Homebrew Grain Synth Has A Rad Step Sequencer

March 19, 2021 by Lewin Day 8 Comments

In the world of homebrew synthesizers, there are plenty of noiseboxes and grooveboxes that make all kinds of wacky and wild noises. However, common projects like the Auduino and Atari Punk Console are often limited in that they can’t readily be programmed to play multiple notes or any sort of discernable rhythm. [Nick Poole] changes this with his Auduino step sequencer build.

The build takes the Auduino grain synthesizer, and modifies it by adding a step sequencer. This is possible as the Auduino code, which runs on the old-school ATMEGA-based Arduinos, is incredibly fast, leaving plenty of processing time for extra features to be added. [Nick] adds eight LEDs and eight buttons to the build, allowing the user to select one of eight steps to modify. Then, the sound parameters for the step can be altered with the standard Auduino controls. This lets the user quickly and easily build up 8-step melodies, something that was previously impossible with the Auduino.

It’s a fun build, and one that makes a great intro into the world of DIY synth builds. The techniques learned here will serve any aspiring maker well if they dive further into the world of modular synthesis and associated arcana. Video after the break.

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Guitar Effects With No (Unwanted) Delay

March 15, 2021 by Bryan Cockfield 23 Comments

MIDI has been a great tool for musicians and artists since its invention in the 1980s. It allows a standard way to interface musical instruments to computers for easy recording, editing, and production of music. It does have a few weaknesses though, namely that without some specialized equipment the latency of the signals through the various connected devices can easily get too high to be useful in live performances. It’s not an impossible problem to surmount with the right equipment, as illustrated by [Philip Karlsson Gisslow].

The low-latency MIDI interface that he created is built around a Raspberry Pi Pico. It runs a custom library created by [Philip] called MiGiC which specifically built as a MIDI to Guitar interface. The entire setup consists of a preamp to boost the guitar’s signal up to 3.3V where it is then fed to the Pi. This is where the MIDI sampling is done. From there it sends the information to a PC which is able to play the sound back quickly with no noticeable delay.

[Philip] also had to do a lot of extra work to port the software to the Pi which lacks a lot of the features of its original intended hardware on a Mac or Windows machine, and the results are impressive, especially at the end of the video where he uses the interface to play a drum machine via his guitar. And, while MIDI is certainly a powerful application for a guitarist, we have also seen the Pi put to other uses in this musical realm as well.

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Peek Into This Synth’s Great Design (And Abandoned Features)

March 9, 2021 by Donald Papp 30 Comments

[Tommy]’s POLY555 is an analog, 20-note polyphonic synthesizer that makes heavy use of 3D printing and shows off some clever design. The POLY555, as well as [Tommy]’s earlier synth designs, are based around the 555 timer. But one 555 is one oscillator, which means only one note can be played at a time. To make the POLY555 polyphonic, [Tommy] took things to their logical extreme and simply added multiple 555s, expanding the capabilities while keeping the classic 555 synth heritage.

The real gem here is [Tommy]’s writeup. In it, he explains the various design choices and improvements that went into the POLY555, not just as an instrument, but as a kit intended to be produced and easy to assemble. Good DFM (Design For Manufacturability) takes time and effort, but pays off big time even for things made in relatively small quantities. Anything that reduces complexity, eliminates steps, or improves reliability is a change worth investigating.

For example, the volume wheel is not a thumbwheel pot. It is actually a 3D-printed piece attached to the same potentiometer that the 555s use for tuning; meaning one less part to keep track of in the bill of materials. It’s all a gold mine of tips for anyone looking at making more than just a handful of something, and a peek into the hard work that goes into designing something to be produced. [Tommy] even has a short section dedicated to abandoned or rejected ideas that didn’t make the cut, which is educational in itself. Want more? Good news! This isn’t the first time we’ve been delighted with [Tommy]’s prototyping and design discussions.

POLY555’s design files (OpenSCAD for enclosure and parts, and KiCad for schematic and PCB) as well as assembly guide are all available on GitHub, and STL files can be found on Thingiverse. [Tommy] sells partial and complete kits as well, so there’s something for everyone’s comfort level. Watch the POLY555 in action in the video, embedded below.

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A Sympathetic Nail Violin

March 3, 2021 by Matthew Carlson 5 Comments

As a hacker community, we are no strangers to beautiful and unique musical instruments. A sympathetic nail violin built by [Nicolas Bras] is a welcome addition to the eclectic family. Working up from the simple idea of a nail in a piece of wood and adjusting the pitch by hammering the nail farther into the wood, [Nicolas] expanded the idea. With careful planning and tuning, the nails can have sympathetic properties. These properties mean that when one nail is played via a bow, it causes other nails to sound, creating harmonies and sustains.

