Home Resources Comparing Large-Diaphragm vs. Small-Diaphragm Microphones: Sensitivity, Sound, And Applications

Comparing Large-Diaphragm vs. Small-Diaphragm Microphones: Sensitivity, Sound, And Applications

by Stuart Charles Black

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Greetings mate and Welcome aboard! Stuart Charles here, HomeStudioBasics.com helping YOU make sound decisions, so…

Before we get into Large-diaphragm vs. Small-diaphragm microphones, grab a snack, sit back, and relax because…

You’ve come to the right place!!

What I will bring you in this article

  1. Introduction
  2. Large-diaphragm vs. Small diaphragm (The long version)
  3. Final Word & The short version

Now without further ado, let’s get rolling!!

Note: If you would rather cut to the chase and not get into technicalities, scroll down to the Final Word!

Introduction

Ah, the magnificently magical world of microphones.

There are so many brands, styles, patterns, & types that it makes you want to slap someone – especially when you’re trying to find the one you need!

It can be very overwhelming.

There are Condenser mics and dynamics,  XLR mics and USB, and countless other factors to consider. Today we’ll focus on a couple in particular.

Large-diaphragm vs. Small diaphragm

There are a few factors to consider when comparing these 2.

Size

A large diaphragm condenser has a diaphragm diameter of 1″ or larger, while a small diaphragm is under 1″.

The smaller diaphragm is more rigid, which prevents other types of distortion.

Self Noise

The small diaphragm microphone has higher self-noise than a large diaphragm.

Air molecules attack the diaphragm, creating air pressure.

Because the smaller diaphragm behaves as a hard surface, the air molecules hitting it exchange a greater amount of energy, producing a higher SPL (sound pressure level) relative to the area and sensitivity of the diaphragm.

Sensitivity

The larger diaphragm mic is more sensitive than a small diaphragm mic.

The small diaphragm MXL 991.

The large diaphragm provides a larger output and is thus easier to move.

It’s also more sensitive because of variances in capacitance.

Basically, the changes in capacitance due to the vibration of the diaphragm are bigger for an LDC.

This means that the output signal voltage is higher.

Also, because the LDC has a larger diaphragm, the sound waves force it to move more than a small one.

The signal-to-noise ratio of an LDC also tends to be higher because of its stronger signal above the noise floor.

An LDC is a good choice when recording a quiet instrument without adding noise from the mic or mic preamp.

An SDC has a lower sensitivity because the diaphragm is smaller, stiffer, and more difficult to move.

Sound Pressure Level

The smaller diaphragm mic can handle a higher SPL than the large diaphragm.

The Large Diaphragm Samson C01.

Inside the microphone capsule, the distance between the diaphragm and the back plate, coupled with the rigidity of the diaphragm, means it can only move so much before distortion becomes too high.

Due to this, a large diaphragm cannot handle a high SPL as well.

The smaller and stiffer small-diaphragm can handle higher SPLs.

Frequency Range

Both large and diaphragms are equally capable of picking up low frequencies, but a large-diaphragm mic has a more limited frequency range than a small diaphragm.

Why?

The upper limiting frequency (ULF), is set by several factors relating to the dimensions of the diaphragm:

  1. The large diaphragm breaks up and no longer acts as a true piston.
  2. The weight of the diaphragm will reduce the displacement of the diaphragm for higher frequencies.
  3. The diffraction around the edges of the microphone capsule will limit the microphone’s capability of handling very high frequencies.

All this means is that the LDC’s diaphragm is bigger and has more mass to move, thus not being able to react as fast to changes in sound.

But…

The LDC is capable of a deeper low-frequency response than an SDC.

Why?

  1. The resonance frequency of the diaphragm is lower in the LDC due to its higher mass.
  2. The grill of an LDC causes internal reflections and filtering, resulting in a rougher response. An SDC lacks a grill and thus doesn’t have this problem.

Because of this:

  • An LDC does better in capturing the deep tones of a tom or some low vocals.
  • An SDC responds better to really high frequencies such as acoustic guitars, cymbals and various other hats and crashes.

Dynamic Range

A small diaphragm microphone has a higher dynamic range than a large-diaphragm mic.

Because of this, its SPL (sound pressure level) can reach greater heights without harmonic distortion.

Proximity effect

Directional mics have a louder low-frequency response when used close. This is its proximity effect.

