ilmenator

MIDIbox SCE

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Hi,

this is a little teaser for my latest MIDIbox-based project: the MIDIbox SCE.

This is a demo of a MIDIbox based DIY project that emulates both PROG- and PCM-cards for the Korg Wavestation line of synthesizers. These units were produced in the early 90s. While they are not exactly collector's items, the RAM-, ROM-, and PCM-cards for these are very sought after today. The DIY project demoed here aims at replacing a RAM/ROM (PROG) and a PCM (waveform) card with a little microcontroller-based circuitry and software that allows to load the corresponding data from SD card. Of course, sound- and waveform-data can also be read from card(s) and saved onto the SD card...

This is a proof-of-concept, hence the whole thing looks quite chaotic :-). But it has the main features already and will evolve into a user project with full documentation once I have the next generation prototype boards tested.

Edited by ilmenator

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Hiya!

This is great news to us WS-ers thumbsup.png I have the old WS-A/D, there's apparently some kind of sample handling difference with the WS-SR (it uses the same format as the 01/W) instead of the common WS/M-series format, will your unit handle conversion back and forth? I've heard that there's more PCM data to be had for the SR, but I haven't come across any yet.

This is like this mythical Zadok thingy (one was on the german Ebay just recently) but with modern storage instead of floppies. What's not to like?

Now if we could only have a way to transfer our own PCM data across to the WS... There was this windows software "PCM Card Workshop" for 01/W-type cards but the site where it used to be hosted is gone...

Thanks for bringing in some fresh air into these old machines!

/J

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This is great news to us WS-ers thumbsup.png I have the old WS-A/D, there's apparently some kind of sample handling difference with the WS-SR (it uses the same format as the 01/W) instead of the common WS/M-series format, will your unit handle conversion back and forth? I've heard that there's more PCM data to be had for the SR, but I haven't come across any yet.

I had this idea in the back of my mind for a couple of years now. I started off developing this about six years ago, on the "old" core8. In the beginning I tried to implement CF card access but somehow never got it to work properly. Along the way I buried the project and resurrected it a couple of times.

I do not own an SR, but I have a A/D and an EX. The SR is probably not a prime candidate for the SCE, as it has more sounds on board already. I do not have any documentation about its PCM sound format. I would suspect that it is rather the form factor of the cards that makes the difference. Back in the day this was probably necessary to accommodate more memory in the cards, as the original WS and M-series PCM cards "only" hold 512k of waveform data.

Also, I doubt that there is more PCM data for the 01/W series than for the M1. I've been collecting the M1 PCM cards, and there were quite a few of them published. Most of them (well, most of the waveforms stored on them) work with the WS. If there was a real demand for conversion (and documentation was available), this could be handled by software on a PC. You would then save the converted set of data to an SD card and have it read by the SCE.

This is like this mythical Zadok thingy (one was on the german Ebay just recently) but with modern storage instead of floppies. What's not to like?

Now if we could only have a way to transfer our own PCM data across to the WS... There was this windows software "PCM Card Workshop" for 01/W-type cards but the site where it used to be hosted is gone...

Yes, I saw that offer as well. BUT, it came without power supply and without the connecting cable to the WS. The latter is a problem, as the SAM1 uses a PCB card with some electronics buried under a block of resin as connector to the synth's PCM slot. I guess no one knows what is inside this but Zadok. I have one of those units myself, but I would not want to ruin mine trying to scrape the resin...

But of course, everybody with a SAM1 could create PCM banks that he could provide to those using a MIDIbox SCE. Maybe that is incentive to some. I always found it quite strange to know that I would probably be the only one who could use the banks I created on the SAM1.

In that sense, the SCE is very different from the SAM1: it cannot (yet?) be used to create PCM banks yourself, it can only make "backups" of existing cards. (Or, it can be attached to a SAM1 to read PCM data coming from there.) I guess I should sell my PCM cards now, before everybody owns an SCE :devil:. I have a copy of the "PCM card workshop" somewhere on my hard drive. Just drop me a line if you are interested.

The SCE prototype you see in the video is based on the STM32 core. The next PCB proto will carry the LPCXPRESSO as a shield. The PCB design is basically ready, I just have to send it off to the "boardhouse" on the weekend. It's quite a complex board...

post-3442-0-92701700-1313134515_thumb.pn

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Haha, sell your Synth&Timeslice card on Evilbay for more money than the cost of a MIDIbox SCE thumbsup.png

The details about the cables connecting the cards to a WS A/D or EX will be interesting to see... I hope the solution won't be something expensive.

Regarding the waveform conversion on the PC side, my incentive would be to add some multi-sampled waveforms treated by real analog resonant filters. That's how it was done in the olden Amiga days! Or maybe to nick some PCM data off other old, but available sample libraries from say Roland, E-mu, Ensoniq or Fairlight for some custom shine. Then again, sample playback with decent filters can be done in a PC/Mac environment fer sure, but I like the wave sequencing plus hardware offload in certain situations.

