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The Story Of The ST4

You may know about this unique hybrid synthesizer / tracker from us. It just went on sale, it went through a successful Kickstarter, but did you know the real beginnings, and all the nitty gritty? Read on!

ST4 with USB keyboard hooked up.

It all began way back in 2014. I, Pieter, had realized the market for analog monosynth had become flooded. At that time I had worked on a prototype monosynth with a good bunch of knobs (the TCE-1M) and had concluded that it was easily possible, even with all the black magic of analog circuit design and layout. But there were many many competitors. And even the big companies were starting to show interest: Arturia, Korg, Roland, you name it.

Logically, the analog polysynth was next and early 2014 I was working my ass off to get a prototype up and running. Actually, a hybrid synthesizer seemed most practical. Analog VCO’s, like the Piggy’s are a hassle to calibrate and having to do 4+ of those for each unit.. Well, I didn’t feel like it. Plus, like for instance on the Shruthi-1 by Mutable Instruments, digital oscillators added so much power to influence the timbre. It was hard to ignore.

At some point I remember that I had 8 digital oscillators running on the Arduino DUE (a microcontroller board which at that time was the most powerful out there). I generated those using the DUE’s PWM hardware pins and I used even more PWM’s for generating CV’s. It actually didn’t sound bad at all, and CPU usage was low. I also worked a little on the VCF hardware. Steiner-Parker seemed to be the most logical, as it was characteristic as hell, multi-mode, and fairly easy to build. A tip from my mate STU. The VCA’s could be basic OTA stuff. Cheap and efficient.

Conceptually the polysynth was intended nothing more than that. Digital oscillators, perhaps 8, and 8 analog VCF’s and VCA’s. A bunch of knobs to set up your patch and then switch instruments using MIDI CC or using the on-board rotary encoder. A small character display would also be included.

In the middle of things, STU came up to me and was very enthousiastic about all the synth developments I had made, and being a long time fan of his music, it was hard to resist. He wanted to do a special synth, not a generic one like I was making. In retrospect, that was a mixed blessing. A unique instrument with its own idiosyncrasies and niche,  that would make some musicians a lot happier, and we wouldn’t have to compete with the big lads directly.

Read more about the original concept in this huge-ass PDF! original concept and development This more highlights STU’s concept, is a bit older document, but contains more photos than here.

On the other hand, the concept was so eclectic that we wondered what niche this would actually apply to, and also how hard this would be to engineer: A microphone and sampler? 2 analog voices and 2 digital? A built-in tracker (basically a sequencer as used on the old 16 bit home computers).. with a (for a synth) luxurious display?

BTW, a lot of people compare the ST4 with the OP-1 from Teenage Engineering. Could be the similarly playful company names, could be that they are both synths with on-board sequencers. But they are actually very different machines. OP-1 is meant purely as a mini/portable music studio, the ST4 is meant as a high-character synth+chip tracker, even for live purposes: all channels can be directly influenced live: that’s a lot of knobs and buttons, but it pays off!

Far too brave, we decided to push forward. I’d take STU on board as a project partner, if it worked out we might join forces more often. Somewhere in June 2014 we figured we’d have a prototype in September. Nothing was further from the truth.. It was a hellishly complex project with super high integration and fiendishly exotic features. All the eclectic features like the microphone, sample RAM, and the tracker.. And added to this my compulsion to want true polysynth functionality: i.e. one VCF and one VCA per channel.. made the ST4 project a nightmare.

I’ll spare you the details, but we suffered problems on every front. It all started with mixing analog and digital on the control boards. I wanted 10 bit resolution on the pots, but with all the flickering LEDs and clock lines around, that was next to impossible. Even worse was the mic pre-amp. Imagine.. A few millivolts signal surrounded by digital clocks and signals all over the place. After I separated digital and analog supply and ground (which cost several iterations) things were looking up, but even then the pots had to be digitally low-pass filtered.

