ADSL Router As Effects Pedal

September 8, 2022 by Bryan Cockfield 11 Comments

Moore’s law might not be as immutable as we once though thought it was, as chip makers struggle to fit more and more transistors on a given area of silicon. But over the past few decades it’s been surprisingly consistent, with a lot of knock-on effects. As computers get faster, everything else related to them gets faster as well, and the junk drawer tends to fill quickly with various computer peripherals and parts that might be working fine, but just can’t keep up the pace. [Bonsembiante] had an old ADSL router that was well obsolete as a result of these changing times, but instead of tossing it, he turned it into a guitar effects pedal.

The principle behind this build is that the router is essentially a Linux machine, complete with ALSA support. Of course this means flashing a custom firmware which is not the most straightforward task, but once the sound support was added to the device, it was able to interface with a USB sound card. An additional C++ program was created which handles the actual audio received from the guitar and sound card. For this demo, [Bonsembiante] programmed a ring buffer and feeds it back into the output to achieve an echo effect, but presumably any effect or a number of effects could be programmed.

For anyone looking for the source code for the signal processing that the router is now performing, it is listed on a separate GitHub page. If you don’t have this specific model of router laying around in your parts bin, though, there are much more readily-available Linux machines that can get this job done instead.

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Improve CD Sound By Shaving?

September 7, 2022 by Al Williams 89 Comments

We always enjoy the odd things that people do to try to get better audio reproduction. Exotic cables, special amplifiers, and higher resolution digitization come to mind. Most of this is dubious, at best, but [Techmoan] brings up something we must have missed back in the day: shaving CDs with a gadget that was marketed as the “CD Sound Improver.” The theory is that bad CD reproduction comes from light scatter of the laser. The solution, according to the maker of this vintage equipment, is to cut a 36-degree bevel to act as a light trap. You can see the gadget in the video below.

The device claims it reduced vibration, improved audio, and even helped DVDs playback better video. As you might imagine, this has little hope of actually working. The box is essentially a motor-driven turntable, a razor blade, and a port for a vacuum cleaner to suck up the mess. You were told to color the edge with a marker, too.

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Touch Tone MIDI Phone And Vocoder Covers Daft Punk

September 6, 2022 by Donald Papp 3 Comments

[poprhythm]’s Touch Tone MIDI Phone is a fantastic conversion of an old touch tone phone into a MIDI instrument complete with intact microphone, but this project isn’t just about showing off the result. [poprhythm] details everything about how he interfaced to the keypad, how he used that with an Arduino to create a working MIDI interface, and exactly how he decided — musically speaking — what each button should do. The LEDs on the phone are even repurposed to blink happily depending on what is going on, which is a nice touch.

Of course, it doesn’t end there. [poprhythm] also makes use of the microphone in the phone’s handset. Since the phone is now a MIDI instrument with both a microphone and note inputs, it’s possible to use them together as the inputs to vocoder software, which he demonstrates by covering Around the World by Daft Punk (video).

We love how [poprhythm] explains how he interfaced to everything because hardware work is all about such details, and finding the right resources. Here’s the GitHub repository for the Arduino code and a few links to other resources.

We have seen MIDI phone projects before, and each one is always unique in its own way: here’s a different approach to converting a keypad phone to MIDI, and this rotary pulse-dial phone went in a completely different direction with the phone itself completely unmodified, using only external interfacing.

You can admire [poprhythm]’s Touch Tone MIDI Phone in action in the short videos embedded below, with each one showing off a different aspect of the build. It’s great work!

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C64 Turned Theremin With A Handful Of Parts

August 30, 2022 by Lewin Day 7 Comments

The theremin is popular for its eerie sound output and its non-contact playing style. While they’re typically built using analog hardware, [Linus Åkesson] decided to make one using the venerable Commodore 64.

The instrument works by measuring the capacitance between its two antennas and the Earth. As these capacitances are changed by a human waving their hands around near the respective pitch and volume antennas, the theremin responds by changing the pitch and volume of its output.

In this case, the humble 555 is pressed into service. It runs as an oscillator, with its frequency varying depending on the user’s hand position. There’s one each for pitch and volume, naturally, using a clamp and spoon as antennas. The C64 then reads the frequency the 555s are oscillating at, and then converts these into pitch and volume data to be fed to the SID audio chip.

[Linus Åkesson] demonstrates the build ably by performing a slow rendition of Amazing Grace. The SID synthesizer chip in the C64 does a passable job emulating a theremin, used here with a modulated pulse wave sound. It’s an impressive build and one we fully expect to see at a big chiptune show sooner rather than later. We’re almost surprised nobody came out with a C64 Theremin cartridge back in the day.

We’ve seen other fancy theremin-inspired builds recently too, like this light-based design.

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Reactive Load For Amplifiers Teaches Lessons About Inductors

August 24, 2022 by Bryan Cockfield 26 Comments

The sound produced by any given electric guitar is shaped not just by the instrument itself but by the amplifiers chosen to make that sound audible. Plenty of musicians swear by the warm sound of amplifiers with vacuum tube circuits, but they do have some limitations. [Collin] wanted to build a reactive load for using tube amps without generating a huge quantity of sound, and it resulted in an interesting project that also taught him a lot about inductors.

The reactive load is essentially a dummy load for the amplifier that replaces a speaker with something that won’t produce sound. Passive loads typically use resistor banks but since this one is active, it needs a very large inductor to handle the amount of current being produced by the amplifier. [Colin] has also built a headphone output into this load which allows it to output a much smaller quantity of sound to a headset while retaining the sound and feel of the amplifier tubes, and it additionally includes a widely-used tone control circuit as well.

There’s a lot going on in the design of the circuitry for this amplifier load, including a lot of research into low-frequency inductors that can handle a significant amount of current. [Collin] eventually ended up winding his own, but the path he took to it was long and winding. There’s a lot of other circuit theory discussed as well especially with regards to the Baxandall EQ that he built into it as well. And, if you’d like to learn more about tube amplifiers in general, take a look at this piece which notes one of the best stereo amps ever produced.

PicoStepSeq Is Small But Perfectly Formed

August 20, 2022 by Jenny List 18 Comments

The Raspberry Pi Pico is what you might call the board of the moment, thanks to its combination of affordability, features, and continued availability during the component shortage. We have seen plenty of great projects using it, and the latest to float past is [todbot]’s PicoStepSeq, an extremely compact MIDI sequencer.

All the components are mounted on a PCB, with the sequencer’s eight steps selected by a row of buttons with integrated LEDs. The interface is via an SSD1306 OLED, and there is also a rotary encoder. Software comes courtesy of CircuitPython, and the output is delivered via a 3.5 mm TRS jack. Finally the whole is wrapped in a 3D printed enclosure.

The result is a sequencer that could almost be a product in its own right, and we think anyone whose interests lie in electronic music should find straightforward enough to build. All the files and information required to build your own can be found in the linked repository, and he’s placed a Tweet with a video online which we’ve embedded below the break.

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LCD Monitor Plays The Hits

August 18, 2022 by Al Williams 1 Comment

In the old days, it wasn’t uncommon to put an AM radio near a computer or a monitor and deliberately cause interference to have a crude form of sound generation. Did you miss out on that? No! Thanks to [luambfb] you can now do the same trick with a common LCD monitor. You’ll need the horizontal refresh rate of the monitor in question.

Of course, doing it is somewhat less interesting than learning how it works. The effect relies on the fact that the LCDs emit signals as it refreshes a row. A black row emits relatively low energy while a white row emits more. Grayscale… well, you get the idea. Continue reading “LCD Monitor Plays The Hits” →