AKAI PC-S56USB card full metal bracket: What's next?

 

Here is the continuation of my previous post...

So, I’m finding myself a bit stuck with this bracket situation. I decided to go with a different solution: a faceplate made out of epoxy that I developed using KiCad. This option will be much cheaper and just as functional, but it will require more work. That's because I need to implement a fastening system to accept a screw, and epoxy isn't designed for that.

In any case, here is what the printed circuit board that will serve as the bracket will look like:

 

 

Presented like that, of course, it doesn’t look like much. But anyway, it will look completely professional once mounted inside the S5000 chassis.

Also, something that doesn’t happen very often: a reader of my blog, who is interested in my card, offered to help me make this metal bracket. For now, I don't know what price will be proposed, but I hope it will fit within the maximum budget targeted for this project. In fact, I've set up a small poll that you can find on this page in the top right corner.

In any case, I had to get back into 3D design. I hadn't used FreeCAD for a few days, and honestly, looking at the main page again, I told myself I absolutely had to find another tool, otherwise I was going to end up having a nervous breakdown!

For the past few days, YouTube has been pushing SolidCraft on me. I hadn't given it a shot yet. A new, free thing? To me, that usually means "bug-ridden" and bound to be paid for in some roundabout way, like ads, registration, or even worse... But hey, since there's a web version, I figured why not finally give it a try.

And I did try it. Forget about the web version. It works, but it bugs out. Not necessarily SolidCraft itself, but I could definitely tell it was asking a bit too much of Firefox, which I was using at the time.

But after playing around with it for a bit, I quickly realized that we are on a completely different level in terms of interface compared to FreeCAD. And so? I installed the desktop version. Although the logic is pretty much the same as FreeCAD, there are still some differences. Where FreeCAD is just a very basic interface for the part, SolidCraft goes a step further and caters more to the designer, rather than the turner/miller who will end up actually manufacturing the part. That’s more what you expect from a software product: actual help, not just a simple interface. Anyway...

So, here is what the part looks like, first as a sketch and then in 3D. The sketch version looks impressive. I know, it’s like a peacock: it’s useless, but it looks fancy in a castle courtyard.

Just to point out that it’s actually not that cluttered, and all the dimensions are directly visible on the drawing. Just that, compared to FreeCAD....
 

 The 3D model is a lot more satisfying...

The magical moment: since I set SolidCraft to mm and I also use this unit in KiCad, I can check that this newly designed bracket fits perfectly onto the USB card:

I have to say that with SolidCraft and KiCad, going from a modification in SolidCraft to visualizing it in KiCad is almost instantaneous. It's still a manual step for now, requiring just 2 or 3 mouse clicks.

To make positioning this bracket easier, I placed a small alignment mark to line it up with a specific spot on the PCB. Because the main difficulty with this type of design is that it involves two different reference points. First, there's the positioning relative to the mounting holes on the S5000 rack, and then there's also the positioning relative to the mounting points and the USB port on the card itself. The risk of error is far from negligible. When you factor that into the equation, paying €300 only to receive brackets with miscalculated dimensions, well... Sure, it's "part of the job," but still!

Well, that’s all for now. I hope I’ll be able to make some metal prototypes, otherwise it’ll be plan B: using the PCB pieces.

AKAI PC-S56USB card full metal bracket?

Quite simply, way too expensive. 

I am going to make this part using a printed circuit board. Given the price of the metal version, I have no other choice, otherwise the final product will be way too expensive.

AKAI PC-S56USB card.

To properly finalize the development of this board—which is a modern clone of the original AKAI card—I need to create the metal mounting bracket for the rear panel of the S5000 rack.

In theory, the card can sit securely in the machine without this metal cover. For now, that’s the case for me. Indeed, the card retention system inside these AKAI units (S5000/S6000) is so well designed that expansion boards simply can't move around. Still, for the sake of proper finishing and EMC compliance, it's better to carry things through to the end.

So, I had to dive into 3D modeling. Since I didn't want to spend a fortune on professional software solutions, I naturally had to fall back on open-source options. That's how I (didn't really) choose FreeCAD. I'm using version 1.1.4.

Well, there’s certainly a lot to be said about using this software. While it isn't overly complicated, nothing about it is straightforward either. Overall, it feels like an archaic solution, inherited from 3D engines and design philosophies from the early 2000s. You’ll find plenty of criticisms about it online, and in my opinion, they are quite justified.

However, its saving grace is that it exists and gets the job done—especially for small projects like this one—without wasting too much time. Assuming, of course, that spending three days to design a simple plate with a few holes can be considered 'not too much time'. Keeping in mind as well that I'm not an engineer and have no background or training in any of this.

So, after a few days of learning, here's what the card should ultimately look like:

 

and the back of the card :

I still have to double-check a few dimensions, because the assembly is pretty precise. Then I'll have a few prototypes made. To do that, I'll need to find the right material and make sure the part's design works well with the supplier's cutting capabilities. It's going to be another learning curve, but it helps me build my skills and will open up new possibilities—especially for 3D-printed plastic parts, now that I can model 3D objects fairly well.

