Dynamic Ribbon Microphones: The In-Depth Guide


The ribbon microphone is a type of dynamic mic that has risen in popularity alongside digital recording for its natural sound.

What is a dynamic ribbon microphone? A dynamic ribbon mic is a transducer that converts sound waves into mic signals via electromagnetic induction. It gets its name from its conductive ribbon-like diaphragm that vibrates within a magnetic field, inducing an AC voltage, which is then outputted as the mic signal.

Ribbon microphones are cherished by musicians, audiophiles, and engineers alike. In this article, we’ll discuss dynamic ribbon microphone in great detail. This will be a longer read, so I’d like to present, to you, a table of contents.


Table Of Contents


Dynamic Microphones And Electromagnetic Induction

When I first started learning about microphones, I thought the term “dynamic microphone” was simply a microphone with a large dynamic range. I was incorrect!

Dynamic microphones are actually named after the electrical dynamo.

A dynamo is an electric generator that works based on the principle of electromagnetic induction. It utilizes rotating coils of conductive wire and a magnetic field to convert mechanical rotation (mechanical energy) into a pulsing DC voltage (electrical energy).

The electric dynamo design was the first electric generator that was made for industry and is the predecessor of many electrical power transducers, including dynamic microphones!

So the dynamo creates pulsating DC voltage, but audio signals are AC voltages. The term “dynamic” is based on “dynamo,” but they are not the same. Perhaps a better namesake would be the AC producing magneto, which is kind of like a dynamo that produces AC voltages.

As a side note, “Dynamo” was first coined by the famous Michael Faraday in 1831 (he also discovered the law of induction that is named after him)!

To learn more about the history of microphone technology, check out my article Mic History: Who Invented Each Type Of Microphone And When?

What Is Electromagnetic Induction?

Electromagnetic induction is the creation of a voltage across an electrical conductor in a closed circuit as it experiences a changing magnetic field.

In a ribbon microphone, the ribbon (electrical conductor) is displaced by sound pressure. It oscillates within a permanent magnetic field supplied by the mic’s permanent magnets.

The magnetic field relative to the moving ribbon is changing. And so once we close an electrical circuit with the ribbon, we will have an electromagnetically induced current across that ribbon. This AC current/voltage is ultimately the mic signal.

There is a physical law that is important to our understanding of electromagnetic induction. This is Faraday’s Law of Induction.

Faraday’s Law Of Induction

The electromotive force (induced voltage) in a closed circuit is proportional to the rate of change over time of the magnetic flux through that circuit.

Let’s break this down into smaller definitions to better understand in the context of a dynamic ribbon microphone:

  • Electromotive force (emf) or “induced voltage” is the voltage created across the conductive ribbon diaphragm as a result of electromagnetic induction.
  • A closed circuit is a complete electrical connection in which current (in this case alternating current) can flow. (The closed circuit in a ribbon mic could consist of the ribbon connected to a transformer by signal wires at each of its ends).
  • Proportional to the rate of change over time” simply means that changing the magnetic flux results in an induced voltage.
  • Magnetic Flux is loosely defined as the total magnetic field which passes through a given area.

In the ribbon microphone design, we have a permanent magnet. The magnetic field produced by that magnet is concentrated around the ribbon diaphragm.

The magnetic field’s strength can be measured with field lines. These are vectors that show both the strength and direction of the magnetic field at any given point.

The magnetic flux is the strength of the magnetic field over a given area:

  • We can imagine a strong magnetic flux as having many strong field lines going through a big area.
  • Imagine a weak magnetic flux as having fewer field lines going through a given area.
  • If no field lines go through the area (like if the area is parallel to the direction of the field lines), there is no magnetic flux!

The movement of the ribbon diaphragm in a permanent magnetic field causes a change in magnetic flux in the ribbon. This change in magnetic flux in the ribbon causes a voltage to be created across it according to Faraday’s Law of Induction!

Depending on the direction of relative movement between the conductive ribbon and the magnetic field, a positive or negative voltage will be applied across the conductor. This means we’re dealing with alternating current.

There are 2 main factors that determine the amount of voltage that will be applied across the conductor of the ribbon microphone. They are:

  1. The velocity of the ribbon: by increasing the velocity of the ribbon, it moves through the magnetic field faster and therefore has a faster rate of change of the magnetic flux.
  2. The strength of the magnetic field: by increasing the strength of the magnetic field, we have a greater potential change in magnetic flux.

In a microphone, the strength of the magnetic field is constant. It is, therefore, the velocity of the ribbon that determines the amount of voltage across that ribbon. The ribbon diaphragm moves according to the sound pressure difference between its front side and back side essentially recreating the sound waves around it.

Back to Table of Contents.


The Anatomy Of A Dynamic Ribbon Microphone

Royer R-121 Ribbon Element

There are many parts of microphone anatomy that are common among ribbon mics. Without getting into every single part of a microphone, let’s talk about the essential elements that make up the ribbon mic.

The three determining parts of a ribbon microphone:

The Ribbon Diaphragm/Conductor

The diaphragm is referred to as a ribbon because, well, it looks like a ribbon! Rather than having a tightly tensioned membrane around circular housing like most moving-coil dynamic and condenser microphones, the ribbon microphone utilizes a long, thin, ribbon-like diaphragm suspended in air, attached only at each end of its length.

Another fascinating thing about ribbons is that they play the part of both the diaphragm and the conductor in the dynamic microphone principle.

The ribbon, as a diaphragm, moves according to the sound pressure variance around it. The ribbon, as a conductor, moves through a magnetic field, inducing a voltage across itself as it does so.

This is unlike the moving-coil dynamic microphone, which has a separate diaphragm and conductive coil.

For more information on moving-coil dynamic microphones, please check out my article Moving-Coil Dynamic Microphones: The In-Depth Guide.

What Is The Ribbon Made Of?

The ribbon is made of an electrically conductive material that is light in weight and has low elasticity. This almost always means aluminum foil (which is less conductive than copper, but much lighter)!

  • Aluminum is very conductive (3.69×107 S/m).
  • Aluminum is lightweight (3.7 g/cm3) and allows the diaphragm to be more reactive than heavier materials.

Some microphones have a thin layer of gold over the traditional aluminum ribbon. This is to help prevent oxidation of the ribbon more than to add conductivity (though gold is more conductive than aluminum).

Yet other microphone manufacturers make use of stronger plastic polymers coated with aluminum to make their ribbons.

The Shape Of The Ribbon And Incoming Sound Waves

Because the ribbon is so thin (typically less than 10 microns), it can’t be stretched too tightly without the great risk of tearing.

Remember we need a thin material with low elasticity. Ribbons are, therefore, crimped along their lengths to increase flexibility and movement when subjected to varying sound pressure levels.

Because the ribbon is lightweight, flexible, and under low tension, its resonance frequency tends to be well below the audible range (more on this in the inherent nature of a ribbon microphone section).

The low mass of the ribbon also means that it’s easy to move across the entire audible frequency spectrum. This is partly due to the fact that the mechanical reactance of the lightweight ribbon is actually less than the impedance of air molecules around it.

In other words, it’s technically easier to move the ribbon than it is to displace the air around the ribbon (though both need to happen in order for the ribbon diaphragm to move).

How Does The Ribbon Fit In The Baffle Of The Dynamic Ribbon Microphone?

The combination of physical parts surrounding the ribbon is called a baffle, which includes the support structure, the magnets, and the magnetic pole pieces. The baffle can be thought of like the housing of the diaphragm since ribbon mics don’t really have a capsule/cartridge.

The ribbon is attached to baffle mounts at each end of its length. These supports are made, at least partly, of non-conductive material as to electrically isolate the ribbon from everything else in the microphone. The ribbon makes contact with these attachment supports and nothing else.

Like the moving-coil of a dynamic microphone, the ribbon essentially sits in a “gap” between two magnetic poles. These magnets come very close to the ribbon without touching it, concentrating a magnetic field around the ribbon to increase electromagnetic induction. The ribbon’s position is such that its surfaces are parallel with the magnetic force lines.

Another reason for the minimization of space between the ribbon and the magnets is to stop air leakage. This stops air from passing around the ribbon.

Air and sound waves, then, must travel around the baffle in order to get from one side of the ribbon to the other. This is important for maintaining the ribbon mic’s natural bidirectional polar pattern.

The Magnet And Its Pole Pieces

The magnet, complete with its pole pieces, makes up a big part of the baffle and sits nearly flush to the perimeter of the ribbon.

One practical design we’ll discuss utilizes 2 “horseshoe” main magnets along with 2 narrowed pole pieces that make up one complete magnetic structure.

The permanent magnet inside a ribbon microphone provides the magnetic field necessary for the conversion of mechanical wave energy into electrical energy. Without the magnet, no electromagnetic induction would occur and no amount of ribbon displacement or velocity would result in any audio signal.

What Are The Magnet And Pole Pieces Made Of?

The main magnets need to be strong for their small size and are typically made of ferrite or powerful neodymium.

The pole pieces need to properly “extend” the magnetic poles of the magnet and need high magnetic permeability. Soft iron is often used. Even better are alloys such as Permendur or Hyperco 90.

How Are The Magnet And Pole Pieces Assembled?

The magnets need to create a powerful and concentrated magnetic field around our thin conductive ribbon diaphragm. We need opposite poles on either side of the length of the ribbon and we need minimal space between the magnet and the length of the ribbon.

This is not practical with a single magnet. Therefore, pole pieces are incorporated into the design.

The main “horseshoe” neodymium magnets provide the base of the strength of the magnetic field. They are set above and below the ribbon and do not typically take up space on the sides of the length of the ribbon. The main magnets are positioned so that their north poles align on one side of the ribbon’s length and the south poles align on the other side.

