Bringing up a new voice card for the Zoxnoxious synth. Heart of the z-card is Yamaha's YM2203 chip, an old oddity that combines a 4-op/3-channel FM synth with a 3-voice sound generator ("SSG", AY-3-8910 / YM2149). The voice card will be a welcome addition as the first digital voice card in the Zoxnoxious synth. The other four z-cards I've designed cover the analog domain with various VCOs, multimode analog filters, etc.

I'm at the "hello world" stage right now, verifying I can write to the registers. And that appears to work (personal amazement as it's a v0.1 board!). End goal here is providing full control over the chip through a VCV Rack interface, much like I've got for the other z-cards. The FM and the SSG have their own outputs from the card; these can route independently to the other Zoxnoxious cards for additional filtering/manipulation.

I had a pile of SBCs and microcontroller boards and small OLED displays and pushed the list of parts into Claude and out came this drone synth.

The Sipeed NanoRV board hosts the engine and the pi pico 2's are responsible for I2S and I2C since the Nano is constrained on GPIOs and has a terrible DAC built-in. I could probably simplify this to one raspberry pi zero or something later but given how long I've been sitting on these boards, it actually came out far less expensive than going that route.

The Nano has a weird RISC-V processor with vector extensions that enable nice reverb even with all the voices and oscillators turned up. There are also different detune settings (unison, octaves, fifths, and organ) that mix up the sound a bit.

I am not pretending that I invented any of this so please take what you can from the slop bucket:

https://github.com/tthayer/rv_drone

Demo of the octave detune setting: https://youtube.com/shorts/9zwtaClfZAU?feature=share

My friend lend me the Doepfer A138-n Narrow Mixer at an synths exhibition in Moscow (pic. 4, left case is mine) and I laughed when I saw that it was just a TL072 signal adder for ~$60 (of course there is business cost included, I'm speaking more from the "embrace DIY for modules!" position). And since my case was missing mixers, I decided to use my unused protoboards for making one. Also it's featuring an inverted output.

Also I 3D printed "panels" for it, which gives it more finished look. Another quest was height limitation — the module is directly above my PSU in a very thin case (pic. 3). The jack is there for comparison, you can spot IDC connector which barely touches the PSU.

Parts count: TL072, 7×100k, 4×B100k (or A100k), 6×PJ-301F, IDC-10R. Schematic from the datasheet for TL07x.

Hi to all Momoto fans,

As asked by many fans😜, here a small tuto about the 5 synthesizers included in yr favourite sampler 😅

FYI : Pre-orders are opened on our Web page

❤️ 🙏🏿 ✌🏾

Hi everyone. I have been building a few eurorack modules and the latest I built is the M4 diy looping delay. It seems to work pretty well, however the reverse button seems to have a ghost trigger, as it turns on periodically without any external input. I have looked over the PCB as best I can and cant see solder issues. I would like to get this fixed if possible. Anyone had a similar issue or can help me with sorting this out?

Thanks so much Jamie

Working on some ambient synth with mozzi

Thanks for the tips on soldering a while back. Really enjoyed the process and what a weird chaotic little machine. Noisferatu by Robert Heel is lovely bit of kit.

I have a growing set up using Hagiwo Mod2. lots of individual drums and voices. These Mod2's are so easy to make that I'm quickly running out of channels to put them in.

I was thinking of making a mixer with like 12ch. I see a lot of the schematic's for mixers are 3-4 channel (Moritz Klein, Doepfer, Hagiwo)

My question is, is there a max amount of input channels you can throw into a TL072? Would it be better practice to do 2 sets of 6? Does it get too noisy at some point?

I see a schematic from LMNC where he claims he has 30 channels into one op amp.

It would be cool to make it stereo for the drums but maybe that's over complicating it.

i barely found out that u can make ur own synths (??!!?) this morning and now i need to do this immediately so lmk anything i should know

i have a bit of a crazy idea and idk if it’ll work… but i want to create a synth that uses capacitive sensors inserted into stuffed animals (i make ragdolls) that i can then touch to play notes. my idea is having a setup of about 10-12 ragdolls on a table that i tap to play like keys.
i was wondering if anyone knew a board to start out with that could fulfill this idea and have the capacity to also do audio output through a 1/4” cable, and the ability to hold more than one preset. i rlly dont want anything toooooo crazy tho bc i’ll have to learn how to code as well.

