Joined: Mar 28, 2006 Posts: 1425 Location: Kansas City, Mo USA
Audio files: 45
Posted: Fri Feb 14, 2025 7:04 pm Post subject:
Build Pictures 2025
Hello everyone,
Looks like I’m kicking off the 2025 Build Pictures thread, just like last year!
My latest build continues my work integrating Arduino-based control modules into my modular synthesizer while keeping the signal path fully analog. Behind the panel is an Arduino Mega with custom interfacing to bridge the 5V logic of the microcontroller with the 10V world of analog synths.
Introducing the KGK251: Quad Voltage-Controlled Envelope Generator
The KGK251 is my first build of 2025 (hence the numbering). It features four independent envelope generators (EGs) that can operate separately or as a group. My goal was a minimalist, intuitive interface, so the module has just:
One encoder for parameter selection and adjustment
One crossfader pot for seamless transitions
Each EG has four front-panel jacks:
Gate In
Trigger In
Crossfader CV In
Envelope Out
Envelope Design: Five Stages with a Unique Dual-Decay Approach
Each envelope features Attack, Decay 1, Decay 2, Sustain, and Release. The two-stage decay system prevents the typical “static” sustain level by allowing the envelope to evolve naturally over time. This keeps the envelope shapes organic and dynamic without requiring excessive complexity.
A/B Parameter Sets & Crossfading
Each EG has two parameter sets (A & B) that can be blended using the crossfader, allowing smooth morphing between two different envelope shapes.
Global Control: The module includes an ALL mode where parameters and crossfader positions apply to all EGs at once.
Per-Envelope Control: Each EG has its own crossfader position plus a dedicated CV input. The total crossfader value is the sum of the Master Crossfader, individual EG Crossfader, and external CV.
Wrapping Behavior: When summed values exceed the range, they wrap around instead of just staying stuck to the B parameter settings.
Additional crossfader modes are in development and will be added later.
Flexible Run Modes: Individual vs. Global Control
ALL Mode: A single pair of A/B parameters can drive all EGs, with individual offsets.
Individual Mode: Each EG can be set independently, with the option to disable the Master Crossfader’s influence for precise shaping.
Coming Soon: Video Demonstration
I’ll be posting a video soon to showcase these features in action. In the meantime, I’ll be sharing photos of the module and an MP3 demo of the patch.
Self-Playing Patch Track: KGK241 & KGK251 in Action
The track below was recorded without looping or overdubbing, showcasing a self-playing modular patch that continuously evolves while maintaining recognizable patterns.
At the core of the patch is the KGK241 Sample/Hold and Voltage Quantizer/Mapper, which captures and sequences voltage samples. The only melodic source is Ken Stone’s CGS-32 1/nfinite Melody Generator, which provides all pitch material. I also incorporated the new KGK251 Quad CV Envelope Generators, though their influence remains subtle.
Originally, this was just a test patch to explore the KGK251 and KGK241 modules together, but I found its relaxing nature enjoyable enough to let it run in the background. That led me to record it as-is.
Musical Approach
The goal was to create a patch that feels organic and ever-changing—where recognizable patterns emerge but never become static.
✔ Control voltages shift between natural minor and pentatonic minor scales.
✔ The sequencer alternates between playing stored material and capturing new sequences from the 1/nfinite Melody Generator.
✔ Panning is modulated dynamically for added movement.
Thank you for reading this
Unlike many of my tracks designed to take the listener on a journey, this one stays in one place—exploring all the possibilities within that space. Thanks for reading, and I hope you enjoy the track!
KGK251OnBench.jpg
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New KGK251 Module on the workbench
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KGK251_OnPanel.jpg
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KGK251 Module installed and working!
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GenImprov_250214.mp3
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Kevin Kissinger -- self-playing modular patch 02/13/2025
Joined: Jan 14, 2010 Posts: 5792 Location: Moon Base
Audio files: 709
Posted: Fri Feb 21, 2025 11:27 am Post subject:
That looks great Kevin!
I like the kind of juxtaposition of the very classic 5mm red LEDs and the OLED display.
I'll have a listen to the patch at a later point, but I am sure it'll sound great.
Joined: Mar 28, 2006 Posts: 1425 Location: Kansas City, Mo USA
Audio files: 45
Posted: Fri Feb 28, 2025 6:29 pm Post subject:
PHOBoS wrote:
That looks great Kevin!
I like the kind of juxtaposition of the very classic 5mm red LEDs and the OLED display.
I'll have a listen to the patch at a later point, but I am sure it'll sound great.
Are those connectors the less common jack size that I think were used for telephone exchanges ?
They look too small for 1/4 and too large for 1/8.
Hi PHOBoS. Thank you for your comments! The jacks are amphenol, 1/8" size. They cost about half as much as the Switchcraft jacks and I think I may "bite the bullet" and order Switchcrafts on the next order. The Amphenol jacks don't seem to work as smoothly as the Switchcrafts. _________________ -- Kevin http://kevinkissinger.com
Joined: Mar 28, 2006 Posts: 1425 Location: Kansas City, Mo USA
Audio files: 45
Posted: Fri Feb 28, 2025 6:34 pm Post subject:
blue hell wrote:
PHOBoS wrote:
[...]I am sure it'll sound great.
