DIY Headphone Tube Amp Builds On Existing Design

July 3, 2014 by Rich Bremer 13 Comments

DIY Tube Headphone Amp

[Simon] wrote in to tell us about a headphone tube amp that he just built. It is based on schematics at diyaudioprojects.com that were actually featured on Hackaday in the past. [Simon’s] design adds an on board regulated power supply and a volume control for the input. Effort was made to keep the PCB single sided to facilitate making this at home.

DIY Tube Headphone Amp The 12AU7 is popular due to its ruggedness and tolerance for low operational voltages. This amp design uses a plate voltage of 12, although the 12AU7 can handle up to about 330. Since the 12AU7 is of the Twin Triode variety, one tube can be used to amplify both a left and right audio channel.

The case for the amplifier is laser cut plywood. The top piece is kerfed so that it can bend around the radii of the front and rear panels. The top also has a hole cut in it to allow the tube to peek out through.The pieces look nice but, unfortunately, he doesn’t show the case and amp in an assembled state.

If you’re interested in building one of these, [Simon] made all of the Eagle and Case files available. The total cost of the project was £25, about $43 US. To learn more about how tube amplifiers work, check out this Retrotechtacular from earlier in the year.

Laser Piano Worthy Of The Band ‘Wyld Stallyns’

July 2, 2014 by Rich Bremer 26 Comments

Laser Piano uses Arduino

[Robi] and [Kathy] from elecfreaks have put together a how-to article about a Laser Piano they just built. Instead of keys, the user breaks beams of laser light to trigger the sounds.

Several laser pointer diodes are wired in parallel and mounted in a box, cardboard in this case. The laser diodes are aimed at photocells that reside on the other side of the box. Each photocellis connected to a digital input pin on an Arduino. When the Arduino senses a state change from one of the photocell, meaning the beam of light has been interrupted, it plays the appropriate wave file stored on an external JQ6500 sound module.

[Robi] admits that there are some improvements to be made, specifically the trigger response time and the piano sounding too monotonous. If you have any ideas, please leave them in the comments section.

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Wooden Ghettoblaster Makes Use Of Recycled Parts

June 30, 2014 by Rich Bremer 7 Comments

Wooden Ghettoblaster made from recycled car audio parts

Humans generate a lot of waste. It is somewhat relieving to see so many great reuses of old items out there on the ‘web. We love covering these types of projects here on Hackaday. [Martin] likes using recycled items in his projects and wrote in to tell us about his recently completed Wooden Ghettoblaster that utilizes a bunch of old parts and doodads he had kicking around.

The main case, believe it or not, is constructed of leftover wood flooring. The fake tape deck, buttons and tuner may look like they are just burnt/etched/stained but they are actually inlaid pieces of darker wood. Once all of the inlays were installed in the front face of the cabinet, the entire surface was sanded smooth and the edges chamfered to add some visual appeal.

Holes for a pair of old aftermarket car speakers were not only cut into the front face of the case, they were also counterbored so the speakers would sit flush with the panel. [Martin] did decide to purchase one component for the project, a set of VU meters. They are mounted to the case via their own inlaid piece of wood and are connected in parallel with the line-level portion of the signal path.

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[Tymkrs] Tombstone Guitar Amplifier

June 30, 2014 by Adam Fabio 16 Comments

tymkrsTombstone

[Atdiy and Whisker], the team behind [The Tymkrs] YouTube channel, are at it again with a tombstone guitar amp project.(YouTube playlist link) Their amp began life as a Philco Tombstone radio which had seen better days. By the time [Tymkrs] got their hands on it, it was just a shell of its former self, as someone had already stripped all the electronics.

The amplifier itself is a disused Leslie tube amp [Tymkrs] had on hand. An LM386 serves as the pre-amp, making this a hybrid solid and vacuum state machine.

The tombstone speaker is especially interesting. [Tymkrs] went with an electrodynamic field coil speaker. Field coil speakers have no magnets, instead using a high voltage (approx 90V DC) coil to create a magnetic field for the voice coil to push against. This sort of speaker was commonplace in the 1930’s, as large magnets couldn’t be made lightweight enough to be used in a speaker. As magnet technology improved, permanent magnets became a staple in speakers.

