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Thread: Question About Encoders: Making Mackie Controller Knob - Possibly Wifi

  1. #1
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    Question About Encoders: Making Mackie Controller Knob - Possibly Wifi

    Hello,

    New to making things with teensy, and while I have experience soldering synth kits, I'll admit my electronic knowledge is fairly rudimentary.

    I have been asked to create a small controller to control the output volume of a studio's speakers. Since they want it to be fairly precise, I figure I'm going to have to go with Mackie Control instead of Midi for the higher resolution.

    That out of the way, I have been scouring the land for encoders. Why? Because they do not want detents, or if they are present, they do not want to feel them. Additionally, they would like the controller to have a push button with it so that they can change between coarse and fine resolution—easy enough to do in code.

    I have always had good experience with alps pots/sliders for being smooth and buttery, which has led me to to these options:

    EC11N1524402 - Mechanical - 30 detents - 15 pulses - With Switch: https://tech.alpsalpine.com/prod/e/h...1n1524402.html

    EC111012010H - Mechanical - Without Detents - Self-return switch (no clue what this means): https://tech.alpsalpine.com/prod/e/h...11012010h.html

    EM11B616140AE - Magnetic - 16 Detents - 16 Pulses - With Switch: https://tech.alpsalpine.com/prod/e/h...1b16140ae.html

    In the past, my experience with knobs and sliders has been in the analog domain. With that, I have a few questions:


    1) I have read on this forum and others that the use of detentless encoders can potentially cause a lot of issues with the teensy/arduino when rotated too fast, or with just debouncing. Is this the case?

    2) Can debouncing be achieved entirely through code, or will I need to creat a schmitt trigger or other hardware supplement in order to clean up the signal? (Found: a few threads created by @ Theremingenieur ) But I saw something about his code does not work with the Teensy 4.0 (although the version 3 will probably be more than sufficient for this use case). https://forum.pjrc.com/threads/44592...rs-(once-more)


    3) Is it worth spending the extra cash on this build for either a magnetic or optical encoder? While the encoders are rated for a hefty amount of rotations, I suspect that this will be accumulated fairly quickly.

    Finally, while they are comfortable with the device being plugged in via USB, they were wondering if there was a way to have the controller be wireless and connect to a specific usb receiver. There are several computers in the control room and for security reasons Bluetooth has to be disabled on all devices. Does anyone know of a decent usb wifi receiver to use (or breakout for older versions of the teensy)?

  2. #2
    Senior Member bmillier's Avatar
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    hello. You didn’t mention if size and price was important. I find that the small Bourns REs, while they have detents, you can’t feel them. But, they are only $2 and noisy. The teensy encoder library will read them OK, but I suspect you couldn’t move them too quickly and get good readings. I have used the more expensive /larger Bourns ECW0J-B16-BE0024L - they are really smooth, very little detent feel.
    I just finished a Teensy 3.6 based project which is my copy of the Presonus IOStation 24. Two channels of USB audio with mike preamp/phantom power, plus a motorized 100 mm pot for volume and lots of pushbuttons. For the encoder wheel I used a Banggood optical encoder. It has a 3 inch knob with spinner and gives really accurate. optical quadrature signals- 400 counts per revolution (Teensy encoder library gives one count for both rising/falling edges of both A/B signals, so 4 counts for each detent “click” on the quadrature encoders like the ones mentioned)
    Have you ruled out a slider pot instead of encoders?. The T3.6 has 12-13 bits of useful ADC accuracy and you can read it so quickly that you can average many samples and get useful values which you can feed to the 14-bit pitchbend messages used by Macklemore controller for volume.
    I suspect alps encoders would be much like Bourns. The small ones would not be very good especially if they were turned a lot. That’s why I like the larger Bourns model mentioned above.
    cheers

  3. #3
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    Thanks for the reply!

    Price per encoder doesn't really matter in this case. Function is more important than anything, as these will be used a ton.

    Overall, we are trying to keep the form factor of the entire device down to something below 6"x 6". Something that we can easily move around desks and handed over to client's tables.

    We thought about using slider pots, but this is for a small little "studio" controller that can be moved around the desks or be handed over to a client during recording sessions. So far, it also has been specced out with a few additional buttons on it to toggle between preset sub-mixes, speaker selection, and talk back. The controller will literally be a single knob with a few buttons underneath it.

    While these will not be used to quickly "ride" for automation, several of our engineers adjust monitoring level really quick to check for spot checking—fast enough to make me concerned about errors.

    We also thought about using regular pots as well, but the coding is also being set up so that way certain presets can be selected, override whatever value the controller currently has stored, and can be used without being locked into a set angle on a pot. We figured this would be easiest on everyone based on how the studio runs. That way, a client doesnt have to mess with anything and can keep turning their volume however which way they want.

    Do you happen to have the banggood optical encoder you used? A friend was saying that magnetic or optical encoders will function better and potentially avoid the bouncing issue of detentless mechanical encoders entirely, but again, I have mostly only built some analog synth schematics.

  4. #4
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    Looked into some more of the bourns encoders, and they appear to have some optical ones as well now:

    https://www.mouser.com/ProductDetail...wOrwJ6VA%3D%3D - 32PPR - 32 Detents - Hard Switch

    https://www.mouser.com/ProductDetail...E4IRgVAkJ0I%3D - 32PPR -32 Detents, and whatever they call their "Standard" switch

    https://www.mouser.com/ProductDetail...Bdq4t2G3DFE%3D - 64 PPR - 0 Detents - Standard Switch.

    They are more pricey for sure, but definitely seem to have some nicer options than the Alps and lower mechanical Bourns.

    I guess this is a matter of trying them and see which is best for the job, because I cannot find reviews anywhere.

  5. #5
    Senior Member bmillier's Avatar
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    Hi. The banggood encoder is BG404113352. Costs about 35 canadian dollars. I really liked the large knurled knob and spinner. Reminds me of high end ham radio transceiver frequency dials. The review on the BG site with the canadian flag is mine.

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