  • An SDC is designed to roll off these lower frequencies or minimize/eradicate them after a certain frequency is met. This is why they are so good for miking an acoustic guitar. Minimal EQ and cutting of unnecessary low end information is needed.
  • An LDC’s proximity effect tends to sound better, making it more useful for vocalists in the studio. The SDC may sound a bit bloated up close.

Transient Response

An SDC is better because of its smaller mass, which enables it to more closely follow any air disturbances that it’s met with.

Its ability to capture acoustics, metal percussion, cymbals, or any other fast transients cleanly is the result.

Off-Axis coloration

  • When sound waves hit the diaphragm off-axis, they are traveling across.
  • High-frequency sounds with short wavelengths tend to phase out or cancel due to interference.
  • The smaller the diaphragm, the less phase shift there is.
  • Less phase shift means less cancellation of high frequencies.

This all means that an SDC has a flatter high-frequency response off-axis, while an LDC rolls off in the highs.

The placement of the capsule also has a lot to do with it.

  1. The capsule in an LDC is inside the grill. This creates reflections and filtering in the grille which affects the response and polar pattern.
  2. An SDC capsule is housed near the end of the mic. The capsule has no grille around it to alter its response and polar pattern.

 

What does this mean?

It’s another reason for an SDC’s lack of off-axis coloration.

When off-axis coloration is a problem

When the sound hits from the side, or at a wide angle.

Luckily SDCs pick up off-axis high frequencies well and work great in recording orchestras, grand pianos, and symphonic bands.

In my experience, using an SDC to record an acoustic guitar is absolutely the way to go and echoes the above sentiment.

Not only is it easier to get a good first take, but you won’t be fiddling around trying to get the perfect angle as you would with say, an SM57.

Closing Thoughts

Wow. That was a lot of mumbo jumbo, huh? To keep it simple:

Choose an LDC (Large Diaphragm Condenser) when:

  1. You need low-noise and high sensitivity
  2. You need a deep low-frequency response.
  3. You need a good-sounding proximity effect on singers.

Applications: Studio vocals, ambiance, deep-sounding drums, miking a drum kit as a whole, quiet or distance instruments or vocals, guitar or bass amps, big brass.

Choose an SDC (Small Diaphragm Condenser) when:

  • You need an extended high-frequency response and need to capture transients and other high-frequency information (Acoustic guitars most notably).
  • You need a flatter frequency response.
  • Lower handling noise.
  • Excellent transient response.
  • You need less coloration, or “Low off-axis coloration” (A wider pattern at high frequencies).

Applications: Acoustic instruments, percussion, cymbals, hats, orchestral, spot miking, woodwinds, other delicate orchestral instruments, and anything with detail that needs to be captured.

In a nutshell?

  • LDC: More flattering.
  • SDC: More accurate.

Interested in a fantastic 1-2 punch and a combo that I personally use for vocals and acoustic guitar?

It’s definitely the MXL990/991. Perfect for those just starting out and they both record incredibly well.

Learn More:

 


Well, that’s about it for today my friend! I hope you’ve enjoyed this article on large diaphragm vs. small diaphragm microphones, and your head doesn’t hurt too much.

Questions? Comments? Requests? Did I miss the mark on something? Please contact me!!

Which mic are you more likely to go with? I would love to hear from you. Until next time…

All the best and God bless,

 

 

-Stu

[Xtr@Ba$eHitZ]

Be sure to check out my Reviews and Resources page for more helpful and informative articles!

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4 comments

Gordon Scott November 30, 2019 - 6:31 pm

Self noise in microphones is due to the electronics, not air molecules, even in a dynamic mic. The first amplifier device and it’s biasing component(s) are the culprits in condenser mics. In dynamic mics, it’s purely down to the resistance of the wire in the coil. Most of this is due to “Johnson noise” in the resistors and which itself is due purely to physics. The first semiconductor in the condenser mic contributes some from it’s own Johnson noise and some, typically “shot noise” from the way the device works.

Good website.

Reply
Stuart Charles Black December 4, 2019 - 4:14 pm

Hey man!

Hmm interesting. So does air come into play at all? It would seem to have some sort of effect, no? Would love to learn more about this. Do you have any good literature on the matter?

Reply
Gary Card April 19, 2020 - 8:40 pm

Great Article. Just what I needed! Thanks a bunch.

Reply
Stuart Charles Black April 28, 2020 - 4:40 pm

Thank you so much Gary!

Reply

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