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Eurorack Knob Idea

mitxela.com

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Re: Eurorack Knob Idea

#111

Post by adrianmonk »

raphman wrote: post #104
adrianmonk wrote: post #101

Apologies if I'm missing something obvious, but why not just stick a potentiometer on the same axis behind the 3.5mm TS jack? Many 3.5mm jacks are open on the back, so you can give the knob a long shaft (longer than 3.5mm obviously), and that shaft can mate with the potentiometer. Alternatively, Eurorack uses TS jacks as connectors for control voltage inputs, right? If you build a module with a TRS jack instead, you…

Yes, this sounds like a simpler solution - the major drawback/advantage would be that you'd need to insert the knob in just the right orientation so that the shaft end fits into the potentiometer's slot. Might be a bit fiddly. On the other hand, the poti would keep its state even when the knob is removed, and you wouldn't accidentally change the value when inserting the knob. Just to nitpick the nitpicker: the knob's…

Oops, yes, 3.5mm is the diameter. I was sleepy when I wrote that, and I knew it didn't seem right.

Good point about the orientation when inserting. I was thinking something like hex or torx or friction fit that would allow you to insert it without thinking about the orientation. But then that causes another problem: any visual markings on the knob aren't guaranteed to be in the right position. I'm not sure if there's a good way get the best of both worlds on that.

Re: Eurorack Knob Idea

#112

Post by hinkley »

scottapotamas wrote: post #7
diggan wrote: post #3

Interesting idea for sure, but how is the feel of actually turning the knob? Seems to offer short to no resistance, which would make fast but precise movements pretty hard, something that is important for things like performances. 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 ele…

You might enjoy https://github.com/scottbez1/smartknob The complexity of this approach (ignoring the display and flair) unfortunately means you won’t see this used too often due to cost.

This is what cars need. Only make the entire dial depressable instead of the embedded screen. Use different haptics for each setting so you can feel which setting you’re changing.

Re: Eurorack Knob Idea

#113

Post by hinkley »

m463 wrote: post #72
csours wrote: post #54

Ok, but why stop here? You've effectively created a rotary potentiometer in one dimension, you could add two more dimensions like an analog thumbstick on a game controller. Do any controllers have a twistable thumbstick? 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?! (he…

reminds me of The Parable of the King's Toaster... it ends with: The king wisely had the engineer beheaded, and they all lived happily ever.

The king wisely had the computer scientist beheaded and they all lived happily ever after.

Re: Eurorack Knob Idea

#114

Post by peteforde »

smj-edison wrote: post #76

Tangential idea, but I've wondered if it would be possible to make synthesizers a lot cheaper by only having a couple rotary encoders. You could have hundreds of parameters on the panel, but each parameter would just be a neopixel LED and button. You could link the rotary encoder with a parameter by pressing it and the parameters' button at the same time. Certainly not as nice as a dedicated knob for each, but you'd…

It's not an obviously terrible idea assuming that your only goal in creating an instrument is cost minimization. (Consider that foreshadowing.)

Like all tools, it's rare for the cheapest possible option to be a good value. This is only a subtle difference to people who don't need to use the tool.

Re: Eurorack Knob Idea

#115

Post by smj-edison »

camtarn wrote: post #109
smj-edison wrote: post #76

Tangential idea, but I've wondered if it would be possible to make synthesizers a lot cheaper by only having a couple rotary encoders. You could have hundreds of parameters on the panel, but each parameter would just be a neopixel LED and button. You could link the rotary encoder with a parameter by pressing it and the parameters' button at the same time. Certainly not as nice as a dedicated knob for each, but you'd…

If you had a little silkscreened circle around each parameter's LED, and a Hall effect sensor underneath, you could even make a passive magnetic knob that you could use to adjust parameters by simply placing it on top of them and twisting. It wouldn't feel great due to the complete lack of resistance but it's a fun idea :)

Ooh! Now that's an idea. Especially if you could 3D print a knob and hot glue a magnet in it.

Re: Eurorack Knob Idea

#116

Post by raphman »

adrianmonk wrote: post #111
raphman wrote: post #104

Earlier quoted context omitted.

Yes, this sounds like a simpler solution - the major drawback/advantage would be that you'd need to insert the knob in just the right orientation so that the shaft end fits into the potentiometer's slot. Might be a bit fiddly. On the other hand, the poti would keep its state even when the knob is removed, and you wouldn't accidentally change the value when inserting the knob. Just to nitpick the nitpicker: the knob's…

Oops, yes, 3.5mm is the diameter. I was sleepy when I wrote that, and I knew it didn't seem right. Good point about the orientation when inserting. I was thinking something like hex or torx or friction fit that would allow you to insert it without thinking about the orientation. But then that causes another problem: any visual markings on the knob aren't guaranteed to be in the right position. I'm not sure if there's…

Something like this might work. When pushing the knob in, a spiral inside it rotates around the tongue that is attached to the potentiometer (or vice versa). Once it is fully pushed in, the groove in the spiral rests against the tongue, allowing the knob to turn the potentiometer. Would probably need a lot of fine-tuning to get all forces exactly right.

https://winterwind.org/_media/pasted/20250426-220417.png

Re: Eurorack Knob Idea

#117

Post by schobi »

I love the out-of-box thinking and clean execution by mitxela. But why not make it the other way round?

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?

Re: Eurorack Knob Idea

#119

Post by lsaferite »

kennywinker wrote: post #41
bondarchuk wrote: post #4

> 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. 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 pa…

Another common pattern is jack + offset. The most useful is when you have jack + offset + attenuator… but most modules pick one or the other for space reasons.

There are dual-knob coaxial setups that are only slightly bigger than a single knob as well. I've seen them mainly used in a course and fine adjustment setup, but you could certainly use them as atten+offset.

Re: Eurorack Knob Idea

#120

Post by lsaferite »

otabdeveloper4 wrote: post #103
mrandish wrote: post #73

Earlier quoted context omitted.

> key velocity and aftertouch pressure. Just a tangential note to say whenever I see these terms in discussion of MIDI keyboards it reminds me how disappointed I am the vast majority of MIDI controller (and multi-thousand dollar flagship synth) keyboards still don't fully support per note velocity or polyphonic aftertouch. It's only been 40 years kids... (sigh).

Not really needed. A synthesizer is not a piano, it's essentially a wind instrument.

I personally disagree. That velocity and aftertouch is all fun modulation input to my eurorack synth. Sure, I have a limited number of polyphonic notes (4) I can support, but it's still more modulation possibilities.
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