XFM: A 32-Voice Polyphonic FM Synthesizer On An FPGA

July 24, 2019 by Maya Posch 27 Comments

There’s something about Frequency Modulation (FM) synthesizer chips that appeals to a large audience. That’s one of the reasons behind [René Ceballos]’s XFM project, aiming to duplicate on an FPGA the sound of pure-FM synthesizer chips of the past such as the Yamaha DX series, OPL chip series and TX81Z/802/816. The result is a polyphonic, 32-voice, 6-operator FM synthesizer stereo module.

The project page goes into a lot of detail about the design choices which ultimately led to XFM being implemented on an FPGA, instead of using a dedicated DSP or MCU. Coming from the world of virtual synthesizers running on PCs, [René ]’s first impulse was to implement something on a Raspberry Pi or equivalent. Unfortunately these boards require a lot of power (ruling out battery-powered operation) and can hardly be called real-time, which led [René ] to abandon this attempt.

The design choice against the use of an MCU is simple: though capable of real-time processing, they lack the necessary power to make them a good choice for audio-processing. Working through the calculations to determine what kind of processing power would be needed, it was found that around 650 MIPS would be needed, a figure which most MCUs struggle to achieve a fraction of.

As one of the further requirements for XFM was that it should be as cheap as possible, this ruled out as too expensive the DSP chips which do have the power and hardware features needed. The component chosen was a Xilinx Spartan 6 FPGA, which though somewhat infamous and shunned in FPGA circles turns out to be a very economical option for this project.

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Vintage Speech Synthesizer Croons The Oldies

June 11, 2019 by Dan Maloney 33 Comments

If you listened to the National Weather Service Weather Radio in the US about 25 years ago, you’ll no doubt remember [Perfect Paul], one of the synthesized voices used to read current conditions and weather forecasts. The voice came from a DECtalk DTC01, a not inexpensive voice synthesizer first made in 1984 that also gave voice to [Stephen Hawking] for many years.

Long obsolete, the DECtalk boxes have a devoted following with hobbyists who like to stretch what the device can do. Some even like to make it sing, after a fashion, and [Michael] decided that making a DECtalk sing “Xanadu”, the theme song from the 1980 [Olivia Newton-John] musical extravaganza, was a good idea. Whether it actually was is debatable, and we’ll take exception with having that particular ditty stuck in our head as a result, but we don’t judge except on the merits of the hack.

It’s actually easy if you have a DECtalk; the song is a straight ASCII file with remarkably concise instructions on which phonemes the box needs to generate. Along with inflection, tone, and timing instructions, the text file looks almost completely unlike English while still somehow being readable. The DECtalk accepts the file over RS-232, which would be easy enough to do with a modern computer, but [Michael] upped his game a bit by using a TRS-80 Model 100 computer as a serial terminal. The synthesized song is in the video below, with the original included for reference by those who didn’t ~~experience~~ endure the late disco-era glory days.

DECtalks seem pretty rare in the wild, so we appreciate this glimpse at what they can do. There are other retro speech synthesizer hacks, though: the simulated walnut goodness of the Votrax and the MicroVox come to mind, as does the venerable TI Speak and Spell.

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Hackaday Podcast 021: Chasing Rockets, Tripping On Vintage Synthesizers, A Spectacular IoT Security Fail, And Early Alzheimer’s Detection Via VR

May 31, 2019 by Dan Maloney 5 Comments

Mike Szczys is on a well-deserved vacation this week, so staff writer Dan Maloney joins managing editor Elliot Williams for a look at all the great hacks of the week. On this episode we’re talking about licensing fees for MIDI 2.0, a two-way fail while snooping on employees, and the potential for diagnosing Alzheimer’s with virtual reality. We also dive into the well-engineered innards of a robotic cheetah, a personal assistant safe enough for kids to use, and how listening to your monitor reveals more about you than you’d think. You don’t want to miss a space nerd’s quest for fire or a hacker’s guide to solder and soldering. And you’ve got to catch the story of a hapless hacker’s contact high from a vintage synthesizer. It’s quite a trip.

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.)

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MIDI Synthesizer From A Sega Genesis

May 15, 2019 by Bryan Cockfield 14 Comments

[Aidan] is really into FM synthesis chips for creating audio, and one of the most interesting chips from that era is found on the Sega Genesis. Anyone involved in the console wars at that time certainly remembers the classic, unique sound that those video game systems were able to produce, so [Aidan] built a device using a sound chip from a Genesis to play any piece of music from any game. The second iteration of that project, though, is able to use those same sound files as a MIDI synthesizer.

