Basic Sequencer For Your Synth Rack

March 2, 2018 by Lewin Day 9 Comments

Sequencers are useful for bringing regular structure to your music, particularly if you enjoy noodling around with rackmount synthesizers. [little-scale] is here to share an ADC Binary Gate sequencer for your setup.

In a quest for ever greater minimalism, the build relies on a barebones ATMega328p without an external oscillator. Instead, the chip’s internal RC oscillator is used instead. It’s possible to still use this with the Arduino IDE, as [little-scale] shares here.

The music production begins with a clock input signal, which is patched in from elsewhere in the rack synth. The sequencing is controlled with potentiometers. There are four potentiometers, and four corresponding output channels. The pots are all read with the onboard analog to digital converters, and the position transformed into an 8-bit value, from 0 to 255. Our best understanding is that the 8-bit number is then used as the sequence to follow. For example, if the potentiometer is set to 255, which is 11111111 in binary, the sequencer will trigger on every beat. If instead the potentiometer was turned to around 2/3rds of the maximum, and the ADC reads a value of 170, in binary this is 10101010 which would trigger on every second beat.

It’s an interesting way to sequence several channels with the bare minimum of input devices. While it may not be the most intuitive system, it really suits the knob-and-dial noodling so relished by rackmount fanatics. Be sure to check out the video below for [little-scale]’s rackmount sounds and impressively pretty videography. Never before did breadboards look so good.

New to rack mount synths? Check this one out.

Real-Time Audio For The PocketBeagle

February 25, 2018 by Brian Benchoff 11 Comments

The BeagleBone has long been a favorite for real-time I/O, and now with the release of the PocketBone — the tiny key fob-sized BeagleBone — there are ever increasing uses for this tiny little programmable real-time Linux module. The Bela Mini, just released, is the latest add-on cape to take advantage of the processing power of the micro-sized PocketBone.

The Bela Mini is a shrinkification of the original Bela, a cape add-on for the BeagleBone. The original breaks out eight analog inputs and eight analog outputs, both sixteen-bits deep. With the addition of powered speaker outputs, the Bela turns the BeagleBone into the perfect tiny audio-Linux-thing, with a special emphasis on Pure Data and other audio wizardry.

The Bela Mini does away with the powered speaker outputs, and instead replaces those ports with stereo audio in and stereo audio out on a three-pin connector. Compared to the original Bela, the Mini loses the eight sixteen-bit analog outputs, but still keeps the analog inputs.

There have been many attempts to add real-time audio to microcontrollers and Linux boards, but few examples have lived up to the hype. Most of the time, this comes down to the choice of microcontroller or module; an ATmega-based Arduino doesn’t have real analog outputs and instead relies on PWMing a digital signal. A Raspberry Pi-based Pure Data box does not have a real-time I/O. This is where the choice of the PocketBone shows its strength. The PocketBone uses the same chip as the BeagleBone, and with that comes the Programmable Real-Time Units (PRUs). This enables the Bela to interface with signals with a dedicated controller in real-time. It’s exactly what you want for audio applications.

A Jukebox For The 21st-Century Kit Blends Raspberry Pi, Sonos, QR Codes

February 19, 2018 by James Hobson 17 Comments

When [Chris Campbell]’s children wanted to play an album in the background over dinner, switching the outputs on his family’s Sonos sound system was perhaps too involved for their budding mastery of technology. This got him thinking about using kid-friendly inputs so they could explore his music collection. Blending QR codes, some LEGO, and a bit of arts and crafts, a kid-friendly QR code reader media controller comes out!

Working with a Raspberry Pi 3 Model B and a cheap camera, [Campbell] whipped up some code to handle producing and reading the QR codes — though he’s running the media server on another computer to maintain fast response times. Once [Campbell] had his QR codes, he printed them out and got his kids involved in cutting and gluing the double-sided cards. Additional cards access different functions — starting a playlist queue, switching output channels, and full album playback, among others. Cue spontaneous dance-parties!

Continue reading “A Jukebox For The 21st-Century Kit Blends Raspberry Pi, Sonos, QR Codes” →

Pulling Music Out Of Thin Air With A Raspberry Pi

February 15, 2018 by Sven Gregori 1 Comment

Pianos are great instruments, but being rather heavy and requiring a fair amount of space they are certainly not known for their convenience. Sure, there are more portable varieties available, but they rarely resemble the elegance and classiness of a grand piano. One option is of course to build a downscaled version yourself — and since you’re already customizing the instrument, why stop at the way you play it. [2fishy] didn’t stop there either and ended up with a wooden, space friendly, light controlled piano housing a Raspberry Pi.

Inspired by the concept of a laser harp, [2fishy] followed the same principle but chose a simpler and safer alternative by using LEDs instead. For each playable tone, a LED is mounted opposite a light dependent resistor, creating an array of switches that is then connected to the Raspberry Pi’s GPIO pins. A Python script is handling the rest, polling the GPIO states and — with a little help from pygame, triggering MIDI playback whenever the light stream is interrupted.

