Teensy Spectrum Analyzer Has 170 Channels

While high-fidelity audio has come a long way in the past several decades, a lot of modern stereo equipment is still missing out on some of the old analog meters that were common on amplifiers and receivers of the 60s through the 80s. Things like VU meters don’t tend to be common anymore, but it is possible to build them back in to your sound system with the help of some microcontrollers. [Mark] shows us exactly how to reclaim some of the old-school functionality with this twin audio visualizer display.

Not only does this build include two displays, but the microcontroller is keeping up with 170 channels in real-time in order to drive the display. What’s more impressive is that it’s being done all on a Teensy 4.1. To help manage all of the data and keep the speed as fast as possible it uses external RAM soldered to the board, and a second Teensy audio board is used to do the real time FFT analysis. Most of the channels are sent to the display hosting the spectrum analyzer but two are reserved for left and right stereo VU meters on the second display.

The project from [Mark] is originally based on this software from [DIYLAB] so everything is open-source. While it was originally built for a specific piece of hardware, [Mark] has it set up with a line in and line out plus a microphone input so it can be used for virtually any audio hardware now. For another take on the classic VU meter, take a look at this design based on an Arudino instead.

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Doodlestation Is Beautifully Musical Furniture

Whether you’re a modular synth enthusiast or simply love the idea of rad electronic jams, we can all get behind the idea of crazy electronic instruments with buttons, dials, and patch cables galore. The Doodlestation is a wonderful example of that, built by [Love Hulten].

There’s a custom 37-key keyboard that lets one input musical notes in the typical way, along with a hilarious animated MIDI visualizer with a man that uses his mouth to shoot rainbows. There’s a theremin built into the chassis, too, allowing your hands to control the sound via the magic of the æther. Even better, there’s a custom-built tape echo in the upright section, and you even get to see the mechanical parts working and the mag ribbon wiggling about. That’s fun.

The custom hardware is joined by a series of off-the-shelf devices that add their own functionality to the mix. It includes a Sequential OB-6 analog synthesizer, a Moog DFAM drum module, and a Hologram Microcosm loop & glitch box for more noodling possibilities.

We love a good musical project around these parts; we’ve featured some great other projects for live electronic jams before, too. Video after the break.

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Character VFD Becomes Spectrum Analyzer

These days, streaming services are a great way to listen to music or podcasts on your computer or on the go. However, they lack one feature of the MP3 players and streamers of old: visualizations! [mircemk] is a fan of those, and has built a hardware spectrum analyzer that pumps with the music.

The build relies on a 20×2 character VFD display that looks great, with high brightness and excellent contrast. It can be easily driven from a microcontroller, as it has a controller on board compatible with the typical HD44780 command set. On Arduino platforms, this means the display can easily be driven with the popular LiquidCrystal library.

The Arduino Nano inside takes in the audio signal via its analog inputs. It then processes the audio with the fix_fft library, which runs a Fast Fourier Transform in order to figure out the energy level of each frequency bin in the audio spectrum for both the left and right channels. This data is then sent to the screen for display. It’s impressively fast and smooth, with the display dancing along with the beat nicely as [mircemk] tests it out with some tunes.

If it looks familiar, it’s because it’s an updated version of a prior project from [mircemk]. We saw it previously as a VU meter that pulsed with the beat, an altogether simpler visualization but still a cool one. Video after the break.

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Artist operating artistic visualizer with MIDI keyboard

Synth And Visualizer Combo Has Retrocomputing Vibe

[Love Hultén]’s latest piece of interactive art is the SYNTH#BOI, a super-clean build with something of the semi-cyberdeck, semi-vintage computing vibe to it. The device is a combination synthesizer and visualizer, with a 15-inch display, MIDI keyboard, and based on an Intel NUC i5 small form factor PC.

There are not many details about the internal workings of the device, but the high quality of the build is very evident. Photos show a fantastic-looking enclosure with clean lines and sharp finish; it’s a reminder that careful measuring and attention to detail can be the difference between something that looks like a hack job, and something that looks like a finished product.

Watch the SYNTH#BOI in action in the video, embedded below. And if the name [Love Hultén] seems familiar, it’s probably because we featured his VOC-25 “Pink Denture Synth”, a concept instrument with a decidedly memorable design of its own.

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LED Spectrum Visualizer Driven By Raspberry Pi

Back in the 1980s, spectrum displays on audio equipment were absolutely must have, and the aesthetic came to define the era. This lingered on through the 1990s, and remains a cool look even to this day. [Arduino Guy] decided to put together such a display using a Raspberry Pi and a large LED display.

The LED display in question is of the 64×64 RGB type, available from Aliexpress and other electronics suppliers online. To run the display, an Adafruit RGB Matrix Hat is used with the Raspberry Pi 3B, which makes driving the panel a cinch. The visual effect is run via a Python script, which plays a wave file and produces the spectrum graphics via a Fast Fourier Transform.

While the code isn’t able to act as a general-purpose equalizer display for any content played on the Raspberry Pi, creating such a script could be an entertaining exercise for the reader. Alternatively, the Pi could be hooked up to a microphone to run the display based on ambient room noise. In any case, we’ve seen great projects like this before, such as this laser-based display. Video after the break.

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FPGA Powers Blazingly Fast LED Matrix Audio Visualizer

[Sam Miller], [Sahil Gupta], and [Mashrur Mohiuddin] worked together on a very fast LED matrix display for their final project in ECE 5760 at Cornell University.

Real time!
Real time!

They started, as any good engineering students, by finding a way to make their lives easier. [Sam] had built a 32×32 LED matrix for another class. So, they made three more and ended up with a larger and more impressive 64×64 LED display.

They claim their motivation was the love of music, but we have a suspicion that the true reason was the love all EEs share for unnaturally bright LEDs; just look at any appliance at night and try not be blinded.

The brains of the display is an Altera DE2-115 FPGA board. The code is all pure Verilog. The FFT and LED control are implemented in hardware on the FPGA; none of that Altera core stuff. To generate images and patterns they wrote a series of python scripts. But for us it’s the particle test shown in the video below that really turns our head. This system is capable of tracking and reacting to a lot of different elements on the fly why scanning the display at about 310 FPS. They have tested display scanning at twice that speed but some screen-wrap artifacts need to be worked out before that’s ready for prime time.

The team has promised to upload all the code to GitHub, but it will likely be a while before the success hangover blows over and they can approach the project again. You can view a video interview and samples of the visualizations in the videos after the break.

Thanks to their Professor, [Bruce Land], for submitting the tip! His students are always doing cool things. You can even watch some of his excellent courses online if you like: Here’s one on the AVR micro-controller.

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More 555 Projects To Enjoy

We love all of the projects that are coming out for the 555 design contest, so we thought we would share a couple more that have caught our collective eye.  Have a 555 project of your own? Be sure to share it with us, and keep an eye out for the contest submission dates. Read on for a few of our project picks.

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