The original ST4 concept had 2 analog voices and 2 digital ones. I changed that to all digital to spare me the drama. Also, there were a lot of dedicated buttons for the tracker. This was eventually dropped for USB keyboard support. A more sensible choice, if it were not for the fact that we were using an MCU: no operating system, no language support, rudimentary USB support.. So even in this form it wasn’t easy. Also there was the plan to have all envelopes directly accessible. That would have taken a 30 cm wide piece of panel and made the unit extremely expensive, and also might have required the front panel to split: a 70 cm wide aluminium panel will inevitably start bending under all the weight.

Besides all this bad news, we also had a somewhat regular meet-up session. STU had left The Netherlands for his hometown in Switzerland. So, occasionally I visited him or he came over to Utrecht. This worked out quite fine, and we could often develop and test a new feature (like the bitcrusher) in such a session. That often worked much better than plain-old Skype.

Somewhere in fall 2014 I had a “breadboard”, or more like spaghetti model ready. TODO: photo. There were real PCB’s, but the connections were done with jump wires. Error-prone and chaotic. The Steiner-Parker VCF had been replaced by an SVF (State Variable Filter) of own design. A SVF using OTA’s is not a new idea, but I added my own twist to it, at least. No external opamps were necessary. Buffering was done inside the LM13700 IC.. and it worked fine.

Feature-complete model of the ST4 in spaghetti form.

Feature-complete model of the ST4 in spaghetti form.

I remember programming the DUE’s microcontroller, the Atmel SAM3X8E, was an absolute joy in the beginning. Zappy DMA controllers, some even quite easy to set up. Easy and fast interrupts. And the beauty of a 32 bit ARM. I started in Arduino IDE, but because this project was far beyond a mere sketch (eventually 50.000 lines of C++), I decided to use my own makefile system and run from the prompt and sublime text ctrl-b / cmd-b for building and jumping to errors.

Growing out of an IDE was just the first of many “Hulk-like” moments. Painful and brutal, you realize that you have to completely replace a tool or a method. I can say that replacing the IDE was a good one, but replacing the internal PWM with external PWM was a bad one. External PWM chips aren’t as flexible. Fixed resolution, for instance. That resulted in the PWM carrier frequency being 10 kHz. Ok for CV generation, but absolutely terrible for EMC. You’d have the carrier whining through your audio like Satan’s dental drill. So, eventually we went for a bunch of simple audio DACs + a MUX to solve that. There are many more of such examples. And all the while the amount of free pins on the DUE got less and less. The display also ate up a huge amount. Integration just got harder and harder as time moved on. An effect to which many experienced engineers can testify.

In the meantime I took up a great freelance job offer (40 hours a week), and also got an intern. I don’t know how I made things meet, but apparently I did 😉

The intern, Koen, turned out to be a valuable asset. His project turned in to the Sawbench synth. Far simpler than the ST4, but a very nice sounding and easy to use piece of kit. Somewhere in winter 2015 that was done and the production needed to get underway. Luckily producing one synth and designing the other is a pretty good combination.

Work started on the tracker. Well, early on it was just a simple step sequencer with a single pattern. Also the digital oscillators were turned into nice anti-aliased ones. They sound very good up to about 5 kHz. Well, that’s the highest piano note, so above that I really couldn’t care 😉

More and more stuff was visualized on screen, like potentiometer settings, LFO levels, etc. USB support came slowly. The USB library from Arduino was only usable from a non-multitasking viewpoint. So in real life it was useless. I had to turn everything into state machines.. To let that USB code return as quickly as possible. That was a very frustrating but ultimately rewarding task.

The ST4 model of that year was the “woodboard” model with proper ribbon cables between all the PCBs and everything nailed down on a solid piece of wood. See the picture below 😉

Developing for the old woodboard, a new screen to display the full LFO MOD matrix.

Developing for the old woodboard at STU’s place, a new screen to display the full LFO MOD matrix.

Also with the software it turned out that integration was hell. Consider the 96 kB of SRAM… consider semi non-existent libs for USB keyboard handling, and minimalistic display libraries.. That means yes, all human interfacing stuff including GUIs, keyboard handling, language, etc, needs to be done by the same coder. I was used to this, many years of game and demo coding had hardened me, but the ST4 still was special. The thing is so feature-rich, yet so underpowered in hardware and software libraries, that almost every new feature will turn into a hassle to code.

