microphone

108 Articles

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” →

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” →

A man's hands are shown holding a microphone capsule with a 3D-printed part on top of it, with a flared metal tube protruding from the plastic.

2025 Component Abuse Challenge: Playing Audio On A Microphone

November 10, 2025 by 5 Comments

Using a speaker as a microphone is a trick old enough to have become common knowledge, but how often do you see the hack reversed? As part of a larger project to measure the acoustic power of a subwoofer, [DeepSOIC] needed to characterize the phase shift of a microphone, and to do that, he needed a test speaker. A normal speaker’s resonance was throwing off measurements, but an electret microphone worked perfectly.

For a test apparatus, [DeepSOIC] had sealed the face of the microphone under test against the membrane of a speaker, and then measured the microphone’s phase shift as the speaker played a range of frequencies. The speaker membrane he started with had several resonance spikes at higher frequencies, however, which made it impossible to take accurate measurements. To shift the resonance to higher frequencies beyond the test range, the membrane needed to be more rigid, and the driver needed to apply force evenly across the membrane, not just in the center. [DeepSOIC] realized that an electret microphone does basically this, but in reverse: it has a thin membrane which can be uniformly attracted and repelled from the electret. After taking a large capsule electret microphone, adding more vent holes behind the diaphragm, and removing the metal mesh from the front, it could play recognizable music.

Replacing the speaker with another microphone gave good test results, with much better frequency stability than the electromagnetic speaker could provide, and let the final project work out (the video below goes over the full project with English subtitles, and the calibration is from minutes 17 to 34). The smooth frequency response of electret microphones also makes them good for high-quality recording, and at least once, we’ve seen someone build his own electrets. Continue reading “2025 Component Abuse Challenge: Playing Audio On A Microphone” →

Hacking Together An Expensive-Sounding Microphone At Home

October 30, 2025 by 11 Comments

When it comes to microphones, [Roan] has expensive tastes. He fancies the famous Telefunken U-47, but doesn’t quite have the five-figure budget to afford a real one. Thus, he set about getting as close as he possibly could with a build of his own.

[Roan] was inspired by [Jim Lill], who is notable for demonstrating that the capsule used in a mic has probably the greatest effect on its sound overall compared to trivialities like the housing or the grille. Thus, [Roan’s] build is based around a 3U Audio M7 capsule. It’s a large diaphragm condenser capsule that is well regarded for its beautiful sound, and can be had for just a few hundred dollars. [Roan] then purchased a big metal lookalike mic housing that would hold the capsule and all the necessary electronics to make it work. The electronics itself would be harvested from an old ADK microphone, with some challenges faced due to its sturdy construction. When the tube-based amplifier circuit was zip-tied into its new housing along with the fancy mic capsule, everything worked! Things worked even better when [Roan] realized an error in wiring and got the backplate voltage going where it was supposed to go. Some further tweaks to the tube and capacitors further helped dial in the sound.

If you’ve got an old mic you can scrap for parts and a new capsule you’re dying to use, you might pursue a build like [Roan’s]. Or, you could go wilder and try building your own ribbon mic with a gum wrapper. Video after the break.

Continue reading “Hacking Together An Expensive-Sounding Microphone At Home” →

The Electret Preamp You Might Need

October 11, 2025 by 16 Comments

Electret capsules can be found in some of the highest quality microphones for studio use, as well as in some of the very cheapest microphone capsules on the market. More care and attention has gone into the high-end capsule and its associated circuitry than the cheap one, but is it still possible to get good quality from something costing under a dollar? [Mubarak Basha] thinks so, and has designed a preamp circuit to get the best from a cheap electret capsule.

These capsules may be cheap, but with the addition of a low voltage supply, a resistor, and a capacitor, their internal FET delivers a decent enough input to many a project. To improve on that will need a bit of effort, and in this the preamp delivers by taking care to match impedance, impose a carefully chosen frequency response, and just the right gain to derive a line level output from the electret’s level. It’s hardly a complex circuit, but that’s not always necessary.

As always in these situations, without appropriate test equipment it’s difficult to gauge quality. We’d say this though, if you make one of these and it falls short, you won’t have spent much. Meanwhile if you’re curious about electrets, here’s our guide.

Maurice Brings Immersive Audio Recording To The Masses

September 7, 2025 by 21 Comments

Immersive audio is the new hotness in the recording world. Once upon a time, mono was good enough. Then someone realized humans have two ears, and everyone wanted stereo. For most of us, that’s where it stopped, but audio connoisseurs kept going into increasingly baroque surround-sound setups — ending in Immersive Audio, audio that is meant to fully reproduce the three-dimensional soundscape of the world around us. [DJJules] is one of those audio connoisseurs, and to share the joy of immersive audio recording with the rest of us, he’s developed Maurice, a compact, low-cost immersive microphone.

Maurice is technically speaking, a symmetrical ORTF3D microphone array. OTRF is not a descriptive acronym; it stands for Office de Radiodiffusion Télévision Française, the fine people who developed this type of microphone for stereo use. The typical stereo ORTF setup requires two cardioid microphones and angles them 110 degrees apart at a distance of 17 cm. Maurice arrays four such pairs, all oriented vertically and facing 90 degrees from one another for fully immersive, 8-channel sound. All of those microphones are thus arrayed to capture sound omnidirectionally, and give good separation between the channels for later reproduction. The mountings are all 3D printed, and [DJJules] kindly provides STLs.