Orgia Mode
Offline
Sea of Souls

I was thinking of making a diy kit that mimics the gameboy's 4 sound channels. Either a series of modules, or one huge module including two Pulse VCO's, a noise generator and, of course, an 8 bit sample player.
Aside from the WAV module which would use a DAC, the modules would be entirely analog. I am sort of torn between making the modules "closely" authentic or "more" analog. I would incorporate quantizers to make inputs "stepped" like the GB's digital registers are, but some of the "stepping" is incredibly small such as the pulse width of each pulse channel or the WAV's volume playback. And there are also no filter to speak of, so I am unsure what to add or overlook.

Pulse 1 & 2 Modules:
Frequency CV input
--- Would allow for FM and sweeping
Pulse Width CV input
--- fixed to 4 widths or analog?
Envelope/VCA
--- ADSR, AR, stepped? Analog?

Sample Playback Module:
Playback rate CV
???
SD card with samples?
8-sliders to draw sample?
Envelope/VCA

Noise Generator
Analog or psuedo random number?

Other components:
USB to +/-12v inverter board
USB MIDI to CV converter
???
---------------------------------------------------------------

I want to hear what everyone thinks, whether you have played with a modular or not.

Should it be one module, or 4+ modules? What kind of user interfaces a do you prefer in a live synth?
Minimal inputs, or extras like Exponential/Linear Frequency modulation?
Any filters/ring mods/ wave shapers, or leave it authentic?
Stereo...?

Last edited by Orgia Mode (Dec 16, 2019 8:45 pm)

rumpelfilter
Offline
Italy

Once in a while I try to build a modular that could work as a chiptune system. I've gotten a few chiptune-ish things in my rack over the years: SID Guts, Edges, some Atari Punk Console things, Equation Composer and the VCNoiz/VCNO.

I do like your idea quite a lot.

I want to hear what everyone thinks, whether you have played with a modular or not.

I do have quite some:

One of the beauties of working with something like a Gameboy is that it's a closed, self-sufficent ecosystem, quite unlike the modular, which is never really closed. I think that what you described above would make more sense as a semi-modular desktop unit. The patchability would be most interesting for self-patching, but would also open it up to talk with other modular and semi-modular instruments.

Self-patching is quite an important aspect here I think, and this would make this quite different from the Gameboy experience.

Also, this is a central point IMHO. Don't try too hard to emulate the Gameboy, since this would be a completely different thing anyway.

You'll also need a mixer and it would be interesting to also have some LFOs and a S&H.

The EG/VCA could be its own block. Maybe a 4ch AD/AR envelope with VCA. I find the way they did it on the Moog Mother 32 quite well done. It's an AD/AR where you toggle between the two behaviours by enabling/disabling sustain.

I would try to add as much CV as possible and add CV outputs to modulation blocks.

A central question here is of course sequencing. Should it be on-board of rely on external gear? Both approaches are possible, but perhaps the latter would make more sense. Even though having an onboard sequencer would make this more standalone. More like an instrument.

---

to reply to some of your questions:

fixed to 4 widths or analog?
Not a huge DMG expert, but I'd say analog. I don't see the huge benefit in keeping this true to the original.

SD card with samples?
Absolutely! You'll want to make it really easy for people to add they own samples and I guess adding an SD slot is easiest to do.

Analog or psuedo random number?
I'd be in favour of peudo random, mostly because it's one of those things that define the chip sound.

Dark_Bit_
Offline

I have no clue how to build any of this, but I'm super interested!

Orgia Mode
Offline
Sea of Souls
rumpelfilter wrote:

One of the beauties of working with something like a Gameboy is that it's a closed, self-sufficent ecosystem, quite unlike the modular, which is never really closed. I think that what you described above would make more sense as a semi-modular desktop unit. The patchability would be most interesting for self-patching, but would also open it up to talk with other modular and semi-modular instruments.

