Before you can decide which is the best type of microphone for recording vocals, or guitar, or which microphone would be most suitable for voiceovers, you need to have a basic understanding of the different types of mics available, and their specs, and then you can make a sensible choice. Once you have chosen the right mic, then you can learn how to connect it up to your computer as part of your home recording studio setup.
Your choice of microphone is very important, whether you have a large or small budget. Because the mic is the source of your recorded signal. It is the first link in your home recording studio chain. If the signal is distorted, or noisy, or tonally coloured, you will be stuck with any flaws through the whole recording process. Much better to get the right type of microphone in the first place and position it correctly!
But there is a big problem – especially if you are new to recording. And that is that spec sheets for microphones have lots of technical terms and complicated looking graphs. So if you are trying to choose the right type of microphone for a particular recording situation, it is easy to get very overwhelmed.
My aim with this post is to go right through the different types of microphones you will come across, and also all the technical terms you will see specified. Hopefully this will be a useful reference – although there is quite a lot of information, so grab a coffee and let us begin!
So, let’s go right back to basics. What is a microphone? How does it basically work? Well it is basically a transducer – ie it changes one form of energy into another. Specifically, a mic changes sound into an electrical signal. You can then amplify and modify this signal, and for computer recording convert it to a digital signal.
Mics for recording can be grouped into three types, depending on how they convert sound to an electrical signal, and these terms may be familiar already to you: dynamic, ribbon, or condenser.
In a dynamic mic, a coil of wire attached to a diaphragm is suspended in a magnetic field. When sound waves vibrate the diaphragm the coil vibrates in the magnetic field and generates an electrical signal. This is why you might sometimes find a dynamic mic referred to as a moving-coil mic. Because of the way it works, dynamic mics tend to be less sensitive but more robust.
In a ribbon mic, a thin metal foil or ribbon is suspended in a magnetic field and sound waves vibrate the ribbon to generate the electrical signal.
A condenser mic has a conductive diaphragm and a metal backplate placed close together. They are charged with static electricity to form 2 plates of a capacitor. When sound waves strike the diaphragm it vibrates. This varies the spacing between the plates. This then varies the capacitance and generates a signal similar to the incoming sound wave. Because of its lower diaphragm mass and higher damping, a condenser mic responds faster than a dynamic microphone and so is more sensitive with bigger frequency response.
There are two types of condenser mics: true condenser and electret condenser.
In a true condenser mic, the diaphragm and backplate are charged with a voltage from a circuit built into the mic.
In an electret condenser mic, the diaphragm and backplate are charge by an electret material in the diaphragm or on the backplate. They can sound equally good, though some engineers prefer true condensers which tend to cost more.
If you are a beginner, don’t worry too much. Spend enough to get a good recording result and get making some tracks first rather than getting too hung-up on which is the ultimate mic for a professional recording studio engineer! Let’s get on and look at some of the technical specs you will see when shopping for microphones, and make some sense of the barrage of numbers and jargon you will be presented with.
Phantom Power/External Power
You need to know that a condenser mic needs a power supply to operate, such as a battery or phantom power supply. Note that if you decide to purchase a USB condenser mic, then the power will be supplied via USB so you do not need to worry.
Phantom power is 12 to 48 volts DC applied to pins 2 and 3 of the mic connector through 2 equal resistors. The microphone receives phantom power and sends audio signals on the same two conductors. Many audio interfaces and mixing consoles supply phantom power at their mic input connectors. You simply plug th mic into the mixer or audio interface with phantom power to power the mic.
Dynamic and ribbon mics do not need a power supply. You can plug these types of mics into a phantom supply without damage unless either signal conductor is accidentally shorted to the mic housing.
Phantom power is an important consideration when choosing an audio recording interface for your computer. For maximum compatibility, choose one with phantom power which will work with any mic. BUT if you are on a tight budget and know already you will only use a dynamic mic for recording then you could economize and buy an interface without.
This diagram shows a cutaway view of a typical dynamic vocal mic and condenser instrument microphone for comparison.
A Summary Of The General Characteristics of Each Transducer Type
Note, if you read on the technical terms used below will be explained in more detail!
- Wide, smooth frequency response
- Detailed sound, extended highs
- Omni type has excellent low-frequency response
- Transient attacks sound sharp and clear
- Great for acoustic instruments, cymbals, studio vocals
- Read more here about the best condenser microphones
- Tends to have a rougher frequency response, but still quite usable
- Rugged and reliable
- Handles heat, cold, and high humidity so more robust than condenser
- Handles high volume without distortion – perfect for live vocal use
- Preferred for guitar amps and drums
- Good for woodwind and brass – can take the ‘edge’ off
- Find out more about which are the best dynamic mics
- Warm, smooth tone quality
- Complements digital recording very well
There are exceptions to the above. Some dynamics have a wide-range, smooth frequency response. And some condensers are rugged and handle high SPLs (SPL = the maximum sound pressure a microphone can handle before it will distort or fail)
The main thing is when you are comparing mics to decide which one is best for you, check the specs and compare the numbers to help you choose.