Drumulator become Drumix.

Yes, because I'm making enough modifications to the original system that I'll christen this future machine with a name all its own! It will be: Drumix (the terrible)!

After a few printed circuit board tweaks, here — in ray tracing, no less — is what the output board will look like. Huh? What? Just the output board?

Yes, for now. But hey, the processor and logic board should be fairly 'easy' to make.
I've already been able to test that whole part with a prototype board connected to the FPGA board with the Trion FPGA I'm going to use. It's only a matter of time now.

Because these past few days I've been working on the MSX cartridge. The goal being to automate the process of loading ROMs into FLASH. That is to say, once the download is complete, the MSX computer reboots by itself onto the cartridge, without having to do that extremely tedious little game of power OFF and ON!
To achieve this rather easy-looking goal, I need to juggle with:

• Kicad for 4-layer boards and 0603 SMD components.
• Electronic implementation of the FPGA with all its constraints.
• VHDL programming for all the switching logic and the download sequencing.
• RISC-V Sapphire programming of the processor embedded in the FPGA.
• Getting familiar with the whole development toolchain and finding the programmers.
• Modifying the generic programmer from Aliexpress to work with the FPGA.
• Getting lost in the sometimes baroque workings of the MSX.
• Programming in C with the MSXgl library to create the download page executed by the MSX.
• Debugging the whole thing without getting too lost in this labyrinth.

Well, you have to admit that all of this is fun. Except that I also have my USB card for the Akai S5000/6000 to finish. I just have left to create the metal mounting plate for the back panel of the Akai RACK. There you go, and no doubt various other things that also take up time. 

I forgot, I have a superb 4-layer FPGA board in a BGA package to assemble. There too, quite a 'sport' ahead. But, I might have something to practice hot-air soldering on. I'm trying to repair a Vivlio TOUCH LUX 5 e-reader whose screen was broken by excessive pressure on the device. And, I've finally just discovered the real reason why the machine won't restart. There's clearly a solder ball on the processor that has come loose. By pressing on the processor at the same time as the power button, well after two seconds, the machine starts up. No choice, it has to be re-soldered with hot air.

Yay for sports!

'So', wie die Deutschen sagen...

A little more than two weeks later, the prototype board for the audio outputs of the new Drumulator is practically finished. The weeks go by so fast it's scary. I haven't only been working on this board. I have other projects going on in parallel, but oh well, routing PCBs isn't my favorite activity.

So, as I was saying in the previous article (I think), although I've fully kept the spirit of the original Drumulator's outputs, I removed the analog multiplexing in order to give each output its own audio converter. The price of quality 12-bit converters has dropped so much that it allows for improving the analog quality of the outputs. No DC-blocking capacitor on the output. The symmetry of the signal with respect to ground is actively preserved.

Although this approach improves the overall audio quality, this simplification doesn't necessarily simplify the creation of the PCB. However, since I particularly enjoy properly separating and delineating the different parts of a function when laying it out on the PCB, well, my goal is achieved.

I do like a certain aesthetic when creating PCBs. A purely subjective aspect, I admit. But after all, that's still what sets manual routing apart from A.I. routing. For now....

So here, at least in 3D representation, is what the analog board of the new machine should look like — provided, of course, that it works as expected once it has been tested.

I may still have a few tweaks to make before sending the prototype board off for manufacturing. But I have to say that I'm finally making progress. 

It's been a really long time now since I "took on" the Drumulator. Without any suitable formal training, several obstacles stood in my way. The lack of expertise in FPGA development on the one hand, and the absence of what I'd call "logistical" hands-on experience when conceptualizing a relatively large project. 

On these aspects, I've made a lot of progress over the past few months. Argh!: a little personal pleasure ;-)

Bak to the Drumulator.

It has been a while since I last posted about the Drumulator. On the one hand, I'm working on other projects in parallel. A project that seemed fairly simple at first glance—namely, implementing the Drumulator on an FPGA—wasn't quite as simple as it seemed. And worse still, as I made progress on the subject, I realized it was becoming increasingly difficult, to the point of reaching a breaking point: a total state of blockage due to my lack of expertise in FPGA programming.

I remained in this state for a very long time, which could be estimated at several years—in fact, far too many years, since I must have been stuck for about five years. Until the end of 2025, when, thanks to the contribution of AI used as a teacher, I was able to unlock my understanding of VHDL and thus make great progress.

The side effect of this new approach to FPGA programming is that I spent the first half of this year working on finalizing the digital part of the Drumulator, and as a result, I also resumed development of the MSX cartridge that I had attempted several times to build using fast microcontrollers, but with unreliable operation.

I also undertook training in 4-layer PCBs, because double-sided boards don't allow proper use of the range of FPGAs I'm currently using, the Efinix Trion FPGAs. And to complete my training on the subject, I decided to make a 4-layer PCB using a BGA-format FPGA. I've actually received the PCB. All that's left is to embark on the adventure of hand-assembling this board.

All of this is to say that I've been quite busy during this first half of 2026.

Since the start of the 'school year', I've therefore studied (again) the analog part of the Drumulator.

