Microphones come in a vast array of shapes, sizes, and designs, each one tailored to suit a specific purpose. However, regardless of their physical attributes, all microphones have one primary goal in common. They convert acoustic vibrations, in the form of air pressure, into electrical energy to be amplified or recorded. To achieve this, microphones use a diaphragm that vibrates in response to sound waves and is connected to another component that either creates or allows a small electron flow. These components work together to convert sound waves into electrical signals, which can then be processed and used in many ways.
Three primary mechanical techniques are commonly used when building microphones for professional audio purposes. Each technique utilizes the same three fundamental components: the diaphragm, the transducer, and the casing. The diaphragm converts sound waves into mechanical vibrations, which are then picked up by the transducer and transformed into an electronic signal. The casing provides mechanical support and protection for the diaphragm and transducer, as well as helping to regulate the microphone’s directional response.
The diaphragm is a critical microphone component, and its weight is crucial in accurately reproducing high-frequency sounds. The lighter the diaphragm, the more accurately it can reproduce high-frequency sounds. The transducer, on the other hand, is responsible for transforming the mechanical vibrations of the diaphragm into an electronic signal that can then be amplified or recorded. Finally, the casing provides support and protection for the diaphragm and transducer and can also be designed to control the microphone’s directional response.
Now, let’s take a closer look at the three types of microphones and how they differ in terms of their design and functionality. With a better understanding of the different types of microphones available, you’ll be better equipped to choose the right one for your specific needs.
The Dynamic Microphone
The dynamic microphone is a highly popular and versatile type of microphone that is widely available in the market to fit any budget. Also referred to as a moving-coil microphone, it functions by utilizing a thin metallic diaphragm coupled with an attached coil of wire that moves inside a permanent magnet.
When sound waves cause the diaphragm to vibrate, the connected coils also vibrate within the magnetic field, producing an electrical current through electromagnetic induction. The weight of the moving parts, including the coil and diaphragm, determine the microphone’s ability to respond to transients and higher frequency signals.
Although the weight of the coil and diaphragm limits the frequency response above about 10kHz, this type of microphone offers a resonant frequency that enhances voice intelligibility, making it an excellent option for vocalists. Dynamic microphones are generally known for their durability and robustness, allowing them to handle high sound pressure levels with ease.
While some models can be relatively inexpensive, dynamic microphones with extended frequency range and a flat response tend to be moderately expensive due to the required manufacturing precision. Dynamic microphones are insensitive to changes in humidity, require no internal or external power to operate, and can be made relatively small.
It’s worth noting that dynamic microphones are also ideal for live performances where durability and ruggedness are crucial. They can withstand rough handling and accidental drops, making them a reliable choice for touring musicians or performers. Additionally, dynamic microphones are typically less sensitive than other types of microphones, which makes them less prone to feedback or unwanted noise. This feature is especially important in live performances, where ambient noise can be a major issue.
Overall, the dynamic microphone is a versatile and reliable option that can be used in a wide range of applications. Whether you’re a vocalist, a live performer, or a recording artist, a good dynamic microphone can make a significant difference in the quality of your sound. With its durability, ease of use, and affordability, the dynamic microphone is a must-have tool for any musician or audio professional.
The Ribbon Microphone
Ribbon microphones operate on the same principle as moving-coil microphones, with a few key differences. Rather than using a separate diaphragm, ribbon microphones use a thin strip of aluminum foil that is light enough to be directly vibrated by sound waves. This design results in a flatter frequency response and higher upper-frequency response of around 14kHz compared to dynamic microphones. Additionally, ribbon microphones handle EQ well, as their resonance peak is at the bottom of their frequency range, avoiding any hype in high frequencies.
Vintage ribbon microphones were once widely used in recordings and broadcasts from the 1930s through the 1960s, but their large size made them less suitable for television broadcasts. Despite this, recording engineers never gave up on ribbon microphone technology, and a few modern manufacturers have revived and improved upon the design. The following companies now make ribbon microphones that are at least as good as, if not better than, the originals:
- Royer Labs
- AEA Ribbon Mics
- Coles Electroacoustics
- Cascade Microphones
Thanks to recent developments in magnetics, electronics, and mechanical construction, modern ribbon microphones can be produced smaller and lighter yet still maintain the sound of their vintage forbearers. Their smooth frequency response, ability to handle higher sound pressure levels, and phase linearity make them ideally suited for the digital formats used in the industry today.
While ribbon microphones provide many advantages, including a relatively flat frequency response and extended high-frequency response, they are also fragile and require careful operation and handling. Continuously applying phantom power can stress the ribbon element, and they are moderately expensive.
The Condenser Microphone
The condenser microphone operates on the principle of a capacitor, with two plates, one movable and the other fixed, and a space between them. The movable plate acts as a diaphragm, and as sound waves hit it, it moves and changes the spacing between the plates, which in turn changes the capacitance. This variation in capacitance causes a change in voltage potential which can be amplified to a usable level. To boost this voltage, a vacuum tube or transistor amplifier is built into the microphone, which requires a battery or phantom power to charge the plates and run the preamp. Unlike dynamic microphones, condenser microphones require an external power source as they do not generate their own electricity. The condenser mic’s omnidirectional pickup pattern can be made directional by punching holes in the backplate. By varying the size and position of the holes, the microphone can have selectable patterns.