The narrowed pole pieces connect the two horseshoe magnets from north pole to north pole and south pole to south pole. The pole pieces run along the length of the ribbon providing the aforementioned opposite magnetic poles on either side of the length of the ribbon!

To recap, the design we’re discussing involves the following:

  • 2 horseshoe magnets (above and below the ribbon): These magnets provide the strength of the magnetic field. They are positioned so that both north poles are aligned on one side of the length of ribbon while both south poles are aligned on the opposite side of the length of ribbon.
  • 2 Pole pieces (extend/connect the 2 magnets the north pole to north pole and from south pole to south pole): The two pole pieces provide the opposite magnetic polarization on either side of the ribbon. They are positioned as close as possible to the sides of the ribbon without actually touching it.

Here is a cross-sectional diagram I drew up to better visually represent the dynamic ribbon microphone 

Dynamic Ribbon Microphone
  • The corrugated ribbon diaphragm/conductor is drawn in purple.
  • The main magnets are drawn in red.
  • The pole pieces are drawn in green.
  • The poles of the overall magnetic structure are labelled N (north pole) and S (south pole).
  • The baffle mounts or “ribbon-housing attachments” are drawn in orange.
  • The signal wires from the ends of the ribbon are drawn in blue, which completes an electrical circuit with the transformer!

For more on magnets and microphones, check out my article Do Microphones Need Magnetism To Work Properly?

The Step-Up Transformer

The voltage induced upon the ribbon during its movement in the magnetic field is too low to be the output audio signal. The electromagnetic force created by the ribbon before amplification wouldn’t travel through much wire before being drowned out by electromagnetic interference, creating a horrible signal-to-noise ratio and unusable signal.

The simple solution to this is a step-up audio transformer!

What Is A Step-Up Transformer?

The step-up transformer is designed with two separate coils of conductive wire, both of which are wound around the same magnetic core. These two coils never make a physical connection with one another and are therefore isolated from each other. These coils are referred to as “windings.”

  • The signal wires (from the ribbon diaphragm and to the mic output) are drawn in blue.
  • The primary winding of coil is drawn in orange.
  • The magnetic core is drawn in red.
  • The secondary winding of coil is drawn in green.
  • The centre tap is drawn in purple.

Let’s discuss each of the windings and their circuits:

  • The primary winding completes an AC circuit with the ribbon of the microphone (this is the microphone transformer “input”).
  • The secondary winding completes an AC circuit (a balanced audio signal) with the microphone output. (this is the microphone transformer “output”).

The windings are typically made of copper wire and the magnetic core is typically made from materials like iron (metal) or ferrite (ceramic).

The alternating current from the primary winding induces a changing magnetic field in the magnetic core of the transformer, which, in turn, induces an alternating current of the secondary winding.

This is due to a phenomenon called inductive coupling that states that whenever an AC signal passes through the primary winding, a related AC signal appears on the secondary winding. Inductive coupling, like the electromagnetic induction that happens in the baffle of the ribbon mic, is based on the principle of electromagnetism.

There are 3 factors that determine the amount of voltage that can be electromagnetically induced on a conductive coil:

  1. The number of loops in the coil.
  2. The velocity of the coil through a magnetic field.
  3. The strength of the magnetic field.

There’s no relative movement or relative change in the magnetic field strength between the primary (input) and secondary (output) windings of the transformer. So the number of loops in the secondary winding must be greater than the number of loops in the primary in order for the signal to be effectively “stepped-up.”

The ratio of turns between primary and secondary windings is theoretically equal to:

  • The ratio of voltage between primary and secondary windings.
  • The ratio of current between secondary and primary windings.

So a step-up transformer increases the voltage of the audio signal while decreasing the current of the audio signal.

What Is The Purpose Of A Transformer In A Dynamic Ribbon Microphone?

Dynamic ribbon microphones are designed with transformers in order to:

  • Increase or “step-up” the voltage of the induced signal.
  • Increase the impedance of the signal voltage.
  • Change the signal into a balanced audio signal.
  • Protect the microphone from DC voltages like phantom power.
  • Aid in isolating the microphone from other electronic devices and RFI.

Let’s discuss each of these points in a bit more detail.

Increase Or “Step-Up” The Voltage Of The Induced Signal

By designing the transformer with more turns in the secondary winding than the primary winding, we step-up the voltage of the signal!

Increase The Impedance Of The Induced Signal Voltage

With all other factors being equal, a greater number of turns in a coil equals a greater impedance. Since the secondary winding has more turns in coil than the primary winding, we effectively increase the impedance and strength of the audio signal! This is important since the signal induced on the ribbon is weak and has a very low impedance.

The ratio of the primary impedance to secondary impedance is the square of the turns ratio, and so there is a considerable increase in impedance between the step-up transformer input and output.

To learn more about microphone impedance, check out my articles Microphone Impedance: What Is It And Why Is It Important? and What Is A Good Microphone Output Impedance Rating?

