Whether you are about to go into the studio for first time to try and capture that killer guitar tone that took forever to get right, or you’re headed back into the vocal booth to record vocals for that new EP, choosing the right microphone is essential for getting the sounds you’re after. But with so many options, how do you choose which one is right for you? What’s the difference between a condenser microphone and a dynamic microphone? What is phantom power? How do microphones even work?
How does a microphone work?
To understand microphones, you must first understand how sound works. Sound is simply vibrations that cause a change in air pressure. When these changes in air pressure vibrate your eardrum, your brain interprets the signal as “sound”. The frequency of sound (how high or low a note is) is determined by how fast these vibrations occur. Think of a microphone like an electronic ear – and a well-designed one can capture sound in unique and pleasing ways.
At the very core – a microphone is simply a device that takes sound vibrations and turns those vibrations into an electrical signal. There are a few different ways of accomplishing this task – and the way that the microphone converts this signal determines which kind of microphone it is. Two of the most common microphones in use today are dynamic microphones and condenser microphones.
Dynamic microphones capture sound in a very simple way, which means no need for external power, and generally their simple design leads to rugged construction. When sound vibrations enter into the microphone they first encounter a very thin membrane or diaphragm, which vibrates in correspondence to the sound coming in. The diaphragm is then attached to a wire coil, which is designed to move with the diaphragm as it vibrates. The coil is surrounded by a stationary magnet, which creates an electromagnetic field. When vibrations hit the diaphragm it causes the coil to move through the electromagnetic field, which in turn generates an electrical signal. Voila! Sound vibrations moving through the air have now been turned into electricity. Pretty cool! Due to the simple and rugged design, dynamic microphones can typically handle very loud sound sources and can operate in less than ideal conditions.
A condenser microphone takes a different approach to reach the same goal of turning sound into electricity. Think of a condenser mic as the “super charged” approach for converting sound. A condenser microphone is similar in the sense that it starts with sound vibrations hitting a membrane causing it to vibrate. However, with a condenser mic – the diaphragm is charged with electricity – removing the need to move a relatively heavy coil through a magnetic field. Because of this, the diaphragm must be made of a material that can conduct electricity. The way that a condenser microphone works, is that the diaphragm is mounted very close to a metal back plate and when charged essentially becomes a capacitor. When vibrations hit the diaphragm, the diaphragm moves while the back plate remains stationary. It is the difference in the space between the diaphragm and back plate that creates the electrical signal, which in turn corresponds to the sound coming in. Because the diaphragm is not responsible for moving a heavy coil, condenser microphones tend to capture more detail and be more sensitive to subtle changes in sound pressure. It also causes them to be more fragile in construction and more susceptible to harsh environments.
There have been books written on this subject – and while you can go as deep as you choose – the big takeaway here is that dynamic and condenser microphones can be expected to behave differently due to how they are constructed and how they turn sound into electricity. Dynamic microphones usually work best on loud sources that would typically overload a sensitive condenser mic. Whereas a condenser microphone is much more useful for capturing the subtle nuances of many voices and instruments. Condenser microphones produce a louder signal, which requires less amplification, whereas a dynamic microphone requires a decent amount of gain to really shine.
Not all circuits are created equal – and choosing the right microphone for your project can involve a lot of trial and error to find the perfect fit. Good microphones are designed to capture sound in a way that is pleasing to the original source. Some microphone circuits are “brighter” or richer in higher frequencies, and some are “warmer” or more pronounced in lower frequencies. The end goal is to find a microphone that compliments the original sound, and brings out its good qualities while minimizing the harsh or less desirable qualities.
Condenser microphones were first developed in the early 1920’s – mostly as test instruments for Bell Laboratories. Radio broadcast and recording had just started to take off and become the “new thing”, and the need for more reliable and higher quality microphones was driving innovation. Their development was also closely related to the invention of the vacuum tube, and the earliest condenser microphones were tube designs. The tube was necessary for changing the “impedance” of the electrical signal – or in other words changing the electrical signal to one that can be useful in real world applications.
