Musical Hacks

917 Articles

MIDI Controller In A Concertina Looks Sea Shanty-Ready

August 18, 2019 by 4 Comments

Did you know that the English concertina, that hand-pumped bellows instrument favored by sailors both legitimate and piratical in the Age of Sail, was invented by none other than [Sir Charles Wheatstone]? We didn’t, but [Dave Ehnebuske] knew that the venerable English gentleman was tickling the keys of his instrument nearly two decades before experimenting with the bridge circuit that would bear his name.

This, however, is not the reason [Dave] built a MIDI controller in the form of an English concertina. That has more to do with the fact that he already knows how to play one, they’re relatively easy to build, and it’s a great form factor for a MIDI controller. A real concertina has a series of reeds that vibrate as air from the hand bellows is directed over them by valves controlled by a forest of keys. [Dave]’s controller apes that form, with two wind boxes made from laser-cut plywood connected by a bellows made from cardboard, Tyvek, and nylon fabric. The keys are non-clicky Cherry MX-types that are scanned by a Bluefeather microcontroller. To provide some control over expression, [Dave] included a pressure sensor, which alters the volume of the notes played depending on how hard he pushes the bellows. The controller talks MIDI over Bluetooth, and you can hear it in action below.

We’ve seen MIDI controllers in just about everything, from a pair of skate shoes to a fidget spinner. But this is the first time we’ve seen one done up like this. Great job, [Dave]!

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MIDI Harp Looks Pretty Sharp

August 17, 2019 by 7 Comments

[Julien] is one of those cool dads who shows his love with time invested rather than money spent. His daughter plays the harp, and you would not believe the price of concert harps. Even the cheap ones are several thousand USD. So naturally, he decided he would build her a MIDI concert harp from the ground up.

This plucky work in progress uses a strain gauge and an AD620 amplifier on every string to detect the tension when plucked. These amplifiers are connected to Arduinos, with an Arduino every nine strings. The Arduinos send MIDI events via USB to a Raspberry Pi, which is running the open synth platform Zynthian along with Pianoteq.

The harp is strung with guitar strings painted with silver, because he wanted capacitive touch support as well. But he scrapped that plan due to speed and reliability issues. Strain past the break to check out a brief demo video.

[Julien] used strings because he wanted to anchor the harpist in tactility. But you’re right; many if not most MIDI harps use lasers.

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Latex Bellows From Scratch

August 12, 2019 by 17 Comments

You would be forgiven for thinking that the semi-spherical bulb [Len], from the Bellowphone channel, is holding is a toilet bowl float. It is a bellows of his design that is similar to the squeezable part of a bike horn but is more substantial and less irritating at six in the morning. These rubber squeeze balls are old-school in the best way, and craftsmanship rolls out from every second of his videos. The backdrops to [Len’s] videos are alive with tools, materials, examples, and instruments the same way our offices and maker spaces erupt with soldering irons, LEDs, and passives.

His video walks through all the steps to make latex bellows starting with a rigid stemmed bulb and painting it with latex. This takes a bunch of coats with the associated drying time, so if you need a lot of bellows, you will want multiple bulbs. After coating of latex, we move to the contraption known as the Snout Master 5000. The SM5K looks like a wooden jig held in a table vise, but it is a purpose-built over-engineered chuck with four ball bearings held in a vise. When the latex is thick enough, the form is removed, and the bulb is repaired, then, more coats. Each ball has roughly twenty layers, and with three hours between coats, this is a weekend job at a minimum. Good things come to those who coat. The final steps are boiling the bulbs and adding a silicone preservative. They can last up to a decade with proper maintenance.

We see lots of electronic and automated instruments here, and spherical balls are definitely on the human interface spectrum, but the techniques we see from [Len] would allow anyone to design their own bellows more conducive to mechanization. [Len] says one of his inspiration is [Harry Partch] and his Blo-Boy, an organ powered by fireplace bellows. We think these squeeze balls are even better.

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Acoustic Lenses Show Sound Can Be Focused Like Light

August 10, 2019 by 26 Comments

Acoustic lenses are remarkable devices that just got cooler. A recent presentation at SIGGRAPH 2019 showed that with the help of 3D printing, it is possible to build the acoustic equivalent of optical devices. That is to say, configurations that redirect or focus sound waves. One fascinating demonstration worked like an acoustic prism, able to send different notes from a simple melody in different directions. Another was a device that dynamically varied the distance between two lenses in order to focus sound onto a moving target. In both cases, the sounds originate from an ordinary speaker and are shaped by passing through the acoustic lens or lenses, which are entirely passive devices.