Keeping it all self-sufficient sounds really great but that would require a sequencer and logic modules to make sequences more interesting and then people will want to save their sequences to the sd card ... etc. lol
I thought adding a MIDI to CV interface would make the system accessible to everyone, but keep it completely patchable. 

rumpelfilter wrote:

Self-patching is quite an important aspect here I think, and this would make this quite different from the Gameboy experience.

Also, this is a central point IMHO. Don't try too hard to emulate the Gameboy, since this would be a completely different thing anyway.

You'll also need a mixer and it would be interesting to also have some LFOs and a S&H.

The EG/VCA could be its own block. Maybe a 4ch AD/AR envelope with VCA. I find the way they did it on the Moog Mother 32 quite well done. It's an AD/AR where you toggle between the two behaviours by enabling/disabling sustain.

I would try to add as much CV as possible and add CV outputs to modulation blocks.

A central question here is of course sequencing. Should it be on-board of rely on external gear? Both approaches are possible, but perhaps the latter would make more sense. Even though having an onboard sequencer would make this more standalone. More like an instrument.

If the unit is to be self-patchable, then it will need LFOs, envelopes and several S&Hs which is good and all, but at some point it just becomes more of a basic modular with 4 super limited oscillators. I feel like if I move away from emulating the gameboy, then the whole project is defeated. I've designed everything listed here already, but nothing brings them together with a strict theme. 

rumpelfilter wrote:

to reply to some of your questions:

fixed to 4 widths or analog?
Not a huge DMG expert, but I'd say analog. I don't see the huge benefit in keeping this true to the original.

SD card with samples?
Absolutely! You'll want to make it really easy for people to add they own samples and I guess adding an SD slot is easiest to do.

Analog or psuedo random number?
I'd be in favour of peudo random, mostly because it's one of those things that define the chip sound.

Here's one of my main concerns. "Where" do we draw the line between authentic and analog? If we keep the noise generator authentic, how come we wouldn't want the pulse channels authentic too?
Granted, yes, the pulse widths are very limited but we can't really use an argument saying that one aspect defines the chip any more than another. In all honesty, I have to agree that I want analog pulse widths and PRNG noise. There are a lot of complaints I have with the DMG CPU and the amount of unused data registers and register bits which is a large part of my inspiration. tongue That and Trippy-H.


-------------------

I guess my main concern is without a set of strict rules to keep this "gameboy inspired" it can very easily lose track of the original view and just become another beginner's diy kit.
I think I am going to look more closely at Trippy-H.

rumpelfilter
Offline
Italy

I thought adding a MIDI to CV interface would make the system accessible to everyone, but keep it completely patchable.

I do think that it's a totally viable solution. My point was more "it would be cool if", but I do think it would be a great thing even without the sequencing part.

"Where" do we draw the line between authentic and analog? If we keep the noise generator authentic, how come we wouldn't want the pulse channels authentic too?

that's a totally valid concern, though I have the feeling that what we consider "authentic" is just a cultural product. I think the music made with the Gameboy defines what is "authentic" much more than the device itself. After all, nobody at Nintendo had designed the device with the chiptune scene in mind I guess...

I would not focus too much on the technical aspects but more on the sound and the workflow. How do you make a modular or semi-modular instrument which does capture the sound of the Gameboy, and how do y ou design a workflow, which feels close to a chipmusic one? Chipmusic has always been a lot about making things with very limited tools, mosly in-the-box, where the box was some form of vintage computer or console. It's always been about working with the chips, trying to find the sweet spots, the bugs, the idiosyncrasies and using those as creative tools.
Keep in mind that most of the things you mention above exist already, and in multiple variations. No need to reinvent the wheel. The only thing missing is probably the sound generation. If you want to stick to a more modular approach why not just create a quad sound generation module that does square, noise and samples with a distinct DMG flavour?

BibbieMok
Offline

Hi....I would suggest you get a pair of much smaller wire cutters. Preferably with one side almost completely flat for close trimming.
Also, it's generally a good idea to fit and solder small groups of components, rather than all at once. You should start with the smallest and most robust ones.

prototype pcb assembly

Last edited by BibbieMok (Apr 24, 2020 7:02 pm)