2015 really was a damn hard year in that respect. The easy part was getting the prototype casing from Protocase. It’s never exactly what you would like, but at least it’s sturdy (and heavy!) as fuck 🙂

ST4 in its prototype steel casing

ST4 in its prototype steel casing

In terms of electronics, the mic board was finished. No real noise there. Perfectly fine for 8 bit sampling. The power supply part was also done. We figured an external AC/AC supply and internal AC/DC with classic regulators and diode bridge could work, and it did. The real work was spent on integration and prototyping, though. Countless times redesigning the wiring and pinning, resoldering, re-routing, re-ordering from PCB factories.. The ST4 was already functionally complete late 2014 (hardware wise), 2015 was only refining and software!

So, late 2015 that prototype was finally done.. It worked very nicely. You could show everyone what the thing could do without wires breaking or so 😉 The tracker and the live tweaking of the filters were especially fun to see people do. Even old musician friends from the Atari scene 🙂

In the meantime I decided to split with STU because I didn’t feel the cooperation worked well enough. As it turns out, making a synth is 90% execution and 10% concept. And the bigger the synth, more the more it skews those numbers! A full-time concept maker (and general techy/musician) is perhaps not best in such a super-critical project.

Still, we decided to do the Kickstarter campaign together. We joined up and shot a video together with a professional cameraman / editor. Then I put the Kickstarter campaign up early 2016. Since we’d already won a Kickstarter for the Sawbench, we’d thought it’d be easier this time. Well, yes and no. People were much more enthousiastic about the ST4. We became big in Japan overnight, even 😉 tens of thousands of views on all kinds of social media. People loved it. Yet the number of pledges was not in proportion. In the end, we just made it. The last night I couldn’t sleep and just sat at the keyboard trying to hype the thing up.

This was one of the biggest things I learned. What people love and what they buy are two different things. Sure, there’s always an overlap, but with the ST4 that turned out to be pretty small. We were puzzled by this. Not everyone can afford a Ferrari, but this is a (simple) Ferrari at rock-bottom price! A 4 channel hybrid with 40 knobs and countless of buttons and LEDs, a gazillion interfaces, a relatively large full color display (for a synth), pretty damn powerful unique functions.. for a mere 800? And most of it is not cheap plastic and consumer parts like in many modern budget synthesizers. It’s all durable metal, automotive rotary encoders, metal sliders! My hypotheses to explain this effect is that either the interested people are poor, the rich guys can’t believe it’s that good, or people don’t trust larger sums of their money with a new brand. Most likely all of the above.

Still, we made it. I asked Jasper and Koen, by then my partners in crime, to help out a bit and they did. I asked a skilled graphic designer (Nuey San Waldman) to design the front plate graphics, logo’s and everything, and he did. I refined the firmware and the last bits of hardware revision were done early summer 2016.

After that the hardware assembly and making of all the DIY kit bags started. We were already finished in August! In the background there was the casing design. The Sawbench had been much easier. The ST4 was multi-mount: 19″ rack and desktop, and there was just so much stuff inside. To shrink down from the over-dimensioned prototype casing down to the sleek one we have now, loads of boards needed to be resized. So we had to assemble some boards all over again.

Mod board kit (bag D) separate kit bags, part 1.

All those kit bags. There are bags A through J, and there are bags in bags.. in bags. This is D: the mod board.

 

Behold, the box. Behold the official ST4 logo!

Behold, the box. Behold the official ST4 logo!

 

But most of it was just finding the right factories for metal, powder coating and silkscreen paint. Iterating and negotiating. That, all in all, took nearly half a year. But in February 2017, a whole year after the Kickstarter, it finally all came together. The final product is very good, if we may say so ourselves. Sure the firmware still has some hick-ups when using some of the more advanced features, but these are being ironed out as you read this. The thing is beautiful to look at and handle. The pots and knobs are the highest quality you can expect. There’s visual feedback on everything and there’s tons of way to use it. Not in the least tracking it live, or using a PC keyboard to play and hack in notes, and then wiggle some VCF controls. What machine can do that? 🙂 We’re extremely proud that we pulled through and did it the hard way. Because love is for the hardest people.