Researchers from the University of Sussex used 3D printing for a modular approach to acoustic lens design. 16 different pre-printed “bricks” (shown here) can be assembled in various combinations to get different results. There are limitations, however. The demonstration lenses only work in a narrow bandwidth, meaning that the sound they work with is limited to about an octave at best. That’s enough for a simple melody, but not nearly enough to cover a human’s full audible range. Download the PDF for a quick read about the details, it’s only two pages but loaded with enough to whet your appetite to know more.

Directional sound can be done in other ways as well, such as using an array of ultrasonic emitters to create a coherent beam of sound. Ultrasonic emitters can even levitate lightweight objects. Ain’t sound neat?

Forming Fipples And Accompanying Accoutrements

August 6, 2019 by 7 Comments

[Dr. Suess] created memorable books with minimal words and bright artwork. He inspired children and adults alike, and one of them, [Len], grew up to create wind instruments for the Bellowphone channel on YouTube. Behind the whimsy of his creations is significant engineering, and this time, we get to see the construction of a fipple. The video is also shown after the break. Even though fipple sounds like a word [Dr. Suess] would have coined, it is a legitimate musical term that means a whistle-like mouthpiece. In this case, it blows air across glass jars to create the sound for [Len]’s bottle organ. Check out the second video below for a performance from The Magic Flute.

[Len] uses clear rigid PVC for the fipples and a custom forming die to shape them while they are soft. The rest is precision hand-tool work with a razor saw, hand file, and wet-dry sandpaper. Once complete, the fipple looks like any musical instrument part produced by exacting construction techniques. Making a mouthpiece is one thing, but if it is not directed correctly it will not make any sound, so we also learn how to turn steel strapping into an organ bottle assembly. If you add some tubing and rubber squeeze balls, you can make your own instrument.

Part of the reason the Bellowphone channel exists is that [Len] found a lot of support in the pipe organ community that showed him the secret inner workings of their livelihood and now is his chance to share that enthusiasm with the maker community.

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Chiptunes Via USB MIDI With The AY-3-8910

July 30, 2019 by 11 Comments

There are many venerable soundchips in the chiptune pantheon, of which the AY-3-8910 is perhaps one of the lesser known. Having not served on active duty for Nintendo or Commodore it’s somewhat unloved in the USA, but it made its name in a variety of arcade and pinball machines and has quite a European following due to its appearance in machines bearing the Amstrad and Sinclair names. [TheSpodShed] decided to whip up a USB MIDI interface for the chip, with the help of the Arduino Pro Micro.

The Arduino Pro Micro is a Sparkfun creation, using the ATmega32U4 microcontroller. Its USB MIDI functionality makes it a perfect candidate for such a build, and it also packs enough digital IO to run the AY-3-8910, with 13 lines required to get things going. [TheSpodShed] whipped up the project on protoboard, with only a few passives needed along with the sound chip and Arduino.

The Arduino code was written with an eye to making the most of the chip’s limited polyphony. The synth prioritises the most recent received notes, while also aiming to keep the highest and lowest of the currently requested notes still playing where possible. This gives the synth the best chance of keeping the expected bass and melody intact when playing a wide variety of MIDI content.

It’s a tidy build, and one that shows some love for a soundchip some have forgotten. Of course, it’s not the only option – we’ve also seen the SAM2695 and YM2612 given the same treatment. Video after the break.

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A Simple Way To Analyze Guitar Pickups

July 29, 2019 by 20 Comments

To the uninitiated an electric guitar seems fairly simple: you pluck a string and the electronics send the corresponding audio signal on the 6.3 mm jack output, all ready for for the amplifier to work its magic. Much of what makes a guitar like that sound good depends on the pickups, however. These are the devices which are placed between the guitar body and the strings. Depending on the guitar there can be one, two, or more of them, of varying types and configurations.

As a Gibson fan who upon getting introduced to a Fender Telecaster just had to replace its pickups with humbucking types, [Ken Willmott] found himself thrown into the wonderful world of pickup design and characterization. After two years of working through a number of designs and approaches, he eventually settled on a preamplifier design featuring a JFET opamp (LT1058) on a custom PCB which amplifies the pickup response from a test signal, acting as a front end signal conditioner.

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