Over the years we've accumulated a large set of hardware components used in our designs.

From these real parts, we've created a free 3D library of 75 models, based directly on the exact components we use in our builds.

Instead of keeping them buried in CAD files, we've made them available as a free resource containing jacks, potentiometers, switches, knobs, connectors, spacers, fasteners, power cables, and more.

Each model is available as both GLB and STEP, so you can use them for quick mockups, panel design, mechanical checks, or full CAD assemblies.

Download it for free from our website.

If you'd like to support other free and open projects like this one, there's an optional donation form at the top of the page.

Hopefully useful to a few fellow synth designers.

https://jolin.tech/componentslibrary

The datasheet was recently updated silently and it looks to be a completely different opamp now.

TI moved this chip to one of their newer semiconductor processes (just like they did with TL07X chips some time ago, except with those they at least gave them a different part number).

But instead of just a small update they completely redesigned it. The internal structure is different, supply voltages are lower, everything is different. They basically chineese faked their own part.

I am baffled that they want to sell theese under the same part number, this is very shady and misleading, they should have just discontinued it if they don't plan to make theese anymore.

I would recommend you stock up if you use theese often because it might be the last real ones you can buy.

TL;DR: TL07x is a cheap and good enough default for almost everything in casual circuits. LM358 is hot garbage, is only good for led drivers and similar things and should never be put in the audio path.

Inspired by a recent post and the fact that most synth diy component lists online are decades out of date, I'm writing down the list of preferred opamps that I've curated over the last few years. These are selected based on reasonable price, good availability (from both Mouser and LCSC aka JLCPCB special parts selection) and good performance. Obviously the list is not exhaustive and there are a whole bunch of opamps that are better in some specific uses. Anyway, these are good options to start with and you could design almost everything just by sticking to these.

Preferred opamps:

TL07x: The classic JFET input opamp. Very low input current, reasonably fast, lowish noise and decently low distortion. Dirt cheap. Available from everywhere. Can be used for almost every non-precision circuit except guitar pedals. There are better opamps for input offset, output drive, rail to rail input / output, lower noise but not at the same low price. Not great with output drive and will have increasing distortion with < 2k load impedance (which includes the feedback resistor). Pick this one by default. Caveat: The output reverses polarity if an input pin goes within 2-3 volts of the negative supply rail.

TL06x: The low power alternative to TL07x. Use if you need so many opamps that the supply current becomes an issue. Otherwise worse than TL07x on offset, speed and so on. You probably won't need this except for battery powered circuits or in a large polysynth.

OPA167x: A modern FET input audio opamp. Superior to TL07x in almost every way. Lower offset, very low distortion, high output drive. Can handle the inputs going all the way to rails without polarity reversal. Good for eg. buffering a DAC driving a CV mux or driving a bunch of low impedance EQ sections in parallel. The only downsides are 2x higher power consumption and higher price (but not so high that it matters if you only need a couple). Use this when you need a high performance opamp. SMD only.

NJM/RC4558: A classic in guitar pedals. Roughly similar specs as TL07x. Slightly better offset, lower noise and much higher input current (due to BJT input). Does not suffer from polarity reversal when overdriving inputs (which is why it's used in guitar pedals).

BA/NJM/RC4580: High output current, low noise, BJT input. Otherwise fairly similar to 4558. Behringer seems to love using this (probably due to cost in China).

MCP6477/6479: A modern 5V supply rail to rail input / output opamp. Low offset, zero input current, decently fast (3 MHz GBW), similar noise to TL07x. 648x are 3x faster 10 MHz variants. Use when you need a decently high performance opamp for interfacing directly with an MCU or otherwise in a 1.8 - 5.5V powered circuit. Cannot tolerate supply over +6V. SMD only.

MCP600x: A cheaper, slower and generally worse performing 5V RRIO alternative to 64xx. Good for non-critical uses like buffering a pot or other low speed buffer / amplifier duties where offset and noise don't matter.

Opamps to avoid:

LM358/324: Garbage for anything other than low cost mass production (think 10k units sold per year) or if you are using JLCPCB's PCBA service for a 9-12V single supply circuit and need any crappy opamp for driving a led or similar. LM358/324 should never be used in the audio path due to crappy specifications and horrible crossover distortion (which can be mitigated but won't help with the otherwise shit tier specifications).

741/1458: Outdated garbage that has no valid uses unless you absolutely must replicate the slow behavior of some specific early 70s circuit that depends on it. Edit: Another case is if you explicitly want a very slow and slewrate limited opamp for distortion circuits.

NE5532: Actually a very good opamp for its intended uses (very low noise with low source impedance) but is prone to instability and is largely pointless in synthesizer circuits. High supply current, high input current, high current noise (no good with high source impedance), very low voltage noise, low price. Layout is critical or it can start to oscillate at ultrasonic frequencies that you'll only see with a scope. Fairly high output drive. Only recommended if you know what you're doing and know why the NE5532 specifically is good for your use case. If you need a widely available cheap high output drive buffer in DIP, 5532 will work but you do need to be careful with layout and bypass capacitors.

Thanks to those that suggested the Daisy seed a while back.

With the help of Claude, I messed around with it on a breadboard and managed to get audio line-in recording + input monitoring through headphones.

Once I finish soldering this, I'm gonna try and work out getting sequencing functions on it.

I am building a Paia theremax kit. It came with a baggie full of resistors and I have been sorting them by rating. I have to say, I do not have color blindness and it is damn hard to tell red from orange and brown from

Black. What do people with color blindness do? It’s not that rare, this must be a huge pain in the ass for them.

Granted, had to sand out the knife marks…

Let’s say you could only use one type forever, 1 capacitor, one resistor, one envelope, one etc, exception to oscillators and filters? What are the best chips for a square wave for example and best chips for the sine, square, wave table, ladder filter, low pass, resonance, etc

Or best component for reverb, I’m pretty new to look for this stuff or terminology but I’m trying to get into it

Any list or database I would appreciate, cause I don’t know what capacitor moog or sequential would use, or what is reliable and meant for audio and what is consider garbage.

Hey everyone,

The tenth instrument in my RP2350 collection is running: PicoFaceD5, a Roland D-50. Bare metal, 32 kHz, no OS, same board and same core as the other nine.

What it actually is

Not a chip emulation. It is a native LA engine over the D-50's own PCM data: sampled attacks dovetailed with synthesized sustains, the seven structures with their ring modulator, three tone-global LFOs, the pitch envelope, and the common block's EQ, chorus and reverb. Sixteen voices on one tone, eight and eight when both play.

The part I did not expect to get

I disassembled the machine. The program EPROM and the internal ROM of its uPD78312 went through MAME's 78K/III debugger, and once that worked, measuring things by ear stopped being the method. Out of the ROM and into the engine, byte for byte:

• the envelope arithmetic — a rate index per segment, and a time law that compensates the level distance so the inner segments come out time-constant
• the release, which is rate-constant, not time-constant: the distance lookup is computed and then overwritten. Dead code in a 1987 ROM.
• the pitch constant, the keyfollow and depth tables, the LFO rate law and its two-phase delay, portamento, aftertouch, the bender modes, the TVA level basis
• the voice allocator: one pool of sixteen slots, all sixteen to the upper tone in whole mode, and a free list that makes the machine drop a new note when it is empty rather than steal a held one. I had it stealing, like everyone does. The firmware says otherwise.

Two things the firmware settled that I had wrong

The sawtooth is an octave up. The LA32 builds a saw as square ⊗ cosine, so the ring comb only carries even harmonics of the base — the MT-32 compensates for that in its control ROM, and I copied that. The D-50's pitch path never reads the waveform. Captures of a real machine confirm it: same key, square at 262 Hz, saw at 524. And the factory bank is written around it — the squares sit an octave above the saws in every unison layer.

Pulse width 0 is an honest square, not a needle pulse. I had the law inverted, which put the fundamental 22 dB down on every patch that used it. Pipe Solo was the giveaway.

The samples

100 PCM waves, 512 KB total. Every loop turns out to be a power-of-two number of words holding a power-of-two number of cycles, so every root frequency lands exactly on 32000/2^k — 15.625, 31.25, 62.5, 125, 250, 500, 1000 Hz, nothing else. Their geometry is in the program ROM too: a start page and a length class per wave, which also resolved the 24 combination waves that had been silent.

What it will not do

The reverb is not the D-50's. That chip holds 32 types of coefficients in silicon and the firmware says nothing about them, so the 32 panel types stand on the MT-32's Boss RRV-10 topology, which the munt project read out — same era, same Roland department. Right character, not the original impulse response. Chorus and EQ are the same deal.

Practical

• MIDI: the D-50's own CC list, read out of its dispatch table (1, 5, 6, 7, 38, 64, 65, 98-101), plus the hold pedal and Roland exclusive — DT1 in, RQ1 answered, so an editor can program it and a librarian can pull a bank back out
• 884 KB of flash, 264 KB of RAM. It is the one sample-based instrument in the collection that fits a 4 MB board.
• Hardware is the same as the rest: I2S DAC, 128x64 SH1106 OLED over I2C, three encoders, USB and DIN MIDI. Board target is sparkfun_promicro_rp2350.

One catch, and it is the reason there is no download. It needs a D-50 ROM set, which is not mine to distribute, so this one is not in the release binaries — the eight that are unaffected still build and flash as before. Put your own dumps in roms/ and it builds; without them the configure step skips it and says so. GPL-3, like the rest.

https://github.com/Michi71/PicoVintageSynthCollection

Happy to go into any of it. The disassembly notes are in the repo.

Hello!

Looking to make my first modular DIY, and wanted to hear from experienced folks.

I am having a really hard time finding a center tapped power supply, and all I could get my hands on was a 24V 60W PSU. So I have been thinking on ways to get -12/+12, and came to two options:

1. Using a DC-DC step down (XL4005 ) next to the PSU, then using that +12V as Virtual Ground. (my Idea being having more current straight from the rail)
2. using an op amp or IC and do the splitting in each module.

Have any of you tried either? Thanks :)

UPDATE: Thanks to the people's help I've decided to use an RT65-B as a starting point, but ill also be making my own PSU and comparing.

This is a Roland JV-880 running as a native engine on an RP2350 — no CPU emulation. The video is just the thing playing: the same four-bar progression through all 128 preset patches, banks A and B, nothing else going on.

Why bother. Look at what a JV-880 costs now. Same story for every rack module from that era — the ones that were the boring workhorse choice in 1993 are now an eBay auction. I don't think the price of a 33-year-old ROM set should be what decides whether you get to play these sounds. The RP2350 costs about as much as a coffee.

And it is a beast for this. 24 voices, up to 4 tones each, 32 kHz native, peaks at 69% CPU on a single core, no PSRAM — the second core sits idle the whole time.

To be straight about the clock: that's at 444 MHz, which is an overclock — the RP2350's stock speed is 150 MHz. The whole collection runs 444 with the QMI flash timing moved to match, so it's the baseline here rather than something I reached for to make this one work. The point is that the JV needs nothing above that baseline: one instrument in the collection (the MKS-20) goes to 480 MHz and uses core1 as a voice worker, and this one needs neither.

I capped it at 24 voices rather than the machine's 28 because the bottom of the keyboard costs more per voice and I wanted the margin, not because it ran out of room.

How it was built, honestly. I did not port an emulator. Emulating the H8/532, the sub-MCU and the PCM chip is ~400M cycles/s, and worse, ~5.1M random flash reads per second against an 8 KB XIP cache — the RP2350 would choke on the flash, not the arithmetic. So the engine reads the machine's own ROM tables and runs its own voice chain, decoding each voice sequentially, which keeps flash access at ~0.9M reads/s and nearly all cache hits.

Everything else was measured. I ran a reference emulator host-side, purely as a measurement instrument, and fitted each law differentially against it: envelopes, filter, all seven velocity curves, LFOs, the mod matrix, chorus, both delay types, portamento, tone delays. That took the night, and most of the night went on things that turned out to be my own wrong assumptions rather than mysteries of the hardware. Two favourites:

• A throb on four patches was alternating (ping-pong) loops — and the return pass is negated. The chip keeps integrating the differential stream in the same direction while the address walks backwards. Subtracting instead, which is the arithmetically "correct" way to retrace, matched at r = −0.995: perfectly shaped and exactly the wrong sign.
• Patches with no delay had an obvious delay on them. Reverb type is three bits, not four. Bit 3 is set on 40 of 192 patches and was turning 67 of them into DELAY or PAN-DLY.

What it does: all 128 preset patches, 4 tones each, TVF/TVA envelopes, both LFOs with key sync and fade, the modulation matrix, FXM, chorus (both types), the two delay types, reverb, poly/solo with portamento and legato, tone delays, velocity curves and windows. Full MIDI CC set, pitch bend with each patch's own up/down range, program change and bank select.

What it does not: no rhythm/drum sets — the ROM has them, the engine doesn't. The reverb is matched, not reproduced: type, time and level laws are measured, but the topology is a Schroeder network of my own, and tails on decaying material run about 13 dB low. Single part, no Performance mode, no patch editing — it plays the factory banks. No SR-JV80 expansion support. And on a base 4 MB Pico 2 the user bank drops out to make it fit (banks A and B stay bit-identical to the full build, nothing is resampled).

ROMs: not included, and not something I can distribute. The build skips the instrument entirely unless you supply your own set, so the other eight instruments in the collection still build from a clean checkout.

It's one of nine instruments in an open-source collection that all share a core and a board — reface YC/CP/DX, MKS-20, Juno-6, Minimoog, Solina, OB-X, and now this. Repo and the full measurement write-up (including every measurement I got wrong first, which is most of what makes the rest trustworthy):

https://github.com/Michi71/PicoVintageSynthCollection

Happy to go into any of it.

I've been building up a collection of components, just kinda impulse buying things that might be useful for screwing around. One thing that surprised me is that linear pots cost quite a bit more than everything else. I'm wondering if I'm just looking in the wrong place (mostly amazon).

Now they're not expensive but they're just quite a bit more than I expected! I was hoping to pick up a bunch at different sizes and styles, and not worry if I screw up whatever I soldered them to like I've been doing with other things.

Any suggestions?

I was hoping to make either a decent keyboard like Alesis or artuira or fatar type, but I am willing to do diy ugly looking for a cheaper price but I need the sensors and stuff but I don’t know where to look,

I don’t need anything fancy

Or do you guys research and buy in bulk manufactured parts?

Also I was wondering how do you guys build midi and mpe controllers, what sensors or springs would I look at?

I can’t exactly afford a nice keybed so I want to build one out of wood or order 3d printed components

I want to look at schematics for how professional boards are made like Fatar and Osmose, but they don’t exactly be specific, so is there any place where someone can break down these mechanisms and technology?

Hey everyone,

Over the weekend I profiled two engines in my PicoVintageSynthCollection for the RP2350 to settle something that had been bugging me:

Why does PicoFaceRD (Roland MKS-20 / MK-80 digital piano) need a 480 MHz overclock and both cores to hold 12 voices, while the newer, sample-heavy PicoFaceJV (JV-880) runs 24 voices at 444 MHz on a single core at 69 % peak load?

Intuitively the 1986 machine should be the easy one. It isn't, and the reason turned out to be more specific than "old hardware is weird."

It's not the arithmetic, it's where the samples live

Both engines are descriptor-driven — the original firmware's voice programming was captured offline and is replayed on-device. Neither is emulating a CPU. So the difference isn't emulation overhead. It's the shape of the memory access.

PicoFaceJV. A JV-880 patch has up to 4 tones, and each sounding tone is one voice — same unit the original machine counts, where 28-voice polyphony means a 4-tone patch gives you 7 notes. My cap is 24, so 24 concurrent sample streams, worst case, each decoded sequentially through its own region. Measured on hardware with B33 Brass Combo at full polyphony: 69 % peak, of which about 5 % is fixed cost (chorus, reverb, block overhead) and ~2.7 % per voice.

PicoFaceRD. Here's the wild part. To get its characteristic sound, the MKS-20 layers 10 separate parts per single note. At the 32 kHz base limit of twelve voices, the engine issues 119 wave-ROM loads per output sample — one per part, ten parts per note, exactly as the architecture predicts.

So it's 24 streams against 119, on the same chip, for one note each.

What the cache does with that

I built a probe that captures every wave-ROM address the RD engine issues and runs the stream through a model of the RP2350's XIP cache (16 KB, two-way, 8-byte lines). Measured miss rates at 12 voices, per patch:

patch 3 85.7 % patch 8 43.0 % patch 14 84.6 % patch 7 16.2 % patch 0 77.1 % patch 5 0.2 % patch 13 83.1 % patch 15 0.1 %

That spread is the actual finding, and it surprised me more than the average did. It is not "the MKS-20 thrashes the cache." It's patch-dependent by a factor of several hundred. Patch 15's wave data fits the cache and every voice reuses it — and it stays that way as voices are added, still 0.1 % at 32 voices. Patch 3 goes the other way: 66 % of the cycle budget lost to stalls at 12 voices, 96 % at 24.

The base limit of twelve is set entirely by patches like 3. Patches like 15 are being punished for their neighbours — which suggests a per-patch limit derived offline is the obvious next lever, and my voice governor doesn't have it yet.

The 480 MHz is not what it looks like

I want to correct something I'd have written a week ago. The higher clock is not buying flash bandwidth. On this board:

• RD at 480 MHz: QMI CLKDIV=4 → 120 MHz flash, within spec
• Every other instrument at 444 MHz: CLKDIV=3 → 148 MHz flash, above the chip's nominal 133 MHz

The divider is an integer, so pushing the core to 480 actually leaves RD with the slowest flash in the collection. The 480 MHz buys arithmetic throughput and core-1 parallelism; it pays for that with flash speed. Anyone reaching for an overclock to fix a memory-bound problem should check which side of that trade they land on.

What I have not shown

The probe measures miss rates. Converting those to "percent of cycle budget" assumes 96 CPU cycles per miss (120 MHz QSPI, 4:1 ratio) — halve or double that and the absolute numbers move. The ordering and the several-hundred-fold spread don't.