Most large-diaphragm condenser microphones are multi-pattern microphones, composed of a single backplate placed between two diaphragms. By varying how much signal from each diaphragm is fed to the preamp, the microphone can have selectable patterns ranging from a tight cardioid to a figure-eight to full omnidirectional, which is why the pattern control on older tube mics is continuously variable. However, condenser microphones often have a built-in top-end response bump that limits the EQ that can be added. Additionally, condenser mics always ring to some degree, typically in the 8k to 12kHz range, and their pattern of resonances is a major part of their character.
While condenser microphones provide many advantages, including a flat frequency response and extended high-frequency response, they are also fragile and require careful operation and handling. Additionally, their high sensitivity makes them prone to picking up unwanted noise. Despite these challenges, condenser microphones are widely used in studio recording applications, thanks to their superior sound quality, versatility, and ability to capture fine details of vocals and acoustic instruments.
The Electret Condenser
An electret condenser is another type of condenser microphone that utilizes a permanently polarized material, known as electret, as a diaphragm, avoiding the need for a biasing voltage, as required in a traditional condenser. Electrets can be made inexpensively and in a very small size, making them a common choice for portable devices such as phones and recorders. High-quality electret condensers often have a built-in preamplifier to match their extremely high impedance and boost the signal. Historically, electret condenser microphones have been known to lose their charge over time, leading to a decrease in output and frequency response, but modern versions are less prone to this issue.
Advantages of Condenser Mics:
- Excellent high frequency and upper harmonic response
- Excellent transient response
- Changeable polar patterns
- Can have excellent low-frequency response
Disadvantages of Condenser Mics:
- Moderate to very expensive
- Requires external powering
- Can be relatively bulky
- Humidity and temperature affect performance
- Low-cost models can suffer from poor or inconsistent frequency response
- Two mics of the same model may sound somewhat different
Overall, condenser microphones provide a high-quality sound that captures fine details of vocals and acoustic instruments. However, they are fragile and require careful handling and operation. The electret condenser is a type of condenser microphone that is permanently polarized, making them an ideal option for portable devices.
Condenser Microphone Myths
There are many misconceptions about condenser microphones that can lead to confusion when choosing the best option for your recording needs. Here are some popular myths about condenser microphones, along with explanations of why they are not true.
Large-Diaphragm vs. Small-Diaphragm
Myth: A large-diaphragm condenser has more low end than a small-diaphragm condenser.
Fact: In many cases, small-diaphragm condensers reproduce the low end just as well as their larger counterparts.
Myth: A cardioid condenser has a better low-end response than an omnidirectional condenser.
Fact: In condenser microphones with an omnidirectional polar response, the bass response is only limited by the electronics. Even a very small-diaphragm mic can have a flat response down to below 20Hz.
Myth: A large-diaphragm condenser has a flatter response than a small-diaphragm condenser.
Fact: Large-format capsules are prone to low-frequency resonance, which means that they can have trouble reproducing low frequencies at a high level. They can also “bottom out” as a result of the diaphragm hitting the backplate, which is the popping that can occur when a singer is too close to an unfiltered microphone. To minimize this, some microphones over-damp the capsule, making the mic sound either thin or alternatively lumpy in response, while some address this by adding a low-frequency roll-off or EQ circuitry to try to put back frequencies suppressed in the capsule.
Myth: A small-diaphragm condenser is quieter than a large-diaphragm condenser.
Fact: The difference in the size of the diaphragm translates into a difference in signal-to-noise ratio. The bigger diaphragm provides more signal for a certain electrical noise level and therefore can be quieter than the small diaphragm.
Myth: Condenser microphones have consistent response from mic to mic.
Fact: Despite what the specs might say, there can be vast differences in the sound between two mics of the same model, especially in the less expensive versions. Unless two mics are specifically matched in their frequency response, differences between them are inevitable. That said, the value of precise matching of microphones is open to much debate. One school of thought says that you need closely matched response for a more precise stereo soundfield, while another school thinks that the difference can actually enhance the soundfield.
By debunking these myths, you’ll better understand the capabilities and limitations of different types of condenser microphones. When choosing a condenser microphone, it’s important to consider your specific recording needs and carefully evaluate the specifications and features of each option. With the right condenser microphone, you can capture high-quality sound that accurately represents the nuances of your performance or instrument.
Condenser Microphone Operational Tips
When it comes to condenser microphones, it’s important to take extra care to ensure their longevity and peak performance. Here are some best practices to keep your microphone functioning at its best:
- Use an external pop filter to prevent dirt and debris from building up on the capsule. Dirt on the capsule can cause the high-end response to fall off, leading to a deterioration in sound quality.
- Keep your condenser microphone cased when not in use to protect it from dust and debris.
- Cover the mic if it will be left set up on a stand overnight to prevent exposure to humidity and temperature extremes, which can have undesirable effects on performance.
- Avoid blowing into the microphone, as this can cause the diaphragm to bottom out and stick to the plate.
- Be mindful of overloading the microphone, which can cause distortion or harshness of tone. Internal mic preamps often have a -10dB pad switch to lower the output from the capsule, and the bottom-end roll-off filter can also reduce power from the capsule if necessary.
By following these tips, you can ensure that your condenser microphone remains in top condition and delivers high-quality sound for years to come.
In contrast to dynamic and ribbon microphones, condenser microphones rely on an external power source to operate. Older tube condensers require an outboard power supply, while electret condensers sometimes use batteries. All other condenser microphones rely on phantom power, a 48-volt DC power source that is fed by a recording console, microphone preamp, or DAW interface over the same cable that carries the audio signal. On most recording consoles, phantom power is switchable, as it may damage the internal ribbon on many older ribbon microphones. It can also cause a loud pop when disconnecting a cable connected to a dynamic microphone.