Not only are there various microphone types, there are also variations in the specs of mics within a particular type, so let’s have a look at some of the terms you are likely to come across and what exactly they mean.
Polar Pattern (also referred to as Pickup Pattern)
Microphones differ in the way the respond to sounds coming from different directions. An omnidirectional mic is equally sensitive to sounds arriving from all directions.
A unidirectional mic is most sensitive to sound arrive from one direction – in front of the mic – but softens sounds entering from the sides or rear.
A bidirectional mic is most sensitive to sounds arriving from 2 directions – in front of and behind the mic – and rejects the sounds that enter from the sides (sometimes referred to as figure-of-8 pattern).
To go even deeper, there are 3 types of unidirectional pickup patterns: cardioid, supercardioid, and hypercardioid. These are big words to explain a relatively simple concept.
If you talk into a cardioid mic from all sides, your reproduced voice will be loudest when you talk into the front of the mic, and softest when you talk into the rear.
The super- and hyper- cardioid mics reject sound from the sides more than the standard cardioid. The are MORE directional, but they pick up more sound from the rear than the cardioid mic.
A microphone’s polar pattern (or pickup pattern) is a graph of its sensitivity vs the angle at which the sound comes into it. You will see the polar pattern plotted on polar graph paper. Sensitivity is plotted as distance from the origin. Here are diagrams of what these pickup patterns look like:
Again, when you are trying to choose a mic, you will find these graphs on the manufacturer’s site and so you can compare different types. And you will see little diagrams of these pickup patterns on mics to show their polar pattern.
Some mics even have a switchable pattern that makes them very versatile. The switch is usually labelled with mini diagrams like those above – so hopefully you will now recognise what each one means!
A Summary Of Different Polar Patterns
- All-around pickup
- Most pickup of room reverberation
- Not much isolation unless you mike close
- Low sensitivity to ‘pops’ (explosive ‘p’s and breath sounds)
- Low handling noise
- No up-close bass boost (aka proximity effect)
- Extended low-frequency response in omni condenser mics, so good for pipe organ or bass drum
- Generally lower cost
Unidirectional (cardioid, hyper- and super- cardioid)
- Selective pickup pattern
- Refection of room acoustics, background noise, and leakage
- Good isolation – so decent separation between tracks
- Up-close bass boost (ie bigger proximity effect – except in mics that have holes in the handle)
- Better gain-before-feedback in a sound-reinforcement system
- Use for coincident or near-coincident stereo miking
- Broad-angle pickup of sound sources in front of mic
- Maximum refection of sound approaching the rear of the mic
- About 6 dB less sensitive at the sides, 15 to 25 dB less sensitive at rear
- Good for stage-floor miking – Maximum difference between front hemisphere and rear hemisphere pickup
- More isolation than a cardioid
- Less reverb pickup than a cardioid
- About 8.7 dB less sensitive at the sides, 2 areas of least pickup at 125 degrees from front
- Maximum side rejection of sound source
- Maximum isolation – pick up less reverberation, leakage, feedback and background noise
- About 12 dB less sensitive at sides, 2 areas of least pickup at 110 degrees from front
Bidirectional (Figure of 8)
- Front and rear pickup, side sound rejected. Perfect for two-part vocal groups or across table interviews.
- Good for Blumlein stereo miking technique (where you cross 2 x bidirectional mics at 90 degrees)
In a good microphone, the polar pattern should be about the same from 200 Hz to 10 kHz – or you may hear off-axis colouration (meaning mic will have a different tonal quality on and off axis). Large-diaphragm mics tend to have more off-axis colouration than small-diaphragm microphones.
Ribbon mics are either bidirectional or hypercardioid. Condenser and dynamic mics can be found with any kind of polar patter (except you cannot have bidirectional dynamic).
Note that the shape of a mic does not indicate its pickup pattern.
Another term you might see: if a microphone is end-addressed, you aim the end of the mic at the sound source. If a mic is side-addressed, you aim the side of the mic at the sound source.
Boundary mics that mount on a surface have a pattern that is half-omni (hemispherical), half-supercardioid, or half cardioid (very much like an apple sliced in half through the stem). The boundary mounting makes the mic more directional so it picks up less of the room’s acoustics.
