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 Forum index » DIY Hardware and Software
Making a midi keyboard shorter
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the19thbear



Joined: Apr 19, 2007
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PostPosted: Fri Aug 09, 2013 10:22 am    Post subject: Making a midi keyboard shorter Reply with quote  Mark this post and the followings unread

Hi. Basically I want to make a midi keyboard i have, shorter by one octave.
I have the row of contacts here, with all the diodes etc. How should i go about making it shorter? In a perfect would, i would be able just to cut the circuit board shorter, end of story. But im guessing i'll end up with some keys not working..

Thanks
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seraph
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PostPosted: Sat Aug 10, 2013 2:56 am    Post subject: Reply with quote  Mark this post and the followings unread

what about selling the one you have and buy a shorter one?

Idea Wink

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JovianPyx



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PostPosted: Sat Aug 10, 2013 8:37 am    Post subject: Reply with quote  Mark this post and the followings unread

I agree with seraph, it won't be a simple job to just slice the keyboard.

The designers of those boards do not take into consideration such modifications, so circuitry placement would be fairly abitrary from that standpoint.

If you don't have the schematic and all of the required skills to restore all necessary circuit paths, then this would be a very risky adventure likely to end in failure.

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Cynosure
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PostPosted: Sat Aug 10, 2013 9:53 am    Post subject: Reply with quote  Mark this post and the followings unread

This is the first time I ever heard of someone wanting a shorter keyboard.

Like JovianPyx said - if you cut a required trace on the PCB then you could screw it up.

However, if you carefully follow the traces on the end that you are removing and see that the only place that they are going is to the key switches, then it might be ok. Most scanning circuits will be checking for a closed circuit from the key switch, so removing it would just make it permanently open.

A service manual would help you identify the traces and if it is possible to only remove the desired keys. What is the make and model of the keyboard?

I am curious - why do you want less keys?
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Blue Hell
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PostPosted: Sat Aug 10, 2013 12:30 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hmm .. well .. there was this person before wanting to cut a Nord Lead in two .. eventually that led to the .. what was it !v chat command? ... (recently i cut my X in half .. oh my ex eh :¬| ).

Apart from that - if you'd want to shorten it you would want to know where all the PCB traces go and what hey are good for; as you already said some other keys may stop working. Probably the keys are put into a scan matrix - so there will be row and column lines, cutting one wrong track may cut an entire set of keys further on on the keyboard, or key on would still work but velocity would not work anymore, stuff like that.

Anyway, when you decide to go on anyway - good luck, and keep us posted :¬)

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bubzy



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PostPosted: Sat Aug 10, 2013 1:43 pm    Post subject: Reply with quote  Mark this post and the followings unread

buy one of these

http://www.ebay.co.uk/itm/like/350730811060?lpid=83&device=c&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0&ff12=67&ff13=80&ff14=83&ff19=0

cheapest midi keyboard around.
save all that cutting in half business.

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PHOBoS



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PostPosted: Sat Aug 10, 2013 2:59 pm    Post subject: Reply with quote  Mark this post and the followings unread

Blue Hell wrote:
Hmm .. well .. there was this person before wanting to cut a Nord Lead in two .. eventually that led to the .. what was it !v chat command? ... (recently i cut my X in half .. oh my ex eh :¬| )


Laughing

Posted Image, might have been reduced in size. Click Image to view fullscreen.
Recently i cut my nord lead 1 in half.

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AndyR1960



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PostPosted: Sat Aug 10, 2013 10:16 pm    Post subject: Reply with quote  Mark this post and the followings unread

If the keyboard has a standard diode matrix, then it's fairly easy to cut down - as long as the matrix PCB is logically laid out (most of them are), and usually only from the top octaves down.

Each key has a pair of associated diodes (note and velocity), so you'll need to find the pair for the last note you need. You can then cut the PCB from that point as well as the keybed.

It can be done, I've recently cut down two CME M-Keys from 49 (4 octaves) to 37 (3 octaves).
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richardc64



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PostPosted: Sun Aug 11, 2013 5:51 am    Post subject: Reply with quote  Mark this post and the followings unread

AndyR1960 wrote:
It can be done, I've recently cut down two CME M-Keys from 49 (4 octaves) to 37 (3 octaves).

This is insane.

I might cut a 4-octave down to 44 keys or a 5-octave down to 56 keys, but never remove a full octave.

Ugh. 3-octave keyboards are esthetically offensive and just plain irritating. Reminds me of the old cheesy blower-driven "Chord" Organs. puker

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bubzy



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PostPosted: Sun Aug 11, 2013 7:14 am    Post subject: Reply with quote  Mark this post and the followings unread

recently I cut my grass in half.

https://twitter.com/Bubzyg/status/366562794323181569/photo/1

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AndyR1960



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PostPosted: Sun Aug 11, 2013 9:05 am    Post subject: Reply with quote  Mark this post and the followings unread

richardc64 wrote:


Ugh. 3-octave keyboards are esthetically offensive and just plain irritating. Reminds me of the old cheesy blower-driven "Chord" Organs. puker


Never did an ARP Odyssey any harm Wink
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the19thbear



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PostPosted: Sun Aug 11, 2013 10:36 am    Post subject: Reply with quote  Mark this post and the followings unread

well whatayanohw - Its not needed anymore - but thanks for all the suggestions and smart remarks Very Happy - I'll end up using the full range, but put pitchbend/mod wheel somehwere else in my design so i actually have room for the whole keyboard..
thanks again!
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Manuel Marino



Joined: Aug 07, 2013
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PostPosted: Tue Aug 13, 2013 7:14 am    Post subject: Reply with quote  Mark this post and the followings unread

why cutting a keyboard? honestly, what's the reason? use it in clubs while playing dance music?

bring it in your favourite sack while doing a travel around the world?

or simply, removing the octave that doesn't work anymore after years of playing?

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the19thbear



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PostPosted: Tue Aug 13, 2013 10:58 am    Post subject: Reply with quote  Mark this post and the followings unread

Making it fit here:
http://electro-music.com/forum/topic-59305.html
-The midi keyboard is a Yamaha KX49 with a built in arp that I want to use with this synth.
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Manuel Marino



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PostPosted: Tue Aug 13, 2013 12:52 pm    Post subject: Reply with quote  Mark this post and the followings unread

ah! ok, now it's more reasonable... well, just a "bit" more Smile
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