[sdiy] Question how to improve rotary encoder feel

[Tom Wiltshire]

Hi Julian,

Like you, I've "gone around and around" on this problem (it seems like an appropriate expression).

I did many experiments trying proportional control of a parameter using the velocity of the encoder. It was a disaster, in short. Mostly much too sensitive, or much too slow. In the end, I finished up with a system like you suggest, where you can push the encoder for fine control.

Since LED rings only typically have 15 or 31 LEDs making the encoder resolution match the LED display is a small problem, but only a small problem. I would expect that the Nord synths use a pretty limited panel resolution and interpolate or filter the output to provide smooth changes in underlying parameter values. Essentially, the encoder might only alter the upper five bits of the parameter value, with the remaining bits filled in by filtering of some form. This could be 12-bits or 16-bits as easily as 7-bit.

Since I haven't got any LED rings, I haven't done these experiments yet, but that's how I'd approach it.

It's also worth pointing out that if they've got 48 cycles per rotation, they've got 48x4=192 separate states around one rotation. That *is* enough to control a 7-bit variable directly, assuming they took advantage of each change of state. This makes much more sense on encoders that don't have detents - do the Nord synths have detonated encoders?

HTH,
Tom

On 9 Jun 2017, at 11:30, Julian Schmidt <elfenjunge at gmx.net> wrote:

> Hello All,
> 
> I have a current idea that could vastly benefit from using encoders instead of pots.
> My only gripe is that I never had an encoder where I liked the feel. With the standard 24PPR encoders you have to make way too many turns to get to a higher value.
> Rotationspeed based value speedups made the feeling even worse on the machines I tried. Also a lot of people complain about encoders on synths for the same reason.
> Best solution so far is something like on the midibox or AN1X where you push the encoder for fine resolution.
> 
> The only one people seem to like are the Nord ones with the LED rings. I never had a nord machine in my hands, but Forum research suggests that they somehow managed to line up the LED movement on the ring with the encoder travel. So if you turn the encoder half a     rotation, the value LED is at half, too.
> 
> Any idea how they've done this? looking up the specs it seems like they are using Bourns ECW1D-C24-SE0049L encoders (http://electro-music.com/forum/topic-50251.html). 
> 49L is not specified in the datasheet, but my guess would be 48L => 48PPR which would still be too little resolution to even bring a 7 bit value up to full range in one revolution.
> Is the front panel resolution just reduced and interpolated on the nords? 
> 
> So if anybody has some hints how to give an encoder a more potentiometer like feeling I'm all ears. Especially if we talk 12 bit instead of 7 bit parameter resolution.
> 
> For practical reasons encoders would be great for layered UIs to share a set of controls between multiple LFOs or preset saving. LED rings are sexy as hell, too. But whenever I use encoders for something other than menu diving and editing settings I wish for a pot in my hands ;)
> 
> Cheers,
> Julian
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