Mini Marble-Powered Synth Pays Homage To Its Bigger Cousins

August 22, 2020 by Dan Maloney 8 Comments

If imitation is the sincerest form of flattery, what then are we to make of something that shares only a few of the original’s design elements, operates in a completely different way, and has been scaled down to a fifth its size? Still seems like flattery to us.

Despite the changes, it’s clear where [Love Hultén] took inspiration for his miniature Marble Machine XS. Readers will no doubt see in it elements from [Martin Molin]’s original Marble Machine, the fantastic plywood and Lego musical contraption, along with his new Marble Machine X, the construction of which never seems to end. Like the originals, [Love]’s miniature version uses a lot of steel balls, albeit considerably scaled down, and it still uses a programming drum to determine where and when to drop them. But rather than strike real traditional instruments, the falling balls strike synthesizer keys, triggering a range of sounds through its built-in speaker. The whole thing is powered by a small electric motor rather than being hand-cranked and is small enough to sit on a desktop, a decided advantage over the mammoth machines to which it pays homage.

We have to say that as much as we love the hacksmanship of the original Marble Machine and the craftsmanship of its successor, the look and feel of [Love]’s machine just blows us away. We’re not sure what materials he used, but the whole hammertone paint scheme and Meccano look is a feast for nostalgic eyes.

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GridSound – An Audio Workstation In Your Browser

August 17, 2020 by Sven Gregori 10 Comments

If you’re into creating music, you’ll have a surprisingly large variety of open source options at your disposal, ranging from Audacity as rather simple audio editor to Ardour as a full-blown, studio-worthy DAW — and LMMS, Rosegarden, MusE etc. for anything in between. With [Thomas Tortorini]’s GridSound project, you’ll have one additional choice on your list now, except this one runs in your browser. So if you find yourself in a sudden moment of inspiration, all you’ll need is a browser and off you go.

From the feature set’s point of view, GridSound leans towards LMMS and offers a drum kit, piano roll, and synthesizer. It appears that you won’t be able to record real world instruments at this point, but it’s also a work in progress, so who knows what the future will bring. The code is available on GitHub and you can explore GridSound itself here — no login required, unless you want to save your work. Running in a browser, GridSound is naturally written in JavaScript and uses the Web Audio API to perform the actual audio tasks.

What’s impressive is that [Thomas] opted against any UI framework-of-the-week, but instead implemented everything from scratch in pure vanilla JavaScript. In fact, the entire code base seems to be self-contained without any third party dependencies, and that alone deserves some respect. Sure, JavaScript isn’t everybody’s cup of tea — “real developers use assembly” — so if you prefer something more physical, how about some cardboard music?

Unique Instrument Plucks Out Notes On A Ruler

August 10, 2020 by Dan Maloney 18 Comments

How does one describe the notes that come from a ruler that is anchored on one end and then plucked? The best word we can come up with is “wubulation”. So would that make this ruler-plucking synthesizer a “wubulator”? Or perhaps a “wubatron”?

Whatever we decide to call it, [Dmitry Morozov] dubbed it the RBS-20, or “ruler bass synth, 20-cm”, for the 20-cm stainless steel ruler that forms the heart of the instrument. The ruler is attached to a linear slide which varies the length of the sprung section. A pair of servos can pluck the free section of the ruler in two different places, providing notes in different registers, while another pair of servos control metal fingers that can damp the vibration, change the sustain, and alter the notes. There’s no resonator; the sounds are instead picked up by a piezo mic. Twelve keys on the base of the instrument can be programmed for various lengths, and an OLED display gives the musician feedback. The video below shows the instrument wubulating, and brings us back to those desktop jam sessions in our grade school days — at least until the rulers were confiscated.

We’ve covered a ton of similarly unique musical instruments before, like this hybrid synthesizer-violin, a symphony of soda bottles, and inexplicably, a leg guitar.

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Spoofing An Analog Rotary Knob With An ATtiny, And Vampiric Power

July 14, 2020 by Donald Papp 22 Comments

[Mitxela]’s repair of a Roland JV-1080 (a rack-mounted 90s-era synthesizer) sounds simple: replace a broken rotary encoder on the front panel. It turned out to be anything but simple, since the part in question is not today’s idea of a standard rotary encoder at all. The JV-1080 uses some kind of rotary pulse switch, which has three outputs (one for each direction, and one for pushing the knob in like a button.) Turn the knob in one direction, and one of the output wires is briefly shorted to ground with every detent. Turn it the other way, and the same happens on the other output wire. This is the part that needed a replacement.

The finished unit uses a modern rotary encoder and microcontroller in place of the original part, and implements a few tricks to power it.

Rather than track down a source for the broken part, [Mitxela] opted to replace it with a modern rotary encoder combined with an ATtiny85 microcontroller to make it act like something the JV-1080 understands and expects. There was an additional wrinkle, however. The original rotary pulse switch is an entirely passive device, and lives at the end of a four-conductor cable with no power provided on it. How could the ATtiny85 be powered without resorting to running a wire to a DC voltage supply somewhere? Success was had, but it did take some finessing.

For the power, it turns out that the signal wires are weakly pulled up to +5 V and [Mitxela] used that for a power supply to the microcontroller. Still, by itself that wasn’t enough, because the ATtiny85 can easily consume more current than the weak pullups can source. We really recommend reading all the details in [Mitxela]’s writeup, but the short version is that the ATtiny85 does two things.

