4 Channels vs. 2 Channels

MIDIbox FM
1

Hey there!

Remembering the good old DOS games sounds and the OPL3 chip, I got myself some YMF262 and YAC512.
I also remembered the ucapps projects, which is why I’m here :wink:
Quite impressed what sounds you got out of there with the additional modulations etc.

So I wouldn’t mind being able to do both - recreate DOS games kind of sounds, and also some of the more “professional” sounding ones like in the ucapps demos.

I want to make my own project with those ICs, though. Some people here probably have experience with using, as in, creating sounds, making music, with the OPL3. So hopefully, you can shed some light for me onto this :slight_smile:

One decision I have to make is: Put 4 channels on there or just 2 channels.
Is it really worthwhile having 4 channels?
The use of that I could imagine would be, for different effect processing, e.g. piano sounds may get some more reverb, bass sounds on extra channels less… *if* I use it multi-timbrally.
But then again, 18 voices perhaps aren’t that many for e.g. an E-piano sound with holding pedal engaged, and continuing to attack new notes.
So maybe it would actually make more sense to use 2 or more YFM262 with each 2 Channels instead 4.
Or is there a really good reason to give the thing 4 channels? (you would think the Yamaha engineers weren’t drunk when designing for this possibility ;) )
Perhaps it could make sense for flexibility? I can have one piano sound with all voices for one “patch”, and although it’s put through 4 channels, the end mixer (be it some studio mixing console, or an internal  mixer I add myself) will put it all together again…, and for other kinds of sounds it’s partitioned differently?
Is this a matter of programming - i.e. having 4 channels physically present doesn’t force me to partition it all on 4 channels?)

You could guess by now that I am not very familiar yet with in what ways you can actually split the voices onto 2 or 4 channels, or what can be done in general with this chip - I could only guess by remembering DOS game music. (damn, now my mind plays WarCraft 1 theme… “dam…dam..daaaaam;…dam…dam…daaaam; duh duh duh duh duh duh duh, duh duh duh duh duh duh duh, …dam…dam…daaaam;” eh… let’s stop it right there..)
I have done very basic SoundBlaster16 programming back in the day, loooong ago, and don’t remember any of it :wink:

Thanks in advance for your input
 

2

Why do you want to make your own project with the ICs?

Have you got the necessary experience and skills in electronics / board design, and programming?

Sounds like you’ll have to reinvent the wheel!

If you do have all those skills then I guess it won’t be a problem for you.

I guess the question about 4 channels can only be answered by you and your personal needs. 

For making dos style “chiptunes” one chip should be enough but for the professional tunes it might be nice to have 2 or more. its pretty cheap to add more anyway. 

I presume you’ve seen Sauraens thread about his custom MIDIbox FM with the 4 chips?

That would be a good start to see exactly what’s involved, he did say it’s not an easy project to replicate though mainly due to his custom control surface that doesn’t have a designated single PCB.

 

 

3

>  Why do you want to make your own project with the ICs

Because I like doing things my way :wink:
From what I gathered I’d need all the MIDIbox stuff on top of the OPL3 board, which is a nice system if that’s what one wants, but I just want my little single board with MCU on it, in the format I like, and all that.
Also, I’d make it all-SMD.

You got a point about reinventing the wheel. Especially because I have other projects ^^
But as I found the ICs on ebay and no salvaging of soundblasters was necessary, I could not resist :wink:
Although the main effort for me would probably be to get into FM programming, as in, creating sounds with that obscure technique, very different from subtractive synthesis. I have zero experience with FM.
Compared to that, implementing the “CPU interface” part of the datasheet doesn’t seem that much effort :slight_smile:
Is there actually C-code for talking to the OPL3 in the MIDIboy projects? I very faintly remember having looked through some code way back, and it was some sort of assembly of an MCU I won’t use, but I may very well be confusing this with something else.
I wouldn’t say no to some head start on the driver implementation, it’s more tedious than difficult.

To get things like some extra modulators running is a relatively small effort, I have done some basic “virtual analog” stuff that I can take code from. 

As for experience, I have designed a few PCBs (less than ten, but hey, this get’s added to the list then :wink: And luckily, I know people who can tell me when I did something horrible layout wise :smiley: ).
And programmed a lot more.
 

I’ll have to look at the other project you mentioned. More important than to see a project, for me, would be to be told the experience of actually using the project!
Exactly because I do not want to make such a design in vain, only to find out later when using it “damn, I should have used 4 channels per OPL3”… But it can also be a waste, of space, for one thing, espc. should I use more then one OPL3 :slight_smile:
Just having the board made a couple times to get more would be viable if you have no, or a cheap MCU on the PCb that only talks to the YFM. But I *might* have a more powerful one on there that does more.
Well, that’s all decisions I yet have to make.
Therefore, I need . . .

4

Go for it! Be aware of the complexity it will include programming this and also the skills it takes to design it.

You have no experience with fm programming? I encourage you to learn this before you plan too much. Basically u are strating in the wrong end if u like this to happen. Many questions will answer itself as you study fm synthesis and mios system and the apps.

I wish you luck, but the people here are mostly all about mios cores so I wouldn’t expect too much effort in helping reinventing wheels. There are some skilled people here that can do all this, and if you are one of them - we will see :slight_smile:

Good luck.

5

You have no experience with fm programming? I encourage you to learn this before you plan too much. Basically u are strating in the wrong end.

Darn, I’m afraid this makes a lot more sense that I’d like it to :smiley:
Perhaps I’ll give it a shot anyway, I just have to make peace with myself that I might have to do another one later :wink:
 

6

Hi..i am a new user here. As per my knowledge for making dos style “chiptunes” one chip should be enough but for the professional tunes it might be nice to have 2 or more. its pretty cheap to add more anyway. I presume you’ve seen Sauraens thread about his custom MIDIbox FM with the 4 chips?

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