audio

396 Articles

Motorized Faders Make An Awesome Volume Mixer For Your PC

January 31, 2026 by 14 Comments

These days, Windows has a moderately robust method for managing the volume across several applications. The only problem is that the controls for this are usually buried away. [CHWTT] found a way to make life easier by creating a physical mixer to handle volume levels instead.

The build relies on a piece of software called MIDI Mixer. It’s designed to control the volume levels of any application or audio device on a Windows system, and responds to MIDI commands. To suit this setup, [CHWTT] built a physical device to send the requisite MIDI commands to vary volume levels as desired. The build runs on an Arduino Micro. It’s set up to work with five motorized faders which are sold as replacements for the Behringer X32 mixer, which makes them very cheap to source. The motorized faders are driven by L293D motor controllers. There are also six additional push-buttons hooked up as well. The Micro reads the faders and sends the requisite MIDI commands to the attached PC over USB, and also moves the faders to different presets when commanded by the buttons.

If you’re a streamer, or just someone that often has multiple audio sources open at once, you might find a build like this remarkably useful. The use of motorized faders is a nice touch, too, easily allowing various presets to be recalled for different use cases.

We love seeing a build that goes to the effort to include motorized faders, there’s just something elegant and responsive about them. Continue reading “Motorized Faders Make An Awesome Volume Mixer For Your PC” →

Know Audio: Microphone Basics

December 30, 2025 by 32 Comments

A friend of mine is producing a series of HOWTO videos for an open source project, and discovered that he needed a better microphone than the one built into his laptop.  Upon searching, he was faced with a bewildering array of peripherals aimed at would-be podcasters, influencers, and content creators, many of which appeared to be well-packaged versions of very cheap genericised items such as you can find on AliExpress.

If an experienced electronic engineer finds himself baffled when buying a microphone, what chance does a less-informed member of the public have! It’s time to shed some light on the matter, and to move for the first time in this series from the playback into the recording half of the audio world. Let’s consider the microphone.

Background, History, and Principles

A microphone is simply a device for converting the pressure variations in the air created by sounds, into electrical impulses that can be recorded. They will always be accompanied by some kind of signal conditioning preamplifier, but in this instance we’re considering the physical microphone itself. There are a variety of different types of microphone in use, and after a short look at microphone history and a discussion of what makes a good microphone, we’ll consider a few of them in detail. Continue reading “Know Audio: Microphone Basics” →

The Music Of The Sea

December 22, 2025 by 8 Comments

For how crucial whales have been for humanity, from their harvest for meat and oil to their future use of saving the world from a space probe, humans knew very little about them until surprisingly recently. Most people, even in Herman Melville’s time, considered whales to be fish, and it wasn’t until humans went looking for submarines in the mid-1900s that we started to understand the complexities of their songs. And you don’t have to be a submarine pilot to listen now, either; all you need is something like these homemade hydraphones.

Continue reading “The Music Of The Sea” →

How To Build Good Contact Mics

December 22, 2025 by 13 Comments

We’re most familiar with sound as vibrations that travel through the atmosphere around us. However, sound can also travel through objects, too! If you want to pick it up, you’d do well to start with a contact mic. Thankfully, [The Sound of Machines] has a great primer on how to build one yourself. Check out the video below.

The key to the contact mic is the piezo disc. It’s an element that leverages the piezoelectric effect, converting physical vibration directly into an electrical signal. You can get them in various sizes; smaller ones fit into tight spaces, while larger ones perform better across a wider frequency range.

[The Sound of Machines] explains how to take these simple piezo discs and solder them up with connectors and shielded wire to make them into practical microphones you can use in the field. The video goes down to the bare basics, so even if you’re totally new to electronics, you should be able to follow along. It also covers how to switch up the design to use two piezo discs to deliver a balanced signal over an XLR connector, which can significantly reduce noise.

There’s even a quick exploration of creative techniques, such as building contact mics with things like bendable arms or suction cups to make them easier to mount wherever you need them. A follow-up explores the benefits of active amplification. The demos in the video are great, too. We hear the sound of contact mics immersed in boiling water, pressed up against cracking spaghetti, and even dunked in a pool. It’s all top stuff.

These contact mics are great for all kinds of stuff, from recording foley sounds to building reverb machines out of trash cans and lamps.

Continue reading “How To Build Good Contact Mics” →

Audio field emission map

Audio Sound Capture Project Needs Help

November 5, 2025 by 20 Comments

When you are capturing audio from a speaker, you are rarely capturing the actual direct output of such a system. There are reflections and artifacts caused by anything and everything in the environment that make it to whatever detector you might be using. With the modern computation age, you would think there would be a way to compensate for such artifacts, and this is what [d.fapinov] set out to do.

[d.fapinov] has put together a code base for simulating and reversing environmental audio artifacts made to rival systems, entirely orders of magnitude higher in cost. The system relies on similar principles used in radio wave antenna transmission to calculate the audio output map, called spherical harmonic expansion. Once this map is calculated and separated from outside influence, you can truly measure the output of an audio device.

The only problem is that the project needs to be tested in the real world. [d.fapinov] has gotten this far but is unable to continue with the project. A way to measure audio from precise locations around the output is required, as well as the appropriate control for such a device.

Audio enthusiasts go deep into this tech, and if you want to become one of them, check out this article on audio compression and distortion.

An Audio Brick For Your Smart Home

November 1, 2025 by 38 Comments

If you’ve ever wanted to pump sound to all the rooms of your house, you might use any one of a number of commercial solutions. Or, you could go the more DIY route and whip up something like the Esparagus Audio Brick built by [Andriy]. 

The concept is simple—it’s a small unit, roughly the size of a brick, which streams high-quality audio. It’s based around an ESP32, which pulls in digital audio over Wi-Fi or Ethernet. The microcontroller is hooked up to a TAS5825M DAC, which comes with a built-in amplifier for convenience. The Esparagus is designed for integration with Home Assistant, allowing for easy control as part of a smart home setup. It’s also compatible with Spotify Connect, AirPlay, and Snapcast—the latter of which provides excellent sync when using multiple units across several rooms.

Design files are available on Github for the curious. We’ve seen other neat projects in this space, before, too—like the charmingly-named OtterCast. Video after the break.

Continue reading “An Audio Brick For Your Smart Home” →

Know Audio: Lossy Compression Algorithms And Distortion

October 28, 2025 by 37 Comments

In previous episodes of this long-running series looking at the world of high-quality audio, at every point we’ve stayed in the real world of physical audio hardware. From the human ear to the loudspeaker, from the DAC to measuring distortion, this is all stuff that can happen on your bench or in your Hi-Fi rack.

We’re now going for the first time to diverge from the practical world of hardware into the theoretical world of mathematics, as we consider a very contentious topic in the world of audio. We live in a world in which it is now normal for audio to have some form of digital compression applied to it, some of which has an effect on what is played back through our speakers and headphones. When a compression algorithm changes what we hear, it’s distortion in audio terms, but how much is it distorted and how do we even measure that? It’s time to dive in and play with some audio files. Continue reading “Know Audio: Lossy Compression Algorithms And Distortion” →