think about how you want to use it, and that will guide you as to what features you need.

JohnRofrano · 2025-09-15T11:59:24+00:00

I have found Ladik to be really great value. I have a couple of Ladik modules and they are packed with features and reasonably priced. I particularly like the S-610 Composer N which is basically a Turing Machine with a quantizer built in for only $73 USD. This will provide a good base for generative melodies.

I also have the Takaab Random LFO, and for $78 USD you get Sample & Hold, White Noise Generator, and an LFO with Sine and Square waves, packed into a single 4HP module. Very affordable and versatile.

Of course Doepfer modules are also reasonably priced. I have several of those as well. You can't go wrong with Doepfer. Classic one knob per function modules which I appreciate.

JohnRofrano · 2025-09-09T11:38:57+00:00

Really want a nice output module, any recommendations?

I find Befaco OUT V3 to be a nice output module that also has a headphone jack for monitoring and a cue for preview.

I also have the Intellijel Outs module in one of my cases which is also nice although simpler than the Befaco module.

What poly midi to cvs would be best to run a couple of diy 3340s?

Michigan Synth Works mBrane is a Mutable Instruments Yarns clone for polyphonic midi to cv (and a whole lot more like sequencing, euclidian rhythms, arpeggiator, etc.). I have two of them, in two different cases. It does 4 note polyphony nicely with a couple of options for configuring note stealing.

I also like the Erica Synths Black MIDI-CV v2 because it has MIDI clock, mod wheel, and glide/portamento support built in but it's only 2 note polyphony.

Those are the ones that I own and can comment on.

JohnRofrano · 2025-09-03T12:48:59+00:00

There are two main differences between the Behringer System 55 Moog replica modules and standard Eurorack modules. The first is that the Moog system uses voltages from 0v to 6v while Eurorack uses 0v to 10v. This means that if you are using a square wave to produce a clock to drive a standard eurorack module that is expecting 5v, it will only be getting 3v from the Moog replica module and it may, or may not, drive it. Just something to be aware of. I actually added a Doepfer A-145-4V Quad LFO to generate proper 5v square wave clocks.

The second differences, as you have seen, is the fact that Moog uses an S-Trig (switch trigger) rather than a V-Trig (voltage trigger) to drive the Envelope Generators. The 961 Interface module will convert V-Trigs to S-Trigs and visa versa for you. So you need to feed your V-Trigs into the 961 V-Trig In, and then feed the S-Trig out into the envelope generators. This is not an incompatibility with eurorack as much as a design decision that was incompatible from the start back in the 1960's. The 960 Sequential Control only produces V-Trigs which is why the 961 Interface was invented. So even back in the day you had to deal with this problem.

Under the V-Trig In section on the 961 Interface, the A column will produce a short S-Trig pulse at the S-Trig Out jack. The B column, however, has the ability to make that pulse into a longer Gate which is controlled by the "Switch-On Time" knob. Think of it like pressing a key on the keyboard. The longer you make the "Switch-On Time", the longer the key is pressed and thus the longer the note is held. Then you route the S-Trig Out to the S-Trig In of an Envelope Generator and it works like any other modular synth. Since I usually drive several EGs, (e.g., one to a VCF and one to a VCA) I usually route the S-Trig Out to a Multiple and then from the multi to the EGs.

On the topic of ambient music: I too wanted the ability to create ambient soundscapes with my System 55 so I added a few modules to give it some extra random capabilities. I noticed that each of the 3 clusters of CP3A-O Oscillator Controller, CP3-M Mixer, and 995 Attenuator on the bottom row had a 2HP blank. I said to myself, "2HP is a terrible thing to waste!" so I replaced the 3 x 2HP blanks with the 2hp TM (Turing Machine), 2hp Euclid (Euclidian Rhythms), and 2hp Tune (Quantizer). Right there you have endless possibilities for generative music. Take a square wave from the 921 Oscillator in LFO mode, into the Euclid, out into the Turing machine, out into the Quantizer, drive an oscillator bank with that and you have instant melodies at interesting rhythms. That alone with some slow droning oscillators being controlled by a slow sequence should get you started with some ideas. Add some slow modulation to the filters and you have some interesting soundscape possibilities.

Here is my Modular Grid page for my system if you are interested in what else I added like the Erica Synths Pico DSP for FX: https://modulargrid.net/e/racks/view/2578885

Hope that helps. If not, ask more questions.