First, it minimizes its power usage by spending most of its time in sleep mode (consuming barely any power at all) and uses an interrupt to wake up just long enough to handle knob activity. Second, the trickle of power from the weak pullups doesn’t feed the ATtiny directly. It charges a 100 uF capacitor through a diode, and that is what keeps the microcontroller from browning out during its brief spurts of activity. Even better, after browsing the datasheet for the ATtiny, [Mitxela] saw it was possible to use the built-in ESD protection diodes for this purpose instead of adding a separate component.

It’s a neat trick and makes for a very compact package. Visit the project’s GitHub repository to dive into the nitty gritty. In the end, a single assembly at the end of a 4-wire connector acts just like the original passive component, no extra wires or hardware modifications needed.

When opening older hardware it’s never quite certain what will be found on the inside. But at least [Mitxela]’s repair duties on this synth didn’t end up with him tripping out on LSD.

Synthesizer Gets An External Touch Screen

July 8, 2020 by Tom Nardi 3 Comments

Like other owners of the high-end Yamaha MODX, [sn00zerman] wasn’t happy with the synthesizer’s integrated touch screen. It’s a bit small, and not at a very good angle for viewing. So he made it his mission to find some way of adding a larger external touch screen without making any permanent modifications to the expensive instrument.

This might seem like a tall order, but he wasn’t starting from zero. It was already known that you could plug an external display into it if you used a USB to DVI/HDMI adapter; but without the touch overlay it wasn’t a particularly useful trick. He pondered adding an external connector for the device’s built-in touch screen overlay, but that broke his no modifications rule. Considering how much one of these things cost, we can’t blame him for not wanting to put a hole in the side.

Sometimes you just have to dig out the right parts.

So he started to look for a software solution to get him the rest of the way. Luckily the MODX runs Linux, and Yamaha has made good on their GPL responsibilities and released the source code for anyone who’s interested. While poking around, he figured out that the device uses tslib to talk to the touch screen, which [sn00zerman] had worked with on previous projects. He realized that the solution might be as simple as finding a USB touch screen controller that’s compatible with the version of tslib running on the MODX.

In the end, a trip through his parts bin uncovered a stand-alone touch screen controller that he knew from experience would work with the library. Sure enough, when plugged into the MODX, the OS accepted it as an input device. With the addition of a USB hub, he was able to combine this with an existing display and finally have a more comfortable user-interface for his synthesizer.

Now all he’s got to do is plug in a USB floppy drive, and he’ll have the ultimate Yamaha Beat Laboratory.

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Turning A MicroKORG Into A MicroKORG S With This Speaker Mod

June 5, 2020 by Maya Posch 11 Comments

When [Michael Wessel] bought his MicroKORG synthesizer/vocoder, he felt less than amused when two years later the MicroKORG S was released, with the ‘S’ standing for ‘sound’, apparently, for the 2+1 speaker system that was added to it. Undeterred, [Michael] figured out that both synthesizers are similar enough that one could likely add a similar speaker system to the original MicroKORG.

The similarities between the two products become apparent when one compares the original with its successor, with the latter seemingly mostly adding said speakers and more presets, along with a snazzy new exterior. (Although the 1970s styling of the original may have more fans.) As the embedded video shows, this mod is fairly clean.

At the core of this mod is a PAM8403-based class D amplifier board. The PAM8403 is a 3 W audio amplifier, originally produced by Power Analog Microelectronics (now Diodes). While not an amazing amplifier, it lends itself well for battery-powered applications like the MicroKORG. Rounding out the build is a 7805 linear regulator to get 5 V for the PAM8403, a few filter capacitors, a switch to turn the speakers on/off, and of course the speakers.

Although there’s quite a bit of space in the enclosure, most speakers tend to be large enough that this can be a bit of a squeeze. [Michael] found some low-profile 20 W full-range speakers that seem to work well for this purpose. To finish wiring this up, all it takes is a hole saw and a way to get the audio output from the MicroKORG.

In this mod, [Michael] opted to get the audio from the output jack on the back, but for a cleaner result it probably could be wired straight into the on-board header.

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Arduino Drums Bring The Noise, No MIDI Required

June 2, 2020 by Tom Nardi 21 Comments

When looking through existing Arduino drum kit projects, [joekutz] noticed that most of them just used the microcontroller as an input for an existing MIDI device. That’s fine if you’re just looking to build your own hardware interface, but he wondered if it would be possible to forgo the MIDI device completely and actually generate the audio internally.

To be sure, this is a lot to ask of an 8-bit microcontroller, which is probably why nobody does it this way. But [joekutz] wasn’t giving up without a fight. One of the trickiest aspects was storing the samples: the 8-bit, 11.025 KHz mono WAV files ultimately had to be converted into C data arrays with a custom Python script.

Unfortunately, since the samples are essentially part of the drum’s source code, he says distributing the firmware is something of a problem. Though it sounds as though there might be a solution to this soon for those who want to play along at home.

But don’t get the impression that this project is just software. Check out the custom impact sensors lovingly crafted from popsicle sticks and metal cut from soda cans, which have been mated with sections cut out of old DVD-Rs. Actually getting the beats out of the Arduino required the addition of a R2R DAC circuit and a TDA2822 amplifier. In the video after the break, you can hear the results for yourself.

[joekutz] is no stranger to homebrew electronic instruments. When we last heard from him, he was turning a very pink keyboard into his own personal circuit bending playground.

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