I found the Card Workshop demo soft using the Wayback machine. Would be interesting to resurrect something similar, cross platform to use with your box later...

/J

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The details about the cables connecting the cards to a WS A/D or EX will be interesting to see... I hope the solution won't be something expensive.

Well, on the SCE it is straight forward: just use a ribbon cable to connect to a small (PROG/PCM) card-size PCB that provides the contact pads. On the SAM1 it is more complicated, I assume because of the line drivers / impedance matching. Their cable is about 80cm. I have not tried what my max. cable length would be.

Regarding the waveform conversion on the PC side, my incentive would be to add some multi-sampled waveforms treated by real analog resonant filters. That's how it was done in the olden Amiga days! Or maybe to nick some PCM data off other old, but available sample libraries from say Roland, E-mu, Ensoniq or Fairlight for some custom shine. Then again, sample playback with decent filters can be done in a PC/Mac environment fer sure, but I like the wave sequencing plus hardware offload in certain situations.

I found the Card Workshop demo soft using the Wayback machine. Would be interesting to resurrect something similar, cross platform to use with your box later...

Sure, this sounds very good! If you get it to run, you could create a 512kB (or smaller) binary and I'll try to load it and see what the A/D can do with it. Then we'll know if the PCM data format is the same or different :twitch:

Best, ilmenator

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Here are a few more pictures of the ugly prototype and development board. The transition from PIC core to the STM32 core on the way required a number of stack boards, e.g. for voltage level shift on the buses, that I had not anticipated when I had the protoboard made... As I said above, the next generation board will carry the LPCXPRESSO board - and will be much cleaner then.

post-3442-0-62462300-1313229168_thumb.jp post-3442-0-60907300-1313229172_thumb.jp post-3442-0-18516800-1313229165_thumb.jp

Here is the user interface, basically a CURSOR cross, ENTER and CANCEL buttons, as well as two dedicated FUNCTION buttons.

post-3442-0-60691100-1313229161_thumb.jp

Here is the card reader for the PROG (RAM/ROM) cards - taken from an old mini computer device.

post-3442-0-41248600-1313229157_thumb.jp

As you can see, I had to use a lot of SMD devices - on both sides of the PCB. The board would have become too big using only through-hole components. Also, some of the components in the original design were only available as surface mounted devices. But the SMD pitch used is still rather DIY friendly :smile: .

Best regards, ilmenator

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Nice, I have a Wavestation SR. However no data/mem cards. I found some usefull info explaining the differences:



  • The SR uses the same PCM cards as the new 01/W series, which have four times
    the
    storage capacity as the older cards. The program data cards are the same as
    the Wavestation, so that all of the existing program card libraries can be
    used.
  • The PCM playback chip used in the Wavestation and 01/W series treated PCM slightly different than its predecessor (used in the M1 and T-series). The interpolation technique requires 2 samples *after* the end of the loop, which the M1's PCM chip did not - so M1 cards don't have those extra samples.

So any program data from org. WS should work.

I have found the PCM Workshop software The old site has some useful info as well. I also found quite an extensive Wavestation ROM collection. However that seems to be meant for the VSTi so not sure if it's any use.

Edited by Shuriken

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This is fantastic. I will be watching this closely... suddenly I feel a need to free up a rack space beneath my WS A/D. I never owned a SAM1, and I never even owned a PCM card. So I'll build this for sure. But may I suggest your final "shield" board include a footprint for a readily available SD Card socket?

Many years ago (in the mid-1990s) I used to run the majordomo mailing list for the Wavestation. It was pretty cool seeing you scroll through old Ben Hall patches.

Nice work!

Edited by nebula

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Thanks nebula!

I remember being on the majordomo list as well - so we've known each other for longer than MIDIbox... :tongue:

The shield board will not feature the SD card socket, but a DIL socket to run a cable to a daughter board, just like on the LPC17-based core. This is because I imagine people to want different configurations of / cases for the SCE. And then it is not clear what the best position for the SD slot would be. On top of that, there is simply no more space on the board, and I do not want it to become larger - look at the KiCAD rendering in one of my earlier posts. As it is now, it has the "Euroformat", i.e. it is 100x160mm, which is pretty much a standard size. Easy to ship, easy to find a case for.

Ahh, by the way, it was exactly my intention to place this thing below the A/D in the rack. Maybe abuse an old Korg M3R? :angel:

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This is really great work! Congratulations on where you are at and I am looking forward to following this project. Love my Wavestation.

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Quote fond of my WS SR, would be very cool to breath some new life into it..

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I remember being on the majordomo list as well - so we've known each other for longer than MIDIbox... :tongue:

Yes, and we're also older than we'd probably like to admit.

Maybe abuse an old Korg M3R? :angel:

Aww cmon ... not if it still makes noise. I will admit I've been wrestling with the idea of hollowing out my old Anatek SMP-7 MIDI patchbay / Mac serial MIDI interface though.

I agree from your rendering that there is not much room for an SD Card socket. Maybe I'm being a bit lazy, but I still have found no published layout for an SD card for MIDIbox that uses an actual socket I can buy. Everything I've seen documented so far is a hack.

