What Is a Dynamic Microphone?

A microphone is a key piece of equipment for recording and performance for a musician. To record well requires knowing the ins and outs about microphones. Choosing the right microphone is the first step.

There are two types of microphones available in the market: condenser and dynamic. Condenser microphones are commonly used in studios to pick up sounds with good detail and accuracy. On the other hand, dynamic mics work best for recording loud sounds. Their output is considerably lower than a condenser, which is appropriate when the signal you’re capturing is already powerful.

Thus, the dynamic mic is best used when you want to capture loud or strong sounds, while a condenser mic is used for capturing delicate sounds with higher frequencies, particularly in a closed studio. Another significant difference between the two is that a dynamic mic does not require additional power, whereas a condenser does.

In this article, we discuss dynamic microphones and their inner workings in detail.

What is a Dynamic Mic?

A dynamic mic uses EM induction to convert sound energy into electrical energy. That’s why a dynamic mic must have:

• A way to generate a magnetic field.
• An electrical conductor that can transfer electric current generated using the magnetic field.
• Something to cause motion between the two, so that current can be generated.

Technically speaking, a dynamic mic converts mechanical energy (sound waves) into electrical energy (audio) using a diaphragm, a permanent magnet, and EM induction.

Em Induction and How It Helps a Dynamic Mic Work 

As mentioned earlier, dynamic mics work via electromagnetism, and specifically the phenomenon called EM induction.

When a variable magnetic field is applied to an electric conductor like copper, a current is produced. This is the same principle on which large electric generators in hydroelectric dams work.

There are two ways to create a “variable” magnetic field: either move the magnetic field or move the conductor. In the case of dynamic mics, it is the latter case. The magnetic field is kept fixed, while the conductor (essentially the diaphragm of the mic) keeps moving as sound waves fall on it. 

Dynamic Mic Designs

Ribbon dynamic microphones and moving-coil dynamic microphones are the two types of dynamic mic designs that help to convert sound into audio. Let us study these two types of dynamic microphone designs and their working mechanisms, characteristics, and varied applications.

Moving-coil Dynamic Microphone: Type 1

This type of microphone is also known as a dynamic microphone and works via elementary mechanisms. 

Workings of Moving-Coil Dynamic Microphones

The moving-coil dynamic mic is passive. It consists of a non-conductive diaphragm with a conductive metal coil attached to its rear part. This coil sits within the magnetic structure, which ​​provides the permanent magnetic field necessary for electromagnetic induction. When there is a movement in the diaphragm, the conductive coil also moves. The oscillatory motion of the coil inside the magnetic field produces AC voltage, which is taken by lead wires as the mic’s audio signals. 

If a step-up transformer is installed in the mic, it helps boost the mic signal’s voltage. It also prevents the DC voltage from damaging the mic. 

Characteristics of a Moving-coil Dynamic Microphone

Moving-coil dynamic microphone and ribbon microphone have more or less the same features. However, there are a few characteristics of these mics that are entirely different from ribbon microphones:

• Low Frequency Response at the High Frequency End: Dynamic microphones consist of a non-conductive diaphragm. Any high-frequency sound has a challenging time moving this diaphragm. Hence, a dynamic mic suffers in output due to high-frequency sound and gives a dark-colored frequency response, resulting in rather sharp high-end roll-offs at low cutoff points.
• Durability: Moving-coil mics are rugged mics, and their parts are made of physically robust material capable enough to withstand significant thuds. Also, its passive circuit is resistant to damage and can bear rough handling. 
• Low price: Dynamic mics are very easy to make and do not require a lot of expertise. Hence they are much cheaper than their counterparts. They have a straightforward construction and so are very simple to manufacture.
• High Max SPL (Maximum Pressure Level) & Low Sensitivity Ratings: Condensers produce a powerful mic signal, but the same is not relevant for a dynamic mic. The circuitry of dynamic mics and passive transducer elements do not have strong mic signals. It is also out of the question to overload the moving-coil dynamic mics with loud sounds. 

