I wanna make a YM2612 keyboard looking for suggestions. (basically a playable genesis)
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Level 17 Mixist
post #80864 :: 2017.03.18 3:24am
  mootbooxle liēkd this
It's really early in development; I'm still coming up with ideas. So anyone got any ideas? I'll probably post new threads on the keyboards development.
Level 19 Chipist
post #80871 :: 2017.03.18 5:28am :: edit 2017.03.18 1:57pm
  RatShack and mootbooxle liēkd this
I don't know a lot of technical things about this all, but you could try and research how the Yamaha FB-01 works; it's essentially a YM2151 that's MIDI controlled.
Level 21 Chipist
post #80877 :: 2017.03.18 8:19am :: edit 2017.03.18 8:29am
  mootbooxle liēkd this
have a look at this (a YM-2151 synth):

Level 9 Chipist
post #80880 :: 2017.03.18 8:47am
  Savestate and mootbooxle liēkd this
I think your best bet is building yourself a midibox http://www.ucapps.de/midibox_fm.html

or cross your fingers and contact littlescale about the status of this http://little-scale.com/genmdm_faq.html
Level 29 Mixist
post #80899 :: 2017.03.18 12:14pm
  cyancoloneels liēkd this
I would just look for a Yamaha DSR-1000 or DSR-2000, which is built around the YM2414 (OPZ) chip, which is very similar to the 2612 in capability.
Level 17 Mixist
post #80941 :: 2017.03.18 3:32pm :: edit 2017.03.18 3:32pm
  mootbooxle liēkd this
That YM-2151 synth looks pretty cool. Despite the fact that I could just get a keyboard that does pretty much exactly what I want my keyboard to do, I want to go through the process of making one, because I think that would be pretty awesome. Maybe I could pick up the chip that the SEGA arcade uses. Also, I don't have any money. So buying a vintage keyboard is out of the question.
Level 29 Mixist
post #80992 :: 2017.03.18 10:35pm
  RatShack liēkd this
I totally understand that! DIY is awesome. But I'm just thinking it would probably be just as expensive to source the needed parts as to buy something second hand that does basically what you want.

the little scale Megadrive MIDI interface looks amazing...I would love to have that. I kinda gather that it's vaporware at this point tho.
Level 17 Mixist
post #80994 :: 2017.03.18 10:47pm
  anewuser, MiDoRi and mootbooxle liēkd this
That's not really true at all. I think I can get all the parts on the cheap, I can get a powerful enough Arduino for like $3 and a YM2612 for like $3, and my school is throwing away a bunch of old keyboards, so, I think I can get it down to < $20 easily.
Level 29 Mixist
post #80997 :: 2017.03.18 11:08pm
oh! well that's awesome. I guess I'm only used to working with analog electronics! Some freakin potentiometers cost more than that!
Level 17 Mixist
post #81057 :: 2017.03.20 12:51am :: edit 2017.03.20 2:27am
  mootbooxle liēkd this
Really? Wow, considering I could get my self a micro-controller for so cheap I would have thought that the rest of the components would be really cheap too. So now I know. Those Yamaha DSR 1000's are extremely expensive. I doubt that the entire project would cost more than that. Hopefully? I'm being optimistic aren't I.

Actually, the more I look at it, the more $3 potentiometers it looks like I'll need. How many individual sliders does the YM2612 have anyway?

Actually cheapo Chinese potentiometers seem to fit my purpose just fine, 24 * $0.30 = $7? yeah, much cheaper.

So $7 potentiometers + $3 Arduino + $3 YM2612 + free keyboard +$6 for other switches + 12V power supply I have + $10 for miscellaneous components (Resistors, LEDs, trinkets, odds and ends, that sort of thing). So total that up: 'Bout 30 bucks? I think?

Again, being too optimistic
Level 29 Mixist
post #81069 :: 2017.03.20 4:06am
  RatShack and themnotyou liēkd this
I think if you have the time and the inclination to do this, it would be an amazing project! As I alluded to earlier, my DIY experience consists of simple analog circuits, so I don't know anything about how to work with digital electronics. I do have about 25 years of experience working with FM synthesis of various types, if that's any help.

Have a look at this if you haven't already- there is some decent documentation for the YM2608 here, which is an earlier implementation of the YM2612 that required a separate DAC chip.
It also has some other extra features, but the FM synthesis and SSG seem to be the same from what I've read.


You're right, you could totally buy some cheap Alpha pots in bulk and save a ton of money. I know quite a few people who do that.
The big question is, how many functions of the chip are you trying to give direct parameter access to? Some things could maybe live in some sort of menu rather than being functions with a hands-on encoder.

Yamaha's usual way of keeping costs down was to have each function on a selection button with one or two data entry sliders and inc/dec buttons to change values.

YM2612 is a 4-operator synth, with 8 possible algorithms, very much like the Yamaha DX100 or FB-01. Unlike those, it has stereo output, plus there's the SSG sound generator (3 pulses and a noise iirc).

So at the very least, you would have to duplicate the individual parameters four times, one for each FM operator, and that's just for the usual stuff like coarse and fine frequency control, output level, envelope controls (I don't know how complex the envelopes are on YM2612, but Yamaha runs the gamut from simple attack/decay EGs to an 8 parameter setup with four env stages (level and rate control for each)).