IMG_9742

The insanely good looks of the ST4 along with heavy Depth-Of-Field 😉

ST4 silkscreens, and the year 2016

Traditionally, there is good news, and there is bad news. This is no exception. So..

Good news, people: the first silkscreen painted casing arrived. See below (click to enlarge). And yes, the power switch is in the Tasty Chips logo 🙂

The first ST4 with silkscreens.

The first ST4 with silkscreens.

Bad news, people: the silkscreen quality isn’t high enough. And this means the delivery will be postponed to next year.

To explain. The silkscreen is spotty and varies in thickness over the plate. We’ll need another iteration to perfect things. Sorry, we just can’t choose to rush this. Especially not on a synth of this class. Which is to say, we will clear this up. No matter the cost!

Now that that’s out of the way. Other news!

Superbooth 2017: April 20..22, Berlin. The most interesting synth fair in Europe. We’re there to demonstrate all our stuff, including formerly classified projects!

In the meantime we’ll keep working on our projects. The ST4 still needs to support more USB keyboard languages 😉

ST4 pre-final photoshoot

With the first batch of ST4 casings in production, we had time to make a photoshoot of the current, pre-final, model. As you can see, it’s easy to remove the lid and keep it opened up for maintenance.. Almost like a car 😉

The first batch is expected to be delivered to us mid November..

 

Front view, power off.

Front view, power off.

 

The obligatory diagonal angle shot.

The obligatory diagonal angle shot.

 

ST4 opened up, looking at the bottom plate. VCF board (large PCB in front), IO board for MIDI and USB, power board (with the Traco DC/DC converter).

ST4 opened up, looking at the bottom plate. VCF board (large PCB in front), IO board for MIDI and USB, power board (with the Traco DC/DC converter).

 

Backside of the lid. Control boards, Arduino DUE, part of the LCD display, Mic board (lower left corner).

Backside of the lid. Control boards, Arduino DUE, part of the LCD display, Mic board (lower left corner).

 

Backside of the lid. Control boards, DUE, part of LCD display, SD card board, and headphone wiring.

Backside of the lid. Control boards, DUE, part of LCD display, SD card board, and headphone wiring.

 

Part of bottom and lid. The PCB with all the phono sockets is the VCA board.

Part of bottom and lid. The PCB with all the phono sockets is the VCA board.

 

Opened up the hood.

Opened up the hood.

 

As you can see the lid comes off nicely and can comfortably rest on the table. No cables have to be detached.

As you can see the lid comes off nicely and can comfortably rest on the table. No cables have to be detached.

 

Powered on. Strutting that nice logo.

Powered on. Strutting that nice logo.

ST4 sample casing 2, New Sawbench

This week the new ST4 sample casing arrived. No silk screen yet, but at least everything fits. Yes, this baby is rackmountable too! So, that takes care of the mechanical bits. Everything is as sturdy and tight as it gets.

Rackmounted ST4

Now the only thing left to do are the silk screens. The designs have been finished a long time ago. We’re ordering 10 pieces to inspect the quality. If it suffices, the first ST4’s will be shipped out early November! If not, then it will be late November/early December. In the mean time we got very little to do on the firmware. From time to time we test it and make some songs.

New Sawbench: the new hardware revision is in. This means they are stocked once again: prebuilt, kit. This has built-in protection against reverse polarity (yes, those nasty guitar pedal supplies!). This is done with a miniature fuse. More details to follow.

Sawbench firmware v1.2 has been released. This makes the Sawbench, well, everything it should have been in the first place. 😉

Bugfixes:
– Tolerant to MIDI clock packets. This is quite a big deal since many MIDI devices send these.. also inadvertently.

New Features:
– Really short attacks and releases are now possible. Just a lot better for everything staccato (can you say acid?).
– Exponential envelope mode. Can be switched with CC 94. Allows for really long attacks and releases.

ST4 September update, DIY kits

Just to keep you informed, another ST4 progress update. In the last weeks we’ve tested the sample casing and we’ve requested another one. Two PCB’s didn’t fit correctly, the other 7 did just fine. This will take until early October.

