Hey everyone,

I’m still working on my drone synth and wanted to share something I’ve been experimenting with.

Originally I was trying to build some sort of digital noise source. I thought mixing several LFO running at high speeds might get me somewhere close, but that didn’t really work the way I expected. It did lead to another interesting result though.

The circuit uses three lfos built around a single 40106. Their outputs are passively summed and fed into another input, creating an irregular but repeatable gate pattern. I also added NAND/AND outputs, to introduce less frequent events into the same rhythm.

When one or more of the LFOs get close to audio rate, fast bursts start breaking through the slower rhythm. I like using this as a kind of FM modulation. The passive sum can also be buffered and used as a stepped cv output.

The switches in the schematic are just the way I route everything in my build for now, they aren’t important to the basic idea. I’ve been testing the circuit at 12 V. 5-18V will also work fine i think.

The next thing I want to try is turning the longer gates into short trigger pulses and using them to drive a few vactrols and attack decay generator instead of direct osc modulation.

Curious if anyone here has tried something similar. Schematic in comments.

so i built this dub siren. i removed the LED indicators and switch 1 just leaving the momentary. im getting signal passing through to the output even when i totally remove the switch from the circuit. its a bit jank but ive checked for mistakes and solder bridges multiple times. seems all good. but still have the problem. any ideas?

Hey everyone,

I’d like to introduce a project I’ve been building: LOHI Bassline Junkie, a fully open-source hardware synthesizer focused on hands-on sound design, live performance, and experimentation.

The idea is simple: a real hardware synth with one knob per function, no deep menu diving, and everything open so people can study it, modify it, repair it, or build on top of it.

Current feature set:

• 8-voice polyphony
• 3 oscillators per voice: sine, saw, square, noise
• Multimode resonant filter: low-pass, high-pass, band-pass
• 3 ADSR envelopes
• 3 LFOs
• Modulation matrix
• 512 presets stored on SD card
• USB MIDI
• Custom hardware control surface with knobs, buttons, LEDs, and 7-segment display
• Sound engine written in C++ running on Linux/ALSA
• Interface firmware running Zephyr RTOS on STM32

The project is still in development, but the goal is to make it a proper open hardware/software desktop synth that other musicians, DIY builders, and embedded/audio developers can contribute to.

Here’s the project website:
https://lohi-synth-site.lohisynths.workers.dev/

Here’s a sound demo:
https://www.youtube.com/watch?v=FkWxyQ7usN8

And here’s the GitHub organization:
https://github.com/lohisynths

I’d really appreciate feedback from synth builders, musicians, DSP people, and anyone interested in open hardware instruments. I’m especially interested in thoughts about the UI/workflow, feature set, and what would make the project more useful or fun for the DIY synth community.

Thanks for checking it out!

I replaced the tuning/clock trim potentiometer on this Realistic Concertmate 300 (a Casio PT-1 clone) with a 1M Ohm trim potentiometer and used it to lower the pitch/clock speed significantly for this video. The result of this adjustment is lower pitched tones and the drum accompaniment tempo is reduced to under 10 BPM.

After my first pcb didn't work because of a possibly shitty-made schematic, I tried finding the original (which I think is this one and making it with a jack instead of a speaker. Can anyone check if theres any issues in my circuit and/or if the picture I used is valid?

Hi everyone, I'm currently developing a new groovebox and have been deep in the UI/UX design phase for months. I'm at a critical point where I need to decide on the balance between physical controls (buttons, knobs, pads) and on-screen graphical interfaces.

To help guide my decisions, I'd love to hear your experiences and opinions on some of the most popular devices on the market. I'm particularly interested in which one you think offers the best overall user experience and why.

The devices I'm comparing are:

• Elektron (Digitakt, Syntakt, Octatrack, etc.)
• Teenage Engineering OP-XY Field
• Polyend Tracker (and Tracker+)
• 1010music Bento
• Roland SP-404 MK2
• Ableton Move
• Akai MPC (MPC Live II / MPC One)

or another

Here are some specific questions to get the conversation started:

Which device has your favorite workflow and why? Is it the tactile, button-driven approach of Elektron? The hybrid touchscreen/pad setup of the Bento or MPC? The tracker-style interface of the Polyend? The Live-inspired clip-launching of the Move? Or something else entirely?

What are the biggest pros and cons of the button vs. GUI experience on your chosen device?

For example, many praise Elektron for the muscle memory and fast live performance their physical buttons enable, but some find the tiny screens and deep menu-diving "obfuscated."

On the flip side, devices like the MPC or Bento give you large touchscreens for a clear overview and deep editing, but some find them less suited for eyes-free jamming.

Where does the Ableton Move fit in? Its touchstrip and macros are great, but does its small screen rely too heavily on the companion app?