[Tymkrs] paid special attention to the finish of the amplifier. They brought the tired old radio back to a high shine, then added a Metropolis inspired overlay from aged copper-clad board. The result is an amp that looks great and sounds great!

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Wait, THAT’S An Electric Guitar?

June 28, 2014 by James Hobson 36 Comments

Mechatronic Guitar

What you’re looking at above is a six-stringed mechatronic slide guitar, where each string and associated servos is assigned its own MIDI channel.

It’s a project [Jim Murphy] has been working on for a while now, and technically, it’s the second iteration — he’s calling it the Swivel 2. The original Swivel was more of a proof of concept, using bulky stepper motors and solenoids — in this one he’s upgraded to hobby style servos, using four per string. One to change the pitch, one to clamp the pitch shifter, and two to pick and dampen the strings.

He’s designed the PCB control boards himself utilizing an Arduino bootloader-equipped ATMEGA328, which takes in the MIDI signal from a computer and moves the servos accordingly — to produce the audio signals he’s been using Ableton Live to write the patterns.

The entire setup was designed in 3D CAD and is designed to be completely modular. He’s even made the guitar pickups himself using 3D printed spools, and hand wrapping the coils with copper enamel wire. Lend an ear after the break to hear it in action.

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DIY Foot Pedal Controller For Guitar Rig 5

June 25, 2014 by Rich Bremer 15 Comments

DIY Modeling Software Control Pedal

Back in the old days, it took external guitar effects pedals to modify a guitar’s sound. As computer processing power has been growing at an exponential rate, software-based effects modelers have been becoming more common. [Matthew]’s dad is running Guitar Rig 5 modeling software on his Lenovo tablet. Although it works well, it is a hassle to change effects and amp models while playing. That’s where [Matthew] comes in. He’s built a foot pedal controller so his old man can change up those sweet sounds on the fly.

Guitar Rig 5 has the ability to change presets with key presses. Even so, it would still be a hassle tapping a keyboard while playing, whether it be physical or on-screen. Since an Arduino-compatible board with an ATMEGA32U4 chip can be used to simulate an HID device, [Matthew] decided to use one as the basis for his project. Standard push buttons mounted in a project box indicate to the microcontroller which keyboard commands to send to the tablet. There are 4 buttons for 4 presets on this build but any number can be used. When a button is pushed, the associated keyboard command is sent to the tablet via a USB cable and Guitar Rig 5 responds to that command by changing the preset. And just so you know where you are, an indicator light adjacent to each button shows which preset is current.

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An ARM-Based DSP Modelling Synth

June 14, 2014 by Brian Benchoff 42 Comments

synth

The great analog synths of Moog, Oberheim, Sequential Circuits, and more modern version from Doepfer are renouned for their sound, the sheer majesty of a rack full of knobs and plugs, and of course the price. Analog synths are simply expensive to build, and given that aficionados even scoff at digitally controlled oscillators, require a lot of engineering to build. [Jan]’s DSP-G1 isn’t like those analog synths – it uses microcontrollers and DSP to generate its bleeps and boops. It is, however, extremely cheap and sounds close enough to the real thing that it could easily find a home between a few euroracks and CV keyboards.

plug The heart of the DSP-G1 is a micro from NXP modeling an analog synthesizer with 15 digitally controlled oscillators with Sine, Triangle, Pulse and Saw outputs, a low frequency oscillator, two envelope filters, and a low pass filter, or about the same accouterments you would find in a MiniMoog or other vintage synth from the 70s. Since this is basically a synth on an NXP LPC-810, [Jan] has packaged it in something akin to a MIDI to 3.5mm cable adapter: Plug a MIDI keyboard into one end, an amp into the other, and you have a synth smaller than the MIDI Vampire, an already impossibly small music creation tool.

[Jan] has a few more versions of his little DSP device with varying amounts of knobs available on his indiegogo campaign. The DSP-Gplug is the star of the show, though, provided you already have a MIDI keyboard with a few knobs for the required CC messages. Videos and sound demos below.

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