Programming the YM2612 as a Vocoder, creating loops.

saxman_52 · Post by **saxman_52** » Tue Apr 19, 2011 7:16 pm

Hey everybody, thanks for taking the time to read this.

I've had a couple of semesters of C++ and Java programming classes back in high school, but my programming knowledge is pretty low. But hopefully someone will read this who's willing to help.

I'm a sax player in college and for my senior recital I'm doing a Japanese-themed program. For one of my selections, I want to create live loops with the YM2612 as well as using it as a vocoder for my sax. I love the sounds the Genesis makes and I want harness those sounds for performance use.

I realize that this is a huge task, but I want to tackle it.

I have a YM2612 chip, a digitial keyboard that has MIDI in/out with the appropriate cables, a computer, and a desire to pull this off.

Would anyone be willing to offer input/resources concerning programming the chip and where I would even start with that? Also, what components would I need to build a circuit. I imagine I'd need a power source, something the connecting the computer program to the chip and then something connecting the chip to a mic if I want to use it as a vocoder.

I've done a certain degree of homework on this. I've printed out the YM2608 manual and I have all that information, but I just don't know what to do with it all, or even what it all means. I've also seen the YM2612 circuit vids on youtube but, again, I don't know how any of that works.

Any help would be greatly appreciated and no advice or criticism is too abrasive, so long as it's actually advice/criticism.

Thanks so much!

Chilly Willy · Post by **Chilly Willy** » Wed Apr 20, 2011 12:30 am

I seem to remember seeing someone else who made a MIDI controlled 2612.

Yeah... take a look over these:

http://chiptech.milkcrate.com.au/#smd
http://en.wikipedia.org/wiki/Arduino

mic_ · Post by **mic_** » Wed Apr 20, 2011 8:24 am

Also this (includes a schematic): http://www.arduino.cc/cgi-bin/yabb2/YaB ... 1229940069

What sort of controls does your keyboard have? I.e. could it be used for tweaking the FM instruments? Or do you want to have static instruments and just send key ON/OFF commands?

saxman_52 · Post by **saxman_52** » Thu Apr 21, 2011 11:51 pm

Thanks so much for the links!

@Chilly Willy:

I take the Arduino module and software is what I would need to connect the programming to the actual chip in the circuit? Thanks for the links; that's just the kind of stuff I was looking for! Do most homebrew circuits use Arduino?

@mic_:

Thanks for the schematic link. My keyboard is a Yamaha Portable Grand DGX-202. http://usa.yamaha.com/products/musical- ... mode=model

It doesn't have direct FM tweaking knobs. I was thinking that I would program the tracks beforehand and introduce them piece by piece into the performance via some sort of trigger, like a foot pedal.

Ideally I would also like to produce a sound from the chip using my sax as some sort of input to the chip. A friend told me though that he was pretty sure that the YM didn't have that capability since it was just an FM chip, but another friend wondered if my sax sound could be sent through a mic, into a mixer, and then have that signal be sent to the chip to produce something in real time with what I would be playing. Any thoughts on this?

While the YM-as-a-vocoder idea seems more and more unlikely, I'd be just as happy with programming tracks beforehand and introducing them layer by layer during performance. And I know I could simplify this whole a idea a WHOOOOLE lot by just using software that could emulate the YM's sound, but I think it'd be more fun to have the actual chip producing the most authentic sounds.

Chilly Willy · Post by **Chilly Willy** » Fri Apr 22, 2011 12:03 am

Well, I wouldn't say MOST, but the Arduino is pretty popular.

As to using a Saxophone to control the chip, there are things you could do, but they would all take work compared to a MIDI keyboard (as an example... I could just as easily say MIDI guitar or MIDI out from a computer). You could wire switches to all the keys, and use a mic to measure the average output to tell when and how hard you were blowing, but that would require you to do a lot of wiring and probably require something like a PIC chip. Another thing you could do is run the sound from the sax through a DSP and examine the frequency space to determine what notes you were playing, using that to control things. That would require a DSP and a controller.

The whole thing here is, if an instrument isn't designed from the start to control a digital appliance (computer, console, whatever), it will be a LOT of work to make it do so. That's why you see lots of projects using MIDI keyboards, and virtually NOTHING ELSE. The MIDI keyboard has a nice serial data stream it outputs than you can then process on the computer/console and use however you feel like.