It's so much to think about, it breaks my brain!
Because that's assuming you are just going to make Megadrive sounds in real time and play them from a MIDI keyboard.
If you actually wanted to make it function like a Megadrive, you'd have to make it multitimbral so you could have a different FM patch on each MIDI channel, up to how ever many voices the 2612 supports.

Just thinking out loud!
Level 22 Chipist
post #81074 :: 2017.03.20 7:33am :: edit 2017.03.20 7:33am
  MiDoRi, themnotyou and mootbooxle liēkd this
"...Unlike those, it has stereo output, plus there's the SSG sound generator (3 pulses and a noise iirc)..."

This is not true, the YM2612 only has the 6 FM Channels and the DAC sample playback parts. The PSG part you're talking about is actually produced by the SN76489 (on the Genesis)

That said, the YM2203 and YM2608 do have PSG channels directly integrated into the chip, but they're an implementation of the popular YM2149F, rather than the SN76489.

Hope this clears up some things.
Level 19 Chipist
post #81078 :: 2017.03.20 7:54am
  mootbooxle liēkd this
FB-01 also has stereo right?
Level 29 Mixist
post #81079 :: 2017.03.20 8:11am
  m9m liēkd this
Thanks m9m! I was making some assumptions without actually checking them. As I said, thinking out loud. :)
Level 29 Mixist
post #81080 :: 2017.03.20 8:17am
  m9m liēkd this
And you're right, RazerBlue6. FB-01 is stereo unit. I still don't completely understand how it's implemented though.
Level 23 Chipist
post #81081 :: 2017.03.20 8:34am
  RatShack, themnotyou and mootbooxle liēkd this
If you don't have $100-$300 usd to buy an old TX module, you may have trouble with the cost of the tools needed. Nevermind if you already have access to a good soldering station and dremel and such.
Level 20 Mixist
post #81084 :: 2017.03.20 12:01pm :: edit 2017.03.20 12:04pm
  mootbooxle liēkd this
This thread calls to mind my obsession with the Yamaha PSS series, specifically the PSS460/470. It's super fun to mess with the chip using the given sliders into a YM3812 2-OP. I believe it's known as the SB16/ADLIB synth!

I was thinking it might be beneficial to pick one of these up since I often see them for sale online for <$50. You could tear it open and get a feel for the components of a smaller scale FM synth and maybe even use some of the parts or use it as a shell for your DIY. The little mini key-beds on these 80s boards are pretty robust and cool! Good luck on your endeavor! Yay DIY!! \o/

Level 29 Mixist
post #81125 :: 2017.03.21 4:23am
  themnotyou liēkd this
Yay themnotyou! I've been a lifelong fan of the PSS-series myself!
The PSS-140 was my first keyboard when i was 5, then a little later I got a PSS-470 which I still have! Recently picked up a PSS-480 and a PSS-570 for $50 each last year!

Here they are!
Level 27 Chipist
post #81131 :: 2017.03.21 7:17am
  themnotyou and mootbooxle liēkd this
hm yeah creating the physical controls for programming the patches alone would be a pretty significant task… you could always flash the patches to the arduino in advance, but that seems a little like cheating / not what you're going for.
Level 10 Mixist
post #81152 :: 2017.03.21 12:05pm
  themnotyou and mootbooxle liēkd this
The YM2612 has a pretty large number of 8-bit registers... good luck coming up with an interface.

Think about coming up with a modular design, leaving the door open for additional chip modules in the future. What you're talking about designing is no small feat, might as well plan for expansion.

You might want to consider multiple MCUs, with one dedicated to interfacing with the YM2612 and a separate one that handles all the I/O. These MCUs are single threaded so they can only do one thing at a time.
Level 20 Mixist
post #81230 :: 2017.03.22 3:25pm
  mootbooxle liēkd this
Right back at ya Moot!! PSS series are so much fun! I have a little team myself!! Started with a pss-280 way back and I can't resist them sometimes for sale so cheap... PSS/FM rescue squad!!

Level 29 Mixist
post #81261 :: 2017.03.23 7:11am
  themnotyou liēkd this
Nice collection! So that's a 280, 380, 460, 680, and 780 right?
Here's a question: when I record my 480, it's really noisy and hissy on the output compared to my others. Do the others in the -80 series have this issue? (If so I imagine it has something to do with the do-everything custom IC those use having a not-so-good DAC).
Level 20 Mixist
post #81267 :: 2017.03.23 11:10am
  mootbooxle liēkd this
Thanks man! and just about! those are twin 680's in the back :P
now about the noise issue on your 480, I became curious myself so I patched all of mine in with 1/4 TRS and recorded a few seconds of each synth with power on, volume full and then followed into the units DEMO music! I also have my original 280 that has a few damaged keys so I used that one first in the demo.


The order goes: #1 280a #2 280b #3 380 #4 680a #5 680b. They all have pretty clean signal paths it seems. The only noise problem I have is with the on-board speakers of one of the 680's. The unit has an audible buzz when the volume is up high.
Level 17 Mixist
post #81322 :: 2017.03.23 11:28pm
  themnotyou and mootbooxle liēkd this
Wow guys! Thanks for the feedback. Definitely going to take all of these into consideration as I build this thing, but first I gotta get my design and tech project out of the way :/

It's like a USB but 10 million times less efficient!

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