Musical Hacks

1393 Articles

Fixing A 30-year Old Roland Bug

October 5, 2022 by 12 Comments

The Roland CM-500 is a digital synthesizer sound module released in 1991 that combines two incredibly powerful engines into one unit. However, in 2005 enthusiasts of the Roland MT-25 (one of the engines that went into the CM-500) noticed a difference between the vibrato rate on the MT-25 and the CM-500, rendering it less useful as now midi files would need to be adjusted before they sounded correct. Now thirty-something years later, there is a fix through the efforts of [Sergey Mikayev] and a fantastic writeup by [Cloudschatze].

They reached out to Roland Japan, who decided that since the device’s lifecycle had ended, no investigation was warranted. That led the community to start comparing the differences between the two systems. One noticeable difference was the change from an Intel 8098 to an 80C198. In theory, the latter is a superset of the former, but there are a few differences. First, the crystal frequency is divided by three rather than two, which means the period of the LFO would change even if the crystal stayed the same. Changing the 12 MHz crystal out for 8 MHz gave the LFO the correct period, but it broke the timings on the MIDI connection. However, this is just setting the serial baud rate divisor, which requires changing a few bytes.

Replace the ROM chip with a socket so you can slot your newly flashed PDIP-28 64kx8 ROM into a quick desoldering. Then swap the crystal, and you’ll have a machine that matches the MT-25 perfectly. The forum post has comparison audio files for your enjoyment. Finally, if you’re curious about other fixes requiring an inspiring amount of effort and dedication, here’s a game installer that was brought back from the dead by a determined hacker.

Trombone Controls Virtual Trombone

September 27, 2022 by 5 Comments

Guitar Hero was a cultural phenomenon a little over a decade ago, and showed that there was a real fun time to be had playing a virtual instrument on a controller. There are several other similar games available now for different instruments, including one called Trombone Champ that [Hung Truong] is a fan of which replaces the traditional guitar with a trombone. The sliding action of a trombone is significantly different than the frets of a guitar, making it a unique challenge in a video game. But an extra challenge is building a controller for the game that works by playing a real trombone.

Unlike a guitar which can easily map finger positions to buttons, mapping a more analog instrument like a trombone with its continuous slide to a digital space is a little harder. The approach here was to use an ESP32 and program it to send mouse inputs to a computer. First, an air pressure sensor was added to the bell of the trombone, so that when air is passing through it a mouse click is registered, which tells the computer that a note is currently being played. Second, a mouse position is generated by the position of the slide by using a time-of-flight sensor, also mounted to the bell. The ESP32 sends these mouse signals to the computer which are then used as inputs for the game.

While [Hung Truong] found that his sensors were not of the highest quality, he did find the latency of the control interface, and the control interface itself, to be relatively successful. With some tuning of the sensors he figures that this could be a much more effective device than the current prototype. If you’re wondering if the guitar hero equivalent exists or not, take a look at this classic hack from ’09.

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3D Printing The Key To A Bass Clarinet

September 27, 2022 by 8 Comments

Playing music as part of a group typically requires that not only are all of the instruments tuned to each other, but also that the musicians play in a specific key. For some musicians, like pianists and percussionists, this is not terribly difficult as their instruments are easy to play in any key. At the other end of the spectrum would be the diatonic harmonica, which is physically capable of playing in a single key only. Other orchestral instruments, on the other hand, are typically made for a specific key but can transpose into other keys with some effort. But, if you have 3D printed your instrument like this bass clarinet from [Jared], then you can build it to be in whichever key you’d like.

The bass clarinet is typically an instrument that comes in the key of B flat, but [Jered] wanted one that was a minor third lower. Building a traditional clarinet is not exactly the easiest process, so he turned to his 3D printer. In order to get the instrument working with the plastic parts, he had to make a lot of the levers and keys much larger than the metal versions on a standard instrument, and he made a number of design changes to some of the ways the keys are pressed. Most of his changes simply revert back to clarinet designs from the past, and it’s interesting to see how simpler designs from earlier time periods lend themselves to additive manufacturing.

While [Jared] claims that the two instruments have slightly different tones, our amateur ears have a hard time discerning the difference. He does use a standard clarinet bell but other than that it’s impressive how similar the 3D printed version sounds to the genuine article. As to why it’s keyed differently than the standard, [Jared] points out that it’s just interesting to try new things, and his 3D printer lets him do that. We’d be happy to have another instrument in our 3D printed orchestra, too.

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Building An Old Guitar From A New One

September 27, 2022 by 3 Comments

Anyone who’s ever played guitar to at least the skill level required to form a terrible garage band knows the names of the most legendary guitars. The driving sound of the Gibson Les Paul played by Jimmy Page, the upside-down and smooth Fender Stratocaster from Jimi Hendrix, or the twangy Rickenbacker made famous by George Harrison are all lusted-after models. The guitar that [Frank] really wanted was a Danelectro DC59 and since they’ve been steadily creeping up in price, he decided to build his own.

