A Transistor-less Sound Synthesizer

October 24, 2020 by Jenny List 34 Comments

A synthesizer without transistors could almost be the basis of a trick question, surely without transistors it must be using a vacuum tube or similar. Not [Dr. Cockroach]’s synth though, instead of transistors it uses coupled pairs of LEDs and light-dependent resistors as its active components. Its oscillator circuit comes courtesy of [Patrick Flett], and uses a pair of LED/LDR combinations to alternately charge and discharge a capacitor. This feeds another LDR/LED pair that appears to act as a buffer to drive a bridge rectifier, with a final amplifier following it.

The result oscillates, though at frequencies in the low audio range with a cluster of harmonics thrown in. Its sound is best described as something akin to a small single-cylinder motorcycle engine at the lower frequencies, and is something we see could have all sorts of interesting possibilities.

This approach of using LDR-based active devices may be something of a dead end that could have had its day back in the 1930s, but it’s nevertheless an entertaining field to explore. It’s not the first time we’ve followed [Dr. Cockroach] at it, in the past we’ve seen the same technique applied to logic gates.

Have a listen to the synth in the video below the break. Continue reading “A Transistor-less Sound Synthesizer” →

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.

Continue reading “Synthesizer Gets An External Touch Screen” →

The Fart Box, A Synthesizer Not Quite Like Others

March 21, 2020 by Donald Papp 20 Comments

[lookmumnocomputer] enjoys creating synthesizers, and early last year he created one called The Fart Box. It is an entirely analog synthesizer with which, according to its creator, it is difficult to make anything that doesn’t sound gassy. It’s not quite like any other synthesizer, and while it is capable of acting like a regular analog synth it is never very far from cranking out farty sounds.

One may think this is just a gimmick, but it can actually be quite musical. There’s a good demonstration at the 7:09 mark in the video of what it can do. Entirely hand-made, it’s definitely a labor of love. There’s a bill of materials and a wiring diagram (of a sort) for anyone who is interested in such details, but it looks like it was a limited run only. [lookmumnocomputer]’s whole video is embedded below, and he demonstrates its ability to act more like a “normal” synthesizer around 8:30.

Continue reading “The Fart Box, A Synthesizer Not Quite Like Others” →

Introducing The XFM2: A New FM Synthesizer Board

February 22, 2020 by Maya Posch 29 Comments

[René Ceballos] contacted us about the new XFM2 FM synthesizer board, successor to the XFM that we covered on Hackaday last year. In addition to changing FPGAs from a Spartan 6 to an Artix-7 35, the DAC was also upgraded from 16 to 24 bits. Since the project is based around two easily available boards for the FPGA and DAC functionality, it is something that should be easy for anyone to recreate.

The project consists of a lower board that features the opto-isolated MIDI-input port, a 24LC1025 EEPROM, and a few passives, on top of which are mounted the Adafruit UDA1334A-based I2S decoder board and a Digilent Cmod A7-35T, containing the Xilinx XC7A35T-1CPG236C Artix-7 FPGA. [René] has made a schematic and BOM available on the XFM2 page. Total part cost should be about $99.

A user manual, installation guide, and the binaries that have to be loaded into the FPGA – using the provided instructions – are all made available. Unfortunately no HDL source is provided, but that shouldn’t take away from the fun of assembling an FM synthesizer board like this.

[René ] said that based on the feedback to the XFM project, he is now working on a visual user interface for the board. Once this is all working and depending on the feedback from XFM2 users, he may decide to start a crowdfunding campaign.

Hackaday Podcast 055: The Most Cyberpunk Synthesizer, Data In Your Cells, Bubbly In Your Printer, And The Dystopian Peepshow

February 21, 2020 by Mike Szczys 2 Comments

Hackaday editors Mike Szczys and Elliot Williams discuss the many great hacks of the past week. Just in case you missed the fact that we’re living in the cyberpunk future, you can now pop off your prosthetic hand and jack directly into a synthesizer. The robot headed for Mars has a flying drone in its belly. Now they’re putting foaming agent in filament to make it light and flexible. And did you ever wonder why those pinouts were so jumbled?