Change The Induced Signal Into A Balanced Audio Signal

The transducer changes our unbalanced signal from the microphone ribbon into a balanced signal at the microphone output. This is done is through a centre-tap on the secondary winding.

A centre-tap is a contact point made at the halfway point of a conductor (in this case the secondary winding). The centre-tap effectively breaks the overall voltage across the secondary winding into two halves and separates it into two signals. These two signals are in opposite polarity to one another.

This is exactly what we need for a balanced audio signal! We take a lead (pin 2) from the “positive polarity” half of the winding and another lead (pin 3) from the “negative polarity” half of the winding.

For more information on microphones and balanced audio signals, check out my article Do Microphones Output Balanced Or Unbalanced Audio?

Protect The Microphone From DC Voltages Like Phantom Power

In theory, phantom power should not affect any transformer-output mic since DC voltages don’t cause an alternating magnetic field and therefore transformers do not pass direct current.

The ribbon is connected across the primary coil while phantom power 48 V DC is connected to both ends of the secondary coil. And so no DC voltage should get transferred to the ribbon.

So yes, a transformer will protect microphones from DC voltage. But that’s not to say that phantom power will not stretch or blow-out the thin ribbon diaphragm of a microphone if it’s shorted or cross-patched.

To learn more about ribbon mics and phantom power, check out my article Will Phantom Power Damage My Ribbon Microphone?

Aid In Isolating The Microphone From Other Electronic Devices And RFI

Transformers also isolate their microphones from other electronic devices and block RFI (radio frequency interference). This is because the primary and secondary do not physically touch one another. We can solve hum problems by isolating (“lifting”) the grounds of different devices.

For more information on microphone noise and how to reduce it, check out my article 15 Ways To Effectively Reduce Microphone Noise.

Note that not all transformers are built the same and that the quality of the transformer will impact frequency response and maximum voltage input before distortion. Cheap transformers will oftentimes degrade the signal. More on this in the “The Inherent Nature of a Ribbon Microphone” section.

To learn more about microphone transformers, check out my articles What Are Microphone Transformers And What Is Their Role? and Do All Microphones Have Transformers And Transistors? (+ Mic Examples).

Back to Table of Contents.


The Inherent Nature Of A Ribbon Microphone: The Pros And Cons

Every microphone model is different, but there are characteristics that are inherently part of certain types of microphones. Due to the nature of the ribbon diaphragm/conductor, baffle, transformer, and of electromagnetic induction, a typical dynamic ribbon mic has the following characteristics:

Figure-8 (Bidirectional) Polar Pattern

The inherent nature of the ribbon microphone design yields a figure-8 polar pattern.

A ribbon diaphragm is equally sensitive to sound waves at its front and back with practically no sensitivity from the direct sides, top, and bottom (due to its extreme thinness and due to the baffle around it).

The natural set up of the ribbon element and baffle, therefore, yields a bidirectional (figure-8) polar pattern.

Let’s look at 3 simple examples to explain how a typical ribbon microphone is bidirectional:

  • A sharp transient sound happens directly on-axis in front of the ribbon microphone. The sound hits the front of the ribbon first, causing it to move from resting position. A short time “T” later, the same sound wave has travelled around the baffle and has hit the back of the ribbon, and there is adequate sound pressure difference to displace the ribbon diaphragm and create an audio signal.
    The microphone is sensitive to sound coming directly from the front.
  • The same is true from the back. Say a transient sound happens directly on-axis from the rear of the ribbon mic. The sound hits the back of the ribbon first, and a short time “T” later hits the front. This also creates an adequate sound pressure difference to displace the ribbon diaphragm and create an audio signal.
    The microphone is sensitive to sound coming directly from the rear.
  • A third sound comes directly from the side of the microphone. It hits the baffle first and travels to the front and back of the diaphragm at the same time “½T.” Because the same sound pressure wave “pushes” on both sides of the ribbon diaphragm at the same time, the diaphragm doesn’t move. There’s no difference in sound pressure to create an audio signal.
    The microphone is not sensitive to sound coming directly from the sides.

To read an in-depth description of the bidirectional polar pattern, check out my article What Is A Bidirectional/Figure-8 Microphone? (With Mic Examples).

Strong Proximity Effect

This goes along with the directionality of the ribbon microphone. Any directional microphone (bidirectional, cardioid, etc.) will be subjected to the proximity effect and figure-8 polar patterns exhibit the greatest proximity effect.

The proximity effect is an increase in bass frequency response as a sound source gets closer to a microphone diaphragm.

  • The lower the frequency, the less its phase component affects the sound pressure difference between the front and back of the diaphragm. However, at close proximities, the amplitude component creates a relatively large difference in sound pressure difference.
  • At higher frequencies, the phase component causes a lot of sound pressure difference. At close proximities, the overall amplitude of high frequencies will cause a difference in sound pressure between the front and back of the ribbon, but the phase component will still play the dominant role in determining the sound pressure difference.