The interesting aspect of these chips is how they use registers to change the audio output. Essentially, there is a complicated register map (one section of his write-up is simply called “Register Hell”) that can be called in order to access the various types of effects one would normally see on a synthesizer. It’s not straightforward at all, though, and got even more complicated once [Aidan] started adding MIDI functionality to it as well. Once he finished sifting through the Sega Genesis technical manuals and a bunch of registers, though, he had a unique synthesizer working that doesn’t sound like anything you’ve ever heard, unless you’ve ever played a Genesis.

If you’d like to check out his first project, the MegaBlaster, which plays the sound files of the old Genesis games directly, we featured that a while ago. Keep in mind though that his latest project isn’t just an updated MegaBlaster, though. He built this entire thing from the ground up.

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A Genesis Inspired Synthesizer That Has Nothing To Do With Phil Collins

January 25, 2019 by Lewin Day 11 Comments

Chiptune is a musical genre built upon the creation of music through the use of chip-based sound synthesizers, found in early game consoles. The Commodore 64’s venerable SID chip and the Game Boy Sound System are the by far the most popular on the scene. However, the Sega Genesis took a different path at the end of the videogame chipmusic era, packing a YM2612 FM synthesis chip to deliver fat basslines and searing solos. [Thea] has always been a fan of these electric 90s sounds, and thus decided to build the Genesynth.

The synth initially allowed only for playback of existing video game scores, but its capability has been expanded as [Thea] took the project from breadboard to protoboard to custom PCBs – with anime artwork, to boot. The synth uses a Teensy 3.5 as the brains, speaking USB to enable the synth to receive MIDI commands from music software. All parameters are exposed over the interface, and [Thea] has several videos showing the Genesynth under control from an Ableton Push.

The sound capabilities of the YM2612 are of an entirely different character to most chiptunes, by virtue of the FM synthesis engine. FM synthesis is a little less intuitive then classical additive synthesis, but we still see it crop up now and then.

Open Source Synthesizers Hack Chat

January 21, 2019 by Dan Maloney 2 Comments

Matt Bradshaw is a musician, maker, and programmer with a degree in physics and a love for making new musical instruments. You may remember his PolyMod modular digital synthesizer from the 2018 Hackaday Prize, where it made the semifinals of the Musical Instrument Challenge. PolyMod is a customizable, modular synthesizer that uses digital rather than analog circuitry. That seemingly simple change results in a powerful ability to create polyphonic patches, something that traditional analog modular synths have a hard time with.

Please join us for this Hack Chat, in which we’ll cover:

The hardware behind the PolyMod, and the design decisions that led Matt to an all-digital synth
The pros and cons of making music digitally
Where the PolyMod has gone since winning the Musical Instrument Challenge semifinals

You are, of course, encouraged to add your own questions to the discussion. You can do that by leaving a comment on the Open Source Synthesizers Hack Chat and we’ll put that in the queue for the Hack Chat.

Our Hack Chats are live community events on the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, January 23, at noon, Pacific time. If time zones got you down, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io.

You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about. And don’t forget to check out the Modular Synth Discussion, a very active chat that digs into the guts of all sorts of modular synthesizers.

Wonderful Sculptural Circuits Hide Interactive Synthesizers

November 29, 2018 by Kerry Scharfglass 14 Comments

When it rains, it pours (wonderful electronic sculpture!). The last time we posted about freeform circuit sculptures there were a few eye-catching comments mentioning other fine examples of the craft. One such artist is [Eirik Brandal], who has a large selection of electronic sculptures. Frankly, we’re in love.

A common theme of [Eirik]’s work is that each piece is a functional synthesizer or a component piece of a larger one. For instance, when installed the ihscale series uses PIR sensors to react together to motion in different quadrants of a room. And the es #17 – #19 pieces use ESP8266’s to feed the output of their individual signal generators into each other to generate one connected sound.

Even when a single sculpture is part of a series there is still striking variety in [Eirik]’s work. Some pieces are neat and rectilinear and obviously functional, while others almost looks like a jumble of components. Whatever the style we’ve really enjoyed pouring through the pages of [Eirik]’s portfolio. Most pieces have demo videos, so give them a listen!

If you missed the last set of sculptural circuits we covered this month, head on over and take a look at the flywire circuits of Mohit Bhoite.

Thanks [james] for the tip!