Take a look at the links below if you want to follow along, and as always tell us what you think about this episode in the comments!

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (60 MB or so.)

Continue reading “Hackaday Podcast 055: The Most Cyberpunk Synthesizer, Data In Your Cells, Bubbly In Your Printer, And The Dystopian Peepshow” →

Thea Flowers – Creating A Sega-Inspired Hardware Synthesizer From The Ground Up

November 22, 2019 by Lewin Day 5 Comments

For those who grew up with video games, the legendary sounds of consoles past are an instant nostalgia hit. [Thea Flowers] first got her hands on a gamepad playing Sonic the Hedgehog, so the sounds of the Sega Genesis hold a special place in her heart. Decades later, this inspired the creation of Genesynth, a hardware synth inspired by the classic console. The journey of developing this hardware formed the basis of [Thea]’s enlightening Supercon talk.

[Thea’s] first begins by exploring why the Genesis sound is so unique. The Sega console slotted neatly into a time period where the company sought to do something more than simple subtractive synthesis, but before it was possible to use full-waveform audio at an affordable price point. In collaboration with Yamaha, the YM2612 FM synthesis chip was built, a cost-reduced sound engine similar to that in the famous DX7 synthesizer of the 1980s. This gave the Genesis abilities far beyond the basic bleeps and bloops of other consoles at the time, and [Thea] decided it simply had to be built into a dedicated hardware synth.

Continue reading “Thea Flowers – Creating A Sega-Inspired Hardware Synthesizer From The Ground Up” →

Hypnotic Visuals Synthesizer

September 26, 2019 by Sharon Lin 12 Comments

Ever wanted to make some seriously trippy retro graphics to go along with your lo-fi hip hop beats? Now you can, with [teafella]’s aptly named Hypno Video Synthesizer, a Raspberry Pi-based video synthesizer that digitally emulates and extends analog video workflows through colorization, shape generation, and feedback, patching the modifications into a compact interface. The device allows music creators to perform with live visuals, or alternatively to create a unique visual source for a video setup. Once the CV input is plugged in, all it requires is a composite display and power to start working.

Hypno takes input through a control voltage (CV) jack using a MCP3008 ADC via SPI, with voltages scaled from -5-5V to 0-5V. The device attaches on top of a Raspberry Pi, using Raspbian for the operating system and the Pi Zero GPIO to interface with an OpenGL Engine. The input parameters are taken from knobs through a multiplexer into a single channel of the ADC, with values offset in software based on the CV inputs.

Using the Hypno ends up being fairly straight forward, as the controls are organized onto two mirrored sides for the two oscillators A & B, with global controls in the center. There are knobs that control polarization, rotation, shape, feedback modes (regular, hyper digital, zooming, rotating zoom), clock in/clock out, frequency, root hue, and master gain, as well as RGB LEDs that provide visual feedback.

A single jack outputs the composite result, although a micro-HDMI plug can also be used on the back. For advanced functionality, Hypno allows for patching, which mixes effects on top of one another and allows for shapes such as oscillator cross modulation. There are also alt-controls that open up self modulation and other shapes. Examples include bipolar drift (smoothly scrolls the oscillator) and mirroring (mirrors the oscillator’s shape in different patterns for a kaleidoscope-eque tiled madness).

The software is written in C++ and GLSL, with the main engine running with one plane in OpenGL, drawing the output of a GLSL shader. The CV and knob inputs are fed into shader uniforms that are used to change the visuals in the engine.

[teafella], a self-professed Arduino user, uses WiringPi for the GPIO interactions. The Shader system is inspired by analog video synthesis, with every shape having a simulated “scan” over the screen and function mapped to it that can be transformed into polar coordinates.

The setup for Hypno is fully compatible with analog CV equipment such as Eurorack synthesizers, which makes it easy for music creators to plug and play. Here’s a couple of sample outputs from some soundtracks inputted into Hypno: