Interest for $20 Eurorack Modules

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johan
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Interest for $20 Eurorack Modules

Post by johan » Tue Jan 26, 2021 4:07 pm

Hi
I have sketched on affordable (less than $20) modular Eurorack devices that anyone can 3D print and build at home (like the LEET devices). Instead of using discreet components, I plan to use a powerful digital microcontroller and high-resolution DACs (24bit I2S). This makes the modules flexible, upgradable and reduces the component count and cost. By using “off the shelve” modules and a 3D printed core, different devices are created like building with LEGO blocks.
Image
Using this approach comes with pros and cons, compared to traditional modules:
Cons:
  • Less professional look – the 3D-printed devices will not look as solid and precise as the metal/ PCB versions typical for Eurorack modules (although custom front plates can of course be added).
  • Digital modules – I’m sure people will argue that a true analog system sounds better, no matter choice of algorithm, resolution and sample frequency.
  • Limited input and output range – without additional circuits, the voltage range will be 0-5V (unipolar). This will reduce the dynamic range (when 1V/ octave is used) and makes it less compatible with other modules (but it is possible to build simple converters to scale voltage, handle bipolar signals etc.)
Pros:
  • Significantly lower cost – An LFO would probably cost around $15 with a graphical OLED. Since you need lots of modules, this will save you hundreds, or even thousands, of dollars for a typical setup.
  • Easier to assemble – Connecting modules with 2.54mm/ 0.1” pitch is easier than soldering tiny SMD components on a PCB.
  • Upgradable – since everything is controlled by software; new features, UI, or even synthesis can be altered by upgrading the firmware.
    Customizable – everything will be open source and can/ should be hacked. If you don’t like the position of the knobs – modify the 3D model and print a new case.
  • Expandable – By using low-cost standardized building blocks, it is easy to expand the system. Need another VCO, VCA, MIDI converter, delay, or want to try a new filter? – Just print, assemble & play ;)
My first question is if there is any interest for devices like this, or if it is too ‘niche’?
My second question is if someone is interested in assisting with FW development? (because it would take me forever to develop this myself)

Check out LEET synthesizer to better understand the concept:
https://vonkonow.com/wordpress/leet-synthesizer/
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Re: Interest for $20 Eurorack Modules

Post by mandarinpile » Tue Jan 26, 2021 5:43 pm

Am I understanding you correctly - the only things required to build a module would be to 3D print your design and order the necessary components from a local dealer? The builder wouldn't have to buy pcb or any parts from you - insted the 3D design to print out and the instructions?
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Re: Interest for $20 Eurorack Modules

Post by DisappearHere » Tue Jan 26, 2021 6:29 pm

I think for sure you will get interest in this from people. If you can really keep the cost that low, it will be very attractive - I'd build one to have a play around with.

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Re: Interest for $20 Eurorack Modules

Post by sir stony » Tue Jan 26, 2021 7:12 pm

Not my cup, not as a tool of sound creation.
It might become a better approach for an arduino platform than the 1010 eurorack shield, however, and as such it'd be worthwhile to create and try out various code. Make it teensy compatible.

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Re: Interest for $20 Eurorack Modules

Post by studio460 » Tue Jan 26, 2021 7:25 pm

Those look super-cool! Bring it on! Maybe your company will be the next Teenage Engineering! Best of luck!
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Re: Interest for $20 Eurorack Modules

Post by Phitar » Tue Jan 26, 2021 7:27 pm

Anyone can do at home... As long as you are an anyone with a 3D printer at home. If you are not an anyone with a 3D printer at home then you probably can't do this at home. :mad:

I don't have a 3D printer at home. I do Eurorack! I don't have time or money for trivial pointless shi t like 3D printing! :lol:
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Re: Interest for $20 Eurorack Modules

Post by gryfon1 » Tue Jan 26, 2021 7:58 pm

Phitar wrote:
Tue Jan 26, 2021 7:27 pm
Anyone can do at home... As long as you are an anyone with a 3D printer at home. If you are not an anyone with a 3D printer at home then you probably can't do this at home. :mad:
[snip]
Anyone in a city with a Maker Space should have access to a 3D printer. Maker Spaces are something the e-music community should be leveraging.
Just my $0.0002 worth

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Re: Interest for $20 Eurorack Modules

Post by thetwlo » Tue Jan 26, 2021 10:10 pm

No, nobody would would ever want anything at such a low price.

