To know which microphone to use for recording, you must first understand its directivity: cardioid, omni, figure of 8, or other…
Directivity is an intrinsic property of microphones that indeed has a major influence on how sound is captured — and thus on the potential quality of recordings.
For example, the Neumann TLM 103 is cardioid, while the Warm Audio WA44 is of the “figure of 8” type.
If these terms are not clear to you, no worries because in this article, you will learn clearly:
- what directivity is exactly;
- and how to choose the right directivity when buying or selecting a microphone for recording.
Definition: What is Directivity?
Directivity is the sensitivity of a microphone depending on the direction from which the sound comes.
Sometimes we refer to it as directional sensitivity.
For example, some microphones will be very directional in that they will only record what is in front of them.
Conversely, others will be able to capture ambient sound more uniformly, regardless of the position of the sound source relative to the microphone.
Obvious consequence: the directivity of a microphone will determine how it can be used.
Representing Directivity
Before diving into the heart of the matter, I suggest we first look at how directivity is represented, to better understand the diagrams present later on.
We use what are called polar diagrams, like this one:
This representation, very practical, is based on a simple concept: you must imagine, at the center, the microphone being studied.
The circles represent the acoustic space surrounding it, at 360 degrees:
- 0° = in front of the microphone
- 180° = behind the microphone
Additionally, each circle is assigned a signal attenuation value measured in decibels (dB).
On this diagram, we finally find a curve (in orange here) characteristic of the microphone’s sensitivity depending on the angle between the sound source and the front of the equipment. This is what represents the directivity.
On the polar diagram of the microphone presented above, for example, we can see that the mic is more sensitive in front than behind.
However, it is very insensitive on the sides.
In short, now that you know exactly what these polar diagrams correspond to, we can dive into the heart of the subject by analyzing all existing directivities.
But first, if you want to have a global overview of the main existing directivities, click on the image below to download it in PDF format, so you can keep it handy and/or print it.
Omnidirectional Microphones
Omnidirectional microphones (often referred to as “omnis”) function as pressure sensors, meaning they record sound with directional sensitivity that is identical in all directions, regardless of the position of the sound source relative to the microphone.
Advantages of Omnidirectional Microphones
Thanks to their design, these mics have several advantages:
- They do not suffer from the proximity effect (see the bottom of the article for a detailed explanation), which means that the sound does not become excessively bass-heavy when the sound source is very close to the microphone.
- They are less sensitive to plosives (the explosive sounds produced by the letters “b” and “p”), unlike directional microphones.
- Their frequency response is often more natural, as they do not color the sound based on the angle of incidence.
Disadvantages and Limitations
However, omnidirectional directivity involves several constraints:
- They are very sensitive to the acoustics of the room, which can be a problem in an untreated acoustic environment.
- They capture all surrounding sounds, making it difficult to isolate a specific sound source, such as an instrument within a group.
- They are more prone to feedback when used with stage monitors.
Common Uses of Omnidirectional Microphones
The most common omnidirectional microphones are lapel mics. Their directivity allows them to capture sound evenly, regardless of the microphone’s orientation on clothing.
In the studio, however, although these mics are less common than directional models, they are regularly used:
- Drum overheads, to capture a natural and balanced sound image of the entire kit.
- Recording acoustic instruments such as acoustic guitar, violin, or piano, where the neutrality of the capture is an asset.
- Recording ambiances, particularly in immersive recording or choir capturing.
In short, many applications are possible, but as mentioned earlier, it is important to record in a room with good quality acoustics.
This is particularly why omnidirectional microphones are used a bit less in home studios, as one does not always have the ability to truly control the acoustics of their room.
An Example of an Omnidirectional Microphone
To give you an example, for studio use, the Neumann KM 183 is an excellent choice.
This omnidirectional condenser microphone is perfect for drum overheads, piano recording, or ambiance capturing due to its relatively low background noise and remarkable precision.
👉 Click here to see the price of the Neumann 183: Thomann Woodbrass Amazon
Cardioid Microphones
What is a cardioid mic?
Well, it is a mic that has a heart-shaped polar pattern, hence their name.
As a result, cardioid microphones are probably the most used in studios and home studios, with their detailed variations discussed a bit further down.
This is explained by the fact that they are only sensitive to sounds coming from the front, which helps to limit unwanted background noise and room reverberations.
Sometimes, they are referred to as “unidirectional” microphones, to emphasize that the microphone is primarily sensitive in a given direction.
Advantages of Cardioid Microphones
But then, why choose a cardioid microphone?
Well, here are the main reasons:
- Isolation of unwanted sounds: Unlike an omnidirectional microphone, a cardioid microphone does not pick up sounds from the rear, which helps minimize ambient noise and feedback phenomena.
- Versatile use: Whether for recording a voice, a guitar amp, or percussion, the cardioid microphone is an excellent choice.
Disadvantages of cardioid microphones
- Off-axis coloration: If the sound source moves laterally, the frequency response can be altered, particularly resulting in a loss of clarity. This is a point to watch for singers who move a lot in the studio or on stage.