Applications of Dynamic Microphones

Dynamic microphones have many applications and are most widely used by musicians for recording a wide variety of distinct sound sources. However, they are most commonly used for:

• Recording vocals in studios: For recording vocals in studios, moving-coil dynamic microphones are widely used. They are great for recording super loud songs generated by more complex genre musicians and singers. Such a mic also colors vocals to be appropriate for live recordings.
• Vocals in Live performances: One of the characteristics of dynamic mics is that they are very durable and can withstand rough handling. This mic feature makes it perfect for live stage performances where singers and musicians usually handle their mics more roughly. The mics are equipped with a boost, which clears the loud vocals during the live audio mixes. Also, the polar pattern, frequency response, and low sensitivity allow for high-gain-feedback. 
• Brass: Many brass instruments such as the trumpet, french horn, tuba, and trombone. These instruments produce a sound that can be best heard through a moving-coil dynamic microphone. These instruments are generally used in recording studios or during live performances, making it all the more important for dynamic mics to be used in such places.
• Instrument amplifiers: Instruments such as guitars and bass guitars produce an output of no more than 5 to 6 Khz, which is not adequately audible during recordings or live performances. Hence there is a need for good mics that can amplify the sound generated. Dynamic mics are good for capturing the sounds of these instruments. 
• Drums (close-miking): Drums produce a loud sound, which can be unpleasant for many listeners; hence dynamic mics are used. The dynamic mics are chosen for their ability to handle these loud sources without issue. 

Ribbon Dynamic Microphone Design: Type 2

The ribbon dynamic microphone design is commonly known as ribbon microphone. It is a kind of dynamic microphone that uses a diaphragm with a ribbon-like shape and is suspended within a magnetic structure. When this ribbon moves along sound waves, you get an AV voltage induced across the ribbon along with electromagnetic induction. 

These ribbon microphones can capture sound energy in the same way as a dynamic microphone. However, the difference between the two is that the active element is aluminum in a ribbon microphone, while in a diaphragm, the active ingredient is a moving coil. However, the ribbon microphones need to be handled with more care than dynamic ones. 

Workings of Ribbon Dynamic Microphones

The ribbon’s magnetic structure possesses a magnetic pole located to the left and another pole situated on the right to create an effective magnetic field. However, some of the ribbon microphones make use of active components for strengthening the signals. The reason is that the ribbon may not work as well as a coil when trying to induce a voltage through electromagnetic induction. Thus, it would help if you have more optimization. Therefore, as the diaphragm starts moving as per the sound waves’ reactions, a current gets induced along with it. In the process, while being taken from each ribbon’s end, electrical leads can create a circuit. 

The best part about these ribbon microphones is that they offer more robust output with more consistent signals than their counterparts. However, these ribbons’ mics are costlier than their counterparts. You can get these ribbons in diverse shapes, sizes, polar patterns, frequency responses, and price ranges; while our how much do microphones cost lists all the prices. These ribbon mics are designed for use in different applications.

Now, in passive ribbon microphones, the circuit of ribbon and signal is completed with the help of a step-up transformer. This said transformer can boost up the signal’s voltage before being outputted. However, in the process, it also protects the ribbon diaphragm from damaging phantom power.

On the other hand, in the case of active ribbon microphones, a functional circuit is used to send the output signal of the element. This amplifies the output signal effectively while optimizing the signal’s impedance before it gets outputted.

Important Aspects of a Ribbon Dynamic Microphone Design

It is challenging to generalize characteristics of a ribbon dynamic microphone design because of the diverse exceptions. However, some specifications are standard for every kind of ribbon microphone:

• Bidirectional Polar Pattern: Ribbon elements closely follow the pressure-gradient design. In a standard ribbon microphone diaphragm, both sides are open to sound pressure equally. This aspect leads to a bidirectional polar pattern.
• Fragility: These ribbon microphone diaphragms are delicate. Thus, activities such as hitting or dropping the microphone, wrong power quotient applied to the ribbon, air gusts, and plosives possess the power to damage the ribbon or snap it. This can make your microphone ineffective unless you use a re-ribbon.
• Transient Response: Both the openness and thinness quotient of a ribbon diaphragm make it possible to react accurately to the different variations of sound pressure it is associated with.
• Low Sensitivity Quotient: A thin ribbon with conductivity can only produce a minor amount of electromagnetic induction. You can expect a low-level signal as an output in the absence of any internal amplification. However, active ribbon microphones possess internal amplification with a higher sensitivity quotient.
• Sound Frequencies: Though the movement of the ribbon diaphragm is immensely accurate, the transducer process results in a minor decrease in the sensitivity quotient with the increase in sound frequencies. This results in a high-end response of sound produced naturally. Also, this response works well with digital recording as well as vivid sources of sound.
• You can read more about these mics in our Ribbon microphone guide.