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Re: Interest for $20 Eurorack Modules

Post by Phitar » Tue Jan 26, 2021 11:56 pm

thetwlo wrote:
Tue Jan 26, 2021 10:10 pm
No, nobody would would ever want anything at such a low price.
Agree! This would totally remove the modular mystique that I've built up around myself that proves to the world that I have spent a vast fortune on electronic devices that ordinary humans aren't even smart enough to understand or appreciate. Besides.... They look plastic! Doesn't look high-tech at all! Who wants modules that look like they are made of Laffy Taffy? :sarcasm:
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Re: Interest for $20 Eurorack Modules

Post by SolidStateSnake » Wed Jan 27, 2021 12:14 am

This rules. Maybe not specifically for me, but there is absolutely a market—and likely a big one.

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Re: Interest for $20 Eurorack Modules

Post by johan » Wed Jan 27, 2021 1:48 am

mandarinpile wrote:
Tue Jan 26, 2021 5:43 pm
Am I understanding you correctly - the only things required to build a module would be to 3D print your design and order the necessary components from a local dealer? The builder wouldn't have to buy pcb or any parts from you - insted the 3D design to print out and the instructions?
Yeah, that’s the general idea. I create the files needed (open source since I do this for fun) and its up to you to order and put everything together. I have deliberately chosen parts that is easy to obtain and avoided anything that is custom. The modules are connected using copper wire, so you need basic soldering skills, but its not that difficult as long as you can identify the hot side of the iron. By using the 3D-printed module as guide for the wires, you don’t need to order, pay, or wait for a PCB delivery.

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Re: Interest for $20 Eurorack Modules

Post by johan » Wed Jan 27, 2021 2:02 am

DisappearHere wrote:
Tue Jan 26, 2021 6:29 pm
I think for sure you will get interest in this from people. If you can really keep the cost that low, it will be very attractive - I'd build one to have a play around with.
My cost estimation is based on ebay and aliexpress prices:
  • CPU: $5
  • OLED display: $3
  • DAC: $2
  • Rotary encoder: $1
  • 3xPotentiometers $1=$3
  • 2x 3.5mm jacks $1=$2
  • PLA for the 3D printer $1
I’m sure people will argue that more expensive DACs, potentiometers and jack sounds better. By using modules those can be replaced without too much effort.
Shipping is usually for free using standard mail, I have not added customs since it varies depending on where you are.

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Re: Interest for $20 Eurorack Modules

Post by johan » Wed Jan 27, 2021 2:11 am

gryfon1 wrote:
Tue Jan 26, 2021 7:58 pm
Phitar wrote:
Tue Jan 26, 2021 7:27 pm
Anyone can do at home... As long as you are an anyone with a 3D printer at home. If you are not an anyone with a 3D printer at home then you probably can't do this at home. :mad:
[snip]
Anyone in a city with a Maker Space should have access to a 3D printer. Maker Spaces are something the e-music community should be leveraging.
Just my $0.0002 worth
There is nothing that prevents someone to make a PCB version using the same modules if that is preferred. It will add to the cost, but PCBs are affordable these days.
A PCB as front panel (with matte black solder mask) can be added to a 3D printed version as well.

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Re: Interest for $20 Eurorack Modules

Post by johan » Wed Jan 27, 2021 2:19 am

sir stony wrote:
Tue Jan 26, 2021 7:12 pm
Not my cup, not as a tool of sound creation.
It might become a better approach for an arduino platform than the 1010 eurorack shield, however, and as such it'd be worthwhile to create and try out various code. Make it teensy compatible.
I totally respect your opinion. Digital is not for everyone, but the ambition is that it should match other digital modules on the market.
I try to be agnostic when it comes to CPUs. I am aware that lots of people use teensy for sound projects, but when you compare the spec it is not that impressive, especially not for that price… Anyway – since the firmware will be written in C and open sourced, there is nothing preventing someone to port it to teensy in the future.