This is something you will always see quoted in microphone specs so lets have a look in more detail. Basically the frequency response is the range of frequencies that a mic will reproduce at an equal level (within a small tolerance). The following is a list of instruments and the mic frequency response that is needed to record with high fidelity. Of course you can go for a wider range response, but don’t go for less!
- Most instruments: 80 Hz to 15 kHz
- Bass instruments: 40 Hz to 9 kHz
- Brass and Vocals: 80 Hz to 12 kHz
- Piano: 40 Hz to 12 kHz
- Cymbals and some percussion: 300 Hz to 15 or 20 kHz
- Orchestra or symphonic band: 40 Hz to 15 kHz
Try and use a mic with a response that rolls off BELOW the lowest fundamental frequency of the instrument you want to record.
For example, the frequency of the bottom E-String on an acoustic guitar is about 82 Hz. A mic used on acoustic guitar should roll off below that frequency to avoid pickup up of low-frequency noise such as rumble from passing traffic. Some mics have a built-in low cut switch. The other option is to filter out the low frequencies on your mixer.
You will often see a frequency-response graph in the specs of a microphone. This shows the mic’s output level in dB at various frequencies. The output level at 1 kHz is placed at the 0 dB line on the graph, and the levels at other frequencies are plotted as so many decibels above or below that reference.
The shape of the response curve suggests how the mic sounds at a certain distance from the sound source. If the distance is not specified, then you can assume it is about 2-3 feet. So, a mic with a wide, flat response reproduces the fundamental frequencies and harmonics in the same proportion as the sound source. It will tend to proved an accurate and natural reproduction at that distance.
If you can see a ‘presence peak’ – ie the curve goes up – at about 5 to 10 kHz then the mic will sound more crisp and articulate because it emphasises the higher harmonics. You may see this type of response referred to as ‘tailored’ or ‘contoured’. It is popular for guitar amps and drums because it adds punch and emphasises the attack. It can also be useful for optimum intelligibility of speech.
Some mics come with a presence boost adapter which is handy if you want one mic to do multiple jobs.
Some mics have switches that alter their frequency response – for example a high pass filter.
Most uni- and bidirectional mics boost the bass when used within a few inches of a sound source. You will have probably heard how when a vocalist sings right into their microphone the sound gets very bassy. This is known as the proximity effect, when there is a low frequency boost related to mic placement. You will often see the proximity effect plotted on the frequency response curve, to demonstrate the effect of ultra close up miking.
The warmth that is created by the proximity effect adds a nice fullness to drums. But generally if you place the mic far too close then you will get an unnatural boomy or bassy sound to the instrument or voice picked up by the mic. This is a common problem if for example you place your mic too close to the sound hole of an acoustic guitar.
Some mics – known as multiple-D or variable-D types – are designed to reduce the proximity effect. These types have holes or slots in the microphone handle.
Some mics have a bass-rolloff switch to compensate for the bass boost. Or you can use your mixer’s equalizer to roll off any excess bass until it sounds more natural. By doing this, you also reduce low-frequency leakage picked up by the mic.
Omni mics, by the way, have no proximity effect and sound tonally the same at any distance. Worth remembering.
Mic placement can greatly affect the recorded tone quality. So you cannot guarantee a natural sound with a flat-response mic because the placement has such as an effect. In other words, when choosing a mic, you can check the spec for the frequency response but then you will have to experiment to make sure you achieve the effect you want.
Impedance is the microphone’s effective output resistance at 1 kHz. A mic impedance between 150 and 600 ohms is low. 1000 – 4000 ohms is medium, and about 25 kilohms is high.
Always go for a low-impedance mic. Then you can run longer mic cables without picking up hum or losing high frequencies. The input impedance of a mixer mic input is about 1500 ohms. If it were the same impedance as the mic, about 250 ohms, the mic would “load down” when plugged in.
Loading down a mic makes it lose level, distort or sound thin. To prevent this, a mic input has an impedance much higher than that of the microphone. But it is still called a low-Z input.
Maximum SPL (Sound Pressure Level)
Sound Pressure Level (SPL) is a measure of the intensity of a sound – or loudness if you like. The quietest sound we can hear, the threshold of hearing, is 0 dBSPL. Normal conversation at around 1-foot distance measures about 70 dBSPL. Loud sound will start to feel painful at above 120 dBSPL.
So if you are looking at the specs of a mic and the maximum SPL is stated as 125 dBSPL, this means the mic starts to distort when the sound source is putting out 125 dBSPL at the mic. A maximum SPL spec of 120 dB is good, 135 dB is very good and 150 dB is excellent.
Dynamic mics tend not to distort even with very loud sounds. You can find some condensers that are just as good. Some mics have a pad you can switch in to prevent distortion in the mic circuitry. But because a mic pad reduces signal-to-noise ration (S/N) use it only if the mic distorts.