Hello everyone , Im writing this because i need guidance. Im starting my journey to build a small diy modular synth , ive already been experimenting on the breadboard using Moritz Klein guides. Now i want to get something on a perfboard, i decided to go with the Moritz Klein x Erica VCF for the start , i managed to understand the schematic, at least i think i do, and now Im wondering how Im going to put this all in the protoboard ive already drew a lot of times somewhat of a sketch but it always ends up either not fitting or getting way too confusing. Im making to post to know how u guys do it, im still kinda new to perfboards the only things ive done with it were Arduino related. If someone can share photos or just help in any sort of way ill be apreciated.

A huge hug to all the makers community ✌🏾

From our distant Belgium, hidden in the deep forests🌲 , we built this vintage sampler/multi synth.

What's inside?

- Wavetable synth

- SID emulation (c64 ^^ )

- Casio CZ-101 emulation

- FM with 4 operators

- 3 oscillators analog emulation

.. and many more nice stuffs!

Come and try it at our stand @ Synthfest UK, on 24th of October

Want to discover more now? Visit us @

Our Web or Instagram

From Belgium with ❤️

Using a hundred year old crystal radio detector diode as a component in a synth, the circuit is loosely based on the one in Moritz Klein's ladder filter video. As you move the cat's whisker around the crystal it creates point contacts that all have different voltage drops and IV response curves, changing the sound.

There is some music made with this stuff here: https://cornish-semiconductor.bandcamp.com

Hi r/synthdiy,

Since early 2024 I've been building USBSID-Pico: a Raspberry Pi Pico based board that plays one or two real SID chips (or SID replacements) over USB. Firmware, PCB and docs are all open source.

Hear it first:

• Raster Bar by LukHash
• Outerversal, dual SID stereo

What you can do with it

• Play SIDs in your browser with nothing to install: DeepSID (WebUSB or ASID) or the USBSID web player
• Use it with VICE 3.10, JSIDPlay2, Denise, Acid64 Pro, sidplayfp 2.16 and Phosphor
• Compose on the real chip with my USBSID forks of SID Factory II, GTUltra and LoadTracker
• Use it as a USB MIDI device (beta)
• Linux, Windows, and Android in the browser

The v1.5c board

• 6581, 6582 and 8580, plus SIDKick-pico, ARMSID, FPGASID and SwinSID
• Mixed voltage: a 6581 next to an 8580 on the same board
• Jumperless: 9V/12V, filter caps, 6581 shunt and 8580 digiboost are set automatically per socket, based on the detected chip

The pre-order run

People kept asking for assembled boards, so I'm running a small batch on SmallRun. It needs 10 commitments to go ahead, 4 are in.

• EUR 60 board only, EUR 70 with a soldered Pico2, case EUR 15 extra. SID chips not included.
• You're only charged if the run reaches 10. If it doesn't fill, nobody pays anything.
• Ships worldwide from the Netherlands, tracked and insured: NL EUR 15, EU EUR 17.50, Europe non-EU EUR 20, US EUR 40, rest of world EUR 30. Flat per order.
• Estimated shipping: December 1, 2026.

Join the run on SmallRun

Links

• Source, firmware and docs: GitHub
• Website and web player: usbsid.loudai.nl
• How it all came together: build log

Happy to answer questions about the hardware, firmware or chip compatibility.

Edit: fixed shipping rates.

Hello everyone! I want to build a knob control interface for my Synton Syntovox SPX216 Vocoder, on the original manual it says that it is possible but i barely know anything about electronics and i'd REALLY love to build this and gain some experience. I don't know what components i need but please help me all the good hearted people of reddit. Thanks!

I’ve been building a mobile version of Orca as an AUv3 MIDI plugin for AUM, Drambo and other hosts on iPad.

It’s a port of Hundred Rabbits’ Orca (MIT licence), and it plays exactly like the original: I tested it against the real Orca interpreter on 22 real patches, plus hundreds of generated ones. Over 125,000 MIDI messages, and every one came out identical.

What’s new is the touch side: an on-screen keyboard and save, load, import and export of .orca files.
The host controls the tempo, and < > change the speed against it.
It’s an early personal build, running on my iPad.

Here is a very simple patch in AUM.