Tube condenser microphones are still amongst the most sought after microphones for recording use. Popular examples include the Neumann M149, the Avantone CV-12 and the Rode NTK. The tube condenser sound is often described as warm, soft, colorful, and musical – as the tube circuit tends to lend a gentle compression to whatever is passing through it. This makes them ideal for recording vocals that sound harsh on other microphones, or in instances where a more vintage/vibey sound is desired. Tube microphones are also typically accompanied by a large external power supply that is responsible for supplying the diaphragm the charge it needs to work.
In the 1960’s the Field Effect Transistor (FET) was invented and the vacuum tube was no longer necessary to maintain a workable signal. The FET condenser microphone is among the most common types that you’ll see today. Common examples include the Neumann U87ai, AKG C414 XL II, Audio Technica AT2020, and the Samson C01. FET condensers are typically “brighter” and known for their accurate and detailed recreation of the original sound source. They also no longer require a big bulky power supply like their tube counterparts.
FET microphones are typically powered by something called phantom power. While it sounds like something you would read about in a fantasy/sci-fi novel – phantom power is actually very useful and quite common when using condenser microphones. Developed by Neumann in 1966 – phantom power is a way to send power into the microphone – over the very same cable that carries the sound from the microphone. Typically you’ll see a +48v button on your mixer/interface. When using a condenser microphone with no external power supply – chances are you need to press this button in.
So when is it best to use a condenser microphone? Condenser mics are absolute king in the recording studio. Due to their sensitive nature they work best in controlled environments where detail and fidelity are of utmost importance. One must be mindful of the environment in which a condenser microphone is being used – as while they can pick up the intricate subtleties of a finger picked acoustic guitar – they can also pick up conversations your neighbor is having in the apartment adjacent to yours, or that car driving by on the street outside your window. Another thing of note is that the room itself becomes a bigger factor when using a condenser microphone– as reflections coming off of the walls are more easily detected due to the sensitive design. Room treatment and reflection filters can help minimize these problems in a less than ideal recording space.
So which condenser microphone is right for you? A good condenser microphone can be an important investment for a small studio, and that answer depends on a lot of factors. If you’re just starting out, it’s best to stick with a good overall studio workhouse– one that sounds good over a broad range of different sounds and sources. An excellent example of these would be the Neumann U87ai or the AKG C414 XL II. These microphones have been used on everything from vocals, to drum sets, to acoustic instruments, to anything and everything in between – on multiple hit records that you’ve likely heard throughout your lifetime. There are more affordable models available from both companies, and there are affordable options from brands such as Warm Audio that attempt to recreate these classic circuits for a fraction of the cost. I’ve also had great luck with the Aston Origin for extremely high sound quality at an affordable price. Other brands worth noting are Shure, Samson, Audio Technica, and Blue, which also manufacture great studio workhorse microphones.
Common uses of condenser microphones include (but not limited to):
- Drum Overheads
- Acoustic Instruments
- Room Microphones
- Hand Percussion
- Brass and Woodwinds
When it comes to a more curated collection of microphones, it really boils down to the frequency and transient response (how the microphone reacts to short loud bursts of sound) to determine how well the microphone will capture the sound you’re looking to record. Most manufactures publish graphs detailing the intricacies of the microphone’s response, and these paired with sample recordings and reviews can help point you in the appropriate direction for what’s right for you. Alternatively, nothing beats walking into your local Sam Ash Music store and talking to an expert about what exactly it is that you are looking to record. With all the charts, reviews, and samples that one can find – nothing beats having the microphone in your own space, with all the rest of your own gear. Who knows – maybe it’s not a condenser microphone you need after all – maybe it’s a dynamic.
*It is also worth note that there are condenser microphones designed to interface directly with a computer via a USB connection – appropriately called USB microphones. These microphones deliver sound and are powered via the USB hub, which eliminates the need for more complex connections. USB microphones are typically designed for recording vocals.
