KORG EX800 up/down buttons as slider

MIDIfication
1

Not really a MIDI question but very related.

The EX800 is a cheap poly synth from the 80s (keyboard-less rack mount module version of a Poly 800 synth), it has a minimal midi with only dumps and pitch-bend. The programming is done by entering a parameter number (all params are printed on the front panel) and assigning a value with a UP/DOWN value buttons. Now the question is can theese buttons be replaced with a knob, if so how. I have a Evolkver synth also that has theese endless rotary controllers that are not smooth but they “jump” a little when turning them, the whole synth (both the evolver and the korg) are digitally controlled.

Are there any knobs that would fit into the Korg to make the programming better, a knob would be amazing.

I have a SCI multitrack where the programming is similar, one knob and an array of params, but it works nice. So doing the same in the korg would be great. I will be looking inside the korg soon to place 3 knobs for the filter cutoff/resonance and dco->cutoff, as described in the Moog Slayer Filter mod for the EX800, so i can give any info on the parts used. Any help is very welcomed.

2

This should be do-able.

You would need to run an interface between the encoder and the existing circuitry in the Korg.

I would suggest you do this with a Core module, a DINx4 module (would allow you up to 16 encoders), and a DOUTx4 module connected to JFET devices or similar to “simulate” the buttons on the Korg unit.

Hope this helps a bit!

3

You might not need the DINx4 module, if you can make a DINx1 on a breadboard, and you could even use PIC pins to drive the switches. I’d suggest using a 4066 to drive the switches.

If I had the need to do something like this, I’d probably go one step further and not bother using MIOS at all… just write some custom code for a PIC16F88 or something similar, and cut it down to just a small PIC and a 4066, driving both off the internal +5v supply. But if you have plans to do anything more than drive two switches from one encoder (or can’t program assember that well), you should stick to using MIOS.

4

Good point. MIOS would really be overkill for an application like this. Come to think of it, most of the 18F family of PICs would be wasted on so simple a mod. My suggestion was for the simplest coding scheme for someone with limited experience. As far as I remember, the 800 series were a very simple interface, where you would enter a parameter number 11 - 88 (octal, not even close to 89, or even 64 parameters), then modify the parameter using up/down buttons. All that would be required here would be a PIC with a simple application.

(this direction means this output for timeout period, multiple clicks mean this many discrete output toggles) 

The parameter numbers would be difficult to enter using an encoder, since I’m not sure how the panel was scanned. The other mods mentioned (filter cutoff, reso, DCO->filter) would all be performed in the analog realm, replacing onboard trimmers and fixed resistors with panel-mount pots.

5

hello

i have the korg and mods …i can say it’s much far away from the original but not more better in use because sometimes it’s like an handicap to have analog pots on every presets…

it is possible to make a midibox with encoders of all midi parameters an have a totall recall when a preset is change in midibox ?

maybe a stupid question :-X

thank you

6

I once read a simple way to replace inc/dec buttons with a rotary encoder, because I was interested in doing the same thing for my EX-800.  I don’t remember the exact way it was done, however.  I seem to think that the encoder was made to rely on the logic of a flip-flop to output a straight inc/dec.  In fact, if I’m not mistaken, it may be an old “unsupported” one of TK’s old articles.

As far as using a pot:  there would be no way to do this without modifying or rewriting the EX-800/Poly-800’s firmware.  This is something that *has* crossed my mind, because it would benefit thousands of synths - and unlock a whole new set of possibilities on a pretty cool old model.

7

UPDATE – I just did a bit of research, and it seems one individual has had some success in disassembling the EX-800 code.  He’s working on a whole bunch of new features, first for the EX-800, then later for the Poly-800.  This would include MIDI CC reception of synth parameters, and other ways at getting at your patch via MIDI.

It looks almost like a Poly-800 version of Europa.

Link:  http://patrioticduo.tripod.com/korgpoly800ex800mkiii/index.html

(I checked the Poly-800 group on Yahoo, and this appears to be current)

If this is true, the addition of a pot/slider as a data entry control could be a trivial task.

8

thats great, however the EX800 has a clone.. the SIEL EX80.. and i would be most interested in encoders working like this.. with the flippety floppety thing.. dont wanna sacrifice a whole core or even a pic to this. i like it simple..

however if people have cracked this firmware too, that would be to die for..

9

hi everybody!

i’m jumping in because i may have some interesting info about this, or maybe i am a bit misinformed myself, hear me out..

The korg EX800 has a lot of family..

big brother: Poly 800 (korg)

cousins from italy: DK80 and EX80 (siel)

and the little known half sister, lives in japan: SX-500 (suzuki)

i was thinking the basics of these machines are similar (especially the ex800/ex80/sx500)…

assuming this is true, i have some information which will you find useful;

the Siel EX80 and the Suzuki SX500 (which i own) have midi implementation of all parameters! it wasn’t easy to find but there is a midi CC# implementation chart on this SIEL website..

http://home-1.worldonline.nl/~smeyer/siel/

so if you set up a midicontroller or build a dedicated one for this machine, you can control all parameters in real time

i don’t suppose the korg is the only one in the family which lacks this feature?

it is possible to make a midibox with encoders of all midi parameters an have a totall recall when a preset is change in midibox ?

so yes i think it is possible to just make patches for this machine with a midibox64(E) in patch mode, but if this is all true; i don’t really understand what these guys are up to:

it seems one individual has had some success in disassembling the EX-800 code.  He’s working on a whole bunch of new features, first for the EX-800, then later for the Poly-800.  This would include MIDI CC reception of synth parameters, and other ways at getting at your patch via MIDI.

(i havent read everything properly so probably i just missed the point) (+_+)

i have the korg and mods …i can say it’s much far away from the original but not more better in use because sometimes it’s like an handicap to have analog pots on every presets…

i don’t share this opinion; i did the dragon slayer mod, and i love it! especially having resonance up to self oscillation (and more)… sonic mayhem!!

for me having (non midi) analog pots on a midi controlled device is great; use one midisequence (you can even use cc# for filter cut and/or res) and offset it with the pot

one thing though, i remember the tutorial for doing it was for the korg (or siel) and i had to do it a little different on the suzuki

cheers, marcel

10

just a quick post.. the suzuki and siel are basicly the same.. the korg is a different beast however..

11

Wisefire

you’re right

i have to say that the dk80 has 2 voices , the ex 80 has 1

i will post pics of inside if you want. the korg is same architecture but not same mainboard …

12

Link:  http://patrioticduo.tripod.com/korgpoly800ex800mkiii/index.html

There is a new blog entry dated Oct. 20, in which this fellow indicates is going to get a small run of circuit boards made.  I emailed to let him know that I’m interested in buying one for my EX-800.

13

I found the flip-flop answer, I’ve set it up on a breadboard, trying to get this to work right!

Link: http://www.vias.org/feee/counters_04.html

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14

thank you Nebula …

let us know about this “tip” i could be usefull for so much machines :wink:

15

Needs a denoiser / debouncer

Suddenly that PIC is looking like a more practical alternative … I could use TK’s encoder-handling code and get the added benefit that it senses how fast it’s being turned.

BTW That firmware update project is finally seeing the light of day … if you haven’t recently visited the site I linked above, check it out!

(FYI the name has not been very specific about my request to add an encoder for editing values)