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Re: Interest for $20 Eurorack Modules

Post by ljwall83 » Wed Jan 27, 2021 3:09 am

I wish you luck- it's a noble objective. Though I agree with the other comment that maybe it could work better as a shield of some sort or it's own format.

Here's the questions I'd have.
* presumably the CPU and DAC are going to be some kind of ready-made development boards? Otherwise you'll need a few more components around them (and probably a PCB?)
* if it's going to be Eurorack and not a fixed architecture synth or it own format then you'll probably want/need some power circuitry, and personally, I'd want to have the circuitry to ensure the when I one day plug a 0->10V LFO into an input, or use a gate signal above 5v or 3.3v (or whatever), or patch an output to an output it's not going to be destroyed. I guess I'm saying, I look at the ornament and crime schematic and I'm not sure which parts I'd want to loose.
* 3d printing, speaking pesonally I'm not gonna buy a 3d printer, and it's a hour's drive to my nearest maker spaces, and they have monthly membership fees. Probably good value if you're in there 3 nights a weeks, but for two months membership I could buy a lot of PCBs from jlcpcb, or even retail from pusherman. If you're just making designs and releasing them to world, then whatever, use the tools you like, for sure a lot of people do have access to that stuff and will appreciate it. If you're planning on making a product however, not sure 3d printing instead of PCB plus PCB front panel is a good trade off.

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Re: Interest for $20 Eurorack Modules

Post by hel1 » Wed Jan 27, 2021 3:21 am

my 2 cents: give it a go!
I agree with some of the comments, but hey, people are not obliged to buy the modules, or print them. it might be a gateway for some people to buy a 3d printer, it might be a gateway for some to try eurorack, it might give us some great modules.
good luck!

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Re: Interest for $20 Eurorack Modules

Post by jube » Wed Jan 27, 2021 4:02 am

I really like the idea, but I would personally not jump in for (perhaps shallow) aesthetic reasons.
ljwall83 wrote:
Wed Jan 27, 2021 3:09 am
I wish you luck- it's a noble objective. Though I agree with the other comment that maybe it could work better as a shield of some sort or it's own format.

Here's the questions I'd have.
* presumably the CPU and DAC are going to be some kind of ready-made development boards? Otherwise you'll need a few more components around them (and probably a PCB?)[...]
As soon as a pcb is needed, I would imagine that the 3d printing becomes unnecessary, but that would also remove my aesthetic reservations.
Last edited by jube on Wed Jan 27, 2021 5:24 am, edited 1 time in total.

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Re: Interest for $20 Eurorack Modules

Post by ihav2p » Wed Jan 27, 2021 4:36 am

I could see this as a controller ... some kind of ableton push for vcv rack

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Re: Interest for $20 Eurorack Modules

Post by sir stony » Wed Jan 27, 2021 5:00 am

johan wrote:
Wed Jan 27, 2021 2:19 am
sir stony wrote:
Tue Jan 26, 2021 7:12 pm
Not my cup, not as a tool of sound creation.
It might become a better approach for an arduino platform than the 1010 eurorack shield, however, and as such it'd be worthwhile to create and try out various code. Make it teensy compatible.
I totally respect your opinion. Digital is not for everyone, but the ambition is that it should match other digital modules on the market.
I try to be agnostic when it comes to CPUs. I am aware that lots of people use teensy for sound projects, but when you compare the spec it is not that impressive, especially not for that price… Anyway – since the firmware will be written in C and open sourced, there is nothing preventing someone to port it to teensy in the future.
Oh, my concern is not that it's digital. My most used osc modules are digital, too.
Let's just say that my life's job experience takes my insight and expectations about electronic sound creation to a level that this design does currently not fulfill. If you said, ok, let's not make it 20 but 35$ (which is still super affordable), and use this extra budget to give this thing a decent analog frontend that will use the full modular voltage scale, add another pair of inputs for cv modulation, clock, sync, trigger, start/stop, whatever, then I'd definitely be interested. But like this, it seems to me more like a "how cheap can it be done" project, sacrificing exactly such aspects that set modular systems apart from the non modular stuff.

