What Is A Ribbon Microphone

by Matthew David | Updated: 09/14/2023

What Is A Ribbon Microphone

Have you ever listened to a vintage recording from the 1930s and 40s and wondered how they achieved such a smooth, natural, and transparent sound? Well, chances are they were using ribbon microphones. Ribbon mics deliver a stunningly realistic sonic character that sets them apart from other mic technologies.

In this beginner’s guide, you’ll learn all about how ribbon microphones work, what gives them their signature sound, when to use them, and some of the most iconic models throughout history. Get ready to fall in love with the warm vintage vibe of ribbons!

A Brief History of Ribbon Microphones

Ribbon technology dates all the way back to the 1920s when ribbon loudspeakers and microphones were invented in Germany by Schottky and Gerlach. Pretty neat right? These guys were pioneers.

Throughout the 1930s, RCA really took ribbon microphone development to the next level in the US with groundbreaking models like the PB-31 and 44A. Vintage RCA ribbons from this era are still prized today for their smooth, natural sound.

Another iconic ribbon mic was the BBC-Marconi Type A used heavily by the BBC from 1934 to 1959. This mic delivered superb transparency tailored for speech recording.

Moving ahead to 1957, German company Beyerdynamic launched the M160 double ribbon mic which quickly became a studio staple. Its compact size made close miking easier than ever.

Later in the 2000s, Chinese manufacturers revived interest in ribbons with affordable re-creations of vintage Russian Oktava designs priced under $200. A real ribbon renaissance!

And most recently, revolutionary nano-material ribbons that are extremely durable have enabled ribbons to handle even the loudest live sound sources while delivering pristine audio quality.

How Ribbon Mics Work – The Technology Explained

So how do these things actually work? Ribbon mics are a type of dynamic microphone, but with a unique twist. Instead of using a diaphragm connected to a coil like regular dynamics, they use an extremely thin aluminum ribbon suspended in a magnetic field as the transducer.

When sound waves hit the ribbon, it vibrates back and forth between the magnets, inducing an electrical current proportional to the velocity of the ribbon. Because the ribbon has way lower mass than a traditional diaphragm, it can respond to a much wider range of frequencies for that silky smooth top end ribbons are known for.

The ribbon material is usually just 1.8 to 4 microns thick. For comparison, a human hair is about 100 microns thick. So we’re talking crazy thin here! This allows it to pick up very subtle nuances in the sound waves.

Unlike condenser mics which detect diaphragm displacement, ribbons detect sound wave velocity. They also naturally have a bi-directional figure-8 pickup pattern thanks to the ribbon’s symmetry.

Because ribbon mics are passive with no onboard electronics, the output voltage is very low compared to other mic types. That’s why they typically use a step-up transformer to bring the levels up.

The minimal mass of the ribbon makes ribbons prone to damage from blasts of air or high SPL. But many modern ribbons use more durable materials that withstand loud volumes.

Characteristics that Define Ribbon Microphone Sound

When you listen to recordings made with ribbon mics, certain sonic attributes stand out that give ribbons their magical sound.

First, ribbons have an extremely smooth and natural frequency response without the harsh boosted highs that condensers often have. They maintain detail and air without getting brittle or fatiguing.

Instead, ribbon mics gently roll off in the highs, resulting in a slightly darkened or mellow tone. This makes them very forgiving because you can easily EQ the top end to taste later.

Because the ribbon interacts with the sound waves differently than solid diaphragms, the harmonic structure produces a transparent, lifelike tone. Vocals in particular shine through ribbon mics.

They also don’t suffer from the oversensitivity of condenser mics. Ribbons isolate the sound source you aim them at, reducing bleeding from off-axis sounds and room ambience.

This highly detailed yet controlled sound makes ribbons ideal for many recording situations. Their smooth character warms up bright or harsh sources beautifully.