It is a pretty nice track, after half an hour I even felt a sudden and unstoppable urge to do something with patch ideas that kept bubbling up
That's great. I would enjoy hearing what you come up with.
Also, I am really happy that you found inspiration from the track. It is working with your creation: Wren -- that gave me ideas and the motivation to pursue microprocessor-driven modules for the modular synth. Glad the track kind of returned the favor! _________________ -- Kevin http://kevinkissinger.com
I have been working on repairing stuff and setting things up in my new studio space (I got rid of about 80% of my gear). Here is what I did last week.
This old mixer needed all the switches taken apart and cleaned. While I was in there doing that, I added depth and rate controls for the builtin BBD chorus.
I will be using this as a sub-mixer for a stack of Yamaha sound modules (3x EMT-10, and 1x EMT-1). I mostly use them for strings and choir sounds, so the chorus will be nice to have.
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Not realy a build picture, but a repair picture this time.
This 24 channel mixing table was donated to me since it was defective.
But after a morning working on it I found 2 false soldering points and after re-soldering the mixer worked perfect again.
Now I have to learn working with this beast of a mixer…
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I have been working on repairing stuff and setting things up in my new studio space (I got rid of about 80% of my gear). Here is what I did last week.
This old mixer needed all the switches taken apart and cleaned. While I was in there doing that, I added depth and rate controls for the builtin BBD chorus.
I will be using this as a sub-mixer for a stack of Yamaha sound modules (3x EMT-10, and 1x EMT-1). I mostly use them for strings and choir sounds, so the chorus will be nice to have.
Not realy a build picture, but a repair picture this time.
This 24 channel mixing table was donated to me since it was defective.
But after a morning working on it I found 2 false soldering points and after re-soldering the mixer worked perfect again.
Now I have to learn working with this beast of a mixer…
wow , that's a large one, nice repair does it have fx send/returns , usefull if you have a couple of old 19" rack multi fx units to hook up , wall mounting the mixer is an option if studio space is a bit tight
Yes, it does have send returns for extern fx, some from the eurorack, or a fx case I have.
My studio doesn’t need much space, the small euro case you can see on the picture already has 12 outputs….
I also have built half an euro case with 3 MiniDexed DX7, so effectively with 24 DX7’s. _________________ my synth
I modified two Roland EM-101 synth modules. It is a paraphonic synth with an IR3109 filter chip (SH-101, Jupiter-8, Juno- 6/60, JX-3P). It has a digital oscillator that stacks divisions of a square wave to create waveforms. It is often referred to as a "poor man's Juno". It is easily modified to add cutoff and resonance controls. The case is extremely cramped, so I added the mods to a little side panel. Here is a demo of them:
Posted: Sat Apr 26, 2025 7:57 am Post subject:
TyCoon Synthesizer Subject description: A Synton Syrinx inspired system
After finishing my Oberheim SEM cloning activities I've just started my new keyboard synthesizer project, the TyCoon synthesizer.
It is a system which is mainly inspired by the famous Synton Syrinx, but beside the Syrinx functions the TyCoon will provide some extra features and additional functions, like MIDI handling, stereo output panner, sequencer and others.
So the first steps are done, the keyboard interface is (nearly) finished and integrated, and first integration tests are made.
List of the TyCoon keyboard interface functions compared to the Syrinx:
1.) Syrinx: Resistor string <=> TyCoon: FATAR interface
2.) Syrinx: Master tune COARSE and FINE <=> TyCoon: as well
3.) Syrinx: Internal monophonic CV and GATE creation <=> TyCoon: as well
4.) Syrinx: Portamento <=> TyCoon: as well
5.) Syrinx: External CV out GATE out <=> TyCoon: no equivalent
6.) TyCoon: Keyboard velocity analysis <=> Syrinx: no equivalent
7.) TyCoon: Portamento switch <=> Syrinx: no equivalent
8.) TyCoon: MIDI OUT <=> Syrinx: no equivalent
9.) TyCoon: MIDI IN/THRU <=> Syrinx: no equivalent
current20250423.JPG
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Current build state
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Click to turn
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Sandwich
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MPU
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Frontpanel back
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Joined: Nov 13, 2009 Posts: 105 Location: Sunny Alberta
Audio files: 1
Posted: Sun May 04, 2025 12:18 pm Post subject:
Hello Everybody!
Lately I've been designing and building a series of modules based on Soviet rod tubes with the goal of creating a complete monosynth with an all-tube audio path.
Here is the first module, a complex VCO that includes waveshaping, sub octave, wavefolding, and more. A total of nineteen tubes are used here, including 1J18b, 1J24b, 1J29b, and 1J37b.
More to come...
Take care,
Doug
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Here is the first module, a complex VCO that includes waveshaping, sub octave, wavefolding, and more. A total of nineteen tubes are used here, including 1J18b, 1J24b, 1J29b, and 1J37b.
Joined: Nov 13, 2009 Posts: 105 Location: Sunny Alberta
Audio files: 1
Posted: Mon May 05, 2025 9:29 am Post subject:
Cynosure, I am planning on making a video of the VCO module in action with sound examples when I get the VCA module completed. I am working on building that module now along with a noise generator.
Thanks for the nice comments, Grumble! I have attached a few more inside pics for you. Lots of stripboard work!
Take care,
Doug
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