- Still sensitive to lateral sounds: One might sometimes believe that cardioid microphones only capture sound coming “from the front.” That said, as can be seen in the polar diagram just above, this is not entirely the case: they also pick up some sound from the sides. This is something to keep in mind when placing absorbent panels during sound recording.
Technology of cardioid microphones
One might think that the shape of cardioids is related to a technology independent of the other directivities presented.
In reality, it is often a combination of the “omni” and “figure-8” directivities.
Indeed, on “figure-8” mics, the electrical polarity of recordings at the back of the device is negative, while that of omnidirectional microphones is always positive.
If we couple these two patterns, using an appropriate electronic circuit, it is thus possible to generate a cardioid pattern.
When to use cardioid microphones?
Unsurprisingly, cardioid microphones are primarily used when one wishes to record a directional sound source:
- for recording vocals in the studio or on stage;
- for miking guitar amps;
- for capturing elements of a drum kit (snare, toms…)
- for recording acoustic instruments (like guitar)
- etc.
Thus, it is the type of microphone most commonly used in studios and home studios.
An example of a cardioid microphone
There are dozens and dozens of cardioid microphones, so it’s hard to choose just one…
But still, to give you a common example: whether live or in the studio, the Shure SM57, shown in the photo above, is very often found. It is one of the most used cardioid microphones for recording snare drums or guitar amps, as it effectively isolates the main sound source while minimizing surrounding noise.
👉 Click here to see the price of the Shure SM57: Thomann Woodbrass Amazon
But for other suggestions of cardioid microphones, feel free to check out my selection of the best condenser microphones.
So, cardioid or omnidirectional microphone?
Well, I think that with the elements already present in the article you can have a clear idea of when to use a cardioid microphone rather than an omni microphone, but let’s take the time to say things clearly.
Most of the time in a home studio context, I recommend using cardioid microphones.
Simply because often home studios do not have perfect acoustics.
However, if you are recording in a place with good acoustics, and you want to take advantage of the more natural sound of omni microphones and/or the absence of proximity effect — then it makes sense to use omni microphones.
Especially if your recording aims to capture an ambiance (choirs, room, etc…).
Supercardioid and hypercardioid microphones
Supercardioid and hypercardioid microphones are simply variations of cardioid directivity.
They are characterized by a more restricted forward sensitivity in terms of angle, but on the other hand, there is more sensitivity towards the rear, as you can see in the polar diagrams below
Characteristics of supercardioid and hypercardioid microphones
Overall, the two are somewhat similar to the cardioid microphones we have already discussed.
That said, in the case of supercardioid microphones, we find:
- a tighter directivity at the front than a classic cardioid, with a reduced pickup angle (on average 115°);
- notable sensitivity at the rear of the microphone.
In the case of hypercardioid microphones, however, we have:
- an even narrower directivity, with a pickup angle around 105°.
- very good isolation from ambient noise and strong resistance to feedback effects.
- but still a more pronounced rear sensitivity than a supercardioid.
In other words, the tighter the directivity, the more the microphone isolates the main sound source, but the more demanding it becomes in terms of placement and usage technique.
Advantages of supercardioid and hypercardioid microphones
- Better rejection of unwanted noise: These microphones are ideal for studio recording or on stage, especially to isolate a voice or an instrument in a noisy environment.
- Sound control on stage: By capturing a more restricted sound field, they reduce the risks of bleed (the sound of other instruments entering the microphone) and limit feedback phenomena.
Disadvantages of supercardioid and hypercardioid microphones
- More precise placement: A hypercardioid microphone is very demanding on positioning. A singer who strays too far from the axis will lose clarity and presence.
- Rear sensitivity to manage: Unlike cardioid microphones, which reject sounds located directly behind, supercardioid and hypercardioid microphones slightly pick up rear sounds. Therefore, it is necessary to avoid placing an undesirable sound source, such as a poorly positioned stage monitor.
Tip: If you are using a supercardioid microphone in a home studio, it is still possible to reduce the effect of the room at the back of the microphone by using acoustic treatment or, for example, an acoustic screen for microphones like this one.
When to use supercardioid and hypercardioid microphones?
Of course, due to their directional specifications, these are somewhat more complex microphones to use than standard cardioid microphones.
As for supercardioid microphones, they can be used to more precisely capture a sound source in rooms where the room acoustics are inadequate…
…but also when you want to capture a precise sound like that of a snare drum while avoiding bleed from other instruments like cymbals.
Hypercardioid microphones, on the other hand, will also be used for drums, but also in certain documentaries, provided of course that the sound source is not in motion.
So, cardioid or supercardioid mic?
If we put ourselves in a studio/home studio recording context, my opinion is that it’s better to start with cardioid microphones.
Indeed, as they are slightly less directional, they allow for greater flexibility: there is little risk that the recording will be mediocre because the singer moved their head a bit.
So, if while reading this article you are wondering “What is the best microphone directivity for recording vocals?”, my answer is clear: cardioid directivity.