Therefore, lower frequency sounds are effectively boosted as they get closer to a bidirectional ribbon microphone.

For more information on microphone proximity effect, check out my article What Is Microphone Proximity Effect And What Causes It?

Gentle Roll-Off Of High Frequencies

Ribbon microphones have an inherent gentle roll-off of high frequencies that is similar to that of human hearing. This is a big selling point in the days of “transparent sounding” digital recording.

Note this gentle roll-off actually put ribbon mics out of favour in the days of analog tape, which also rolls off high-frequencies, leading to a dull sound when combined with ribbons!

One could argue that ribbon microphones have “better” frequency responses than moving-coil dynamic and condenser microphones.

  • Moving-coil dynamic mics typically have many resonant frequencies and sharp high-frequency roll-offs that some may call muddy and unnatural.
  • Condenser microphones have extended “flat” frequency responses that some may call harsh and unnatural.

Ribbon microphones have that inherent “slow” roll-off of high frequencies, making them sound “warm” and “natural.” Of course, these are subjective descriptions.

First, a side note on the resonance frequency of the ribbon diaphragm itself. To protect the ribbon from being torn by sound pressure, it is not to be under high tension. The corrugation of the ribbon helps to realize this low tension without causing the ribbon to sag. Because of the low tension, a ribbon’ resonance frequency will typically lie well below the range of human hearing. This means no audible resonance peak, unlike moving coil and condenser mics!

From my research, the ribbon’s high-end roll-off is due to 4 main points:

  1. Irregular shape of the ribbon diaphragm.
  2. The low weight of the ribbon.
  3. Phase relationship between the front and back of the ribbon diaphragm.
  4. Proximity effect.

For more information on high-end roll-off and microphone frequency response, check out my article Complete Guide To Microphone Frequency Response (With Mic Examples).

Low Output Levels

The big drawback of utilizing such a thin, low tension, diaphragm/conductor is that it doesn’t induce much voltage as it moves through the magnetic field. In fact, passive ribbon microphones are among the mics with the lowest sensitivity ratings. This low voltage also comes with extremely low impedance.

This is simply a physical limitation of electromagnetic induction on such a small scale.

Moving-coil dynamic microphones are also “low output.” However, because they utilize a moving-coil with many turns, they induce more voltage than a ribbon.

As we’ve discussed, step-up transformers are used to bring up the voltage to usable audio signal levels with proper impedances. But still, transformers can only do so much, and so when using a ribbon microphone, it’s important to have good, clean gain at the preamp stage.

To learn more about mic level signals and microphone gain, check out my articles Do Microphones Output Mic, Line, Or Instrument Level Signals? and What Is Microphone Gain And How Does It Affect Mic Signals?, respectively.

We’ll note in the next section that active ribbon mics have active electronic circuitry to further boost the signal so that our microphone preamplifiers don’t have to work as hard!

Accurate Transient Response

The big advantage of utilizing such a thin, low tension, diaphragm/conductor is that it reacts to sound pressure with great precision.

This comes down to inertia. The greater the mass of a diaphragm, the more energy it will take to move it. In other words, heavier diaphragms are less sensitive to sound pressure and react more slowly than their lighter counterparts.

The extremely lightweight ribbon diaphragm has very little inertia and, therefore, a very accurate transient response.

Fragility

This is perhaps the most important general characteristic of ribbon microphones. They are relatively fragile.

Think about it. We have a ribbon acting as both our diaphragm and electromagnetic conductor. It’s a very important piece of the microphone design. And it’s thinner than a strand of hair!

As you can imagine, caution must be taken to protect your microphone and give you more time between re-ribbons!

I think that the best way to describe the fragility of ribbon microphones is to run through a “do’s and don’ts.” Let’s get into it:

  • Don’t expose the microphone to wind or blasts of air
  • Do use a pop filter when recording vocals
  • Do use a windscreen if working with a ribbon microphone in windy environments
  • Do position the microphone off-axis when recording loud SPL sources
  • Don’t hot patch the ribbon mics with phantom power engaged
  • Do use quality mic cables with proper wiring
  • Don’t subject the ribbon microphone to foreign particles
  • Do use a “mic sock” when transporting a ribbon mic
  • Do store the ribbon microphone properly when it’s not in use
  • Don’t “mic drop” a ribbon microphone

Don’t Expose The Microphone To Wind Or Blasts Of Air

Think of the ribbon as you would a sail on a sail ship.

The ribbon is very sensitive to any change in sound and especially to wind and blasts of air (like vocal plosives). These forces of the air have the potential to stretch the thin ribbon or even tear it. That’s obviously not good, and the microphone will not function properly until it’s re-ribboned.

To learn more about vocal plosives and how to weaken them before they reach your microphones, check out my article Top 10 Tips For Eliminating Microphone Pops And Plosives.

Do Use A Pop Filter When Recording Vocals

This is good advice for any microphone. No one wants plosives in voice tracks and they can ruin an otherwise great vocal take.