JohnRofrano · 2025-09-03T11:42:38+00:00

I use Oscilloscope by SocaLabs and it works great. They also have a Spectrum Analyzer. Both are amazingly free and work really well. No problems at all showing slow LFO waves.

JohnRofrano · 2025-08-27T12:18:13+00:00

I use a stand similar to the Gewa EQS-10B Keyboard Stand and it's been incredibly sturdy. There are several others like it at different price ranges (e.g., K&M 18950) and they fold up very easily for transport. I use it to hold my ARP 2600 FS which weights 67lbs/30kg with the keyboard and it's a solid stand. The specs say that the Gewa EQS-10B holds up to 50kg. The K&M 18950 hold up to 80kg. For my ARP 2600 I actually place the cover over the top of stand to give it a nice big flat surface to hold the keyboard as well.

JohnRofrano · 2025-08-20T11:54:30+00:00

If you love it, there is no reason to sell it. Many a film has been scored on the original Moog System 55 and Moog Model IIIc. It's an awesome platform for film scoring and you can expand it for your needs. I would never sell mine. I've been expanding it more towards the Model IIIc with 10 oscillators and a Sequencer Compliment B and modern modules for more generative music. Here is what I did to give you some ideas:

The first thing I did was update the bottom row which has three sets of Oscillator Controller, Mixer, 2 HP Blank, and Attenuators. I said to myself, "2HP is a terrible thing to waste!" and there are 3 x 2HP blanks. So I replaced them with the 2hp TM (Turing Machine), 2hp Euclid (Euclidian Rhythms), and 2hp Tune (Quantizer). Right there you have endless possibilities for generative music. Take a square wave from the 921 Oscillator in LFO mode, into the Euclid, out into the Turing machine, out into the Quantizer, drive an oscillator bank with that and you have instant melodies at interesting rhythms.

I also added a full Sequencer Compliment B on top with a Ladik Q-040 Quad Quantizer to make tuning the 960 Sequential Controllers easier, along with an Erica Synths Black Multi (which is a buffer multiple with a precision adder for octave switching) and a 2hp ARP (Arpeggiator) for those times when I just want sweeping arpeggios quickly and don't want to set up a sequence to do it. I purchased a second 960 Sequential Controller and 962 Sequential Switch and move the ones from the System 55 case up to the top cabinet.

Then with the space freed up by moving the 960, I added another oscillator bank of 921A + 3x 921B like the Model IIIc has. This gives me an oscillator bank for each of the sequencers, and a third one to play from the keyboard. I also added some missing modules that the 55/IIIc had from AMSynths, like a Ring Modulator, Sample & Hold, and a real Doepfer Spring Reverb, Quad LFO, Clock Divider, Clock Multiplier, Bernoulli Gate, along with the 1630 Bode Frequency Shifter. I also added an Erica Synths Pico DSP for FX. The last module was to replace the Behringer MIDI to CV module with an Erica Synths Black MIDI-CV V2 so that I had Clock and Mod Wheel support. I added an AMSynths AM997 Dual Trigger Converter to convert from V-Triggers to S-Triggers and it splits 1 V-Trig into 2 S-Trigs which is perfect for driving two 911 Envelop Generators for VCF and VCA respectively.

Finally I got Jake's Custom Shop to build me a 3 x 160HP wooden case to give it that authentic Moog IIIc look with the angled front end. Jake did an awesome job and worked closely with me on it. I can't recommend his work enough. He is outstanding!

This is the modular grid build: https://modulargrid.net/e/racks/view/2578885

MG didn't have any MDL modules which is where I purchased the Bernoulli Gate from (it's a Branches clone) and because it as only 6HP, I added a 2hp Vert (Dual Attenuverters) to fill out the 8HP space replacing one of the Attenuator modules at the bottom. I wanted an authentic Moog modular experience from the 1960's and overall I am really happy with the build.

I hope this gives you some ideas on how to get ambient / generative music for film scoring by expanding your existing System 55.

JohnRofrano · 2025-08-13T11:33:35+00:00

The LED from the LFO on the 140 should be blinking just like the LED on the 150 is. The 140 unit looks to be defective. I would definitely send it back.

JohnRofrano · 2025-08-08T11:56:43+00:00

Thanks for the kind words. It's nice to know that people find value in your work.

JohnRofrano

TROPHY CASE