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Eurorack Knob Idea

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Re: Eurorack Knob Idea

#101

Post by adrianmonk »

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 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.)

Re: Eurorack Knob Idea

#102

Post by gitroom »

been messing with gear for years and honestly the obsession with cramming everything into tiny boxes always cracks me up, but the idea of knobs you can move around is actually kinda sick. you ever feel like stuff gets too complicated and takes away from just having fun making sound?

Re: Eurorack Knob Idea

#103

Post by otabdeveloper4 »

mrandish wrote: post #73
robotresearcher wrote: post #53

Earlier quoted context omitted.

It would likely be very, very expensive. A compromise that is affordable and does exist is programmable response curves to key velocity and aftertouch pressure. It can make sense to have different curves for eg. piano vs harpsichord even if you can’t change the mechanical key impedance. I haven’t seen it in the wild, but using this you could make the wrong notes quieter/louder or even play a different sound. But I th…

> 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.

Re: Eurorack Knob Idea

#104

Post by raphman »

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 shaft needs to be longer than 15 mm, right? "3.5 mm" is the diameter, not the length of a small T(R)S jack.

Re: Eurorack Knob Idea

#105

Post by skinpop »

UltraSane wrote: post #92

Eurorack is very cool and I totally understand the appeal of having physical devices to interact with but one thing I never understood is how you can recreate a specific configuration you liked later. Do you manually document every connection? Or just take pictures?

Once it's gone it's gone. That's part of what I like about analogue modular synthesizers. It's a liberating approach to doing music if you embrace it for what it is.

Re: Eurorack Knob Idea

#106

Post by UltraSane »

skinpop wrote: post #105
UltraSane wrote: post #92

Eurorack is very cool and I totally understand the appeal of having physical devices to interact with but one thing I never understood is how you can recreate a specific configuration you liked later. Do you manually document every connection? Or just take pictures?

Once it's gone it's gone. That's part of what I like about analogue modular synthesizers. It's a liberating approach to doing music if you embrace it for what it is.

So it is more of a toy than an actual tool.

Re: Eurorack Knob Idea

#108

Post by camtarn »

diggan wrote: post #16
pakue wrote: post #13

Earlier quoted context omitted.

Should be doable to add that. The BLDC needs to add a proportional (or any other function) force against the rotation direction until it reaches 0.

Sounds reasonable, wonder how that would actually feel in real life? As far as I understand, this would pass through digital parts, adding a little bit of (maybe noticeable) latency, but I wonder if the latency gets high enough for it to be a bit jarring that the resistance is dynamically changing as you apply torque.

In practice, when latency is small enough (on the ~1ms level, which is trivial to achieve using even pretty cheap parts) it's imperceptible.

I sometimes develop control loops for prototype systems which use a motor to emulate a combination of spring + friction damper, and even though I know that my code only runs every 1ms, it's really remarkable how much it feels like a real continuous analogue system.

Another good example is power steering, which uses a motor to remove resistance instead of add it. If I understand it correctly, it senses you applying torque to the steering column and adds proportional amounts of boost - but because it happens so fast, it just feels like the steering is magically lighter.

Re: Eurorack Knob Idea

#109

Post by camtarn »

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 :)

Re: Eurorack Knob Idea

#110

Post by wbl »

robotresearcher wrote: post #50
kennywinker wrote: post #41

Earlier quoted context omitted.

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.

The attenuator-inverter is super handy too. A gain knob that goes from -1 to +1 X.

That's a neat trick. Only way I can think of to do it involves two op amp buffers, one inverting one not and take the signal from the wiper.
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