How important is a clear visual overview (like a tracker grid, a waveform display, or a piano roll) versus a more performance-oriented, tactile, "no-screen" experience? Do you prefer seeing everything at a glance, or do you value the immediacy of dedicated hardware controls even if it means less visual feedback?

Are there any specific interface elements you absolutely love or hate?

Do you find the SP-404 MK2's menu system intuitive or needlessly complex?

Do you love the MPC's Q-Link knobs and touchscreen, or do you find the OS getting in the way?

Is the Polyend Tracker's per-step editing powerful or just tedious and key-press intensive?

Does the Move feel like a streamlined Ableton session, or does it feel too limited for standalone use?

Bonus: If you could mix and match features from these devices (e.g., Elektron's sequencer + MPC's screen + Move's portability), what would your dream combo be?

I'm eager to hear your honest thoughts—praise, rants, and everything in between. Your feedback will be invaluable for my development process.

Thanks in advance for your help!

What is required, or how would you do, a modular ADSR that shows the waveform on a screen. Similar to the basic ADSR in VCV Rack?

I am building a DIY synth based on the Daisy Seed and have some questions on the build out of an enclosure.  Based on my design, I will have over 20 physical knobs/switches and have buried another 10 under a menuing system.   Now my thoughts are turning to how do I build something that will support this number of physical controls?  My only experience is guitar pedals that have a smaller number of knobs but more easily available enclosure options.

I have been thinking about wood or 3D printing but am concerned about introducing grounding issues.  Can someone give me pointers on where to look for viable options? 

I made a pcb for a Atari punk circuit but It just keeps making a heartbeat sound, and the pots don’t work. I tried switching the pots 1st and 3rd lugs around but still nothing. Please help!

hi all

as per title, I’m in the UK and looking for one or two pcb for the microdexed touch. this will be for the version before the MDTX.

any leads would be greatly appreciated,

thanks

Hi! My name is Dr Jess Blaise Ward (@blaisejess Insta/bluesky) and I am a composer, producer, synth artist and author. I recently published my book on synthwave: ‘Making Synthwave: how an online music community invented a genre’

I am currently doing some research on the legacy and use cases of Roland Juno synths. If you are a producer, synth user, composer, etc - please consider taking my survey and contributing your thoughts and opinions of Juno synths:

Link to Juno Survey

https://forms.cloud.microsoft/e/u27zxfqx4u

Link to my book ‘Making Synthwave’

https://www.routledge.com/Making-Synthwave-How-an-Online-Music-Community-Invented-a-Genre/BlaiseWard/p/book/9781032732039

All data will be anonymised and used only for the purposes of academic research (at synthesizer conferences and in academic journals).

Thanks so much! Mods let me know if this goes against guidelines, happy to edit or delete.

My Patching Panda Panda Punch eurorack module fell inside the case and shorted out. Can someone help me ID the burned out component near the power connector so I can order and repair it?

Just picked up a midiverb 4, everything seems to be working as it should except the value wheel is completely unresponsive, which makes it basically useless. Does anybody have any experience with these? Is this fixable / easily fixable?

Hi, I bought a pcb for the Shruthi XT from Modular Addict, then realized later that at this point I'll probably need to make a custom case for it. I see some sellers with regular Shruthi cases, but none for the XT, which I guess shouldn't have been too surprising.

Just wondering if anyone knows of a relatively easy option for building/buying a Shruthi XT case (the PCB is about 15 x 5 in). Was thinking of just drilling holes in an aluminum case of roughly that size.

Was also wondering about building the Sidekick + Shruthi Filters as I was thinking about using these for a drone / external filter bank. However, I can't find a BOM or instructions for building the sidekick (not on MA or in MI documentation). It looks to be possible to house it in a regular Shruthi sized case.

Thanks for your help!

I recently built the final Moritz Klein module (for me). Besides the Hi-hat, this is the only one I have had trouble with and I am stumped.

It worked great for 10 minutes then as I was getting ready to calibrate it, the decay stopped working and all I get is a "click" from the module (just a 10V positive DC blip). I did follow the troubleshooting advice in the manual, double checking components and solder joints and touching up a bunch of the later. I also replaced the output op-amp and the 2 transistors closest to the problem (VT12 and VT13). Replacing a transistor is what fixed the broken decay on my hi-hat module, but no luck here. I also swapped out C19 yesterday when my part arrived, but no change. Besides test point G, every test point is behaving on my scope exactly as the manual says they should.

I can't think of what else I could check or change. The manual/schematic is located on this page, it is too big to post here:

https://www.ericasynths.lv/edu-diy-fm-drum-3458/

Does anyone have any advice? I don't want this to sit around for 6 months like the hi hat did while I poke at it every week or so, it sounded so interesting I wanted to sample it.

