A Tube Guitar Amp For A Modest Budget

November 27, 2023 by Jenny List 17 Comments

There’s a mystique among both audiophiles and musicians about vacuum technology, thus having a tube amp still carries a bit of a cachet. New ones can be bought for eye-watering prices and old ones can be had for the same price with the added frisson of unreliability. Happily it’s surprisingly straightforward to build your own, as [_electroidiot] shows us with a fairly inexpensive build.

The design is inspired by the guitar amps of the 1950s and 1960s so it’s not for audiophiles. The circuit is a pretty conventional single-ended one with a two stage double triode preamp and a single power output tube. The transformers are usually the difficult part of a build like this one, and here instead of resorting to using a mains transformer for audio they come from a defunct 1960s Phillips radio. We especially like the old-school construction technique with a folded aluminium chassis and liberal use of tag strips on which to build the circuits.

The result is something that would have been in no way out of place in the 1960s, and proves that tube circuitry isn’t beyond the constructor in 2023. If it’s whetted your appetite for more, we can help you there.

A Yamaha DX7 On A USB Dongle

November 24, 2023 by Lewin Day 24 Comments

The Yamaha DX7 was released in 1983, with its FM synthesis engine completely revolutionizing the electronic music world at the time. It didn’t come cheap, and still doesn’t today, but we are blessed with emulators that can give us the same sound on a budget. In that vein, [Kevin] decided to whip up a Yamaha DX7 you can carry around in a little USB dongle.

The build centers around the use of a Raspberry Pi Zero, Zero W, or Zero 2W configured to run the MiniDEXED DX7 emulator. The Pi is then set up with a dongle adapter board that allows it to run in USB Gadget mode. The Zero line of Raspberry Pis are perfect for this use, as they draw less current and so can, under the right conditions, run off a computer’s USB port. The Pi receives MIDI commands over the USB interface, and outputs sound via a Pimoroni Audio Shim. Effectively, the result is a single-channel DX7 synth that plugs in via USB; or eight channels if you use the more powerful Zero 2W.

[Kevin] readily admits that there probably isn’t much use for a DX7 dongle, given that you could just load a DX7 emulator in your DAW of choice instead. Regardless, it’s a fun build, and one that ably demonstrates the USB Gadget mode of operation for the Raspberry Pi. Video after the break. Continue reading “A Yamaha DX7 On A USB Dongle” →

Turning A Saxophone Into A MIDI Controller

November 22, 2023 by Lewin Day 6 Comments

Most of the time, if you’re looking for a MIDI controller, you’re going to end up with some kind of keyboard or a fancy button pad. The saxophone is an altogether more beguiling instrument that makes for one hell of an interface, but there’s a problem: they’re seldom MIDI-compatible. This build from [AndrewChi] changes all that.

This digitized sax relies on a SparkFun ESP32 Thing as the brains of the operation. It uses Hall effect sensors, the digital switch type, to detect the action of the keys of the sax. Choosing parts that are quick to respond is key for musical use, so [AndrewChi] selected the Texas Instruments DRV5023 for its unipolar operation, short output delay and fast rise time. Beyond setting up the basic keys to send MIDI notes, the instrument also received additional octave controls for greater range. With sensors and magnets attached to the saxophone and keys with Sugru, the instrument is ready to serve as a capable MIDI controller. Thanks to the ESP32, it’s capable of sending MIDI data wirelessly over Bluetooth for the maximum freedom of performance.

It’s a nifty build, and a great way for wind players to get into the world of controlling digital synthesizers in an intuitive fashion. We’ve seen some great MIDI controller builds before, too.

Continue reading “Turning A Saxophone Into A MIDI Controller” →

Two-Channel Guitar Stomp Box Makes Momentary Switches Latching

November 19, 2023 by Dan Maloney 12 Comments

When we first saw [Maarten Tromp]’s article about a “momentary latching switch” for guitar effects pedals, we have to admit to being a bit confused. When it comes to push-button switches, “momentary” and “latching” seem to be at odds with each other, with different mechanisms inside the switch to turn one into the other. What gives?

As it turns out, [Maarten]’s build makes perfect sense when you consider the demands of a musical performance. Guitar effects pedals, or “stomp boxes,” are often added to the output of electric guitars and other instruments to change the signals in some musically interesting way. The trouble is, sometimes you only need an effect for a few bars, and the push-on, push-off switches on many effects pedals make that awkward.

[Maarten]’s idea was to build a stomp box with momentary switches that act as inputs to an ATtiny2313 microcontroller rather than directly controlling the effect. That way, a bit of code can determine how long the switch is tapped, and activate a relay to do the actual switching accordingly. A short tap of the button tells the microcontroller to latch the relay closed until another tap comes along; a long press means that the relay is held open only as long as the button is held down.

