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Korg Delta MIDI
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celebutante



Joined: Jun 29, 2007
Posts: 37
Location: Los Angeles

PostPosted: Sat Feb 07, 2009 8:54 pm    Post subject: Korg Delta MIDI
Subject description: impossible, or just a pita?
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I'd like to MIDIfy my Korg Delta. Since it's a divide down synth, it doesn't appear to use any sort of key matrixing system for the keyboard; from my somewhat limited schematic reading ability (and physically looking at the wiring), it appears to be set up literally as 49 switches turning notes on/off on all three big divider chips.

I found a couple of options; the first was the Tom Scarff 64-note MIDI encoder but it's set up for keyboards with matrix switching, so I'm not sure it'll work (there's a wiring diagram on the site, so maybe I can wire it to "fool" the interface board).

The other option seems to be the Doepfer MTC (sorry no link, but the displayed URL never changes on their site; it's the "OEM/DIY section). This converts MIDI into up to 64 +5v terminals. But I'm not sure what the switching scheme is on the Delta... not sure whether it needs to see a pos voltage or a short switch? (the ideas of wiring up 49 transistors-resistors to convert to shorting switches doesn't sound appealing).

I posted the page of the serv manual with the dividers... there's a six nine-pin plugs coming from the keyboard that go straight to the divider chips show here.

thanks,

Mitchell


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andrewF



Joined: Dec 29, 2006
Posts: 1176
Location: australia
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PostPosted: Sun Feb 08, 2009 12:14 am    Post subject: Reply with quote  Mark this post and the followings unread

I'm sure you can do it but indeed a pita.
You will have to work out the signals sent when keys are pressed and develop a cct to mimic that. Maybe with Toms midi board you can use AND or NAND gates to get the desired signal, otherwise 49 transistors and associated components, not too bad as it will just be a lot of repetition, just need a big veroboard.
At least the ext. trigger circuit already exists.

Well, good luck
would like to hear how you get on as i have a set of Delta PCBs in a box somewhere and no keyboard
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Sebo



Joined: Apr 27, 2007
Posts: 564
Location: Argentina

PostPosted: Sun Feb 08, 2009 9:28 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi:
Check the MIDIbox forum, there are people there midifiying organs that
could help you.
http://www.ucapps.de/

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Rvlt



Joined: Mar 05, 2008
Posts: 33
Location: Berlin

PostPosted: Sun Feb 08, 2009 10:58 am    Post subject: Reply with quote  Mark this post and the followings unread

I second that.

especially this threat:
http://www.midibox.org/forum/forums.html/topic,9388.0.html

I built the same circuit with 61 relays to midify my juno 6, and it worked (exept some minor flaws), but it was not cheap (> 100,- euros) and quite a bit of soldering.

I wanted to make some pictures in the next few days.

cheers.
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celebutante



Joined: Jun 29, 2007
Posts: 37
Location: Los Angeles

PostPosted: Sun Feb 08, 2009 1:23 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for the speedy replies. Will look into the links- it's pretty much like an organ, so that should help.

Andrew- it is a pretty neat synth. Obvious limitations (you can't really think of it like a real polysynth), but it makes neat noises and the filter sounds really "honky" and unique.

Mitchell
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NerveJam



Joined: Oct 26, 2005
Posts: 105
Location: United Kingdom

PostPosted: Fri May 06, 2016 8:12 am    Post subject: Reply with quote  Mark this post and the followings unread

The problem is that it's paraphonic, not monophonic.
CV/gate works fine when there's only one incoming pitch value, but falls apart when there are multiple - in this case, up to 49..

Logically, you'd have to convert incoming MIDI to 49 separate on/off outputs which parallel the actual keys. (via relays?)

Sounds like a job for an arduino? Not sure how you would control 49 separate relays though..

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NerveJam



Joined: Oct 26, 2005
Posts: 105
Location: United Kingdom

PostPosted: Fri May 06, 2016 8:31 am    Post subject: Reply with quote  Mark this post and the followings unread

Rvlt wrote:
I second that.

especially this threat:
http://www.midibox.org/forum/forums.html/topic,9388.0.html

I built the same circuit with 61 relays to midify my juno 6, and it worked (exept some minor flaws), but it was not cheap (> 100,- euros) and quite a bit of soldering.

I wanted to make some pictures in the next few days.

cheers.


404 ERROR!

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tupinamba



Joined: May 14, 2010
Posts: 24
Location: France

PostPosted: Thu Jan 19, 2017 10:57 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi !
Celebutante, I was wondering if you had found a way to midify your Korg Delta, as I would love to do that too!...
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celebutante



Joined: Jun 29, 2007
Posts: 37
Location: Los Angeles

PostPosted: Wed Feb 01, 2017 2:55 am    Post subject: Reply with quote  Mark this post and the followings unread

tupinamba wrote:
Hi !
Celebutante, I was wondering if you had found a way to midify your Korg Delta, as I would love to do that too!...


I never got around to it (one day I will!), but I believe the Doepfer MTC64 board is the best way as it converts MIDI note on/off data to up to 64 digital switches.

http://www.doepfer.de/mtc.htm

If you scroll down the page, someone shows how they used this to MIDI a vintage Solina string synth... this should apply to the Delta as well.
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tupinamba



Joined: May 14, 2010
Posts: 24
Location: France

PostPosted: Wed Feb 01, 2017 6:01 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks!
I'll have a look at the Midibox solutions as well, as I have already built several Midibox projects...
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