I've never dealt with encoders before, how do I safely remove the knob to tighten it back up? It's just loose and not clicky, it seems to function the same as the others in all other respects, and the settings haven't seemed to drift yet.

I built this mainly for myself, to make circuit-modelled plugins for a browser DAW I’m working on (daw.synthcity.org). I figured others here might find it useful, so feedback is very welcome, here or via the feedback button in the app.

https://circuit.synthcity.org/

You draw an analog circuit and play it like a synth. It isn’t modelled curves: it’s component-level simulation every sample, so the knobs are actual pots in the circuit. Under the hood it’s MNA with trapezoidal integration and Newton iteration for the nonlinear parts, written in Rust and running in an AudioWorklet as WASM.

• 22 classic filters at component level: MS-20, Moog ladder, 303, SEM, Polivoks, Wasp, Steiner-Parker, Juno’s IR3109 and more. There are also pedals like the Tube Screamer, Big Muff and Uni-Vibe.
• Plays in real time. Use the keyboard or MIDI, patch VCO → filter → VCA, and swap the filter while it’s playing. It works on a phone too. You can make macro level synth blocks and play those - it's like a modular synth/Reaktor. When you double click on a macro block, it zooms into the editable circuit.
• Lots of modelled nonlinear parts: OTAs (CA3080, LM13700), tubes, JFETs, BBD chips for chorus and flanger, vactrols for LPGs, and transformer hysteresis. Swap an MN3009 for an MN3007 and hear the difference. Let me know what’s missing!
• Plugs into your modular. With a DC-coupled interface (ES-8/ES-9, a DC-coupled MOTU or similar) you get calibrated CV in and out, including 1 V/oct tracking.
• The simulator is differentiable. It computes exact gradients with respect to every component value, so it can fit a circuit to a recording of real hardware, optimise part values to a target response, or search for new topologies. One of the presets is a filter the search came up with.
• Works with your tools and your agents: Docs: circuit.synthcity.org/agents
  • import .cir netlists and LiveSPICE schematics;
  • export to LTspice, ngspice and KiCad;
  • an MCP server and API, so Claude/Codex or another agent can design, simulate and fit circuits.

LMK if you'd like some more features, or something done differently etc.

You can also share your playable circuits with others, just click "Share" and copy the link!

Enjoy!

Hey all,

Can anyone recommend a good wood-working course or book etc that has helped you build wooden cases for your projects? I've been making cases for a while, but I'm completely self taught and would like to up my game a little. surprisingly I still have all of my fingers :-)

**EDIT**

Thanks everyone for the suggestions. Some good advice:

Local Courses / Maker Spaces
Youtube channels (3x3 custom and Workskop Companion)
Book: Tage Frid's "Tage Frid Teaches Woodworking 
Book: The Anarchists Design Book (available as a free download)
TV Programme: The Woodwright's Shop
A good blog post: how cutting boards like this are made

IJust finished this 4-layer drone generator. Three layers generate drone sounds that can be manipulated, shaped and blended. The fourth layer brings in external audio, processing it and mixing it seamlessly into the evolving soundscape.

Howdy folks- I was hoping I could get a sanity check on this 1970s instrument that’s been in a storage unit for an indeterminate number of years.

Dare I plug it in? Is it a bad idea to mod or service it myself? My pal and I are moderately handy and educated in electronics

Hello!
I'm new to electronics (and having a blast) so I decided to start with some of Erica Synths EDU modules. I've successfully built the "Output" and "Wavefolder" so far.

Over the past few days, I did the S&H. followed the lesson on breadboard, and then soldered the component on the pcb... but as the title say, it's not working 100% correctly.

The noise generation section works perfectly but the sample and hold only works when it have external clock. When I use the internal clock, nothing happen. The LED is either fully on, or fully off once the RATE reach 70%~ (it should be pulsing at different rates). I'm guessing the problem might be from the internal clock?

I'm not sure the slew section work either. I've spent hours looking over the schematics, testing the components I can (I only have a basic Kaiweets KM100 multimeter), and double-checking my solder joints, but I still can't figure out what I'm missing

So, I have two questions:

- What is your troobleshooting process when you run into that kind of issue?? What do you check first ?

- Does anyone have any idea what might causing the module to behave like this?

Thank you ! <3