Yes, he could have used a 555, a fact which [Maarten] readily acknowledges, but with some loss of flexibility; he currently has the threshold set at 250 milliseconds, which works for his performance style. Changing it would be a snap in code, as would toggling the latching logic. A microcontroller also makes expansion from the two-channel setup shown here easier.

Looking for more effects pedal action? We’ve got a bunch — a tube-amp tremolo, an Arduino Mega multipedal, a digital delay line. Take your pick!

Lessons In Mass Production From An Atari Punk Console

November 16, 2023 by Dan Maloney 7 Comments

Sometimes the most interesting part of a project isn’t the widget itself, but what it teaches you about the manufacturing process. The story of the manufacturing scale-up of this Atari Punk Console and the lessons learned along the way is a perfect example of this.

Now, don’t get us wrong — we love Atari Punk Consoles. Anything with a couple of 555s that bleeps and bloops is OK in our books. But as [Adam Gulyas] tells the tale, the point of this project was less about the circuit than about the process of making a small batch of something. The APC was low-hanging fruit in that regard, and after a quick round of breadboarding to decide on component values, it was off to production. [Adam] was shooting for 20 units, each in a nice enclosure and a classy package. PCB assemblies were ordered, as were off-the-shelf plastic enclosures, which ended up needing a lot of tweaking. [Adam] designed custom labels for the cases, itself a fraught job; glossy label stock and button bezels apparently don’t mix.

After slogging through the assembly process, boxing the units for shipping was the next job. [Adam] sourced jewelry boxes just a bit bigger than the finished APCs, and rather than settle for tissue paper or packing peanuts, designed an insert to hold the units snugly. That involved a lot of trial and error and a little bit of origami-fu, and the results are pretty nice. His cost per unit came out to just a hair over $20 Canadian, including the packaging, which is actually pretty remarkable for such a short production run.

[Adam] includes a list of improvements for larger-scale runs, including ordering assembled PCBs, outsourcing the printing processes, and getting custom boxes made so no insert is needed. Any way you cut it, this production run came out great and teaches us all some important lessons.

Virginia Cave Is The Largest Musical Instrument In The World

November 9, 2023 by Richard Baguley 23 Comments

Hit something with a hammer, and it makes a sound. If you’re lucky, it might even make a pleasant sound, which is the idea behind the Great Stalacpipe Organ in Luray Caverns, Virginia. The organ was created in 1954 by [Leland W. Sprinkle], who noticed that some stalactites (the ones that come down from the ceiling of the cave) would make a nice, pure tone when hit.

So, he did what any self-respecting hacker would do: he picked and carved 37 to form a scale and connected them to an electronic keyboard. The resonating stalactites are spread around a 3.5 acre (14,000 square meters) cave, but because it is in a cave, the sound can be heard anywhere from within the cave system, which covers about 64 acres (260,000 square meters). That makes it the largest musical instrument in the world.

We’ll save the pedants the trouble and point out that the name is technically an error — this is not a pipe organ, which relies on air driven into resonant chambers. Instead, it is a lithophone, a percussion instrument that uses rock as the resonator. You can see one of the solenoids that hits the rock to make the sound below.

This is also the sort of environment that gives engineers nightmares: a constant drip-drip-drip of water filled with minerals that love to get left behind when the water evaporates. Fortunately, the Stalacpipe Organ seems to be in good hands: according to an NPR news story about it, the instrument is maintained by lead engineer for the caverns [Larry Moyer] and his two apprentices, [Stephanie Beahm] and [Ben Caton], who are learning the details of maintaining a complex device like this.

Continue reading “Virginia Cave Is The Largest Musical Instrument In The World” →

Oh, The Places You’ll Go With Stop Motion Animation

November 5, 2023 by Adam Fabio 5 Comments

Robots made of broken toy parts, stop-motion animation, and a great song to tie it all together were not on our bingo card for 2023, but the results are perfect. [Mootroidxproductions] recently released the official music video for I Fight Dragons 2019 song “Oh the Places You’ll Go”.

The song was written by lead vocalist [Brian Mazzaferri] with inspiration from the classic Dr. Seuss book. [Brian] wrote it for his newborn daughter, and we’re pretty sure it will hit any parent right in the feels.

[Mootroidxproductions] isn’t a parent themselves, but they expanded on the theme to create a video about sacrificing oneself to save a loved one. With a self deprecating wit, they take us through the process of turning broken Bionicle parts, bits of Gundam, Lego, and, armature wire to make the two robots in the film. He also explains how he converted garbage into sets, greebles, and lighting effects.

The robots had to be designed so that they could fulfill their roles in the film. From the size of their hands down to their individual walking gaits, he thought of everything. His encyclopedic knowledge of Bionicle parts is also on full display as he explains the origin of the major parts used to build “Little Blue” and “Sherman”

Click through the break for both the main video and the behind-the-scenes production.

Continue reading “Oh, The Places You’ll Go With Stop Motion Animation” →