Applications of Ribbon Dynamic Microphone Design

Ribbon microphones are brought into use for recording diverse sources, and they sound brilliant with different sources. Here are the various applications of ribbon microphones:

• Brass: When you use a ribbon microphone, brass instruments can add a brilliant touch to your recording studio. Qualities of ribbon microphones such as their accuracy and dark character can highlight these brass instruments brilliantly.
• Vocals: The best aspect of these ribbon microphones is that they sound natural, which makes them brilliant with vocals. However, you cannot use them in live performances on stage because of their fragility and bidirectional patterns. Also, while using them in the studio, you will need to be careful not to hamper the ribbon when you are singing and thereby send the plosives into the microphone. Thus, it is advisable to tilt these ribbon microphones a little off-axis and maintain a distance between the microphone and the vocalist.
• Drum Overheads: Though these condensers are used with drum overheads, you can also make use of ribbon microphones. The reason is that these ribbon microphones can capture the sound of a particular kit effectively.
• Guitar Amplifiers: Guitar amplifiers best complement these ribbon microphones. The reason is that these ribbon microphones can capture the amplifier with ease and also capture the room’s airiness without increasing the sound.

Passive and Active Dynamic Microphones

Some dynamic microphones are active, while a few are passive. How can we tell if a microphone is active or passive?

Dynamic mics with moving coils are always passive. The output sensitivity of dynamic mics with moving coils is low. Moving coil microphones are simple to use due to their simple construction. It looks almost like a loudspeaker and helps convert the sound into electrical signals (electromagnetic induction). They do not require external power and thus are very sturdy mics that are great for stage use. Moving coil microphones are the most common microphones with a durable construction. Therefore these are called passive mics.

Ribbon microphones have active models with active internal circuitry.

Active ribbon mics do not use phantom power. A ribbon microphone works in the same manner as electromagnetic induction. The ribbon mic uses narrow strips of aluminum foil. The strips are skinny. Thus, the membrane itself moves inside the magnetic gap via an electrical conductor. We can say that a ribbon microphone uses the movement of the sound waves more accurately than moving-coil mics, making them active, dynamic microphones.

Differences Between Dynamic and Condenser Microphones

Dynamic Microphones

Dynamic microphones are mics that turn sound waves into voltage with the use of magnets. They are like speakers but in a reverse way. It has three main components: 

the voice coil, the diaphragm, and a permanently charged magnet. When sound waves fall on the diaphragm, they make the coil vibrate. When the coil moves, the magnetic field creates an electric current proportional to the strength of the sound.  

Dynamic microphones have a straightforward and rugged construction. These mics also handle extremely loud sound signals very well, and they also help reduce background noise. Sound waves vibrate the diaphragm that creates electricity. The transformer uses electricity to make sounds. Dynamic mics are great for regular use, and most radio jockeys use dynamic mics.

Condenser microphones

Condenser mics have three components:

• The diaphragm case 
• The backplate
• The diaphragm

The diaphragm and backplate together form a capacitor, and another name for a capacitor is a condenser. This is why these mics are called condenser mics. When sound waves hit the diaphragm, they cause it to move back and forth, thus causing the condenser to generate an electric current that is inversely proportional to the distance between the two plates. Thus, the sound waves get translated into electric current. 

There are two types of condenser microphones:

• Standard mics: These use phantom power to charge the capsule.
• Electret mics: These are permanently charged and do not need phantom power or any other external power. 

Remember, all condenser microphones have active circuitry that requires power. So, even if the condenser is permanently charged, you still need phantom power.

Condenser mics are more complex but have a better frequency response. They also have better sensitivity and give out a more natural sounding output. We have written up an extensive guide titled what is a Condenser microphone?

However, a disadvantage of this mic is that it cannot be used with very loud noise.

How do these microphones differ, and which is better?

The general difference between the dynamic and condenser mics is the audio conversion principle.

Dynamic mics are advantageous in the following ways:

• Are highly durable.
• Use electromagnetic induction to convert sound into audio.
• Due to their low sensitivity, there are fewer chances of the mic getting damaged.
• Can take noise with ease as these mics are passive.
• Reject background noise pretty well.
• If you want a noticeable broadcast sound that you hear on radio stations, then a dynamic mic is the best.
• Are best for drums, brass instruments that play very loudly.
• Have either a cardioid or supercardioid pattern. (Learn more about What is a Cardioid microphone and what is a Supercardioid mic)

 On the other hand, condenser mics are advantageous in the following ways:

• Would be used in a noise free place like a studio as these mics are active.
• Use electrostatic principles to convert sound into audio.
• If you control all the audio into the microphone; then, a condenser mic is the best.
• If background music is not a big concern, and you are looking for a crystal clear sound, then these condenser mics are great.
• Capture a more natural tone.
• Can follow any pattern and switch that can change the tone and the polar patterns.

Frequently Asked Questions

Further reading

• What Is a Hypercardioid Microphone?
• What Is an Omnidirectional Microphone?