Raspberry Pi Becomes A Guitar Effects Processor

January 28, 2013 by Brian Benchoff 34 Comments

One of the more interesting use cases for the Raspberry Pi is exploiting its DSP capabilities in interesting ways. There’s a lot of horsepower inside the Raspberry Pi, more than enough to do some very interesting things with audio, all while being powered by a small wall wart adapter. [Pierre] over on the Pure Data mailing list has a proof-of-concept working that uses the Raspi as a guitar effects processor. The results are very encouraging – [Pierre] is able to use his Raspi as a delay, pitch shifter, and of course a classic flanger, phaser, and chorus with a latency of about 16 ms.

There are a few steps necessary to get low latency with the Raspi’s audio interface. [Pierre] is running his Pi headless, and allocated more RAM to the CPU.

If you’d like to try this out for yourself, [Pierre] has a tutorial for setting up Pure Data with the Raspberry Pi. He’ll be updating his blog soon with more tutorials and verified USB audio interfaces later.

Check out the processor in action after the break.

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Tired Of Playing The MacBook? Play The Raspberry Pi!

January 21, 2013 by Brian Benchoff 29 Comments

pithingy

Hit up any club, party, or get together where musicians are present and you’ll probably find a DJ booth stacked to the gills with faders, various MIDI devices, and a MacBook. However abundant an OS X-based DJ platform is, we haven’t heard hide nor hare of a Raspberry Pi being used as a sequencer, MIDI device, or MaxMSP box.

[James] over at Illuminated Sound put together a great tutorial for making all those cool electronic music devices play nice with a Raspberry Pi. He used a Novation Launchpad, an 8×8 MIDI controller that can act as faders, a keyboard, or even a functional equivalent to the pads on an MPC.

Hardware is nothing without software, so [James] used Puredata and libusb to turn the MIDI data into notes and audio effects.

[James] added a download that includes the Launchpad driver and a Puredata sketch to test everything out. You can see how it all fits together in the video after the break.

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Turning A Broken Bass Into A Headless Bass

January 11, 2013 by Brian Benchoff 5 Comments

bass

A while back [Michael] inherited a broken bass guitar from a friend. The headstock for this bass was cracked right down the middle, and the friend attempted a repair with a bolt and a couple of washers. After trying to figure out what the addition of a bolt was trying to accomplish, [Michael] set to work repairing this bass and ended up doing a headless conversion.

A headless bass, just as the name implies, does away with the headstock and moves the tuners to the other side of the guitar – in [Michael]’s case, right below the bridge. After sawing off the broken headstock above the truss rod, [Michael] made a string retainer and bolted it on to the remainder of the neck.

The tuners had to be moved, of course, so [Michael] routed out a section of the body below the bridge. Four holes were drilled and the original tuners slipped right in. The result is a perfectly functional bass that would fit right in to the tour van of an 80’s metal band.

You can check out [Michael]’s bass down in the pocket.

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Reading Piano Rolls Without A Player Piano

January 7, 2013 by Brian Benchoff 22 Comments

detection-example

A while back, [Jacob] played around with a player piano. After feeding a roll into the machine and trying to figure out how a fifty year old machine using hundred year old technology can replicate a skilled pianist, he decided to take a crack at decoding piano rolls for himself. He came up with a clever way of doing it over Christmas break, using a camera and a few bits of OpenCV.

The old-school mechanics of a player piano use a bellows and valve system to suck air through dozens of holes, making the action hit a string whenever a hole is present in the piano roll. To bring this mechanism into the modern age, [Jacob] pointed a video camera at the active part of the piano roll and used OpenCV to translate holes in a piece of paper to a MIDI file.

The synthesized version sounds just as good as the original paper scroll-based version, as seen in the video after the break. There are a few sync issues in the video and the resulting MIDI file isn’t in the right key, but that’s easily fixed by anyone willing to replicate this project.

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Put That Headphone Jack Anywhere You Want It

December 25, 2012 by Mike Szczys 17 Comments

yamaha-keyboard-headphone-jack-hack

Check out this brand new Yamaha keyboard. The fact that we’re seeing the guts means that [Todd Harrison] can kiss his warranty goodbye. But by now you should know that he doesn’t look to others when something goes wrong with his electronics. This time around he’s not repairing anything. He didn’t like having to plug in headphones on the rear of the keyboard. He cracked it open and relocated the headphone jack to a more convenient location.

As you can see, there’s a ton of room inside once the MDF base which holds the speakers and some sounding boxes has been removed. While he’s in there he takes a good look at the mechanics of the keys. They’re weighted with metal rods (seen above) to help the electronic instrument feel more like an acoustic version to the player. But he doesn’t neglect the chance to gawk at all the electronics as well.

After pulling out the PCB that has the headphone jack on it he goes to work with a solder sucker. With the solder gone he cuts through the glue that holds the jack on the board. All that’s left is to solder some wire in its place and give it a nice project box as an enclosure. To complete the hack he mounts the box on the MDF base and now the headphones connect on the front. See the entire process in the video after the break.

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Organ Pedals Fill In When Your Bass Player Is Missing

December 18, 2012 by Mike Szczys 10 Comments

organ-foot-pedals-instead-of-string-bass

Since his string bass player isn’t always around [Antoine] built his own electric bass stand-in using the pedals from an old organ. The project — which he calls the Organ Donor — was inspired by a similar standalone organ pedal bass project. That instrument was built using a 555 timer to generate the sound. But [Antoine] has a little more room for growth as he’s using an old microcontroller development board to generate sound.

The octaves worth of pedals were pulled from an old broken Yamaha A55 Electone organ. After extracting the assembly from the instrument he built a nice wooden case around it. This doubles as a stand for the amplifier which broadcasts the sound. An old Freescale development board is wired up to twelve of the keys (the top C is unused). It generates a square wave at the appropriate frequency for each key. This signal is fed through a low-pass filter before being routed to the audio jack on the back of the case.

Future improvements include building an amplifier into the pedal assembly. We would also love to see different signal processing to expand the range of sounds the pedals can generate. We’re not sure of the capabilities of that microcontroller, but it would be neat to hear tone generation using stored samples.

Tablet Rig Takes Sheet Music Digital

December 12, 2012 by Mike Szczys 12 Comments

music-stand-tablet-holder

[Bill Dudley’s] wife wanted to use a couple of different tablets for displaying sheet music. Sure, a proper music stand will have no trouble supporting the weight of the device, but if it’s not secured it place you may soon have a broken device. [Bill’s] solution was to build this tablet stand out of PVC.

The image above doesn’t tell the entire story of how he did this. But if you look really closely you’ll notice that the pipe is actually acting as a frame rather than a cradle. After measuring, cutting, and gluing all of the components together he cut a channel around the inside of the u-shaped PVC frame. The channel is the exact thickness of the tablet and holds the device securely. A base from a music stand makes up the rest of the rig.

Pages can be turned using a USB foot pedal. This is fantastic for gigging musician who use digital music collections like the Real Book.