New design

Design Concepts
1

I am thinking about creating a MIDI controller with a unique spec, 61 keys in one layout, think computer keyboard type layout but 6 rows of 10 keys at roughly the same size. I want to use it as a suppliment to a full sized keyboard. I know I could easily just buy a small quater sized keyboard and shift up octaves but I would like to have access to a range of 61 notes at once. I also feel comfortable playing notes on a computer keyboard but want to make a similar experience that isn’t as limited and is more like a hybrid between playing on a computer keyboard and MIDI keyboard. Velocity sensitivity would be a big plus.

One option is to simply buy a MIDI controller and take it apart and reassemble the components in the case according to my desired layout and then hook the key contacts up to my buttons. My question is this; Does anyone have an idea of what I should expect from the innards of a modern MIDI controller keyboard? Since the footprint of the controller I wish to make is so small, I’m afraid that the inside of the MIDI keyboard I want to dissect will be too large or long. Is this the case? Or is it such that aside from the large external container of the keyboard, inside is just small modular parts which I would be able to rearrange into my idea for a small case. Has anyone taken one apart? Any idea if I could accomplish what I want to do by using the insides of an existing MIDI keyboard?

Is there a MIDIBOX project that sounds like the right fit for my idea? Could someone tell me the best shop to purchase buttons, have a unique case made and other parts for my design? Here is a picture of what I have in mind.

2

interesting idea - 1 row down = 2 semitones up

3

I was also thinking of making a Shift + Caps Lock type key where when you hold it, it shifts the entire keyboard up an octave, the Caps Lock equivalent would keep the keyboard an octave up. And also a few banks where you could switch the keyboard to send CC’s.

Does anyone have an idea how I can make this thing velocity sensitive? I would imagine this isn’t possible but it would be great to have semi-weighted keys.

4

maybe it would be cool to have an octave shift for every row?

velocity: AFAIK the cheap midi keyboards do this by measuring the time delay between 2 points of the vertical position of the key.

5

I can’t figure out if it’s vertical or horizontal… if it’s vertical… I wanna see you play chords with that thing :wink:

OTOH, there could be new interesting chords possible due to the small size of this thing!

I’d advise you to make it horizontal, and one octave per row - this way you could e.g. play an arpeggio and then, going down one octave would just mean going down one row. Easy!

Also playing some chords could be easier this way :slight_smile: Like playing C2-C3-D3

cheers!

Damian

6

Does anyone have an idea how I can make this thing velocity sensitive?

FWIW- I ripped open an SR-16 drum machine a while back and noticed that it really only uses 2 or 3 “global” velocity zones and all the buttons are just a cheap matrix of contacts on the PCB. I guess the piezos on the board are giving off the recent pressure on the whole thing and tacking it on to whatever note message just occurred, so maybe if you whacked the plastic case while you lightly hit one of the keys it would give off a full velocity or something.  :o

It does seem to work pretty well regardless of how they’re doing it. There could be some type of “crosstalk”/false-trigger detection happening between the piezo group. I know my Roland PAD-80 (Octapad) has individual piezos under each pad, but then a few additional chassis piezos assumed to be for something like that.

That does look like a really unique idea, and practical for many. Definitely different and possibly better than the miniature single-octave key sections you see on some of the portable sequencers and drum machines. I’m actually a drummer, so not having the sharps and flats in their usual “in-between keys” locations wouldn’t bother me at all. It may even make it easier to find the correct notes. A controller with a vertically linked or duplicate harmonic relationship from row to row would also help in that regard.

Good luck! (and don’t let Behringer see it  ;D )

                                                                                  -George

PS- I’m finding more and more actual “individual” momentary switches in computer keyboards, etc. than I used to suspect were out there. It’s the PC/PS2 stuff that never seems to have them. I’ve got a dissected electric typewriter here with fine looking black Cherry switches, and it appears that most of the older beige ADB Mac keyboards have them (the Classics up thru Quadra’s and Beige G3’s).

  • I knew I had that big pile of old Mac crap in the basement for something. ;)   
7

Ysv,

I just re-read your question on the MIDI keyboard guts. I’ve got a full-sized Roland controller here (MKB-200 maybe) and I’ve had to open it to clean a dirty key years ago. I’ve got the service manual too. From what I remember, it was simpler than you’d expect. I think each key had one or two of those regular matrix style contacts under a long multi-key rubber membrane. I think there may have been more than one per key (top and bottom). I’m not sure, but it could have measured time differences between two switch closures to get the velocity (I think I’ve seen that somewhere), or it might just have the global piezo thing. I got a really good deal on it used, and it was a pretty nice controller for a “non-keyboard player”, so I guess whatever method they used was an acceptable common one.

