So I got another Mirage, but this time I'm going to change it

Well, I got another Ensoniq Mirage. This time I am going to change it. So I am lookinging for any information and details people may have on it.

For starters, I am going to remove the CEM3328. If you are interested in a few, send me an offer. I am more inclined to make a small batch of hand-made Eurorack filters though. Or see if they sound better/are compatible in my SQ80 and then do the same with the CEM3379 chips.
If I do nothing else, I can just run the oscillator filter input to the amps and have 8 filterless oscillators, but I am not doing that. I am hoping to make a custom firmware with preloaded samples. I know it is feasible, but any information on how to do that would be great.

Now for the interesting part. I want to group the oscillators together in sets of 3. So osc(1+2+3) and osc(4+5+6) this leaves osc7 and osc8 open as audio rate wavetable modulators. This also leaves a lot of computer envelopes and LFOs open for routing. Crazy modular possibilities. There are 3 envelopes per voice and also one LFO per voice. I will either have to hardwire the routings or make a few logic switches with external input. This should also be feasible thanks to the Mirage expansion port.
I would also like to make the sampling input osc(4+5+6) output. This means no holes will have to be drilled into the case. That is good as it is a metal Mirage.

Now about the filter, I was just going to put in two multimode filters of my own design. I hope to get close to the C64 filter, but with stronger resonance. These filters will take the output from the amps and then run it through the filter then put it out though its own amp. This will allow for the filters to be overdriven for extra coloration.
Basically it will be two modular mono synths in one box. I could even send the modulations out via a multiplexer to CV outs if I were so inclined. A bit of smoothing and shifting would have to take place, but that isn’t too many parts to add per out.

I’ve put quite a bit of thought into this, and right now I only plan to make this a one-off project. However, interest would change that.

So any other thoughts on this project? I will say that it will take a while for me to get it done as I am only in the research phase of the project.

Seems like an extremely ambitious and cool project. I’m curious, is it really feasible to do custom firmware for these old proprietary machines?

Yes, the Mirage has no idea what is is until you load a program from a floppy.
Here is an old Transoniq Hacker that has some detals on how someone added a totally different OS that synthesizes instead of samples.
Not to mention there is currently a Mirage OS disc that can be bought that has Ensoniq wavetables and ESQ-1 like synthesis on it. I can not find the link for that at the moment. I wonder where that went?
That is part of the reason why I am posting here. Someone may have a great link to information that I don’t.

I will say that there isn’t too much in the way of propriety once you get past the floppy formatting and how the CPU addresses the analogue components.

Once I get past having the oscillators play in sync as well as loading the right samples, it is all an issue of hardware. I can even have an external CPU (atmel, arm, sharc, pick your poison) do the signal multiplexing/demultiplexing.
Once that is done, I hope to add more straightforward MIDI editing. Also, you can edit everything from MIDI with MASOS, so it is definitely feasible. The goal is to change the hardware as little as possible while changing the synthesis architecture drastically.

There a couple of great mod boards for the Korg Poly/EX-800 out there that add all kinds of functions the original synths didn’t have, and the guy who developed them is even talking about creating a whole new set of oscillators for the synth. In the end though, you arguably reach a point where you may as well just design a whole new synth from scratch, using more modern components than those available in the 80s.

The other obstacle of course is the UI of the synth. With only a 4-digit LED display, a number pad and inc/dec keys to work with, actually using the upgraded synth with all these extra, hidden functions, is painful.

The Mirage has a 2-character display, so the same is going to apply, only more so…

I’m probably being overly negative, so feel free to ignore…


These old synths are often Z80 or 6502 controlled. There’s quite a few people who can hack the code around, reverse engineer what’s what.

People manage to do similar things for complex things like SLR cameras, so an old sampler isn’t too difficult if you’re that way inclined.

That is where the Mirage expansion port comes in handy. The poly 800 has no such thing. :wink:
Also I have a lot of Mirages.

@audiohoarder Interesting, I hadn’t read that issue. I wonder if the latest MAME/MESS developments, with supposedly half-working emulations of some old Ensoniq’s, could aid the development. I’d personally like a stable OS for my ASR :slight_smile:

Anything at this point is good information for me to read. :slight_smile: So if you could post some links that would be appreciated.

I just found this resource right now. Very bare bones, but it has some good data. So I am not alone in this crazy endeavor.

