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Custom MIDI controlled NJM2069 Project

Custom MIDI controlled NJM2069 Project

2014-09-13 by bperkins211@...


Hello all,



I could use advice/help in recreating a NJM2069 VCF/VCA circuit.


I am going to use the DW8000 service manual as a reference, since I have one of the "voice" boards from that synth to use parts from..
I might as well re use the caps from one voice to simplify things.. there's an op amp in there too..
I already have all the filter chips removed.. might as well recycle the OEM caps and anything else I might manage to desolder with useable leads.



Here's a link to a nicely scanned DW8000 Service Manual


http://manuals.fdiskc.com/flat/Korg%20DW-8000%20Service%20Manual.pdf




I'd like to know what would be a good, cheap way to get a dual/bipolar supply

Any ideas better than this?

Dual 5V Power Supply Mini Board
looks like it would be about $10 + $4shipping for one of those.






I am going to attempt to make an interface that will control a NJM2069 with a MIDI interface system..
This one..
  (I have a few of them on hand, even though they were sold out/discontinued)

MPA: MIDI Decoder with 4 Digital Potentiometer Outputs and 8 Logic Out – Highly Liquid Store


This custom controller will have a standard MIDI jack to send it MIDI msg's.
The controller will have a 4x digital potentiometer 10KOhm.
It will also have a few ports for G/+5v to toggle so I can possibly trigger/gate a  SSM 2056 ADSR I have on hand as well.



The point is to use an assigned MIDI CC msg to open/close the VCF cutoff, Resonance and perhaps both VCA's
I can also assign it to respond to any MIDI Note ON/OFF msg. to trigger once or retrigger the trig./gate for the ADSR.

I was also thinking of placing pots on the exterior of the case to control mainly the ADSR setup so it is purely analog.
Maybe a way to add a couple pots to also over ride the MIDI controls and have pure analog control of the filter CO and resonance.

Then I can create a custom VST controller (the easy part) so I can map all the controls to hand drawn waveforms and such inside a DAW.

Basically it should be able to not only control a raw input's Filtering/Resonance, but also the Volume so it can "beat sync" or Slice the input sound using the DAW's built in editing.

anyone interested in chiming in some help/advice?

~Blaine





Re: Custom MIDI controlled NJM2069 Project

2014-09-13 by ultragalore@...

I have succesfully used a Teensy to process midi messages. This might be a board you would like to check out. It's in fact a small Arduino with USB.

Cool thing is you can program the teensy to be any usb device you want. You could plug it into your computer and make it act as a midi interface (with built in NJM in this case) AND have a midi port attached to it for standalone control. On top of that you can connect pots and switches to the board.

There's already a good library for handling MIDI messages which would probably make your project a lot easier. Check them out, there are different Teensy flavours (CPU power and i/o ports differ) (but all are not expensive at all). 

PJRC Store

 




Re: Custom MIDI controlled NJM2069 Project

2014-09-13 by bperkins211@...

thanks for the comments ultragalore,


I was actually planning to use the MIDI board I linked to in my OP since I already have 3 of them...

MPA: MIDI Decoder with 4 Digital Potentiometer Outputs and 8 Logic Out – Highly Liquid Store

 


the Firmware Manual for it has a ton of info on how it can convert MIDI msg's into Digital Potentiometer and 5v Logic control.







---In korgpolyex@yahoogroups.com, <ultragalore@...> wrote :

I have succesfully used a Teensy to process midi messages. This might be a board you would like to check out. It's in fact a small Arduino with USB.

Cool thing is you can program the teensy to be any usb device you want. You could plug it into your computer and make it act as a midi interface (with built in NJM in this case) AND have a midi port attached to it for standalone control. On top of that you can connect pots and switches to the board.

There's already a good library for handling MIDI messages which would probably make your project a lot easier. Check them out, there are different Teensy flavours (CPU power and i/o ports differ) (but all are not expensive at all). 

PJRC Store

 




Re: Custom MIDI controlled NJM2069 Project

2014-09-14 by ultragalore@...

I understand you want to use the stuff you have lying around but I thought I'd just send you this board because its a small, fast, cheap and easy to develop stuff like this on.

I can imagine you can generate the ADSR on the Teensy too, like they did on a similar IC, the Microchip PIC here:
Voltage Controlled ADSR Envelope Generator (VC ADSR 7B)

 



Maybe a few IC's which can help you interface other logic to the MPA board you have (or maybe it's on there I don't know):

The ULN2003/ULN2008
darlington arrays which you can connect motors/actuators/relays on (maybe you need to trigger a sound that way)

or HC4066 quad analog switch

image-Google around for them and see what people use it for.

Sorry it's a bit fragmented tips but maybe it will you get inspired so you can solve a piece of the puzzle you're looking at.