jaytee

Using Midiphy eurorack modules with MIDIbox SID

8 posts in this topic

Wasn’t sure where to post this, but decided to put it here since the Midiphy modules don’t have any visibility here. Also, just wanted to tag @latigid on to make sure he sees this.

I’ve always wanted to add CV/gate to my MB-6582. The new Midiphy eurorack modules that got posted about today seem...pretty ideal, eh? It seems like I would need to build and hook up the three eurorack modules (an AOUT, a DOUT, and a line RX), run a DB25 cable from the line RX to a line TX installed on the DB25 in the MB-6582....

And that’s where I’m at. Not sure how to hook up the line TX to the MB-6582.

Anyway, I was hoping to get a general discussion going on this topic. I can’t be the only one who thinks integrating the MIDIbox SID engine into their modular sounds really rad. Hopefully we can figure out the hookup details, iron out any issues, and put together a tutorial for others who want to make this happen.

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Seems like it should work:

http://ucapps.de/midibox_sid_manual_cv.html

I thought the 8 gates would be on J5s, but apparently you can also assign them to a shift register. This means that you can use the J89 on the LineTX, I guess connected to the end of the SRIO chain. You would probably need to build a new firmware .hex file.

J6 on the MB-6582 would connect to the J19 header on Line TX. The pinout is different but you can use flying wires or DuPont cable/hot glue.

Seems like the Line TX should fit in the Pactec case. If it hits the CS PCB, then you might find another location for it and use the alternate 26-pin IDC header with a corresponding DB-25 ribbon connector. 

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Alright, that actually seems easier than I expected. I did expect I’d have to rebuild the hex file...I’ve used modified firmware once before on my sammichSID; was years ago but if I figured it out back then it can’t be too difficult to manage.

So, as far as things go that I still have to figure out (this list is more for my own benefit so I don’t forget)

* Which pins on the MB-6582 correspond to the shift register chain? (I’m guessing the PIC Core8 documentation is what I want to look at here...or should I be looking at the SID-specific documentation?)

* How does the pin arrangement between J6 on the MBSID need to be rearranged in order to connect to J19 on the LineTX? (It seems this is the relevant documentation.)

* How to cram the line driver into the PAC-Tec case? I think there’s a decent chance it’ll fit connected directly to the DB25 port on the back, but as you mention, that’s not the only option. I’ll have to figure this one out once I have everything on-hand.

So all in all, this seems to be not so difficult now that Latigid (I assume?) has done all the hard work of designing the eurorack modules themselves. Score one for the modular nature of MIDIbox; really cool that a solution built for one project translates almost seamlessly to a completely different project.

Thanks so much for the quick help here. I eagerly await the release of your new eurorack modules. MIDIbox SID might be kind of an odd application for them, but the way I see it, the MB-6582 should be able to stand in for all sorts of CV-generating modules, to say nothing of integrating some SIDs into my analog setup. Super cool.

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To answer some of my own questions...

On 3/31/2019 at 6:28 PM, jaytee said:

* Which pins on the MB-6582 correspond to the shift register chain? (I’m guessing the PIC Core8 documentation is what I want to look at here...or should I be looking at the SID-specific documentation?)

It seems like J8/J9 are the relevant headers here, near the lower left of the board. Not to be confused with the core-specific J8/9 headers, I guess.

On 3/31/2019 at 6:28 PM, jaytee said:

* How does the pin arrangement between J6 on the MBSID need to be rearranged in order to connect to J19 on the LineTX? (It seems this is the relevant documentation.)

Looking over the documentation I linked to here, along with the Core8 documentation, this seems pretty straightforward. Do I need to connect both J6 and J7?

On 3/31/2019 at 6:28 PM, jaytee said:

* How to cram the line driver into the PAC-Tec case? I think there’s a decent chance it’ll fit connected directly to the DB25 port on the back, but as you mention, that’s not the only option. I’ll have to figure this one out once I have everything on-hand.

Again, real confirmation will have to wait until I have PCBs and components on-hand, but I’ve been looking through old build photos of my MB-6582 and it seems it should fit on the DB25 connector no problem. Worst case scenario, I may have to solder the driver chips directly to the PCB instead of socketing them in order to reduce component height, but I doubt this will be the case.

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I’ve been brushing up on the MB SID documentation and perusing the setup_mb6583.asm file and the modifications I need to make to the code before recompiling a new hex seem pretty well laid-out, which is nice.

However, I’m having a bit of trouble wrapping my head around the patch-specific analog out settings vs the ensemble-specific analog out settings. It seems that multiple (conflicting) parameters can be forwarded to a single analog out—how is this handled? For instance, if I have K2A set up in the asm file to go to CV1 and turn this on in the Ensemble menu, and then also set up an LFO to output to CV1 at the patch level, what takes precedence? Or are they summed?

For that matter, what happens with conflicting ensemble settings? You seem to be able to assign multiple x2A functions to a single CV out in the asm file (and in fact it is set up this way by default). Or you also seem to be able to assign multiple SID cores to a single CV out from the ensemble EXT menu, though of course they could be (almost always *are*) sending conflicting data. Again, what is the expected behavior in these situations?

The answers to these questions will influence how I end up setting up my CV outs. But additionally, I’m curious if anyone has any “recommended” setups/assignments that they like to use for this?

Ultimately, I’m hoping to accomplish four main goals from adding CV to my MB-6582.

1. I want to integrate the MB-6582 into a modular setup (ie, control external filters and oscillators, trigger external envelopes, etc). This seems like it could be done at either the patch or ensemble level, depending on what precisely I want to do.

2. I want to use the MB-6582 as a basic MIDI-to-CV device. Pretty straightforward. Seems like it’s best to do this at the ensemble level, using K2A or O2A.

3. I want to use the MB-6582 as a bassline sequencer for analog synths. Basically use the Bassline engine to get 303-like sequences from other synths. Again, seems best to use the ensemble settings for this?

4. I want to use the MB-6582 as a modulation generator for analog synths. In other words, use the Lead engine mod matrix to  send LFOs, envelopes, and other CV to other synths. Not as immediate as having dedicated modules for these functions, but OTOH, very deep and complex modulations should be possible and it seems like kind of a Swiss Army knife for situations when I find myself just one envelope short of the patch I want to build, etc. Seems this has to be done at the patch level.

Is it feasible to get all four functions from a single MB-6582 without swapping back and forth between different modified asm files? I don’t necessarily need all four functions simultaneously (would be nice I guess but speaking realistically I’ll probably only be doing one at a time), but I don’t want to be constantly reuploading slightly different firmwares to swap between AOUT setups.

Any guidance is much appreciated. (Hopefully @TK. can chime in, I’m not sure there are many others with any experience adding CV/gate to MB SIDs.)

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Posted (edited)

Bumping this thread again now that the modules are available. Anyone familiar enough with the MB SID CV/gate outputs to know how potentially conflicting assignments work? Any other insight re: the questions in my last post?

I guess I can always build the modules and just see what happens but it would be nice to have some idea of expected behavior.

Edited by jaytee

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Hi jaytee,

am a bit restricted on time at the moment with all the ongoing documentation, but just wanted to tell you, that i am with you and will try to replicate your setup a bit later on, if you manage to get it going!

As we are using a normal AOUT implementation with MAX5500s and standard DOUT digital gates, i hope it should work somehow with the MB6582.

The SSM2044 bassline demos here sound too awesome not to try: :)

http://ucapps.de/midibox_sid_manual_cv.html

- and we should be able to do this in "modern" eurorack world now, i'd be really keen to combine a SID stereo pair with a pair of Polivoks filters :)

Have a good time and best regards!
Peter

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Thanks for the encouraging words! I feel like it *should* pretty much just work, but of course I’m sure there will be some hiccups along the way. 

I think the Bass Engine will be particularly fun with CV and gate outputs. Lead engine seems like it adds basically an entire rack of modules to a modular system.

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