The body of the clone guitar is hollow and made from effectively scrap wood, in this case plywood. As the original guitars were in fact famous for using the least expensive materials possible, this makes it a great choice for a clone. [Frank] made the guitar using almost exclusively hand tools and glued everything together, but did use a few donor parts from a modern Stratocaster-type guitar. With most of the rough shape of the guitar finished, it was time to add the parts that make the guitar sound the way that a real Danelectro should: the lipstick-style pickups. He purchased these completely separately as they are the most important part to get right to emulate the tone and feel of the original.

With everything finally soldered and assembled, [Frank] got right to work recording a sample audio track which is included at the end of the video. It certainly sounds like the original to our untrained ears, and for around $100 it’s not a bad value either. If you’d like to see a guitar built from the ground up without using another as a clone, take a look at this build which brings a completely original guitar into existence, entirely from scratch.

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three sensory bridge audio spectrum analyzers, one in use with a lit LED array plugged in, the other facing the camera and leaning against the third, all on a table

The Sensory Bridge Is Your Path To A Desktop Rave

September 26, 2022 by 7 Comments

[Lixie Labs] are no strangers to creating many projects with LEDs or other displays. Now they’ve created a low latency music visualizer, called the Sensory Bridge, that creates gorgeous light shows from music.

The Sensory Bridge has the ability to update up to 128 RGB LEDs at 60 fps. The unit has an on-board MEMS microphone that picks up ambient music to produce the light show. The chip is an ESP32-S2 that does Fast Fourier Transform trickery to allow for real-time updates to the RGB array. The LED terminal supports the common WS2812B LED pinouts (5 V, GND, DATA). The Sensory Bridge also has an “accessory port” that can be used for hardware extensions, such as a base for their LED “Mini Mast”, a long RGB array PCB strip.

The unit is powered by a 5 V 2 A USB-C connector. Different knobs on the device adjust the brightness, microphone sensitivity and reactivity of the LED strip. One of the nicer features is its “noise calibration” that can record ambient sound and subtract off the background noise frequency components to give a cleaner music signal. The Sensory Bridge is still new and it looks like some of the features are yet to come, like WiFi communication, accessory port upgrades and 3.5 mm audio input to bypass the on-board microphone.

The stated goals of the Sensory Bridge are to provide an open, powerful and flexible platform. This can be seen with their commitment to releasing the project as open source hardware, providing firmware, PCB design files and even the case STLs under a libre/free license. Audio spectrum analyzers are a favorite of ours and we’ve seen many different iterations ranging from ones using Raspberry Pis to others use ESP32s.

Video after the break!

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This Found-Sound Organ Was Made With Python And A Laser Cutter

September 25, 2022 by 17 Comments

Some readers will no doubt remember attaching a playing card to the front fork of their bicycle so that the spokes flapped the card as the wheel rotated. It was supposed to sound like a motorcycle, which it didn’t, but it was good, clean fun with the bonus of making us even more annoying to the neighborhood retirees than the normal baseline, which was already pretty high.

[Garett Morrison]’s “Click Wheel Organ” works on much the same principle as a card in the spokes, only with far more wheels, and with much more musicality. The organ consists of a separate toothed wheel for each note, all turning on a common shaft. Each wheel is laser-cut from thin plywood, with a series of fine teeth on its outer circumference. The number of teeth, as calculated by a Python script, determines the pitch of the sound made when a thin reed is pressed against the spinning wheel. Since the ratio of teeth between the wheels is fixed, all the notes stay in tune relative to each other, as long as the speed of the wheels stays constant.

The proof-of-concept in the video below shows that speed control isn’t quite there yet — playing multiple notes at the same time seems to increase drag enough to slow the wheels down and lower the pitch for all the notes. There appears to be a photointerrupter on the wheel shaft to monitor speed, so we’d imagine a PID loop to control motor speed might help. That and a bigger motor that won’t bog down as easily. As for the sound, we’ll just say that it certainly is unique — and, that it seems like something [Nicolas Bras] would really dig.

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CMOS Oscillator Circuit Gets An Eatable Input

September 24, 2022 by 9 Comments

In interaction designer [Leonardo Amico]’s work Processing Decay, lettuce is used as an input to produce sound as an element within a CMOS circuit. 

We’ve all seen lemons and potatoes doubling in science-fairs as edible batteries, but lettuce is something else.  [Leandro]’s circuit uses alligator clips to insert lettuce into oscillators in this audio generating circuit — we think they’re behaving like resistors. Without refrigeration, the resistance of the lettuce changes, and so does the oscillation in the circuit. In a matter of hours, days, and weeks the cells degrades slowly, modulating the system and its sonic output. What a way to make music!

This hack isn’t the freshest — the video dates from nine years ago — but this is the first lettuce circuit we’ve seen. Of course, we love other food hacks like these multi-wavelength lasers used to cook 3D-printed chicken, or maybe the circuit can make use of this neural net detecting fruit ripeness.