This is the page that got me interested years ago. Unfortunately it mostly links to 404s. However, it still has the expansion port reference, and it is good because I forgot that early Mirages have a -12 V instead of -8V power supply. The one I have is a later serial number, so I would have been fine if I forgot.
Anyway, the expansion port gives 16 bits of data on 16 separate lines. 100mA MAX on -8V. 100mA MAX on +12V. And around 250mA MAX on +5V. Not to mention the clock output and serial input. Hooking an atmel to this should be a cinch. Or even a Z80. I do have a Microprofessor, so I can test with that, haha. I can add lots of extra stuff. There are also 4 unconnected lines, so I can add in 4 8 bit multiplexed signals of my choosing. This would mostly be for controlling hardware switches that the Mirage CPU would ignore. No need to overtax the oscillators and modulators.

At this point I think it would be smart to have the 16 bits go to a patchbay that can be patched externally. So I can have 16 sources and up to 64 destinations. I think that some hardwired routings will help in this regard so the signals don’t have to be processed by a second CPU all the time. I can also do a multiplex buffer from the serial output of the CPU too. I think that would be better for the internal routings though. I also think that the osc 7 and 8 audio rate modulators will have to have their own dedicated lines because it would be silly to not use their amp output that is in the hardware anyway. There should be enough room to slip an insulated cable past the expansion port.

The bottleneck is going to be those 4 unused pins. The more efficiently I use them, the more I can add.

After this, does anyone want to make modulars with Z80/6502 logic hardware and hackable atmel microcontrollers that interface with it? Sounds like fun to me. You would be surprised what you can squeeze out of them, and they are dirt cheap and very reliable. Well, Z80s anyway.

MESS mirage driver (not working)
MESS ES5503 chip emulation

There are some WIP on other Ensoniq machines as well, this was what originally caught my eye: Ensoniq SD-1 emulation in MESS

Still, I would love the most to have the ASR-10 working, since it is all digital. It’s not quite there yet, and sure, the emulation won’t replace the feel of the real thing.

I assume you’ve already read this

@audiohoarder I can send you the files from “Tim Victor’s Mirage Hacking” because that’s me and I still have it all. (I kinda let it drop when aol member pages went away because I suck on stringed instruments too but not as badly as I do on ebony/ivory keyboards.)

Also: gordonjcp is the man, and he’s still active with this stuff unlike me.

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@audiohoarder so you’re planning to use the expansion slot, in tandem with custom firmware loaded from floppy, to mod the machine, without modifying the internals of the sampler at all, hardware-wise? Interesting…


@Bjarne: Thanks for that information. When you said MAME I thought of Multiple Arcade Machine Emulator, but I didn’t think that group would be emulating Ensoniq gear. It does make sense as several arcade games have Ensoniq sound chips in them. I know Taito used them. I hope that my OS is stable. Besides, if this project is a boon, I could - in theory - toss an emulation on a SHARC. This would mean no hardware Mirage would be necessary. I did think about that, so it is nice to know it is already feasible.

@timv: That would be very appreciated. I will PM you my email address. Any links or contacts you have that may be interested in this project would be of great value to me. :slight_smile:

@toneburst: There are hardware mods, but it is mostly for oscillator routing. Also, I am going to remove the default CEM filter and replace them with a multimode filter with strong resonance. Also, the sampling input will become the second voice output.
Anything else that I add will not replace any components on the board. No new CPU or RAM or ROM or anything. Just the Mirage CPU talking to and receiving some data from another microcontroller. In fact, they may never know what they are talking to or listening from if I get the data types 100% modular. Basically everything talking in bits and bytes.

Well, I got a portable DOS computer by accident. It came with a NIB purchase as a bonus. So now I have a dedicated machine for writing code for the project and other floppy machines. After installing DOS and Windows 3.1. After replacing the CMOS battery too; at least it isn’t a synthesizer this time! Yay. I will also have to figure out how to get files from my main computer on to it, but that is what the serial port is for, right? :slight_smile: Anybody have a stash of 5 1/4 inch floppies they no longer need?
Who needs floppy emulation? :wink:

Seriously, me. I should not be excited about a “portable” computer weighing the same as a Mirage that runs DOS, but I am!

Actually have 3x 5 1/4 diskettes lying next(ish) to me, planning to put them in a frame with a 3.5 inch floppy in the middle…

Go for it; I don’t think shipping a few discs overseas makes any sense. It’s kind of like a little family in that configuration.

Exactly - Could add a old SD card just below it, as a sort of “look how far we’ve come” type of deal… Hrmm, we’ll see… Gotta make sure that the 3.5 “floppy” has commander keen on it though… :wink:

I have a 5 1/4" OS disk for a Synclavier. Randomly found it on the street one day.


Yes, that sounds like a plan.

Also, that is funny to find a Synclavier floppy in the street.

I have plenty of 3 1/2", but now I also have a computer with a dedicated 5 1/4"
I will have to figure out how to fit both of them in because of the huge internal drive. I can try removing that and putting in a newer one with the floppy sandwiched between it. That will be interesting. Or just remove the cover and let the IDE cable out the side. I think I am going to do that.