However, if you are working in complex environments where sound precision is important (I am mainly thinking of drums or live settings), then yes, it might be worth switching to supercardioid microphones.
“Figure 8” or “bidirectional” microphones
Typically the directivity found in ribbon microphones.
“Figure 8” mics, unlike omnidirectional ones, work as pressure gradient sensors. That is to say, they measure a pressure difference between the front and back of the capsule, rather than the pressure itself.
Consequence: they are sensitive to sound sources located in front of and behind the mic, while sounds coming from the sides are in a dead zone. This is what we observe on the polar diagram next to it.
It should be noted that generally, the corresponding polar diagram is identical regardless of the frequencies, which is not the case for all microphones.
Advantages and disadvantages of bidirectional microphones
“Figure 8” microphones are somewhat special microphones that are not used very often.
From an advantage perspective, we can note:
- effective lateral isolation: Thanks to their total rejection of sounds coming from the sides, figure 8 mics allow for effective isolation of two distinct sources placed in front of and behind the microphone.
- marked proximity effect: Like directional mics, bidirectional microphones exhibit a significant proximity effect, which can be used to enrich the capture of voices or instruments with added warmth.
However, they also come with a set of disadvantages:
- Increased sensitivity to room acoustics: A bidirectional mic picks up equally from the front and back, which can be problematic in a noisy or poorly treated acoustic environment.
- Proximity effect: Although this effect can be an advantage for certain sources, it can also weigh down the sound and require mixing treatment to avoid overly “boomy” capture.
- Less suited for live stages: Due to their high sensitivity to rear sounds, they are more prone to feedback in concerts, especially if stage monitors are placed in the axis of their capture.
- Fragility (in some cases): a number of “figure 8” microphones are ribbon microphones. However, these microphones are quite fragile and should not be powered with 48 volts (phantom power), at the risk of damaging them.
When to use “figure 8” microphones?
Indeed, the sensitivity to the front and back of these bidirectional microphones makes them useful for capturing the sound of a room while remaining minimally directional.
Many uses are possible:
- recording a duo of singers, placing the performers on either side of the mic.
- recording a solo singer/guitarist, capturing both the voice and the instrument simultaneously without too much lateral pickup.
- recording a guitar amp, especially with a ribbon mic to capture both the direct sound of the amp and the ambiance of the room.
- Mid/Side (M/S) recording techniques, allowing for great flexibility in stereo mixing.
- orchestral or piano recordings, where a bidirectional mic can be used to record the instrument while subtly integrating the acoustics of the room.
An example of a bidirectional microphone
To give you an example, the WA-44 from Warm Audio shown in the photo above is indeed a ribbon microphone… which features a “figure-8” polar pattern.
👉 Click here to see the price of the Warm Audio WA44: Thomann Woodbrass Amazon
Microphones with multiple polar patterns
Some microphones are equipped with advanced technology that allows for changing the polar pattern based on recording needs.
Rather than being limited to a single pickup mode, these mics offer valuable flexibility in the studio and in professional sound recording.
Thanks to an embedded electronic circuit or a design using multiple internal capsules, these microphones can switch between different polar patterns, ranging from omnidirectional (uniform pickup at 360°) to bidirectional (figure-8), including various intermediate modes such as cardioid, supercardioid, or hypercardioid.
A prime example of this type of microphone is the famous AKG C414 (photo on the side), which features an integrated polar pattern selector allowing you to choose from nine pickup modes.
This versatility makes it a valuable tool in the studio, suitable for recording both vocals and acoustic instruments or ambient sounds.
This is typically the case with the famous C414 from AKG (photo on the side), for which a slider on the microphone allows you to select one of the 9 available polar patterns.
👉 Click here to see the price of the AKG C414: Thomann Woodbrass Amazon
A word about the proximity effect
The proximity effect is a well-known phenomenon that primarily impacts microphones with a cardioid or figure-8 polar pattern.
Simply put: the closer the sound source is to these mics, the more pronounced the bass will be.
This can be desired or not.
Typically, on vocals, this allows for a warmer or more intimate sound, with more character.
The technique is thus regularly used in rap and for anything related to “spoken words”.
A typical example?
Leonard Cohen without hesitation! 🙂 :
In conclusion
In summary, the three main polar patterns are as follows:
- Cardioid — the most commonly used in studio and home studio, it corresponds to microphones that are sensitive only to sounds coming from the front;
- Omnidirectional — these microphones are sensitive to sound equally from 360°, regardless of the position of the sound source;
- Figure 8 — the microphone picks up sound from the front and the back but is not sensitive to lateral sound sources.
And this is complemented by intermediate directivities, such as supercardioid and hypercardioid directivities.
Of course, each directivity corresponds to a certain number of possible uses, even if in home studio the cardioid directivity is the most common for obvious recording condition reasons.
Continue reading: The Complete Guide to Studio Microphones
(Note: The images of polar diagrams are modified from an original creation by Galak76 and are under license CC BY-SA 3.0.)