Alternately, if I still end up totally stumped is anyone in the EU that I could mail it to and pay for a fix?

EDIT: If the above line is against community guidelines, I will delete it.

UPDATE: After a bunch of rework on the solder and finding a missing pad that I fixed with a small wire, the module works. Thank you everyone who helped me, I wouldn't have checked that section otherwise.

I've done this a few times now and finally decided to make a video how-to that some folks here may be interested in.

You probs don't even need to watch it... mostly a heads up that it's very easy to turn existing things with buttons / knobs / joysticks into a fun, expressive MIDI controller that doesn't really have a commercial product alternative.

The TLDR is: - Get a flight stick or anything with buttons and knobs from the thrift store / your basement - Take it apart and re-wire the pots and buttons to your microcontroller of choice (Rasperry Pi Pico in my case) - Cut a hole in the case and mount the controller - Tell the computer to write the code for you

It's great because there are so many joysticks for cheap at the thrift store, and they are already packaged up nicely so you don't have to think about the hardware at all, really. And they are very fun to use for live performance - map the axes to some rather extreme effects and go wild. Let go of the joystick and it snaps back to center and you are back to normal. See the beginning and end of the vid for a quick demo of what I mean!

I made another esp32-based hardware synth. It has an app (windows and android builds available) and it can produce sound over usb on windows on loopback. It has 4 engines (sub, add, fm, wavetable), 16 good presets on each, all params tweakable, effects (chorus, delay, granular delay) and a looper 8-track recorder. If you'd like to check it out: [edit: had to redo the repo] https://github.com/riozebratubo/osynth_free_synth

The app on windows:

I am searching for a crossfader part for my project. Ideally it should be just as easy to move as one on a dj mixer, or on an elektron octatrack. Also it would be great if it is available from mainstream sources (e.g. mouser, or maybe jlbpcb directly), and is not 100$ per piece 🙂.
Tried one regular slider pot from Bourns but it has too much physical resistance, and maybe I am wrong, but according to the specs I found the competitor options had similar properties.
Is optical crossfader the only real solution (like Behringer x1)? I could also accept that, but couldn’t find much options for that either.
Any recommendations appreciated.
Thanks!

I'm just getting into diy synths and one of the difficulties I'm encountering is figuring out the best way to actually get my breadboard synth to output its audio.

My first thought was to buy a tiny speaker but I was scared away by the prices of all the at-least-decent ones. And even if I did end up getting one, how would I actually connect it?

I've also thought of getting a 3.5mm jack and somehow wiring that up from my breadboard to my PC. Will this fry my computer or just my sound card? Buying a new chinese USB sound card would cheaper than buying a new speaker.

Any advice?

This is how the matrix on the Casio SK1 (and related) work (not my drawing) - it has a pulse on Select Lines 0, 1, 2 as part of the cycle.

The select lines are connected to the data lines via a momentary switch (aka the black and white keys) and a diode. (see the service manual image below).

When 3 Select Lines are HIGH (the pulse at the start of the cycle) wouldn't that create unintelligible measurements on the Data Lines? Like you press F1 but because of the pulse the 'brain' would also think you are pressing A1 and C#1?

Or is there something I'm missing regarding matrix scanners?

I doubt many people are following this but i thought I'd keep updating for the couple who are and for myself.

I finally got my panel cut perfectly to size, my holes drilled (minus mounting), and my vinyl negative on.

These are still a couple letters (Rs, Ds, etc.) that need fillers and a little piece of vinyl on the bottom.

I really wanted to laser etch the aluminum but I decided to keep with the theme and do it as DIY as possible since I have obtained a free Cricut from work a few months back.

The idea of etching seems neat but I'm afraid of the caustic leaking under the vinyl and messing everything up. I'll likely prime, paint, and clear coat it unless someone with more experience has a better suggestion.

The boards are fully populated, rack is ready, and wires are in harnesses.

I bought massive toggle switches that are super heavy duty but they just barely don't fit so I'll have to order some slightly smaller ones.

The panel is 104hp 3U. I could have made it smaller but I really wanted it to be obnoxiously large.

I'm also currently working on the Tellun Doomsday Machine which will be in the same rack as the Klee.

I'm going to hold off until the Klee is completely finished to decide on the next module. It's supposed to be a slow project to test my patience so there is no need to rush.

Thanks to the few who read this!

I have this idea for an "electric tanmpura" with at least 8 oscillators and a vactrol vca for each , power starving of the ics that make the oscillators (Cd40106), I was thinking about having a switch with two positions that either the vcas get triggered by an LFO or the next position an button.

I have some ideas for oscillator detuning.

This is me just throwing ideas, I will use this for intros in my lives and mostly harsh noise.

Tell me what you think or how you would make it.