The size of a condenser microphone’s diaphragm is a key differentiator between mic types. As the title suggests, condenser mics can be separated into the categories of large-diaphragm and small-diaphragm (and miniature diaphragm if we count lavalier mics).
What are the differences between large-diaphragm condensers (LDCs) and small-diaphragm condensers (SDCs)? LDCs generally have a diaphragm diameter greater than 1″ while SDC diaphragm diameters are typically less than 1/2″ (this means there’s a grey area in between). LDCs are often quieter and have more character while SDCs benefit from more accurate/consistent frequency, transient, and polar responses.
In this article, we’ll go into depth about the key generalities of large and small-diaphragm condenser microphones and uncover their differences along the way!
Large-Diaphragm Vs. Small-Diaphragm Condensers
Tables are an easy way to disseminate information. Let’s look at the differences between SDCs and LDCs in the following table:
|Small-Diaphragm Condenser Microphones||Large-Diaphragm Condenser Microphones|
|Diaphragm Size||1/2" (12.7 mm) or less||1" (25.4 mm) or more|
|Transient Response||More accurate||Less accurate|
|Frequency Response||Flatter and more extended||More coloured especially in the high-end|
|Address Type||Top or side||Typically side|
|Polar Patterns||Any polar pattern. Very consistent||Any polar pattern. Less consistent|
|Price||Cheap to very expensive||Inexpensive to very expensive|
Similarities Between Large-Diaphragm And Small-Diaphragm Condenser Microphones
As the names suggest, whether the microphone has a small diaphragm or a large diaphragm, it is still a condenser transducer and operates on the same electrostatic principles.
Other than the diameter of the diaphragms, LDCs and SDCs both have the same essential parallel-plate capacitor capsule design.
They both have a movable diaphragm (front plate) and a stationary backplate. Both LDC and SDC capsules hold a constant charge (via electret material or an external polarizing voltage. As the diaphragm moves in either mic type, the capacitance of the capsules changes and an AC voltage (mic signal) is outputted.
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SDCs and LDCs are both active mics and both come in tube and FET varieties.
To learn more about tube and FET microphones, check out my related article What Are The Differences Between Tube & FET Microphones?
The most obvious difference between SDCs and LDCs is in the name: LDCs have large-diaphragms while SDCs have small diaphragms.
Small-diaphragms are typically classified as being 1/2″ (12.7 mm) or less in diameter while large-diaphragms generally have diameters of 1″ (25.4 mm) or more.
Though many condenser microphones will have diameters in one of these two ranges, there are some mics that have diaphragm diameters between 1/2″ to 1″, so this classification is not perfect.
In this grey area, a microphone will generally behave like an SDC if its diameters is closer to 1/2″ than 1″ but this isn’t always the case. The same goes for a microphone acting more like an LDC if its diaphragm diameter is closer to 1″ than 1/2″.
To read more about microphone diaphragms, check out my articles What Is A Microphone Diaphragm? and What Is A Microphone Capsule? (Plus Top 3 Most Popular Capsules).
A precise transient response means a microphone will accurately react to transient sounds at its diaphragm. Transients are described as the high-energy short-lived bursts of sound. These transients most obviously accompany percussive instruments but are found at many initial sounds from sound sources (ie: the pluck of a string, the first blow in a horn after a rest, etc.).
Large-diaphragm condenser microphones generally have accurate transient responses.
The thin diaphragms of LDCs are typically pretty precise at capturing transients.
Some LDCs do react a bit slowly to transients due to their size and inertia, but this typically isn’t noticeable. These “slower diaphragm” still capture a very accurate sonic picture.
Small-diaphragm condenser microphones generally have very fast transient responses.
Smaller diaphragms have less give and take much less time to react to sound waves. The relatively quick movement of SDC diaphragms gives them a very fast transient spot.
Most of the time, this means accuracy and precision. However, some SDCs portray some overshoot, where they overreact to transients and cause a somewhat unnatural capture. Note that this typically ins’t the case, but when it is, the overshoot can be used to our advantage or to our disadvantage, depending on the sound we’re going for.
Condenser microphones are known for their wide frequency responses and accuracy when it comes to capturing the full character of sound across the audible spectrum. So how do large-diaphragm condensers differ from small-diaphragm condensers in terms of frequency response?
Large-diaphragm condenser microphones generally have flat frequency responses with slight boosts in the upper range followed by slight roll-offs in their very top end.
LDCs generally have very accurate frequency responses. The diaphragm itself is typically imperfect and has inherent colouration and resonances. However, the LDC capsules are tuned in such a way that the frequency response is flattened.
Fixed as the frequency response may be, LDCs generally exhibit a slight boost in the presence and upper frequency ranges (roughly 4 kHz – 15 kHz). LCDs often have a roll-off off frequencies above this point.
This results in a bright sound. Some LDCs are described as bright and present while others are called harsh.
Small-diaphragm condenser microphones generally have very flat frequency responses that extend even beyond the audible range.
Small-diaphragm condenser capsules are also tuned. However, the small diaphragm naturally has less resonant cancellations at high frequencies (shorter wavelengths) of sound.
This essentially flattens the frequency response out, often resulting in a clean, uncoloured frequency response across the entire range of human hearing (20 Hz – 20,000 Hz) and even above this range.
To learn more about microphone frequency response, check out my article Complete Guide To Microphone Frequency Response (With Mic Examples).