There are enough LED/LDR pairs to play one full octave and have some additional control inputs for menu and octave shifting. This concept will naturally require some adjustments to your playing — you can get an idea of it in the demonstration video after the break. And if this design is still not the right size for you, or if you prefer to play in total darkness, this similar MIDI instrument using ultrasonic distance sensors could be of interest.

Continue reading “Pulling Music Out Of Thin Air With A Raspberry Pi” →

The Furby Organ

February 12, 2018 by Steven Dufresne 30 Comments

Sometimes you have an idea that is so brilliant and so crazy that you just have to make it a reality. In 2011, [Look Mum No Computer] drew up plans in his notebook for a Furby organ, an organ comprised of a keyboard and a choir of Furbies. For those who don’t know what a Furby is, it’s a small, cute, furry robotic toy which speaks Furbish and a large selection of human languages. 40 million were sold during its original production run between 1998 and 2000 and many more since. Life intervened though, and, [LMNK] abandoned the Furby organ only to recently take it up again.

He couldn’t get a stable note out of the unmodified Furbies so he instead came up with what he’s calling the Furby Forman Fusion Synthesis. Each Furby is controlled by a pair of Ardunios. One Arduino sequences parts inside the Furby and the other produces a formant note, making the Furby sing vowels.

We love the label he’s given for what would otherwise be the power switch, namely the Collective Awakening switch. Flicking it causes all 44 (we count 45 but he says 44) Furbies to speak up while moving their ears, eyes, and beaks. Pressing the Loop switch makes them hold whatever sound they happen to be making. The Vowel dial changes the vowel. But you’ll just have to see and hear it for yourself in the videos below. The second video also has construction details.

Continue reading “The Furby Organ” →

Circuit Bent Casio SK-1 Gets An Arduino Brain

February 5, 2018 by Tom Nardi 28 Comments

The Casio SK-1 keyboard is fairly well-known in the “circuit bending” scene, where its simple internals lend themselves to modifications and tweaks to adjust the device’s output in all sorts of interesting ways. But creating music via circuit bending the SK-1 can be tedious, as it boils down to fiddling with the internals blindly until it sounds cool. [Nick Price] wanted to do something a bit more scientific, and decided to try replacing his SK-1’s ROM with an Arduino so he could take complete control it.

Replacing the ROM chip with header pins.

That’s the idea, anyway. Right now he’s gotten as far as dumping the ROM and getting the Arduino hooked up in place of it. Unfortunately the resulting sound conjures up mental images of a 56K modem being cooked in a microwave. Clearly [Nick] still has some work ahead of him.

For now though, the progress is fascinating enough. He was able to pull the original NEC 23C256 chip out of the keyboard and read its contents using an Arduino and some code he cooked up, and he’s even put the dump online for any other SK-1 hackers out there. He then wrote some new code for the Arduino to spit data from the ROM dump back to the keyboard when requested. In theory, it should sound the same as before, but with the added ability to “forge” the data going back to the keyboard to make new sounds.

The result is what you hear in the video linked after the break. Not exactly what [Nick] had in mind. After some snooping with the logic analyzer, he believes the issue is that the Arduino can’t respond as fast as the original NEC chip did. He’s now got an NVRAM chip on order to replace the original NEC chip; the idea is that he can still use the Arduino to reprogram the NVRAM chip when he wants to play around with the sound.

We’ve covered some pretty fancy circuit bent instruments here in the past, but if you’re looking for something a bit easier to get your feet wet we ran a start-to-finish guide back in the Ye Olden Days of 2011 which should be helpful.

Continue reading “Circuit Bent Casio SK-1 Gets An Arduino Brain” →

Flexiphone Rises From The Ashes Of Broken Instruments

February 2, 2018 by Adam Fabio 7 Comments

The mechanics of an old Rhodes Piano, and a set of chromatic saucer bells rescued from a reed organ. What do these two things have to do with each other? If you’re [Measured Workshop], they are the makings of a new instrument. The Flexiphone is a transposable instrument with a piano keyboard and interchangeable sound source.

The Rhodes is a great stage instrument. Unlike a piano with strings, it uses tines mounted above the key mechanism. It is also relatively compact for an analog instrument. This made it perfect as a donor for the Flexiphone’s keyboard. [Measured Workshop] cut they mechanism down to 30 keys, just under 2 octaves. The key mechanism was also cleaned up and restored with new felt.

The sounding portion of the Flexiphone is a set of chromatic saucer bells. The bells are mounted on a felt covered threaded rod, which itself sits in a wood frame. The bell frame sits on top of the base in one of three slots. Each slot is a halftone transposed from the last. Simply moving the bells allows the player to transpose the entire instrument. The bells and their rod frame can also be completely removed and replaced with any other sound source.

The Flexiphone sounds great — sometimes. As [Measured Workshop] says, bells contain many harmonics. playing single or double notes sounds rather sweet, but chords can sometimes become a shrill assault on the ears. Still, it’s an awesome hack with plenty of potential for future mods.

Continue reading “Flexiphone Rises From The Ashes Of Broken Instruments” →