When and How to Use Ribbon Mics

Now let’s explore some of the most common and effective uses for ribbon mics to take advantage of their strengths:

Electric Guitar Cabs – Ribbons add warmth and body to smooth out the icepick highs from heavily overdriven amp tones. They capture all the grit and articulation with a chest-thumping low mid punch.

Brass Instruments – Trumpet, trombone, and sax sound clear and larger than life through ribbons. The mics tame the harsh upper register while preserving the natural warmth and richness of the sound.

Woodwinds – For reed instruments like clarinet, oboe, and flute, ribbons reproduce the true tonality accurately without hyping any frequencies. You get the sound you worked hard to develop acoustically.

Strings – Even small string sections sound huge and cinematic through ribbons thanks to their spatial bloom and rich harmonics. The smoothness lets you increase the mic distance to control ambience.

Drum Overheads – Ribbons as overheads give you refined cymbal definition without brittle fizziness. This approach can provide excellent drum kit coverage with minimal mics.

Blumlein Pair – The figure-8 polar pattern that ribbons have natively makes them perfect candidates for the Blumlein stereo technique. This provides excellent channel separation and realistic imaging.

Close Miking – When close miked, sound sources really benefit from the isolation ribbons provide. You can capture all the subtle nuance and detail without leakage from other instruments bleeding in.

Mid-Side (M-S) Stereo – The bidirectional pickup also suits ribbon mics for mid-side techniques. The phase coherence ensures mono compatibility and flexibility in post production.

Variable Impedance Preamps – With passive ribbon mics, preamp impedance makes a big difference. Variable impedance lets you effectively EQ the low end, reducing boominess by lowering the impedance.

Distance from Rear Wall – Placing ribbon mics at a distance from the rear wall changes the proportion of reflected ambience to direct sound for creative room tone effects.

Ribbon Mic Models and Types

Ribbon technology has evolved over the decades and many flavors exist today from accurate vintage reproductions to radical new modern designs:

DIY Ribbon Mic Building

Part of the appeal of ribbon mics is that they’re much simpler electrically than other mic designs. This makes it possible to build your own ribbon mic at home with basic components and tools.

Ribbon transducer elements can be purchased pre-assembled or you can get creative and try sourcing the parts separately like magnets, aluminum ribbon, and frame materials.

There are also complete ribbon mic kits available that provide all the necessary parts to guide you through construction and assembly. With just basic soldering and woodworking skills, you can own a hand-crafted custom ribbon!

While the acoustic tuning requires finesse, the electrical side is far more approachable than building a condenser from scratch. All you need are the ribbon element, transformer, and output connector.

DIY ribbon projects let you learn hands-on how these amazing mics work while creating your own unique design. It’s incredibly rewarding and makes you appreciate ribbons even more.

Ribbon Mic Preamp Considerations

To get the most out of ribbon mics, having a preamp designed for their needs is extremely beneficial. Here are some factors to consider:

Proper Impedance Matching – Passive ribbon mics require an ideal impedance match from the preamp for full frequency response and output. Mismatched impedance dampens bass and presence.

Specialty Ribbon Preamps – Purpose-built preamps like the AEA TRP2 are optimized specifically for ribbon mics with perfect impedance matching and gain staging.

Active Electronics – Modern ribbon mics with onboard active circuitry are far less sensitive to impedance. But a ribbon-friendly preamp never hurts!

External Impedance Boosting – Devices like the Cloudlifter CL-Z raise the impedance seen by passive ribbons and provide clean preamp gain before A/D conversion.

Vintage Ribbons and Phantom Power – Passive vintage ribbon mics connected improperly can be damaged by phantom power on mixers. Polarizing the ribbons prevents this.

Conclusion

Hopefully this guide has illuminated exactly what makes ribbon microphones so special and when you might want to reach for one. Their smooth frequency response, detailed transient response, and signature midrange clarity have captivated engineers for almost a century.

With improved durability and lower costs, ribbon mics are more accessible than ever. Even hobbyists can get in on ribbon action by building their own. Once you experience ribbons on vocals, guitars, brass, and other sources, you’ll be hooked!