Musical Hacks

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A man sits in front of a wooden table. There is a black box with a number of knobs hand-labeled on blue painter's tape. A white breadboard with a number of wires protruding from it is visible on the box's left side. An oscilliscope is behind the black box and has a yellow waveform displaying on its screen.

A More Expressive Synth Via Flexure

February 28, 2023 by 13 Comments

Synthesizers can make some great music, but sometimes they feel a bit robotic in comparison to their analog counterparts. [Sound Werkshop] built a “minimum viable” expressive synth to overcome this challenge. (YouTube)

Dubbed “The Wiggler,” [Sound Werkshop]’s expressive synth centers on the idea of using a flexure as a means to control vibrato and volume. Side-to-side and vertical movement of the flexure is detected with a pair of linear hall effect sensors that feed into the Daisy Seed microcontroller to modify the patch.

The build itself is a large 3D printed base with room for the flexure and a couple of breadboards for prototyping the circuits. The keys are capacitive touch pads, and everything is currently held in place with hot glue. [Sound Werkshop] goes into detail in the video (below the break) on what the various knobs and switches do with an emphasis on how it was designed for ease of use.

If you want to learn more about flexures, be sure to checkout this Open Source Flexure Construction Kit.

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A series of five cymbals sitting on white and black speckled carpet in front of a green loveseat. Each cymbal is assembled from four printed sections. Their colors from left to right are yellow and grey, red and black, black, teal and black, and white and black. A sixth, grey and black cymbal is sitting in the middle of the loveseat cushion.

Challenging The Limits Of 3D Printing With Cymbals

February 28, 2023 by 22 Comments

We’re big believers in 3D printing here at Hackaday, but it’s important to recognize that there are plenty of applications where additive manufacturing (at least, from a desktop machine) just isn’t suitable. But that doesn’t mean we don’t want to see what happens if you try. For example, [The Drum Thing] wanted to test the limits of 3D printing by printing a set of cymbals.

[The Drum Thing] had a friend design a cymbal in CAD and then the printed quarters were glued together. In the name of science, they produced them in six different materials to compare performance. Each cymbal was played for a short period or until it failed, including some very interesting slow motion camera work showing the vibrations traveling through the cymbals.

As one might expect, bashing “wafer thin” pieces of printed plastic with a wooden drumstick didn’t work out well for most of the cymbals, although the TPU, carbon fiber, and nylon cymbals were did largely survive their time in the limelight. The other cymbals all failed, either shattering, cracking, or failing at the glue joints. Based on the video, it seems the same glue was used for all of the cymbals, so making sure to have a better match between material and adhesive could help with the glue failures.

Maybe future testing can involve playing these cymbals with a quadrotor?

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Lo-Fi Tchaikovsky

February 22, 2023 by 4 Comments

[Kevin] over at Simple DIY ElectroMusic Projects recently upgraded his Lo-Fi Orchestra. To celebrate his 400th blog post, he programmed it to play Tchaikovsky’s 1812 Overture. Two Arduino Nanos, four Arduino Unos, four Raspberry Pi Picos, and one Raspberry Pi have joined the Lo-Fi Orchestra this year, conducted by a new Pico MIDI Splitter. Changes were made in every section of the orchestra except percussion. We are delighted that the Pringles tom and plastic tub bass drums remain, not to mention the usual assortment of cheap mixers, amps, and speakers.

Tchaikovsky’s score famously calls for some “instruments” not found in the typical orchestra — a battery of cannon and a carillon, for example. Therefore [Kevin] had to supplement the Lo-Fi Orchestra for this performance with extras — a JQ6500 MP3 module on clash cymbals, a bare metal MiniDexed Raspberry Pi playing the carillon, and a MCP4725 with a Lots-of-LEDs shield firing off cannon and fireworks, respectively.

Although slightly disappointed that the MCP4725 beat out Mr. Fireworks in the auditions, we do like the result. [Kevin] reports that the latest version is much more reliable and predictable, having eliminated various MIDI faults and electrical noise. It presents a stable platform for future musical presentations, a kind of on-demand Lo-Fi Orchestra jukebox, as he describes it. A detailed review of all the changes can be found in his explanatory blog post. Check out an earlier performance of Holst’s The Planets suite from our coverage back in 2021.

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A Better Playlist Shuffle Algorithm Is Possible

February 19, 2023 by 52 Comments

When listening to music, most of us reach for the shuffle button on the regular. This is then followed by a bunch of frustrating skips as we hear the same four or five tracks that have been regularly replayed for the last few days. [Ron Miller] wants to fix unsatisfying shuffles, and he’s developed the Miller Shuffle algorithm to do so.

