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YM3812 (OPL2) with all parameters patch-able
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page 1, 2, 3  Next [all]
Author YM3812 (OPL2) with all parameters patch-able
Reckless_Experimenter
So I want to make a module around the Yamaha YM3812 chip, without the need for a display and menu diving to get it set up. So I came up with this face plate:

There is a patch point for each knob or switch, enabling CV (or gate if its a one bit parameter ) override or all of the potentiometers.

I just sent the PCB to fab, this will be a wire to board style prototype. I'm only having 3 PCBs made, as I am sue there will be a few things that can be improved on something like this.

I will update this thread when I get the PCBs in and build the first prototype.
mckenic
Thanks for posting!

Is yours the module that was featured on MatrixSynth a few times?
The videos were very cool.

Watching this with great interest.
Spivkurl
OMG I would love to do this! I was researching this chip for a while, but got onto other projects.

I will watch this topic!
Grumble
nice! love to see or hear more about this applause
rosch
Nice!
Reckless_Experimenter
mckenic wrote:

Is yours the module that was featured on MatrixSynth a few times?

I have never been to that site, but I have heard that there is discussion of my videos over there.

Spivkurl wrote:

OMG I would love to do this! I was researching this chip for a while, but got onto other projects.

I will have 3 copies of the PCB, if there arn't any major mistakes on this version, I will make 2 of them available for sale.

Grumble wrote:

nice! love to see or hear more about this

Some more details:
All the toggle switches and adjoining patch inputs are connected though XOR logic, so that a gate input will invert the logic state of the switch.

There will be inputs for both Sustain and Sostenuto. This will allow for limited polyphonic sound with only one tone/gate input.
Spivkurl
Does this require some sort of processor programming? I like the idea of CV control for the params!

This is a euro format panel in the picture, correct?
Reckless_Experimenter
Spivkurl wrote:
Does this require some sort of processor programming? I like the idea of CV control for the params!

This is a euro format panel in the picture, correct?

Yes, the 40pin IC on the upper part of the PCB is a micro-controller, a PIC18F46K22 to be exact. It has a 10bit analog to digital converter which is the same or greater bit depth than any parameter on the YM3812. All the chips below the processor are for buffering and multiplexing inputs. All the sound is generated by the 4 chips in row across the top of the board.

This isn't my first YM3812 module, the first 2 versions had menu systems and displays. This should be a fun departure from that.

Yes, euro formate.
Spivkurl
Will the micro-controller be available? I have no experience in this sort of programming and related things.
Nick Barnard
Very cool!

I picked up some YM2612s a while ago with the view to doing something similar so I'll be following this with interest!
Reckless_Experimenter
Spivkurl wrote:
Will the micro-controller be available? I have no experience in this sort of programming and related things.

Of course. Writing the code will be at least 50% of the effort to build this project. The good news is that it only needs to be done once. And any PCB I would offer would include a pre programed chip.

Nick Barnard wrote:

I picked up some YM2612s a while ago with the view to doing something similar so I'll be following this with interest!

After a quick glance at the documentation for the YM2612. A module along the same lines would work. You would just need twice as many potentiometers/jacks, as the YM2612 has four operators instead of two.
Nick Barnard
Nice, with 4 operators might be a wee bit too busy though!
adam
might be ok, this is a software editor for one:



might be 40 knobs or so (some of those functions are done in software, so not part of the IC's functionality)
jimfowler
Nick Barnard wrote:
Nice, with 4 operators might be a wee bit too busy though!


Nonsense! I yearn for the day I can build a 4-op fm synth with knobs galore.
Reckless_Experimenter
jimfowler wrote:
Nick Barnard wrote:
Nice, with 4 operators might be a wee bit too busy though!


Nonsense! I yearn for the day I can build a 4-op fm synth with knobs galore.


If this OPL2 build works out, my next big project will be the OPL3, which is 4 operator. Actually I can hardly wait, but one thing at a time.

But sense we are talking about what if builds right now. Why not go all in and use motorized pots, so you can save settings in the most over the top way possible.
Grumble
Nick Barnard
Reckless_Experimenter wrote:

But sense we are talking about what if builds right now. Why not go all in and use motorized pots, so you can save settings in the most over the top way possible.


That's a thing? eek!
adam
ssl consoles did that i think
Spivkurl
Reckless_Experimenter wrote:
Spivkurl wrote:
Will the micro-controller be available? I have no experience in this sort of programming and related things.

Of course. Writing the code will be at least 50% of the effort to build this project. The good news is that it only needs to be done once. And any PCB I would offer would include a pre programed chip.


Sounds awesome! Looks like an amazing project!
av500
wait, the OPL2 has 9 voices, no? so you need 9 of the panels? smile
d.simon
Grumble wrote:


right...and then the quadgenesis with led-ring encoders, 3-d printed translucent buttons and led-pipes



http://wiki.midibox.org/doku.php?id=mbqg_fp
Reckless_Experimenter
Project update: first three boards are out of Fab and in the mail, I should have them Friday

av500 wrote:
wait, the OPL2 has 9 voices, no? so you need 9 of the panels? smile

Of course, and though an elaborate series of jumper wires still only use one OPL2 chip. razz It's peanut butter jelly time!
In seriousness, by using the Sustain and Sostenuto inputs, more than one note can be active at the same time. And using all 9 voices set to the same settings, you can have some really long decay times without foreshortening the sound.

d.simon wrote:
Grumble wrote:


right...and then the quadgenesis with led-ring encoders, 3-d printed translucent buttons and led-pipes



http://wiki.midibox.org/doku.php?id=mbqg_fp


Reckless_Experimenter
First run of PCBs are here, now to get soldering.
Only 437 connections on the PCB (lots of underside SMT), another 60 to the face plate and about 80 on the faceplate itself. hihi
Spivkurl
Neat looking PCB's!

Here's hoping for great initial results!
Reckless_Experimenter
First PCB populated, initial smoke tests passed.
Now to wire it to the face plate.

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