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Re: Interest for $20 Eurorack Modules

Post by mandarinpile » Wed Jan 27, 2021 6:08 am

johan wrote:
Wed Jan 27, 2021 1:48 am
Yeah, that’s the general idea. I create the files needed (open source since I do this for fun) and its up to you to order and put everything together. I have deliberately chosen parts that is easy to obtain and avoided anything that is custom. The modules are connected using copper wire, so you need basic soldering skills, but its not that difficult as long as you can identify the hot side of the iron. By using the 3D-printed module as guide for the wires, you don’t need to order, pay, or wait for a PCB delivery.
That is pretty nice! I would be interested in something like this. Where I live ordering a DIY kit from a small designer, paying for shipping and import fees often gets expensive. But I am not so advanced to build circuits myself on a breadboard. If I can do with just printing your design and getting common parts from a local dealer, then this could help me get into DIY. I would add my own front panel to make the design fit better into the whole system.
Toms Lazdovskis

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Re: Interest for $20 Eurorack Modules

Post by chrisj » Wed Jan 27, 2021 6:19 am

"I plan to use a powerful digital microcontroller and high-resolution DACs (24bit I2S)."

This is the part that got my attention, combined with your desire to build these using minimal extra parts. Are you going to have some kind of Arduino device available with such a DAC built in? I'm currently using Teensies clocked as high as 768k sample rate to brute-force suppress aliasing (seeing as some of the waveforms I'm generating are only 1 bit). Even if your audio wasn't amazing it sounds like you'd have amazing granularity for control voltages. Most of all it sounds like you've got some little PCB in mind that's got everything needed onboard (so long as all your voltages stay within the required range) and anybody familiar with this stuff knows you can throw a TL074 in there and have some safely scaled and controlled control voltages. Whether that's part of your own concept isn't as important: point being, if that's all it takes to adapt your compute hardware/DACs to other purposes, that's pretty trivial to do.

So the question is, will you have some tiny PCB that comes with your complement of ICs built in, presumably with minimal outside parts needed other than the switches and LEDs you have in mind? It looks like you have very few support parts in your designs, implying that the core's got those onboard DACs and ADCs. Are the ADCs 24 bit too? What sort of programmatic control have you got over how they're configured?

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Re: Interest for $20 Eurorack Modules

Post by Kattefjaes » Wed Jan 27, 2021 6:31 am

If you can build something like that that is super-cheap, doesn't create nasty interference to adjacent modules through the power bus or the air, and is reasonably powerful and reflashable, I'm sure lots of people would want to take a punt on one. Modular people are generally not automatically opposed to digital bits- they are opposed to not having options. It's all flavours and preference ;)

At that sort of price, it's cheaper than quite a few passive LPG modules, so counts as an impulse buy. Personally, I'd probably look for a pre-built one from someone like Pusherman if these ever existed, but certainly wouldn't struggle to resist temptation if it was that cheap.

Regarding FW development, if you could get the module to the point where it could run a reasonable Puredata patch (and it was reasonably easy for hobby developers to load their own), I suspect that'd prove fertile ground. That way you wouldn't have to write hundreds of interesting algos yourself- maybe provide some examples and that's it*. Possibly worth considering, though obviously I have no idea how powerful the silicon that you're considering might be.

Edit: "Too niche" is not something you have to worry about in modular very much. It IS a niche. People regularly produce crazy low-volume devices for other weirdos to play with.


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Re: Interest for $20 Eurorack Modules

Post by johan » Wed Jan 27, 2021 8:11 am

chrisj wrote:
Wed Jan 27, 2021 6:19 am
"I plan to use a powerful digital microcontroller and high-resolution DACs (24bit I2S)."

This is the part that got my attention, combined with your desire to build these using minimal extra parts. Are you going to have some kind of Arduino device available with such a DAC built in? I'm currently using Teensies clocked as high as 768k sample rate to brute-force suppress aliasing (seeing as some of the waveforms I'm generating are only 1 bit). Even if your audio wasn't amazing it sounds like you'd have amazing granularity for control voltages. Most of all it sounds like you've got some little PCB in mind that's got everything needed onboard (so long as all your voltages stay within the required range) and anybody familiar with this stuff knows you can throw a TL074 in there and have some safely scaled and controlled control voltages. Whether that's part of your own concept isn't as important: point being, if that's all it takes to adapt your compute hardware/DACs to other purposes, that's pretty trivial to do.