But this advice is especially important with ribbon microphones because too much of a vocal pop could potentially stretch the ribbon!

To learn more about microphone pop filters, check out the following My New Microphone articles:

What Is A Microphone Pop Filter And When Should You Use One?
Why Do Microphones Have Screens? (Pop Filter, Grille, Windscreen).
Do I Need A Pop Filter For Streaming With A Microphone?
Best Microphone Pop Filters.

Do Use A Windscreen If Working With A Ribbon Microphone In Windy Environments

Again, great advice for any microphone. Hearing wind in a microphone signal renders it pretty much useless unless that is the specific (terrible) sound you’re going for!

But once again, this applies to the safety of the ribbon as well, since gusts of wind have been known to stretch and ever tear the thin ribbon diaphragms.

Do Position The Microphone Off-Axis When Recording Loud SPL Sources

Ribbon microphones tend to have true figure-8 polar patterns. This means little to no coloration of sound off-axis!

So if we are to use a ribbon mic to capture really loud sound sources like a kick drum, for example, tilting the mic off-axis will capture the same “sound” as it would on-axis, but the sound pressure won’t cause nearly as much wear on the ribbon.

If we choose to close-mic a loud, plosive, sound source, it may be a good idea to also guard the mic with some sort of pop filter as mentioned above.

Don’t Hot Patch Ribbon mics With Phantom Power Engaged

Hot patching in a 1/4″ TRS (tip-ring-sleeve) patch bay will effectively short phantom power momentarily. This is because TRS jacks/plugs (unlike microphone XLR cables) do not make all three connections simultaneously.

Although momentary, this shorting of phantom power sent to a passive ribbon microphone can jolt the ribbon and has the potential to stretch it or tear it. These passive microphones are not designed to handle phantom power shorting!

It’s always best practice to disengage phantom power when hot patching!

Note that hot patching active ribbon microphones should, in theory, be fine… But please refer to the sentence above on best practice.

Do Use Quality Mic Cables With Proper Wiring

To add to the above point, miswired cables also have the potential to send shorted phantom power to a ribbon microphone, causing damage to the ribbon.

This also applies to the fact that ribbon microphones have low output signals and therefore require low-noise, well-shielded cables in order to get the audio to where it needs to go without signal degradation.

Once again, best practice to use high-quality cables on all professional microphones.

To learn about my recommended mic cables, check out Best Microphone Cables.

Don’t Subject The Ribbon Microphone To Foreign Particles

There are powerful magnets inside the baffle of a ribbon microphone. These magnets can attract many tiny metal particles into the gap between the magnets and the ribbon. The slightest amount of friction or contact with a sharp particle could cause permanent damage to the ribbon. To make matters worse, even non-magnetic particles have to potential to get caught up in the baffle of the microphone if precautions aren’t taken.

Do Use A “Mic Sock” When Transporting A Ribbon Mic

Using some sort of filter or even covering the grille of the ribbon mic with your hand while travelling will help protect it from “wind” (movement of the mic through the air) while also subjecting it to less airborne particles.

Do Store The Ribbon Microphone Properly When It’s Not In Use

If you’re skipping tear down for a particular job, it’s a good idea to cover any ribbon mics with a mic sock to reduce their exposure to airborne particles.

An even better place for ribbon microphones when they’re not in use is inside their protective cases. Store the microphones out of the way, and even go as far as to stand the microphone upright rather than on its side to prevent the ribbon from sagging while in storage!

Don’t “Mic Drop” A Ribbon Microphone

If a quick gust of air, a short of 48 volts DC, or a tiny metal particle stuck to the magnet of ribbon microphone can blow up the ribbon diaphragm, there’s a good chance that physical trauma (dropping, hitting, etc.) can do the same.

Perhaps this is why we see more Shure SM58’s than Royer 121’s in singers’ hands on stage!

The bottom line is simply “be careful!” Ribbon mics are wonderful, precision instruments and should be treated as such.

Other Requirements

Yes, ribbon microphones are transducers that offer a very accurate reproduction of sound. But they don’t always “play nice” with other gear. Let’s talk about the other requirements that need to be met in order for a ribbon microphone to live up to its full potential:

  • Pre-amplifier with more clean gain than is typical of a preamp: Passive ribbon microphones will output a fairly low-level signal. We need good clean gain at the preamp stage to keep noise issues to a minimum, especially when recording quiet sources.
  • Pre-amplifier with high input impedance: Typically we want our load impedance (impedance of the preamp) to be at least 5x that of the microphone output impedance or, optimally, more than 10x. Although passive ribbon mics typically have low rated nominal output impedances, their impedances vary with frequency, often become very high at low frequencies. Having a low input impedance in a preamp will cause deterioration of the low-end response of the microphone. It can also cause a dulled transient response and distortion in the signal.

Note that we can get creative with the “requirements” and actually utilize different preamps to effectively change the sound of these ribbon microphones.