With a bit of careful woodworking and a scant touch of metalwork, an instrument was crafted. It offers vast flexibility as it can be played by bow, by plucking with your finger, or by strumming. There are several levels of nails, each level having a paired sympathetic nail. This allows for a diverse and versatile instrument.

Here at Hackaday, we seem to have a thing for tiny violins, whether physical or virtual. While the nail violin may not look like your traditional violin, we can certainly appreciate the wonderful music it creates.

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An Homage To Daft Punk In Fan-Made Helmets Through The Years.

March 2, 2021 by Jenny List 32 Comments

It’s with sadness that we note the end to an end. The French dance music duo Daft Punk have split up, announced in a video that’s has already clocked 22 million views.The band have inspired hardware geeks across the world not just with their music but the way they present themselves. A perennial project has been to replicate in some way their iconic robot helmets.

Ben Heck's 2009 take on the helmet — Harrison Krix’s 2009 take on Guy-Manuel de Homem-Christo’s helmet.

The artists themselves have been reticent about the exact technology that powers their headgear, but while this is a source of endless mystery and speculation to the music press it’s safe to assume from our perspective that their designers have the same parts at their disposal as we have. Microcontrollers, EL wire, and LEDs are universal, so the challenge lies in artistic expression with the helmet design rather than in making the effects themselves. We’ve reached into the archives for a bit of Daft Punk helmet nostalgia, so stick on Harder Better Faster and lets take a look at them, er, one more time.

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Audio Out Over A UART With An FTDI USB-To-TRS Cable

February 24, 2021 by Maya Posch 41 Comments

What is the easiest way to get audio from a WAV file into a line-level format, ready to be plugged into the amplifier of a HiFi audio set (or portable speaker)? As [Konrad Beckmann] demonstrated on Twitter, all you really need is a UART, a cable and a TRS phono plug. In this case a USB-TTL adapter based around the FTDI FT232R IC: the TTL-232R-3V3-AJ adapter with 12 Mbps USB on one end, and a 3 Mbps UART on the other end.

[Konrad] has made the C-based code available on GitHub. Essentially what happens underneath the hood is that it takes in a PCM-encoded file (e.g. WAV). As a demonstration project, it requires the input PCM files to be a specific sample rate, as listed in the README, which matches the samples to the baud rate of the UART. After this it’s a matter of encoding the audio file, and compiling the uart-sound binary.

The output file is the raw audio data, which is encoded in PDM, or Pulse-Density Modulation. Unlike Pulse-Code Modulation (PCM), this encoding method does not encode the absolute sample value, but uses binary pulses, the density of which corresponds to the signal level. By sending PDM data down the UART’s TX line, the other side will receive these bits. If said receiving device happens to be an audio receiver with an ADC, it will happily receive and play back the PDM signal as audio. As one can hear in the video embedded in the tweet, the end result is pretty good.

If we look at at the datasheet for the TTL-232R-3V3-AJ adapter cable, we can see how it is wired up:

When we compare this to the wiring of a standard audio TRS jack, we can see that the grounds match in both wirings, and TX (RX on the receiving device) would match up with the left channel, with the right channel unused. A note of caution here is also required: this is the 3.3V adapter version, and it lists its typical output high voltage as 2.8V, which is within tolerances for line-level inputs. Not all inputs will be equally tolerant of higher voltages, however.

Plugging random TRS-equipped devices into one’s HiFi set, phone or boombox is best done only after ascertaining that no damage is likely to result. Be safe, and enjoy the music.

PVC Pipes Play “Popcorn” Perfectly

February 22, 2021 by Kristina Panos 16 Comments

There are all sorts of fun ways to make music with empty jugs and other things that resonate with a popping sound when poked with a finger. Should you ever get stuck on that proverbial desert island, you can entertain yourself by making cheerful, staccato music with nothing but a fingertip and the inside of your cheek. At the very least, it will keep your spirits up until you can fashion an ocarina from a coconut.

[Nicolas Bras] loves to make homemade instruments. When he saw all the scrap pieces of perfectly finger-sized PVC tubing piling up around the workshop, he decided to make an instrument specifically to play the effervescent synth tune “Popcorn”. (Video, embedded below.) He plays it by plugging and quickly unplugging wood-capped pipes with his fingers, and using another PVC tube to blow across the tops of them to fill out the orchestration.

[Nicolas] started by making a two-octave chromatic scale with 25 pipes ranging from C4 to C6. He kept building on it from there in both directions, ultimately ending up with a poppin’ 68-note pipe organ that sounds fantastic. If you’re interested in getting the sound samples, [Nicolas] has those and the instrument plans available through Patreon.

Be sure to check out the build and demo video below — it’s a joy to see it come together, and the whole thing clocks in under six minutes. Take our word for it and don’t jump to the “Popcorn” cover, because the build-up is necessary for maximum enjoyment.

Hungry for more “Popcorn”? Here’s a robotic glockenspiel busting out a striking cover.

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