DIY MIDI keyboard

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I have been away from this some time and look what happened....

I recently got the idea to make a bit more music myself. As I can only play keyboard intruments and I want to be able to move my instrument alone, a midi keyboard came to mind. The last requirement is essential: an upright piano or electronic organ is not portable enough, got both and you definitly need at least 3 people to move those and a large van.

So I started with the idea to make it myself. Biggest problem are the mechanics. How do you make a keyboard? I have seen an organ builder do it, but this is out of my leage, I need it in a few months, not years and a woodworking course later.

Played a bit with the idea of geting hold of a defunct piano and midifying the keyboard after sawing/hacking away the not needed bits.

What I need:

- portable
- good touch, it needs to resemble a piano, but Steinway (TM) class is not essential
 
Depending upon how realistic you want it to look, you could remove the internal bits from a piano, including the keyboard. Then, make a platform where the keyboard was, and install a new electronic keyboard. I've seen this done at the "dueling piano" style bars. From the audience, it looks like they're playing real pianos, its not until you get up close and look at the keyboard do you realize they're fake. (Or sit close enough to realize you only hear keyboards through the P.A. and not from the pianos themselves)

If you want to use the existing keyboard and modify it to use electronics instead of the hammers on strings, I'd have to think more....
 
That would be a very big project.

Imagine all the electronic and mechanic involved. Hope that you don't want touch response.

I don't say that this project can't be done but it's going to be hard. And I think that a new korg triton ius going to be less expesive than building a keyboard yourself.
 
Scheaf: it's your second one I want. Re-use a defunct piano keyboard. Not modify a piano to take a synth.

JBL: No, it does not have to be. The goal is only a slimed down master keyboard. There need to be no sound generation on board.

This brings down mechanics to attaching some kind of switches to the hammers (or somewhere else). Thats why I want to re-use exsisting mechanics, I can't make those myself.

Aftertouch will indeed be next to impossible. But who knows, that's why we tackle this with the power of the numbers. Most of the electronics have already been done before so that would be up to the maker to decide wich way to go. Or it could be done again here, but that is definitely for later on.

HAs anyone ever got the possibility to play (mess) around with an "unusable" piano keyboard?
 
JBL is right. This is one of those projects that just doesn't make sense to DIY. Making a keyboard with an acceptable response and feel, especially a piano style weighted one, is a serious pain no matter how you slice it. AFAIK, Roland and Yamaha are the only companies that actually make their own. Everyone else OEMs from Fatar.

Repurposing a old piano keyboard probably wouldn't work very well anyway. There's a lot more to it than ripping out the keys, because the way a piano action works mechanically is very different from a keyboard controller. To retain any semblance of the feel, you would have to retain the hammer mechanisim. If you feel you can deal with the resulting beast, then you would have to devise a good method of measuring velocity, and program a controller to turn this into MIDI, as this is not a feature of most cheap DIY MIDI controller projects.

This project will definetly cost more than the $350 or so a used Fatar will run you.

If you DO make it work, please post pictures so I can be REALLY IMPRESSED!
 
Now I understand... You want the feel of a real piano keyboard, so you want to take the keyboard out of a real piano and put it in something close to a synth case, right? Now, that's completely different...

How complicated do you want to go? I just had some pretty bizarre thoughts as to ways of doing this, but you would end up with something pretty clunky.... (It involves keeping the hammers with the keys, and adding a whole bunch of piezo elements) At the bare minimum, you'd need a microcontroller to convert the keys into MIDI events, as others have stated, so you'd be looking at some type of programmer board in addition to the controller. (getting more expensive now)

Depending on how much you want to spend, and how clunky you're willing to live with, it'd be do-able... My idea might even be do-able without the hammers, but using something under the keys themselves. (This would also actually give you touch-sensitivity, I think) But, I don't think it would be easy....
 
I never saw a keyboard with the feeling of a real piano. The keyboard will always lach the inertia of a real piano key. So the key will always be easier to press and will not have that small kickback the piano have.

Altought thet if you make one, sell it to keyboard manufacturer.

Big project indeed.

Even if you keep the same key of the piano I d'ont think that it would be possible.
 
Hi all,


JBL said:
I never saw a keyboard with the feeling of a real piano. The keyboard will always lach the inertia of a real piano key. So the key will always be easier to press and will not have that small kickback the piano have.

keeping the whole mechanic construction of course keeps "the feeling of a real piano".
But the sound won't improve, you would at least have to find a way of generating velocity-messages to control the attack (when using MIDI).

cheers,

bob
 
strings or no strings?

Hi JBL,


JBL said:
You need to keep everything, including the string to get the same feeling.

Are you sure? I don't think that the whole touch would be lost only by not using strings. I don't know exactly how it works, but I think the main factor influencing the feeling is definitely the mechanical system.

