Questions about Design

[PmCimini]

Hello there, first poster here, but long time reader... :ahappy:

In a brief introduction, I am a guitar pedal solder jockey, but I have only programmed PICs while in technical school... I know basic to intermediate Java, but I am totally new to MIDI programming.

Either way, earlier this year, I've decided to build an analog synth. I decided to use primarily MFOS' SoundLab MiniSynth Plus as the analog system, with some modifications. I bought a broken small kids' keyboard in order to get the keys from it, and make it a keyboard-integrated system. However, when I received the keyboard, I realized that the keys are very small for reliable play. Even so, I thought it would be hard to get a good set of keys (velocity-sensitive), and these keys would give the synth a "toy-like" feel, but, for live play or sequencing, I would rely on another system to control it. Originally I thought about using an analog keyboard CV controller, but since I realized I would end up needing MIDI, why not also implement the keyboard controller digitally? It would simplify things a lot... And still in this thinking process, I also thought that if I am using a whole MIDI system, why not also implement a sequencer and some MIDI controls in it? It would all end up in a single core, and it would become a "MIDI Controller/Analog Synth" kind of thing. I made this concept drawing some months ago.

The problem that I face now is the following:

I think I've decided to dive too deep into something that I am not familiar with. Would it be really hard to adapt and join pieces together to write a program that would take care of all these pieces? An x0xb0x-like sequencer, a MIDI controller and a MIDI-CV converter, to run the synth itself?

I mean, this project was on halt for a while, and right now, I am thinking that taking off all the MIDI features and simply using an analog keyboard controller, and a MIDI-CV module (this one is completely documented) would be a LOT easier than programming all of this.

Also, for the regular players out there, how useful, in your opinion, something like this would be? Or would it be better to make something as a MIDI-controller separate from the Analog Synth (however, I would still want the sequencer to be embedded into the synth itself).

Anyway, I am really looking for some veteran opinions on this. Thank you in advance :frantics:

[Hawkeye]

Hi and welcome!

Your design looks nice and may be the thing of choice to build, if you have severe space restrictions.

But.. if you have room, I would recommend to go for separate units (bought or self-built), as this simplifies things enormously...

Pursuing a modular MIDI concept allows for nice separation of responsibilities and more easy extendability... you can buy or build launchpad-style midi controllers, build a well-designed and very stylish looking wilba-style mbseq v4 (with cv-out) and extend this with a bought good midi master keyboard with weighted and proper-size keys...

Bye,

Peter

Edited December 12, 2010 by Hawkeye

[nILS]

I like it. Really.

There's a few things you need to consider imo:

A) Cost. This is gonna be pretty damn pricey.

B) Component spacing - partially the components seem closer together than physically possible (faders), some seem to close to use (pots). A printout helps - put the knobs you wanna use on the printout and pretend to be working with them :)

C) Single-Core. Since you need a custom app anyways, I would probably not worry about making it all run on a single core.

D) Arrangement of components. Typically people prefer to play keyboards with the right hand. That's why I think the keyboard should be the right-most thing.

[PmCimini]

Yeah, considering the comments, I'd like to say that the electronics side isn't a problem at all... All the spacement between components is correct, and I am used to designing very cramped boards... About the price, I also already have most of the components bought. The case will be laser cut acrylic, with bent sheets on the sides. That won't come out that expensive either.

The real issue is on the programming side of things. I have no idea on how to write a custom firmware to run all of these functions... Thats why I posted here, as Hawkeye said, I could simply build a v4 seq, to take care of the sequencing, and a MIDI-CV, to control the analog synth... However, I wanted to implement most of these funcions in a single package.

Either way, another thing that I thought about (mainly because, as stated before, the keyboard is very flimsy, and shouldn't be used for real playing), is to take out all of the MIDI features, and leave it simply as a MIDI-controlled analog synth (maybe with a simple, x0xb0x-stlye sequencer included). This way, it would be more of a musical instrument, and wouldn't control anything. However, I would still need a core, to control the MIDI-CV.

So, some questions about this new concept are:

Is the LCD (and the buttons) necessary for MIDI-CV configuration/playing? I wanted to leave something with no digital controls...

Also, the MIDI-CV page says that it can control 8 12-bit CV-outs. How can this be achieved with the AOUT_LC? I could see it being 4 12-bit outs and 4 4-bit outputs, but could I theoretically achieve 8 12-bit outputs, using 12 74HC595 ICs, instead of 8?

Thank you

[nILS]

Yes, you'd simply chain more shift registers. I am pretty sure I wouldn't wanna go with the LC though.

You can technically use the mbCV w/o an LCD. For instance by adding lotsa buttons and LEDs (which means more coding) or not changing the parameters a lot.

[PmCimini]

Yes, you'd simply chain more shift registers. I am pretty sure I wouldn't wanna go with the LC though.

You can technically use the mbCV w/o an LCD. For instance by adding lotsa buttons and LEDs (which means more coding) or not changing the parameters a lot.

I gave this a better thought today and I realized that what I was really looking for was something as a x0xb0x (MIDI sequencer + Analog Synth + MIDI-CV interface) in combination with a MIDI controller. The thing is that I feel that I am not ready for designing my own project as of now, and I guess I never really looked into the MIDIbox seq because to me it had no use since it didn't make the sound itself, but I see that it is a very powerful tool, and if you embed the 8 CV outs, it would take care of all my sequencing needs for a while, instead of my PC's own MIDI out capabilities... But seeing it this way, I would end up with three separate units: A sequencer (lets say the seqV4, with the CV-out module), the synth itself, totally analog with CV/gate inputs, and a MIDI controller. However, could I (or should I) integrate this MIDI controller to the MIDIbox seq? On its page, it's stated that no AIN would be used, which means no faders.

In a sum, what I am trying to get is a system like Thorsten Klose's, when he uses a Korg microKontrol to control some attributes on the seq...

[nILS]

If you're good at coding, I am fairly sure you could get all that functionality out of a single core32. You seem to have a general misconception about what happens if you don't though - using multiple cores to make the whole thing easier doesn't mean it'll be "separate boxes". In your PC, there's a whole bunch of processors, and you don't think of it as different units, do you? Once boxed up, the cores can act as a single system. I am simply suggesting that cause it'll make the programming so much easier if you can split the different tasks that you want done across different processors.