What's even better, though, is a coupled knob + jack where the knob turns into an attenuator for the input when a cable is plugged in, and works as a standalone knob otherwise. I think this is quite a common design.

I believe I've also seen patch cables with built-in attenuators.

He's right about the interface being the point of Eurorack. Plugging things into other things is the whole point. When I have a module that has hidden state, I forget what state it's in or what the knobs mean. I end up avoiding those modules. With cables and knobs, I can see the state of the whole system. I need good cable management to make sure it's not spaghetti, but I already do that in code already, and it's not that different.

Alternatively, Eurorack uses TS jacks as connectors for control voltage inputs, right? If you build a module with a TRS jack instead, you have an extra pin (R) that you can connect a removable potentiometer + knob to. And you can still plug in regular TS cables.

(Note: the article uses "TRS" loosely when it means "TS". I mean them literally.)

What would be a huge bonus point (but maybe unrealistic? I don't quite understand how the current implementation actually works) would be software-configurable resistance (physical, not electrical). I've spent a lot of time for my DIY modules to find the right knobs, or the right process to adjust the resistance of my existing knobs, being able to control that digitally could introduce a whole new level of fun.

Also, like other commentors have stated - this could be a jack too, so you could have a jack knob analog stick.

BUT WHY STOP THERE?

You could mount it on a linear pot/slider.

BUT WHY STOP THERE?! (help me)

You could daisy chain pluggable rotary analog stick jack stacks...

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The madness has taken him

Eurorack (and modular synths in general) seem like funny things. Like guitar pedals, I sense there are a lot of enthusiasts that do a lot more tinkering than actually playing them. Watching Rick Beato and guests on YouTube ... seems like a lot of musicians are looking instead for simplicity. Like a few good sounding pedals that, ideally, each have just a knob or two.

Maybe the synth-heads are in a whole different headspace though.

I'm kind of surprised he didn't start with a knob with a tiny accelerometer, mcu and battery in it to produce some sort of output signal into a stock plug depending on how the knob is oriented with respect to gravity.

Putting electronics inside the plug is nearly a mitxela trademark. https://mitxela.com/projects/flash_synth

While that might be true, what is expensive for me is chump change for someone else. However, that is very difficult to grok as there was no prices mentioned anywhere that I could see. Sure, it'll be expensive to me because I have to ask. But I also know that I cannot afford a fully spec'd out MacPro, but at least I can see the numbers.

> It's a nice dream, of a synthesizer where any knob can be pulled out and replaced with a patch cable, and any jack can have a knob plugged into it to set it to a fixed value. Whether it's actually practical to build a synth like this I'm unsure. It would probably only be worthwhile if you applied it to every single control on the modular, which rules out using other people's modules. You would have to invest heavily into the Eurorack Knob Idea. You couldn't even port other modules that easily, as many of them would expect a real potentiometer, whereas the encoder can only produce a voltage. Coupling it with a voltage-controlled potentiometer would work, but would be even more expensive.

Yeah, it's hard to imagine this fitting in nicely to everything since it's defintely more effort and work than just having a knob and a jack for the control of a particular thing. Esp. since most of the time, as a convention, you'll have a knob that controls the value, but when a jack is plugged in, this same knob acts as the attenuator for the signal.

I would have appreciated having an image or a pdf of the schematic for the design to understand it properly - i can get it from your github but I don't have kicad installed on this computer.

I'm esp. interested in the normalized behavior - ie. when you have a signal plugged in to the jack that is _not_ the potentiometer.. does it get passed through or does it have to go through this chip as well?

Having to supply a 3V to this to make it work as well is also an extra requirement of its usefulness in normal eurorack circuits - not a total dealbreaker but that does add extra requirements, and extra components to one's design.

Anyways... really cool idea :)

But even then I'd wonder if it worth it, because of the high pcb space usage. With potentiometers as attenuators or attenuverters you can fit two pots next to each other in a space of 20mm which neatly aligns with the standard panel widths. Theoretically you could certainly get smaller with thst solution, but the hall effect IC needs to be accounted for as well. With existing pots I can use the space underneath. If your module is just 10mm wide that space is pretty premium..

A few people have pointed out that the knob can act as an attenuator when it's being modulated via a jack, but sometimes the goal is space. I can also imagine a version of this that uses the same technique, but where the knob has an audio jack on it. You wouldn't need to unplug it to connect the incoming cable, and you could use the still-connected knob as an attenuator if you wanted to. This would get you the best of all worlds— maximum space, an intuitive interface, and attenuators if you so choose to have them.

2. Speaking of knobs, I am writing a toy software synth for smartphones. Are there any design guidelines for mobile UI for audio? Knobs are hard to use and sliders take up a lot of space with only a little more precision. I experimented with curved sliders (inverted parabola or sine), but they are confusing since height doesn't really encode anything and the curvature is there only to make the slider longer. I didn't find any design systems focused on audio components.

There's a miniature case study in thinking about innovation here. This is what the germ of a really neat idea looks like but you have to keep going and that's hard.

Yes, there'd be an extra wire to the power supply module, but that seems fine for a modular.

Can't wait for the y-combinator module.

Downsides: you need enough magnetic knobs and store them when not in use. If this becomes popular, will all knobs be compatible? What if you loose some? If you buy a used module? This idea somehow creates a new set of problems.

Idea: Knob with a plug!

The outer dimension of a knob is limited by how easily you can grab it. Even if used as a socket, you need the sideways spacing anyway. But the knob face is not used. Why not have the socket in the center of the knob?

How to build this? You would need a hollow knob riding on a bearing surface around the socket. I vaguely remember magnetic position decoders that work off-axis? Or maybe have multiple magnets in the rim of the knob, in an orientation that creates a uniform magnetic field in the center? The current prototype would even be suitable for trying.

Benefits: no extra removable components. Knob and socket can be used at the same time. Can you still reach around a plugged-in cable? Is this even useful?

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