Notice how I included the prefix “passive” when describing the microphones above? This brings us to our next point: that there are both passive and active ribbon microphones!

Back to Table of Contents.


Passive And Active Ribbon Microphones

Passive ribbon microphones are pretty much what we’ve been discussing up until this point. They consist of:

  • Ribbon diaphragm/conductor.
  • Baffle, complete with magnet(s) and/or pole pieces.
  • Passive circuitry and a step-up transformer.

The active ribbon microphone consists of the same key parts but has active circuitry added to the design. This active circuitry requires power in order to function.

The addition of active circuitry aims to overcome the requirements needed from the classic passive ribbon microphone. The active circuitry is designed to:

  • Produce more gain before the microphone output, improving the signal-to-noise ratio.
  • Create a consistent impedance over the audible frequency spectrum.
  • Bonus: Protect the microphone from phantom power.

For easy reading, let’s break down the advantages and disadvantages an active ribbon has compared to a passive ribbon microphone:

  • Higher output level.
  • Better signal-to-noise level.
  • Consistent sound when used with different preamplifiers.
  • Protection from phantom power.
  • Needs power to function.
  • Has self-noise.

The interesting point, to me, is having to do with preamps and their coloration of ribbon microphones. With passive ribbon mics, we can get experimental with our preamp selection and get different sounds out of the mic. With active ribbon mics, we have consistency, so we know what the mic should sound like when plugged into any audio device.

For more information on phantom power and ribbon microphones, check out my article Will Phantom Power Damage My Ribbon Microphone?

To read more on the differences between passive and active microphones, check out my article Do Microphones Need Power To Function Properly?

Back to Table of Contents.


The Energy Chain: From Sound Source To Microphone Output

Let’s recap and describe the energetic path of vocals through a ribbon microphone. I’ll refer to the sound/audio as energy for the sake of furthering our understanding of the microphone as a transducer (a device that changes one form of energy into another form of energy).

Here is how I’ll name the types of energies for this segment:

  • Mechanical wave energy: the energy associated with the motion and position of a physical object.
  • Acoustical energy: the energy associated with the vibration of matter in a fluid (air) along a mechanical wave (sound wave).
  • Electrical energy: the energy associated with voltage and current through a circuit.

Note that these are not perfect descriptions, but simply brief explanations to help avoid confusion in this section of the article!

Let’s get into it! In point form:

  • Sound vibrates around the ribbon.
    Acoustical Energy.
  • The changing sound pressure against the front and back of the ribbon causes it to vibrate back and forth about its resting position.
    Transduction of Acoustical to Mechanical Energy.
  • The movement of the ribbon in the magnetic field causes an AC voltage to be induced across it.
    Transduction of Mechanical to Electrical Energy.
  • A signal wire from each end of the ribbon creates a circuit with the primary winding of the step-up transformer.
    Electrical Energy.
  • The AC voltage across the primary winding induces a changing magnetic field in the transformer’s magnetic core.
    Electrical Energy.
  • The changing magnetic field in the step-up transformer induces a great AC voltage in the secondary winding.
    Electrical Energy.
  • The secondary coil is centre-tapped, creating reverse polarity on pins 2 and 3 (balanced audio).
    Electrical Energy.
  • Pin 1 is grounded in the microphone, and together with pins 2 and 3, the audio signal is sent through the microphone output.
    Electrical Energy.

Where we send this output audio signal is beyond the scope of this article, but it could be to a microphone preamplifier, an audio-interface, directly to a mixer or loudspeaker, etc. There are plenty of options!

Back to Table of Contents.


5 Common Dynamic Ribbon Microphones

I figured I’d assemble a short list of common ribbon mics and discuss how they relate to the general characteristics expected of ribbon mics.

Instead of creating “mini-reviews” of each of the 5 common mics, I’ll just share the specs I feel best to represent them. I’ll also link to the spec sheets I’m referencing so you can take a better look at the microphone specs (particularly the frequency response charts).

Much like how Shure took up most of the list for moving coil dynamic mics, Royer takes up most of the ribbon microphones list.

Note that I’ll add links to check to the prices of these microphones. This is not a buyer’s guide, but if you’re interested in purchasing any of these mics while helping to support this blog, consider using the affiliate links provided!

So here are 5 common (if not the most common) ribbon microphones on the market:

The Royer R-121 and Coles 4038 are featured in the My New Microphone article 50 Best Microphones Of All Time (With Alternate Versions & Clones).


Royer R-121

Royer R-121

The Royer 121 is the flagship ribbon microphone of the flagship ribbon microphone company.

Link to check the price of the Royer R-121 on Amazon.

The characteristic specifications of the Royer R-121:

  • A frequency response of 30 – 15,000 Hz ± 3dB.
  • Figure-8 (bidirectional) polar pattern.
  • 2.5-micron aluminum ribbon.
  • Rare Earth Neodymium magnets.
  • Output impedance of 300 Ohms @ 1K (nominal).
  • Max SPL of 135 dB @ 30 Hz.
  • Sensitivity of -47 dB (re. 1v/pa).