For what you’re planning, you’d have the benefit of being able to use the much nicer, more reliable, single PCB mounted switches, if Thorsten or someone here can shed some light on the pressure/velocity issue.

Sorry my memory isn’t all that great on the keyboard guts. I’ll try to remember to check the service manual tonight, but I wouldn’t dare to open it again. The one thing I definitely DO remember is that it was one of those “jack-in-the-box”/“snake in the nut can” type things where all the parts jump out in your face when you open it, and you can’t figure out where they all came from. >:( 

                                                                                     -George

Note----> Just saw Kokoon’s post on the time difference thing. Now I’m pretty sure that’s what it uses.

8

In my search for resource to construct this design, I stumbled upon POS keyboards, or the special keyboard that shops set up and program to add up orders or checkout customers among other things. They came in all shapes and sizes and configurations, in many cases you just pop on the color of keycap you want on each key. Just look at some of these (they are expensive here, but can be found on ebay for considerably less)

http://www.posmicro.com/KEYBOARDS/Logic%20Controls/Logic%20Keyboards.htm

The other option is to buy individual cherry keys, mount them on a PCB and wire then into an 8x8 scan matrix or 4xDIN’s. The idea of dissecting a keyboard and rearranging the innards to suit my design is attractive to me mostly because of the ability to power off USB, plug and play, etc. I figure I could get a 49 key board with lots of knobs, LCD, etc. for ~$100.

Then again, MIOS sounds very attractive also. I would love to have some sort of key that pushes up or down an octave when held down. Sort of like a shift key but for octave’s when playing the keyboard. I also come from a background where I am comfortable playing on a keypad as opposed to standard keyboard. This is the reason for the key layout. It’s compact, but still retains it’s own logic. You can see a pattern forming, cascading if you look at the key layout on my unit. It might take some getting used to, but it’s just a new, efficient, compact way of having a full size keyboard right at your fingertips.

9

The other option is to buy individual cherry keys

I definitely wouldn’t pay for new ones, but I do also have a small rework (desoldering) station here.  ;D On the plus side, the two types I’ve scavenged only had two pins each, so they might be OK even with a pump. I think the beige Mac keys are a sure thing for non-matrix (maybe Cherry’s), and they’re all considered old thrift store junk now. If you need a jpg of the type that came out here, let me know.

Then again, MIOS sounds very attractive also. I would love to have some sort of key that pushes up or down an octave when held down. Sort of like a shift key but for octave’s when playing the keyboard.

This has come up occasionally in various forms. I’ve wanted a simple one to switch all of a board’s buttons between solo/mute/select (to remap to an optional set of output messages while in “shift”,etc. mode), either with a global momentary switch, setting a “mode” variable somewhere and activating a corresponding LED with the output message map table somehow tied to the variable state, or even a toggle with the input pin being polled before the output message was determined.

There’s another similar idea here-

                          http://www.midibox.org/forum/index.php?topic=1898.0

Unless I’m overlooking something, none of it sounds unrealistic, even to me. There were much more confusing things I’d considered tinkering with since I got into this MB stuff. I’m surprised someone here hasn’t already got it going.(?) I’m trying to re-balance my PIC/MIOS energy with all the electronics, soldering and etching junk. I’m building a new test board that’s laid out like my board design (which uses shifts). If I can knock that out soon, I’ll get back to the assembler mess and try to tackle that button thing. I figure if I can get anywhere near it, maybe TK or someone here can pull me through the tail end.   

BTW- I flipped through that keyboard service manual for a minute last night. Aside from some aftertouch button or something, it’s all about what was figured with the pair of switches per key. Also found an Octapad SM with it (piezos for each pad/ 2 for the plastic frame below them).

                                                       -Take Care

George

PS- It just occurred to me that I was thinking of all that output message code as if it were all in one or two places. I’ve got a nasty feeling that some of the “post-compile” patch edits, bank data, etc. would need to know about some part of the “alternate message” thing. ??? 

10

I figured with the flexibility of MIOS, all it would take is assigning the command that is normally reserved for octave up/down to another button or key. Mmmm, I’m also assuming that MIOS can shift through octaves, I’m not really sure though.

11

I don’t think it’s got anything like that at the moment.

If the octave up/down command you’re talking about is like a transpose message or something, I’d guess you mean throwing one at the receiving device or sequencer??? I’ve never had to do anything like that in real time, but I would suspect that having MIOS add 12 or whatever to the note bytes would come out faster.

I think we need to get somebody in here that knows what *we’re* talking about. ;D

-George