Dynamic microphones really came into their own after WWII when magnet technology finally became small enough to make dynamic microphones practical for everyday use. The goal was to create a microphone that was less fragile than a condenser, which was susceptible to humidity and other harsh environments. Because of their ruggedness and inexpensive manufacturing costs, dynamic microphones are the most common microphones that you’ll encounter today. There aren’t many microphones that are as iconic in look as the Shure SM58.
Dynamic microphones work best when the signal they are capturing is already loud. Due to the nature of their design, the electrical signal created by a diaphragm moving a coil is considerably lower than what a condenser provides. However, this makes them ideal for getting up close to that super loud guitar amp, or putting a microphone right up against the drumhead of a snare. Also, because they are less sensitive, you aren’t very likely to hear those next-door neighbors or that car driving down the street when using a dynamic microphone.
As far as finding that studio workhorse dynamic, there are a few options that would fit nicely in any studio. Entire records have been recorded with a Shure SM57 – as it’s virtually indestructible – and does an equally good job on capturing loud sources such as guitar amps or snare drums, as it does acoustic guitars or even certain vocals. Another good solution for a solid all-a-round dynamic microphone would be the Audix i5.
Due to the up-close-and-personal nature of dynamic mics, there are several microphones that are designed with a specific purpose in mind. The size of the diaphragm and the rest of the electrical components can be custom tailored for pleasing results on specific instruments. The Shure Beta52a is a microphone that is designed specifically to capture a bass drum up close and personal. The Sennheiser E906 is designed with loud guitar amplifiers in mind. The EV ND44 is designed specifically for toms and other percussion sounds. The Shure 520DX (affectionately called the “green bullet”) is designed specifically to be pleasing for harmonica players.
As far as recording vocals in the studio, typically it makes the most sense to use a condenser microphone – but not all the time. A good example of when a dynamic microphone might work better would be with a loud, screaming, metal type voice in which the larger Shure SM7b very well may be the perfect microphone for the take. Also, if you’re recording in noisy or less than ideal environments, the dynamic microphone does a much better job with only picking up what is in front of it instead of capturing a sea of background noise. In live recording scenarios it’s very common to see dynamic mics being used on everything to eliminate unwanted bleed caused by all the instruments being in the same room.
Common uses of dynamic microphones include (but not limited to):
- Guitar Amps
- Close Drum Mics
- Loud Percussion Instruments
- Live Recordings
- Screaming Vocals
- In Noisy Atmospheres
- Anything Loud and Up Close
So now that you’re ready to start recording it’s time to pick up that sweet condenser mic – or wait was it a dynamic – or…? Well, the answer really depends on you. A jazz quartet looking for that gooey vintage sound is going to need much different equipment then the latest pop singer, or that super technical metal band looking for perfection. I’ve found in my experiences that sometimes the best sounds occur when using both types of microphones in conjunction with each other. A professionally recorded drum set often uses dynamic microphones closely miked on all the individual drums and condensers as overheads and room mics. Try placing a SM57 right up to the grill of your guitar amp, with a large diaphragm condenser such as the U87 a few feet back – the best of both worlds.
*It’s worth noting that in the digital age there have been some amazing innovations in the last few years. There now exists “virtual microphone” systems that use condenser microphones for recording – but once the recording has taken place the user is able to change the type of microphone via software in their DAW. A good example of these systems are the Slate VMS and the Antelope Audio Edge. These are great options for someone who is just getting started and wants to be able to explore the sonic differences between different types of microphones.
At the end of the day, recording music is an art form – and there is no “wrong or right”. Experiment as much as you can with mic placement (as this can sometimes have an even bigger impact than using a different mic) and use your ears to decide what’s right for you. You can read articles about recording and microphones all day long, but nothing beats having the gear in front of you, turned on, and ready to go.