JBL said:
Could still try to put magnetic pickup on every string.:D

Yeah, like a Fender Rhodes- but the "strings", if you can call them strings, are a bit different though.... :rolleyes:

cheers,

bob
 
JBL said:
Maybe you could just place something instead of the strings.

Some triggers? :)

JBL said:
If their is nothing to stop the hammer the key is going to lost the feeling it was having at the end of the travel.

Notice, that if you hit a key and keep it down, the sound remains -> after hitting the string, the hammer sets immediately back to the starting point. The hammer therefore has no connection back to the mechanics.

If I had an old, wrecked piano I'd love to try it, but my mother would :skull: me if I took apart our piano - after all I have to practice on it......

cheers,

bob
 
Yep, I agree there would have to be some kind of strike plate. It will be something to keep it silent!

Velocity is not that difficult. Most projects use some kind of switching under the keyboard and for starters I would go that way too. One contact opens when you start pressing the key, the other closes when you hit the end of the travel. Maybe use only the open key under the keyboard and put the close key under the hammer on the strike plate?

Electronics are plenty on the web, just do a search for "diy midi keyboard".

Aftertouch I forget for the moment. Never seen it done on a diy job.

Liked the Fender idea!
 
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Welll, clearly the hammer has to strike something, but maybe it's true that by the time the hammer hits the string, the key isn't really connected to it anymore. That is really an observation that helps with this project, and makes it seem more doable. Should be confirmed though! The piezo pad for the hammer to hit certainly sounds like the first best approach.
They could each be trimmed with software to give an appropriate MIDI level output so the response is consistant.

Something to keep in mind- pianos are amazingly modular.
I saw a piano tech remove the action from a Steinway baby grand in about two minutes and carry it away. The action ,which is all that is needed here was exactly the width of the keys, and about two feet from fron to back. Aout 125 mm tall A whole lot smaller and lighter than the piano!!
 
Well, I don't know that yet. Thats one of the reason of the thread here: to get as much info as possible before starting.

Trimming will be needed, as not each piezo will be as sensitive as the other, and there will be differences between keys (remember, we are not using the steinway baby grand), and tolerances are greater as this is a diy job.

But I still fail to see why you guys are so keen on piezo sensors. Read my previous post about the sensing with 2 switches. When the first open, you start a counter in soft, when the second closes you stop the counter, the larger the value of the counter, the smaller the velocity. It will need just as much trimming.

The best would be a combination: use the switches for sensing the velocity, use the piezo as a start for sending the data. That way you avoid having to do AD conversion on each input.
 
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I am guilty of not picking up the switch approach you mentioned- it looks good and will require less or no trimming I would think
I suspect that any piano is pretty modular. It wouldn't surprise me if they all have removable actions- even cheap uprights. The action includes the hammers.

It really isn't that hard to get a piano free or quite cheap. Check the want ads. People are always moving and the weight often makes people happy to just have someone carry it away!
 
The reason I go on about piezos is because you said you wanted touch sensitivity. Of course, I didn't think about the release of the key stopping the note. So, my route, you'd still need at least one of the switches. As for the A/D, most of the microcontrollers out there today can come with an A/D built into them, so its not a big deal. You just watch the voltage on the piezo, and that tells you how hard the key was hit. The two switches idea is another possibility, but, may require more software capability than what's available on most microcontrollers. Remember, you're not talking about watching just one key, but up to at least 10 at one time, and possibly more! That's at least 10 high-speed timers needed, beyond what most controllers have. Granted, you'll have similar problems with the piezo elements, but you're watching them for a much shorter time, and you could add a little hardware to do the samples for you, and just send the digital level back to the controller.

As for what was meant by "trimming" as stated by Variac, he simply means, that each element is going to offer a different curve, so you'll have to adjust things for each element. (in essence, calibrating it)

I also agree with Variac, pianos (at least in the states) are usually pretty easy to come by. Heck, if you were somewhere near North East Ohio in the U.S., I could get you one for dirt cheap!!
 
Most AD's in controllers are quite slow. Well, the controllers I looked after (not that many). Also you would need to sample it several times to get the peak amplitude.

You would not be watching all the keys all the time. Just a scenario, probably not the best but the basic thing I was thinking about. Each key as a memory location set to 0 to start. You start scanning the keys. Once you detect a key being depressed, you add 1 to the memory location and continue scanning. Now while you continue to depress that key, the cpu keeps scanning and adding to the memory corresponding to that key. Once it hits the bottom switch, the note on command is send, together with the velocity info. and scanning continues. Once the bottom key opens again (you released the key), the note off command is send and the memory cleared. Should be feasible. Better ideas welcomed! I'm more electronic hardware minded then sofware.

I'll try to check for a piano around. Until now I did not see anything affordable (well not for this job). I'm afraid shipping to Belgium from North East Ohio would be a bit on the expensive side, but thanks for the offer :)
 
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