The address type is an important but often overlooked microphone design specification. A microphone’s address type tells us where the on-axis angle is or where the microphone is “pointing” in order for us to capture the sound in the best way possible.
There are two microphone address types:
- Side-address: where the microphone capsule points out of the “side” of the microphone.
- Top-address or end-address: where the microphone capsule point out of the top of the microphone.
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Mics typically have cylindrical/tube-type bodies, so it’s usually easy to determine the “side” and the “top” of the mic.
Large-diaphragm condensers are all side-address.
I’ve never come across a top-address LDC, though it would be completely possible to design one.
So perhaps it’s better to say that nearly all LDCs are side-address (I’m sure there’s a top-address LDC somewhere).
This is particularly true with multi-pattern dual-diaphragm LDC microphones, where the capsule design must be equally exposed to sound pressure.
Small-diaphragm condensers are usually top-address but can also be side-address.
Top-address SDCs are often referred to as “pencil mics” and make up the majority of small-diaphragm studio condenser microphones.
That being said, there are some popular SDCs (like the Neumann M50) that have a small-diaphragm and are side-address.
A note on miniature lavalier/body mics: these mics are technically small-diaphragm but are typically classified separately. Miniature mics are generally top-address because this form factor takes up less space.
Different polar patterns excel in different applications. Because condenser microphones are so popular, it’s important to understand the general differences in polar patterns between LDCs and SDCs.
Large-diaphragm condenser microphones have somewhat consistent polar patterns.
First I’ll note that studio-grade LDCs will often have multiple polar patterns at the flip of a switch. These are known as multi-pattern mics.
By combining different amplitudes and polarities of back-to-back cardioid diaphragms, a multi-pattern mic can easily achieve most common polar patterns.
Shotgun microphones do no utilized large-diaphragms. They’re too big to be held at the end of a boom. So LDCs have pretty much every polar pattern except shotgun/lobar.
As for consistency, LDCs often have variation in their polar patterns along the frequency spectrum. At lower frequencies, the pattern becomes more omnidirectional while at higher frequencies, the pattern becomes more narrow and unidirectional.
This is true of all microphones, but is especially true from LDCs. Sound waves of varying amplitude and frequencies have a large surface area to affect at many different angle. This leads to all sorts of complicated cancellations that narrow or widen the polar pattern.
LDCs, in this way, are less focused but more forgiving. Many engineers like LDCs for vocals partly due to the fact that they give the vocalist a bit more room to move without drastically altering the sound the vocals.
Small-diaphragm condenser microphones have very consistent polar patterns.
The relatively small surface areas of SDCs yield more consistency in the mic’s polar pattern across the audible frequency spectrum.
Therefore, SDCs are cherished for their consistent polar patterns and see a lot of use in situations where isolation is key in noisy environments (like spot-miking in an orchestra, for example).
SDC pencil microphones can have any polar pattern except bidirectional due to the design of the mic body. It’s impossible to have both sides of the diaphragm equally exposed to sound in a top-address pencil mic design.
SDCs are the go-to capsules for shotgun mics. They are lightweight, small, and consistent. Adding an interference tube in front of a unidirectional SDC capsule creates a very directional shotgun mic.
For more info on microphone polar pattern, check out my article The Complete Guide To Microphone Polar Patterns.
Self-noise is an important specification that applies to all active microphones (including LDCs and SDCs). When recording professional audio, it’s essential to keep the noise floor as low as possible. Choosing mics with low self-noise helps tremendously in this pursuit.
Large-diaphragm condensers have lower-self noise than small-diaphragm condensers.
Self-noise is mostly due to the active components of a microphone adding noise to the signal as they process (and oftentimes boost the levels) of the mic signal.
It’s not that the LDC capsules are naturally less noisy than the SDC capsules. Rather, the large-diaphragms are capable of transducing stronger mic signals. This means that the signal-to-noise ratio in LDCs is better than SDCs if both mics have the same quality of active components.
SDCs outperform LDCs in terms of polar pattern consistency, frequency response accuracy, and transient response. However, LDCs are the better mics, in general, when it comes to self-noise.
To read more about microphone self-noise, check out my article What Is Microphone Self-Noise? (Equivalent Noise Level).
In terms of price, LDCs (especially those with tubes) are much more expensive that SDCs.
Even when dealing with studio-grade FET microphones, LDCs typically command a higher price point that SDCs.
For more information on microphone pricing, take a look at the following My New Microphone articles: How Much Do Microphones Cost? (With Pricing Examples) and Top 20 Most Expensive Microphones On The Market Today.
What are the differences between tube and FET microphones? Vacuum tubes and field-effect transistors both act as impedance converters and pseudo-amplifiers in active microphones that require that sort of processing. Tube mics have vacuum tubes while FET mics have FETs. In general, tube technology adds more colour and is more fragile than solid-state FET.
What are the differences between condenser and dynamic microphones? The main difference between dynamic and condenser mics is that dynamics convert sound to audio via electromagnetic induction while condensers do so via electrostatic principles. This leads to differences in design and overall sound. Condensers are active while dynamics are usually passive.
To read more about the differences between condenser and dynamic mics, check out my article Differences Between Dynamic & Condenser Microphones.
For more information on moving-coil dynamic microphones, check out my article Moving-Coil Dynamic Microphones: The In-Depth Guide.