[sdiy] Question how to improve rotary encoder feel

[Roman Sowa]

That description is exactly what that pot is, I mean the picture Julian 
posted. At first glance it looks like regular pot, but it has 2 wipers 
rotated by 180 degrees.
And here's my DIY attempt to make such pot from regular cheap dual pot:
http://www.synthdiy.eu/files/endlesspot.jpg

Roman

W dniu 2017-06-09 o 13:49, rburnett at richieburnett.co.uk pisze:
> The Ion pots are available from Alesis as replacement parts for repair
> work.  Perhaps you could buy one to play with, then see if there is any
> manufacturer's info on it to suggest if it's made by one of the usual
> suspects like Bourns, Alps, Alpha, etc...
>
> I don't have an Alesis Ion, but an engineer friend who has one explained
> the operation of the pots to me like this:
>
> Dual track potentiometers, except one track is rotated 180 degrees
> relative to the other track, and no mechanical end-stops so they can
> rotate continuously.  When the wiper for one track goes over the
> discontinuity in its track, the other wiper is in the middle of its
> track.  Some clever software is then used to read the voltages from both
> wipers and "hide" the discontinuities in each track by using data from
> the other track at that time.  You then get smooth high-resolution
> parameter adjustment with endless rotary control, and free from any
> glitches or mechanical detents.  That's the theory anyway, perhaps some
> Ion users can comment on how well it works in practice?  They've been
> around for a while now, so it would be interesting to know how well the
> well-used pots are holding up!
>
> I hope that explanation made sense.
>
> -Richie,
>
>
>
> On 2017-06-09 12:26, Julian Schmidt wrote:
>> I found 2 pics of the ION parts
>> http://studiorepair.com/gallery/Alesis/Ion/slides/Alesis_Ion_Potentiometer__STUDIOREPAIR_04032501_1510157530.JPG
>>
>> http://studiorepair.com/gallery/Alesis/Ion/slides/Alesis_Ion_Panel_PCB__STUDIOREPAIR_04032501_1510087626.JPG
>>
>>
>> julian
>>
>> Am 09.06.2017 um 13:17 schrieb Julian Schmidt:
>>> I'm all ears if you know a part number or source for affordable
>>> endless pots.
>>> All I can find are expensive industrial ones in the >10€/piece range
>>> and although being 360° endless rotation parts, the resistive taper
>>> spans only 340°
>>> The Ion pots look more like the normal, cheap 1-2€ pots but my
>>> research turned nothing up, yet.
>>>
>>> julian
>>>
>>> Am 09.06.2017 um 12:53 schrieb rburnett at richieburnett.co.uk:
>>>> You could look at using continuous rotation pots like the Alesis Ion
>>>> supposedly uses.
>>>>
>>>> -Richie,
>>>>
>>>>
>>>>
>>>> On 2017-06-09 11:30, Julian Schmidt 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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