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Yes, and we're also older than we'd probably like to admit.

Aww cmon ... not if it still makes noise. I will admit I've been wrestling with the idea of hollowing out my old Anatek SMP-7 MIDI patchbay / Mac serial MIDI interface though.

I agree from your rendering that there is not much room for an SD Card socket. Maybe I'm being a bit lazy, but I still have found no published layout for an SD card for MIDIbox that uses an actual socket I can buy. Everything I've seen documented so far is a hack.

Seppoman made a pcb for Not sure if the actual design is available somewhere though.

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Seppoman made a pcb for Not sure if the actual design is available somewhere though.

Seppoman hasn't been seen in months, and the Eagle file does not seem to be available. If it was, I would get a couple made. I tried to PM him back in May; no response :cry:

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Saw a package containing the piano PCM card on Evilbay.

Meanwhile I started to scour my old creaky HDDs for patch banks. How to share those? Dropbox or just attach a zip? It'll take a couple more days to bring it all together. Bank God bonanza and all that jazz...

/J

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Now if we could only have a way to transfer our own PCM data across to the WS...

Forgive my ignorance, but I don't completely understand why we can't do this. Would it be really difficult to reverse-engineer the PCM card data? Or is there some other reason I'm overlooking?

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I was thinking this is a PC-side operation that requires coding up some software to round up the capabilities of this solution. Just fishing to see what comes up...

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Saw a package containing the piano PCM card on Evilbay.

The shipping costs to Norway are almost prohibitive. If one of the MIDIboxers from Sydney would be interested enough...

Forgive my ignorance, but I don't completely understand why we can't do this. Would it be really difficult to reverse-engineer the PCM card data? Or is there some other reason I'm overlooking?

Of course it would be possible to reverse-engineer the PCM format. It's only a matter of finding someone crazy enough to invest a decent amount of time into something that is obsolete :whistle: . I may already seem like such a person, and I probably am, but right now I have to get the revised prototype board made and do the documentation for what is there. And it's summer here, and everybody knows that such activities are better suited for winter time...

Actually, I think that there was quite a decent description of the format on the PCM Card Workshop site which is referenced in one of the postings above. But that was the 01/W and Wavestation SR format. The question is whether the "regular" WS and M1 share that, or if they are different (apart from the different form factor of the storage cards).

I was thinking this is a PC-side operation that requires coding up some software to round up the capabilities of this solution. Just fishing to see what comes up...

It would be easier editing the samples on the PC and putting them together to form a "set". You can do that on a microcontroller and a 2x24 display, but I can tell you it's no fun - my Zadok SAM1 offers this.

Right now, the SCE is not meant to be capable of creating your own PCM cards - that's a different beast, and may be something for the future. It can merely extract data from existing cards, store it on SD card, and read it back from there to present it to the WS as if the original card was there. The advantage of this over using actual PCM cards is that you only need the data, not the actual physical card.

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I was thinking this is a PC-side operation that requires coding up some software to round up the capabilities of this solution.

Agreed ... there's no real advantage to doing this on the MIDIbox, since the samples are most likely to be PC-resident anyway.

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So I went to download the PCM Card Workshop files, but could not get the program to run on WIN 7. As they have included a demo file supposed to be ready to use, I took a look at it with a hex editor and noticed that the header is somewhat different from the WSC cards made for the "regular" Wavestations. It seems as if the WS SR cards used a 16bit wide encoding for header and waveform names, whereas the older WS cards use 8bit.

Anyways, I put the demo file on an SD card and loaded it into the MIDIbox SCE. The loading went fine, and the SCE displays the card's name (taken from its header) somewhat correctly, but the Wavestation does not see the waveforms. It complains that there is *NO CARD*.

This makes me conclude that the PCM Card Workshop program may not be the right tool to create new PCM cards for the original Wavestations (and EX and A/D models). For this, one would still need the Zadok SAM1. Or reverse-engineer the original format and come up with a new software tool.

Best regards, ilmenator

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Back from business trip and the protoboard has arrived :frantics:

post-3442-0-78869600-1316032803_thumb.jp

I hope to find the time to solder it over the weekend. Laen's PCB service was excellent as always - thanks!

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Wow, great work! :)

Best Regards, Thorsten.

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Nice one! I've always wanted to check out the Wavestation, especially now. BTW what kind of buttons are those? They look like the same type the oberheim xpander uses.

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The board is not soldered yet - no time...

The buttons are recycled from a video editor - they are absolutely great. I forgot who manufactures them, but I think they are still available new. Unfortunately, their footprint is not compatible with the ones commonly used in MBSEQ and the Sammiches.

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BTW what kind of buttons are those? They look like the same type the oberheim xpander uses.

Just to follow up: these are Marquardt switches, model 6425 - you can find them for example at Distrelec, and they can be had with or without LED. You can also get a version that is double the width, which makes for a nice ENTER button. The datasheet is here.

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