Thanks to my new 'skills' in FPGA development, I was able to consider a different way of operating this analog part. Also taking into account the final cost of the board, its ease of integration not only for the Drumulator but also possibly for another machine of this type, the simplicity of assembly, the quality of the audio processing, and finally the possibility of operating with a simple 5V power supply such as a USB charger, well, I ended up with something that has nothing to do with the original Drumulator circuit, while scrupulously respecting its spirit.

I no longer use multiplexing at the output of the audio converter. Each output now has its own converter. I also no longer use per-channel volume control via an external digital-to-analog converter. The volume will be calculated directly in the digital domain by the FPGA. Furthermore, I'm using 12-bit linear audio converters, rather than 8-bit companded ones as in the original. A simple conversion table directly converts the signal, and does so very simply since 8 bits only gives 256 values to process. Finally, the output capacitors on the audio path have been removed thanks to the 0V centering servo.

Moreover, all the filters present at the output have been kept strictly identical, in order to provide the exact audio feeling of the original Drumulator. This produces a circuit with a lot of components, but one that should be fairly easy to route. For information, here is the 3D rendering of both sides of the board before placement and routing.

 

We're still going to have to be patient to make the best possible circuit...

Back to business, but not empty-handed : Akai S56usb clone.

What do you mean, a clone of Akai's S56usb USB card?

As often happens, it's a long story that began in the early 2000s with the purchase of an AKAI S5000. 

The machine seemed very interesting to me and had the advantage of being remotely controllable by a windows PC. Well, as a remote control, it's really just a replication of the machine's control panel on your PC. A sort of front panel – not hardware-based like on the S6000, but software-based. This was on Windows XP. Obviously, Akai never updated their software, which was called Aksys I believe, and they had no reason to, since the machine hasn't been available since 2002. Too bad.

In fact, I 'believe' Aksys could also directly control some features and edit the S5000's samples. Still, considering just the 'remote control' functionality, it was already excellent.

However, a few years ago, a French compatriot developed the equivalent of the Aksys software for Windows 10 & 11. 

Not as pretty as Akai's interface, but it gets the job done, and that's what counts.

He also set up a Discord account dedicated to the development of his software : http://s56sys.free.fr/index.html. While browsing his Discord, I realized that there were people interested in his application, but that unfortunately, not all S5000 owners had acquired the USB card enabling communication with the PC. This card having become rare, it can be found, but at a fairly steep price – typically between $140 and $180, according to my Internet research.

S56usb Akai card.

Beyond the price, the real problem is the availability of this USB card. A little nudged by the software developer, who was able to give me some information on the various signals on the card's S5000 connector, I ended up taking on the challenge of reverse-engineering this card.

Knowing that I had the pinout for the S5000 bus connector – which was supposedly valid – and that I also had an original card, I figured it shouldn't be too difficult to determine the entire wiring of the card, given that it's a double-sided board with no internal copper layers.

However, the card has an address-decoding PAL that doesn't just decode addresses. I've always had my doubts about the role of that PAL.

Be that as it may, I went ahead with reverse-engineering the card. As expected, it didn't take me long to draw up the schematic in KiCad – a few hours, and then a few more hours of verification. Which didn't stop me from making a glaring mistake. But hey...

With that done, I still had to figure out the equations governing the PAL. This component doesn't just handle address decoding and other read/write signals to and from the S5000 – it also generates two timing signals based on a simple RC cell. I don't know exactly what these two signals are for, but I imagine they advance a state machine. In any case, I went with that assumption and took on the PAL with a 'brute force' approach using a Pi Pico.

The Pi Pico I had was the version 1, with the pull-up issues. I had to tinker a bit to get a working setup. Once that was done, I cycled through all the binary possibilities on the input pins, sending the output pin readings via serial link to my PC for analysis. From that point on, it wasn't difficult to recover the logic equations.

 

Except, of course, for the two input signals coming from the two RC cells. Because, in fact, I had to look at all the outputs potentially affected by these two signals, as well as the other incoming signals involved in this setup, to choose the right configuration. Actually, I went at it by dichotomy. Between that or wasting tons of time with the logic analyzer, I tried the first option. A GAL makes that kind of thing easy to play around with.

Anyway, after a certain amount of time, the card finally ended up being recognized by the S5000 and the PC.

So I was able to test the communication with my PC running Windows 11 and confirm that practically everything works. The only issue at the moment concerns file transfer from the sampler to the PC. It doesn't work and triggers a USB time-out error on the S5000. Since transfer from the PC to the S5000 works fine, and having observed the same behavior with the original USB card, I concluded that it's a software issue on the PC side, not a problem with my USB card.

So I reported it to the software developer on Discord. He's given me an appointment in a few weeks' time, to give him time to fix the bug. Because it seems to me that when I shared my findings with him, he had a pretty good idea of where it might be coming from. So I'm hopeful that he'll sort it out. Especially since he plans to add sample editing functions, which would undeniably be a plus, bringing the application closer to Akai's original one.

I do enjoy interesting and productive ways to get back to business...