In the meantime all the presets have been added, the DIY manual has been updated with better tables, and we’re ironing out all the firmware bugs. ..And.. we’re finally compiling all the DIY kits. Still, that’s not too much work. The casing is the only real work that’s left. We strive for November, but the planning is now in the hands of the casing factory.. At least you’ll be getting your gear when you spend most of your time indoors. It makes sense 😉

The current collection of kit bags (half of it, actually).

The current collection of kit bags (half of it, actually).

In the meantime we did a minor Sawbench hardware revision (to protect against wrong AC/DC converters) and we’re looking forward to test the 1.2 firmware with its improved VCA/VCF envelopes and improved MIDI support.

Kit bag, with spiffy new label. ;)

Kit bag, with spiffy new label. 😉

When the final casings arrive we’ll start shipping out the kits ASAP! This is done in first-come-first-served order:

1. Kickstarter DIY backers first to last
2. Kickstarter assembled version backers first to last
3. Pre-order list DIY first to last
4. Pre-order list assembled version backers first to last

Today we’ll send out a questionnaire to ask you guys which version you want: rackmount or desktop.. and to ask you for your postal address.

Casing, boxes, and plugged holes

Dear ST4 backers,

This is not the post you’ve been waiting for.. not yet. But we’re close. Very very close.

Today the sample casing was completed.. and it’s on its way here. The casing is without silkscreen paint, but all the metal and powder coating is there. It comes furnished with metal impact standoffs to easily and reliably fit all the electronics. And as you can see the rear electronics can be fitted in two ways, for either:
– rack mount
– desktop

Powdercoated ST4 sample casing.

Powdercoated ST4 sample casing.

Just like we promised. In desktop form the holes on the bottom plate can be plugged. Cover caps are supplied for this. Note that we will ask whether you want the rack or desktop version when the time arrives. And yes, you can still easily switch from rack to desktop or vice versa.

Furthermore, the cardboard boxes were also delivered to our office!

Behold, the box. Behold the official ST4 logo!

Behold, the box. Behold, the official ST4 logo!

Firmware 1.0 is as good as finished. As planned, we succeeded in making LFO and modulation settings per instrument. We’ve included the option to sort 100+ long sample file names. We’ve hit a point where new features just eat a bit too much CPU and/or memory and that means we _have_ to finish up. We’re just doing testing right now, and adding presets!

No telling when the big moment will be there. November seems pessimistic, while mid september seems optimistic. It all depends on if the electronics fit in right away, or we need to move some bits around. The silkscreen paint jobs _seem_ trivial right now, but with the Sawbench, for instance, the color was a big issue for the previous factory. Digital printing turned into silkscreen and in the end that delayed things by 4 weeks.. But we choose quality!

We’re sorry for the delay. We especially underestimated the casings. This is not a small or simple device like the Sawbench, so logically there are more questions, more things to discuss, and more price and feature negotiations. We just didn’t know how much more, exactly. Thank you for your understanding.

ST4 casing continued

Yet again another ST4 development update.

The casing negotiations are still ongoing. To reassure you: we’re still talking to the same factory. There are just details to be discussed. We expect to have the first proof casing ready late August. When the final casings will arrive we don’t know yet. We expect late September. As mentioned before, the casings take way more time than anticipated. We will try to stick with the current factory when we start producing the next batch.

There’s other news: half of the PCB’s have now been tested. And firmware is reaching a level of maturity where controls work the same in all of the GUI screens. The GUI has become more readable, intuitive, faster and there’s an intro animation. And it looks like we’ll add spanish and french keyboard support soon.

The last firmware development work involves the instrument editor. In the next weeks the firmware will grow to be able to choose from at least 100 samples on SD card. We’re also trying to get LFO settings per instrument, which is very useful to control the timbre. If that succeeds we might still go for a digital chorus per voice.. if there’s still enough CPU time left..

ST4 – Electronics production done

All electronics for the ST4 kickstarter have been completed!

All electronics for the ST4 Kickstarter have been completed!

Take a good look. Yes, all those PCB’s have been assembled. And over half of them in-house. That means we just have to hook it all up and test it.