So the question is, will you have some tiny PCB that comes with your complement of ICs built in, presumably with minimal outside parts needed other than the switches and LEDs you have in mind? It looks like you have very few support parts in your designs, implying that the core's got those onboard DACs and ADCs. Are the ADCs 24 bit too? What sort of programmatic control have you got over how they're configured?
I have avoided any custom PCBs and are leaning against using a nodeMCU ESP32 board that have lots of power, low cost, easy to program, USB serial for debugging, power management (and even Wi-Fi/Bluetooth) integrated. This is the module at the back of the module in the rendering. The only disadvantage is that the built in DAC that is 8bit. I therefore plan to use external breakout boards for the DAC (24 bit I2S), with the added bonus that the signal will be 0-5 instead of 0-3.3V. (These are the two boards standing at the lower part of the module)
As I mentioned I plan to use 0-5V and not add extra buffers to the ports. You can always complement with a TL074, but I want to avoid complexity, ground planes and cost drivers.
Last edited by johan on Wed Jan 27, 2021 9:01 am, edited 1 time in total.

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Re: Interest for $20 Eurorack Modules

Post by johan » Wed Jan 27, 2021 8:15 am

ljwall83 wrote:
Wed Jan 27, 2021 3:09 am
I wish you luck- it's a noble objective. Though I agree with the other comment that maybe it could work better as a shield of some sort or it's own format.

Here's the questions I'd have.
* presumably the CPU and DAC are going to be some kind of ready-made development boards? Otherwise you'll need a few more components around them (and probably a PCB?)
* if it's going to be Eurorack and not a fixed architecture synth or it own format then you'll probably want/need some power circuitry, and personally, I'd want to have the circuitry to ensure the when I one day plug a 0->10V LFO into an input, or use a gate signal above 5v or 3.3v (or whatever), or patch an output to an output it's not going to be destroyed. I guess I'm saying, I look at the ornament and crime schematic and I'm not sure which parts I'd want to loose.
* 3d printing, speaking pesonally I'm not gonna buy a 3d printer, and it's a hour's drive to my nearest maker spaces, and they have monthly membership fees. Probably good value if you're in there 3 nights a weeks, but for two months membership I could buy a lot of PCBs from jlcpcb, or even retail from pusherman. If you're just making designs and releasing them to world, then whatever, use the tools you like, for sure a lot of people do have access to that stuff and will appreciate it. If you're planning on making a product however, not sure 3d printing instead of PCB plus PCB front panel is a good trade off.

Excellent questions and feedback, I reuse the answer: I am leaning against using a nodeMCU ESP32 board that have lots of power, low cost, easy to program, USB serial for debugging, power management (and even Wi-Fi/Bluetooth) integrated. This is the module at the back of the module in the rendering. The only disadvantage is that the built in DAC that is 8bit. I therefore plan to use external breakout boards for the DAC (24 bit I2S), with the added bonus that the signal will be 0-5 instead of 0-3.3V. (These are the two boards standing at the lower part of the module)
As I mentioned I plan to use 0-5V and not add extra buffers to the ports. You can always complement with a TL074, but I want to avoid complexity, ground planes and cost drivers.

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Re: Interest for $20 Eurorack Modules

Post by sir stony » Wed Jan 27, 2021 9:24 am

johan wrote:
Wed Jan 27, 2021 8:15 am
[...]the added bonus that the signal will be 0-5 instead of 0-3.3V. (These are the two boards standing at the lower part of the module)
As I mentioned I plan to use 0-5V and not add extra buffers to the ports. You can always complement with a TL074, but I want to avoid complexity, ground planes and cost drivers.
That is exactly where this thing falls short. Ground planes eat up stray HF and EM emission noise, and we don't want those inside a modular system. The 0-5V is not a "bonus" but still far short from the commonly agreed modular signal levels. Being "modular" is more than just fitting in the same case and using the same power supply. Don't go valueing stinginess over technical standards if you want to join into a system. It's not like that bit of extra would drive the cost beyond the imaginable. You want to sell a car that drives on open roads? Don't just give it a seat and an engine, but it also needs brakes and a steering wheel... even if it will move without those.

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