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My adventures with Sound Voltex at home.

I've become kinda-sorta-mildly obsessed with Sound Voltex, often shortened to SDVX.

It's a rather fun arcade rhythm game by Konami featuring six buttons and two analog knobs. It's a little tricky to pick up, and extremely tricky to master (some of the knob patterns get absolutely insane and I'm pretty far from being able to mentally parse them, let alone physically do them), but it is very satisfying managing the buttons and twirling the knobs. You absolutely feel like some kind of DJ wizard working the controls, and it's much more intuitive than Konami's other big DJ rhythm game, Beatmania IIDX, a game that I am very slowly struggling to learn how to play over several weeks due to the fairly unintuitive layout. In contrast, SDVX took me like two days before I was semi-comfortable with it.

Unfortunately, I need to drive like 40+ minutes away to my local Round 1 arcade to play on the cabinet, and it's quite expensive as a result; even if I weren't paying per play (and it's not terribly cheap, nothing at Round 1 is terribly cheap, all the rhythm games work out to be at least $1), it's still a fair bit of money in gas. I really wanted to play Sound Voltex at home.

There are a few ways to do so -- Konami does have an official PC version with a $15/month subscription (link to setup guide, since everything is in Japanese), and there are clones like USC, the Unnamed SDVX Clone. I chose the latter option, and if you want to follow in my footsteps, you can look up "USC SDVX songs" to get song packs for it.

Unfortunately, playing on keyboard is awful. Really awful. Seriously, I tried for a while, but handling the knob notes and dealing with the significantly more cluttered layout of a keyboard was a deal-breaker; you just had to move your hands around too much. Nothing like feeling like you're hitting everything and then realizing that your hand is pressing enter or caps-lock instead of shift. I guess you could do the crazy option of getting a cheap keyboard and removing all the keycaps outside of the ones you need for the game (the six main buttons, and then two pairs of buttons for handling knob twists), but that feels a bit unhinged. Would probably work though, and a cheap keyboard is like $10... although, you probably aren't getting one where you can press upwards of 6 keys at once at that price point, and you'll need to.

Ignoring the modified keyboard option, there are a few dedicated controllers available, but they're all expensive since this is a very niche market. After buying a HitBox from my buddy to play fighting games, I was absolutely tapped out on the idea of getting an even more niche single-purpose controller, especially since I could at least use the HitBox for most fighting games without issue. The cheapest Sound Voltex controller that I saw was still like $120 before shipping. At least, that was the cheapest I could buy right now -- I know for a fact that there was a $70 kit available at one point, and I would have bought that if it were still in stock.

After balking at the prices, I immediately looked to DIY options, and there were PCB and 3D printer files available for the Pocket SDVX v4... but then I looked into how much it'd cost to actually build the thing and I abandoned ship once I started looking into the bill of materials. IIRC, the PCBs with surface mount components from JLCPCB were like $60 after shipping, and then the shipping from the places I'd need to get the buttons and other minor parts from added up to like $20 from each site, doubling the price of everything. Doing the math, it just didn't make sense; I could buy the $160 after shipping Pocket SDVX v5 for a nice, premium (if small) controller that required no effort on my part and much less waiting.

Bit of a shame -- the Pocket SDVX v4 really was pretty cheap in terms of individual parts, but shipping and the PCB surface mount stuff (since I have no knowledge or experience with surface mount parts) shot the price sky-high for a single unit production run.

Ultimately though, I decided to build the cheapest piece of garbage I could, a cardboard box controller. I bought some fairly garbage parts on Amazon -- some terribly small buttons (my own fault for not looking at the size) and some knobs that are a little less fit for purpose than I'd like (this one wasn't quite my fault, the listing didn't have the information I needed; almost none of the listings for encoder knobs did in fact). This was a mistake, but like, not the worst one. The result works, it was a very good learning experience, and it'll inform my decisions on what I'd do differently next time. That being said, please buy actual arcade buttons and make sure your knobs can turn smoothly. My buttons have terrible bouncing issues, and my knobs have a detent in them to make them spin in discrete steps instead of smoothly, and I don't know how to remove it. It's still quite playable, but not nearly as much as a dedicated controller should be.

If you want to follow suit, you'll need at least seven arcade buttons (for the main six gameplay buttons, bigger is better), two (good) encoder knobs, a cardboard box or some other way to mount everything, and a Pi Pico. I remembered too late that I had some nice spare Sanwa brand arcade buttons from my HitBox, enough for the six main buttons; I'll get another cardboard box and rebuild the thing at some point using them.

With all the parts mounted up where you want them, you can flash the SDVX version of the Pico Game Controller firmware onto your Pi Pico (hold the button on the Pico while plugging it into your PC, then drag the .uf2 file onto the drive that shows up) and then wire up your buttons and knobs. I just directly attached plain wires to everything and used a Pi Pico with headers -- there are definitely better ways to do it, and I had to do a fair bit of re-wiring because I screwed up, but alas.

Here's the pinout to know how to hook everything up for the firmware to recognize the buttons -- I didn't see this documented anywhere in text; I had to look in the firmware source and follow the schematic for the Pocket SDVX v4, since the firmware was meant to be used with a PCB that you'd just put the buttons and knobs in the correct place on. Just wire the control up to the labeled pins, all the GPIO pins have GP next to them with the GPIO number. If you have more then seven buttons on hand and want to wire up more, the firmware supports up to nine.

If you've never worked with buttons or encoder knobs, for the buttons, attach one pin of the button to ground, and one to the indicated GPIO pin. The Pi Pico doesn't have that many ground pins, so run a wire off of one of them, and attach all your grounds on the controls to that one wire. For the encoder knob, there will be three pins to attach -- with the three pins facing you, the left one goes to the first GPIO pin listed, the center one goes to ground, and the third goes to the second GPIO pin listed. The top two pins (if present) will likely be for the knob's own button, you can wire those to the unused button pins if you want. I didn't bother.

Ultimately, despite how terrible my setup is with the cheap buttons, cardboard body, and very un-sensitive knobs... it works? It definitely works much better than on keyboard. I'll still drop notes because the knobs are screwy and the buttons require a lot of force to push, but I can absolutely clear songs. Maybe not quite as high level songs as I can play in the arcade, but I'm not stuck on absolute beginner ones either.

I had a lot of fun making the thing and I'm having a lot of fun using it. I'm also now extremely tempted to use that Pico Game Controller source to make custom controllers for other games that need non-standard setups to play properly. Don't cheap out too much on the parts, but you can absolutely get everything done for less than $60 if you buy nicer parts. My cost was like $30 (Pi Pico, box of encoder knobs, box of buttons), and the overall cost would probably be $22 if we only counted what I actually used in the build since the knobs and buttons were sold as a set, but I definitely didn't spend enough.