On other fronts: the firmware has progressed nicely. Apple USB keyboards are now supported, German keyboard layout is supported, and it looks like UK is up next. If you have a kayboard layout you want to see supported, you can send it to us and we’ll code it! tastychipselectronics@gmail.com.

USB hubs are (somewhat) supported, which opens doors to new avenues like USB MIDI controllers. The tracker now features half and double speed options. The display has the feature to show multiple controls (up to 4) at the same time, and controls have set points. Huge amounts of features to control the signal path have been added: LFO sync, LFO cross modulation, frequency controllable LFO random noise, channels may be bundled in one big group (for instance, set cutoff for all channels with a single pot). Poly and mono (non-)legato modes are available. There’s now a PWM mode and LFO modulation can control it. That’s not all, LFO can also control bit crusher parameters!

We’re currently negotiating the casing with a number of factories. This is a lot time consuming as previously thought. The ST4 casing is multi-functional (desktop and 19″ rackmount), has a display and this involves a lot of details and choices to be made. When we’ve invested months and months in electronics and software, we’d like to do the same for the casing. We’ll see which ones comes out best. The cardboard box design now also has been done. The DIY manual is 95% finished and the user’s manual is about 70% complete.

In the meantime we’ll continue making the firmware better and better. Most features will be made available through the two onboard rotary encoders, not only through the USB keyboard. The goal is to have everything except sequencing and typing in names possible with on-board controls.

In short, it’s primarily casing stuff and firmware polishing from here on. Late august does seem somewhat feasible.

ST4 Production

In recent weeks the ST4 electronics production has kicked off. Many of the simpler boards have now been produced and are ready to be built into the ST4 units. These were handmade right here at Tasty Chips labs in The Netherlands, just like the Sawbench synth was.

A stash of assembled ST4 VV boards.

A stash of assembled ST4 VV boards.

The more complex boards (exp, vcf, vca) are being assembled by machine in a fab nearby and should be done by the end of the month. Concerning the manual labor, we still have to do the voice and the mod boards. The DIY manual has also seen some major progress and many of the board pages are supplied with photos of all the soldering steps: ST4 DIY resource. More and more detailed information will appear on this DIY resource in the coming weeks.

In parallel, the firmware is still being worked on. Some news:
– Poly mode now works fine and is intelligent enough to allow 3 finger chords + solo.
– The ST4 tracker can now send MIDI out clock signals.
– The ST4 tracker accepts MIDI clock input (preliminary).
– Samples can now be tuned.
– Sample looping can be turned on or off individually per instrument.

The casing (graphic) design is ongoing. We’ve got an excellent graphics artist on board to help us with the silkscreens. The details of the fabrication are being negotiated at the moment.

Last but not least. We’ve had multiple requests whether the ST4 will become available to the public after Kickstarter. The answer is YES! Also, we are taking pre-orders. These are completely free of charge and the interested party is not obliged to buy in any way. Just send your name, postal address, and the version you want (kit, or built unit) to tastychipselectronics@gmail.com. Price for built unit will be 850 eur, 550 for the kit. Units are shipped out on a first-come-first-served basis.

ST4: Power up!

Last update reported on the ST4 power problems. The European government basically killed off the AC/AC power bricks on which the ST4 depended. So we were forced to take a step back to redesign. You’ll be pleased to hear this was successful and with that the electronics are complete! Finally!

The new PSU design is not only more “eco”, but it’s especially better for the user as now only a standard 12VDC PSU is necessary. Easy to find and replace, and equally cheap. And, as promised, such a power brick will be shipped along with the ST4! 🙂

Not only this, but we’ve already moved ahead and started assembling the first ST4 systems. In the coming days (weeks) the DIY manual will be put online. A start can already be found here!

The casing development has made good progress. The technical drawings of the front, back, and bottom plates are almost completely finished and we already made a test run on our C&C with this to good effect. What’s more the graphic design has made similar progress. But we’re not going to spoil it this post.

New front plate test.

Fresh from the CNC: the new test front plate.

So, what’s left to do:
– The casing
– DIY manual
– Hardware production
– Firmware 1.0

The good news is that most of these activities can be done in parallel.

Mid july sounds like a realistic release date.

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