Click here for the referenced Royer 121 Spec Sheet.


Royer R-122 MKII

Royer R-122 MKII

The Royer 122 MKII is like the active brother of the 121. Notice that there’s a difference in sensitivity but not in max SPL rating. These specs tell us that the active circuitry in the Royer 122 MKII increases the gain at microphone output! Also notice that the output impedance is “balanced” rather than “nominal” like the 121.

Link to check the price of the Royer R-122 MKII on Amazon.

The characteristic specifications of the Royer R-122 MKII:

  • A frequency response of 30 – 15,000 Hz ± 3dB.
  • Figure-8 (bidirectional) polar pattern.
  • 2.5-micron aluminum ribbon.
  • Rare Earth Neodymium magnets.
  • Output impedance of 200 Ohms, balanced.
  • Max SPL of 135 dB @ 30 Hz.
  • Sensitivity of -36 dB (re. 1v/pa ±1 dB).
  • Phantom power required.

Click here for the referenced Royer 122 MKII Spec Sheet.


Royer R-10

Royer R-10

The Royer R-10 is an “affordable” Royer passive ribbon microphone. It’s built smaller but more rugged than a typical ribbon mic and is even marketed for live applications! I would still be very careful with it though!

Link to check the price of the Royer R-10 on Amazon.

The characteristic specifications of the Royer R-10:

  • A frequency response of 30 – 15,000 Hz ± 3dB.
  • Figure-8 (bidirectional) polar pattern.
  • 2.5-micron aluminum ribbon.
  • Rare Earth Neodymium (Grade 52) magnets.
  • Output impedance of 100 Ohms.
  • Max SPL of 135dB @ 50 Hz and 160dB @ 1kHz.
  • Sensitivity of -54dBv (re. 1v/pa).

Click here for the referenced Royer R-10 Spec Sheet.


Coles 4038

Coles 4038

The Coles 4038 has been a high-level ribbon microphone for decades now. It’s even featured on My New Microphone’s Top 12 Best Vintage Microphones (And Their Best Clones).

Link to check the price of the Coles 4038 on Amazon.

The characteristic specifications of the Coles 4038:

  • A frequency response of 30 – 20,000 Hz.
  • Figure-of-eight (bidirectional) polar pattern.
  • 59.7 mm long x 4.7mm wide x 1.8 micron thin corrugated aluminum ribbon
  • Neodymium magnets.
  • Output impedance of 270 Ohms.
  • Max SPL of 140 dB SPL, 1 kHz at 1% T.H.D.
  • Sensitivity of 2.25 mV/Pa.

Click here for the referenced Coles 4038 Spec Sheet.


AEA R84/R84A

AEA R84 (left) and AEA R84A (right)

AEA really make great ribbon microphones. If I were to write this same article 5 years from now, I’d bet that AEA would have one or two more microphones on the “common” list. The AEA R84 comes in two versions: Passive (R84) and Active (R84A). Check out the differences here:

Link to check the price of the AEA R84 on Amazon.

The characteristic specifications of the AEA R84:

  • A frequency response of “<20 Hz to >20 kHz.”
  • Native bidirectional, figure-of-8 pattern.
  • 1.8-micron pure aluminum corrugated ribbon.
  • Magnet material not specified.
  • Output impedance of 270 Ω nominal.
  • Max SPL of 165 + dB SPL (1% third harmonic > 1 kHz).
  • Sensitivity of 2.5 mV/Pa (-52 dBv/Pa).

Link to check the price of the AEA R84A on Amazon.

The characteristic specifications of the AEA R84A:

  • A frequency response of “<20 Hz to >20 kHz.”
  • Native bidirectional, figure-of-8 pattern.
  • 1.8-micron pure aluminum corrugated ribbon.
  • Magnet material not specified.
  • Output impedance of 92 Ω broadband.
  • Max SPL of 141 + dB SPL (1% third harmonic > 1 kHz).
  • Sensitivity of 6.3 mV/Pa (-44 dBv/Pa).
  • Phantom power required (48V, 7mA).

Click here for the referenced AEA R84 Spec Sheet.

For a complete list of microphone specifications (with descriptions), check out my article Full List Of Microphone Specifications (How To Read A Spec Sheet).

Back to Table of Contents.


Are ribbon mics good for vocals? The natural sound of a ribbon mic can capture vocals amazingly well and add a pleasant character to the vocal performance. For best results when using a ribbon mics on vocals, it’s best practice to use a clean preamp and strong pop filter to boost the weak signal and avoid overloading the diaphragm.

Will phantom power destroy my ribbon mic? Not likely. Modern ribbon mics are designed with transformers and other passive electronic devices that block phantom power from damaging the ribbon diaphragm. However, hot patching or shorting DC voltage to a ribbon mic may fry the diaphragm, so it’s best practice to not apply phantom power.


This article has been approved in accordance with the My New Microphone Editorial Policy.

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