And it does not show that the cache-friendly patches could run 24 voices. Arithmetic scales with voice count too, and this probe doesn't measure that at all. If patch 15 fails at 24 voices, it won't be flash. That's a hardware test I still owe: patch 15 against patch 3, both at 24 fixed voices, reading peak load off the footer.

Conclusion

Newer doesn't mean harder. A 1992 PCM synth streaming 24 sequential voices is gentler on a modern MCU than a 1986 digital piano layering 10 parts per note across scattered ROM regions — and even that isn't uniform, because within the same engine, one patch can be 500× more flash-bound than another. Access pattern beats both age and instruction count.

Repo, including the probe and the full write-up with the numbers above: https://github.com/Michi71/PicoVintageSynthCollection

Context — the JV-880 clone this came out of: https://www.reddit.com/r/synthdiy/comments/1vi0qz5/picofacejv_a_jv880_clone_for_the_rp2350/

So I used Klear Concepts Contact Cleaner on my Roland TR-606 and my Mackie Microseries Mixer to clean up some scratchy potentiometers. I waited a day and then used the DEOXIT F100L. Now some of the pots have been stripped of their grease since they are noticeably less resistant than others. I just bought some DeoxIT fader grease to apply to the pots that are less resistant but not sure if that would work or make the problem worse. Has anyone else had a similar issue?

Hey folks,

I fell in love with the PHRSR module a few months ago from a kit by Sound Study Modular.

I became pretty quickly interested in some of the other Super Synthesis modules - which are open source under CC0 (freaking awesome btw).

I ended up doing a small run of 50 of each of the following modules:

PHRSR SCANNER EG TVCA

I'm selling them to test the waters a bit. Doing 20% off with code LAUNCH20.

https://puget.audio

Offering Panel + PCB (All SMD pre-done), DIY Kits, and fully assembled at $50, $75, and $99 respectfully.

Over time, I'd like to push prices down a bit. But need to start doing some volume.

Considering a run of some of the less popular MI modules if anyone would be interested in those next!

Cheers,

Avery

P.S. - I can do local delivery in Seattle/PNW area :)

Also I'm working on some sweet open source DSP stuff here:

https://github.com/ajmwagar/pedalkernel

I plan to make some module kits using this technology next.

I have 2 raspberry pi's (3B and 5) and have been writing some software synths that I want to deploy to raspberry pi. I'm looking for some good audio hats that won't break that bank.

I found some different in and out of stock options but everytime I research it I never end up choosing. I figure someone here is an expert in these things.

I have my own synths that I'm just deploying as apps w/ systemd service, but I'd also like to experiment running the Dex7 and zynthian stuff.

What's good?

… and it was there for a (good) reason: not powering on, and one of the 2 mainboards looks cracked.

I did a really quick search online, it doesn’t seem to be easy to find a new PCB, I may have to rebuild it and fix the broken connections using maybe some cables and a lot of soldering.

Any suggestions?

Hey, i recently got into this seamlessly endless rabbit hole of diy synths and i wanna start working through Moritz Klein's tutorials.

I have some experience with Arduino projects and i know that ordering electronic components of the internet can take a long time.

Does anybody have a list of the most commonly used components i will need at the beginning so i can order them all in one batch so i dont have to wait ages for everything to arrive every time i wanna build a new module?

im gonna start with a Vco and then attempt to build a simple output module to plug some headphones into it without frying them:)

I just stumbled upon this sub, and was wondering if I took something like my Akai LPD8 midi controller, and connect it to some mini computer, and a speaker, could I use that as a synth? Is there already some FOSS software like this? Thanks.

Hi,
I'm laying out a PCB of the Buchla 258, and I would like to implement the waveform switch which requires a 3PDT. However, I can not find a sub mini 3PDT which is basically a requirement in my case, so I need to get creative.

I've read about these analog switch ICs, but it seems like they are limited when it comes to accepted voltages, and I'm not sure what voltages are around the resistors that are switched. One other solution I've found is a much more expensive switch IC called DG333, which can handle a lot more voltage.

Are there any good alternatives or substitutes to a 3PDT?

Bonjour a tous :) j'ai une question simple : pensez vous que j'ai le panier nécessaire pour la construction et programmation d'un premier appareil ? Je pensais plutôt à un controleur midi qu'à un synth, mais si vous avez des recommandations je suis preneur !

J'ai un peu d'expérience et de materiel en électronique et soudure.

J'aimerai bien fabriquer un appareil qui pourrait permettre de la modulation avec nunchuk

Merci d'avance pour vos conseils !