[Ron] realized that many big name streaming services use incredibly simple algorithms to choose shuffled songs. This can often be as simple as songIndex=random(NumOfSongs). The problem with this is that even with a good random number source, you’ll get a lot of premature repetitions. If your music service doesn’t keep track of your shuffle-point between sessions, you’ll often get annoying repeats if you’re listening on a day-to-day basis.

To fix this, the Miller Shuffle algorithm aims to offer good randomness and no repeats without the excess resource usage of the commonly-cited Fisher-Yates algorithm. [Ron] explains it like this: “The way the algorithm works its magic is by utilizing multiple computations which are ‘symmetrical’, in that the range of values which go in are the same values which come out albeit in a different order.” Since its a deterministic fixed list, there’s no need to keep track of what songs have already been played to avoid repeats. Instead, the player must simply step through the index in order, one track after another. As long as a referenced index point is maintained, along with an ID of the shuffle order being used, no repeats should come up.

If you’re implementing a shuffle algorithm for your own music, you might want to give [Ron’s] work a look. He’s taken into account details like resource usage and small and large list sizes, to account for implementation issues for even very large streaming services. If you’re more interested in shuffling cards than songs, though, we can help there too!

How To Build Jenny’s Budget Mixing Desk

February 15, 2023 by 35 Comments

Jenny did an Ask Hackaday article earlier this month, all about the quest for a cheap computer-based audio mixer. The first attempt didn’t go so well, with a problem that many of us are familiar with: Linux applications really doesn’t like using multiple audio devices at the same time. Jenny ran into this issue, and didn’t come across a way to merge the soundcards in a single application.

I’ve fought this problem for a while, probably 10 years now. My first collision with this was an attempt to record a piano with three mics, using a couple different USB pre-amps. And of course, just like Jenny, I was quickly frustrated by the problem that my recording software would only see one interface at a time. The easy solution is to buy an interface with more channels. The Tascam US-4x4HR is a great four channel input/output audio interface, and the Behringer U-PHORIA line goes all the way up to eight mic pre-amps, expandable to 16 with a second DAC that can send audio over ADAT. But those are semi-pro interfaces, with price tags to match.

But what about Jenny’s idea, of cobbling multiple super cheap interfaces together? Well yes, that’s possible too. I’ll show you how, but first, let’s talk about how we’re going to control this software mixer monster. Yes, you can just use a mouse or keyboard, but the challenge was to build a mixing desk, and to me, that means physical faders and mute buttons. Now, there are pre-built solutions, with the Behringer X-touch being a popular solution. But again, we’re way above the price-point Jenny set for this problem. So, let’s do what we do best here at Hackaday, and build our own. Continue reading “How To Build Jenny’s Budget Mixing Desk” →

An Open Hardware Eurorack Compatible Audio FPGA Front End

February 13, 2023 by 4 Comments

[Sebastian Holzapfel] has designed an audio frontend (eurorack-pmod) for FPGA-based audio applications, which is designed to fit into a standard Eurorack enclosure. The project, released under CERN Open-Hardware License V2, is designed in KiCAD using the AK4619VN four-channel audio codec by Asahi Kasei microdevices. (And guess what folks, there’s plenty of those in stock!) Continue reading “An Open Hardware Eurorack Compatible Audio FPGA Front End” →

Building A Plasma Piano Ain’t Easy

February 8, 2023 by 17 Comments

Electronic arcs can be made to “sing” if you simply modulate them on and off at audible frequencies. We’ve seen it done with single Tesla coils, and even small Tesla choirs, but [Mattias Krantz] took this to extremes by building an entire “plasma piano” using this very technique.

The build relies on ten transformers more typically used in cathode ray tubes. The transformers are capable of generating high enough voltages to create arcs in the air. The transformers are controlled by an Arduino, which modulates the arcs at musical frequencies corresponding to the keys pressed on the piano. Sensing the keys of the piano is achieved with a QRS optical sensor strip designed for performance capture from conventional pianos. For the peak aesthetic, the transformer outputs are connected to the metal hammers of the piano, and the arcs ground out on a metal plate in the back of the piano’s body. This lets arcs fly across the piano’s whole width as its played. Ten transformers are used to enable polyphony, so the piano to play multiple tones at once.

Building the piano was no mean feat for [Mattias], who admitted to having very limited experience with electronics before beginning the build. However, he persevered and got it working, while thankfully avoiding injury from high voltage in the process. This wasn’t easy, as Arduinos would regularly freeze from the noise produced by the arcs and the system would lose all control. However, with some smart software tweaks to the arc control and some insulating panels, [Mattias] was able to get the piano playable quite well with a beautiful chiptune tone.

It bears stating that HV work can be dangerous, and you shouldn’t try it at home without the proper understanding of how to do so safely. If you’re confident though, we’ve featured some great projects in this space before. Video after the break.

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