This measurement tells you how much output voltage a mic produces when driven by a particular SPL. High-sensitivity mics put out a stronger signal (higher voltage) than low-sensitivity mics when each are exposed to an equally loud sound.
If you use a low-sensitivity mic you will need more mixer gain – and this can result in more noise. So if you want to record quiet music at a distance (eg classical guitar, string quartet) then use a mic of high sensitivity to override mixer noise. When you record loud music, or mike close, then the sensitivity matters less because the mic signal level is above the mixer noise floor. In other words, the S/N is high. (Signal to Noise). Typical sensitivities are:
- Condenser: 5.6 mV/Pa (high sensitivity)
- Dynamic: 1.8 mV/Pa (medium sensitivity)
- Ribbon or small dynamic: 1.1 mV/Pa (low sensitivity)
The louder your sound source, the higher the signal voltage the mic puts out. So a very loud instrument like kick-drum or guitar amp can cause a microphone to generate a signal strong enough to overload the mic preamp in your mixer. This is why many mixers have pads or input-gain controls to prevent preamp overload from hot mic signals. Most audio interfaces also have input gain on the pre-amps.
Self-noise, or equivalent noise, level is the electrical noise or hiss a mic produces. It’s the dBSPL of a sound source that would produce the same output voltage that the noise does.
When you see the self-noise spec it is usually A-weighted. That means the noise was measured through a filter that makes the measurement correlate more closely with the annoyance value. The filter rolls off low and high frequencies to simulate the frequency response of the ear.
So what do the numbers mean?
An A-weighted self-noise of 14 dBSPL or less is excellent (quiet). 21dBSPL is very good, 28 dBSPL is good, 35 dBSPL is fair – not good enough for a quality recording though. So the lower the number the better.
A dynamic mic has no active electronics to generate noise, so has very low self-noise (hiss) compared to a condenser mic. This is why if you look at the spec sheet for a dynamic mic it will generally not specify self-noise.
Signal-To-Noise Ratio (S/N)
This is the difference in decibels between a mic’s sensitivity and its self-noise. The higher the SPL of the sound source at the mic, the higher the S/N. So given an SPL of 94 DB, an S/N spec of 74 dB is excellent; 64 dB is good. The higher the S/N ration the cleaner and more noise-free the signal, and the bigger the “reach” of the microphone.
Reach is the clear pickup of quiet, distant sounds due to high S/N. You will not see reach specified in any data sheets for mics, because any microphone can pick up a sound source at any distance if that sound is loud enough. Even a cheap mic can pick up a thunderclap at several miles away!
This is the polarity of the electrical output signal to the acoustic input signal. The standard is “pin 2 hot” What that means is the mic produces a positive voltage at pin 2 with repsect to pin 3 when the sound pressure pushes the diaphragm in – ie positive pressure.
You have to be very careful your mic cables do not reverse the polarity. On both ends of each cable, the wiring should be pin 1 shield; pin 2 red, pin 3 white or black. OR the wiring on both ends should be pin 1 shield, pin 2 white, pin 3 black.
If some microphone cables are correct polarity and some are reversed, and you mix the mics to mono, then the bass may cancel.
So now we have covered (at length!) all the specs and technical terms you might find, let’s go back to the different types of recording mics available.
Large-Diaphragm Condenser Microphone
This is a condenser mic, usually side-addressed (aim sound source at side of mic), with a diaphragm that is 1 inch or larger in diameter. It generally has very good low-frequency response and low self-noise. Large-diaphragm condenser mics are commonly used for studio vocals and acoustic instruments such as acoustic guitar.
Small-Diaphragm Condenser Microphone
This is a stick or “pencil” cardioid condenser mic, usually end-addressed (aim sound source at the end), and the diaphragm is under 1 inch diameter. Small-diaphragm condenser mics generally have a good transient response and detail, making them a good choice for close-miking acoustic instruments – especially cymbals, acoustic guitar, and piano.
Dynamic instrument Microphone
This is a stick-shaped dynamic microphone, end-addressed. Although it may have a flat response curve, it generally has a presence peak and some low-frequency rolloff to prevent “boominess” when used up close. The dynamic instrument mic is often used on drums and guitar amps.
The live-local mic is a unidirectional microphone and shaped like an ice-cream cone with a large grille used to reduce breath pops. It can be a condenser, dynamic or ribbon type, and usually has a presence peak and some low-frequency rolloff.
The ribbon mic can be side- or end-addressed. It is generally used wherever you want a warm, smooth tone quality (sometimes with reduced highs).
These type of mics are designed to be used on surfaces. You can tape them to the underside of a piano lid, or tape them to the wall for pickup of room ambience. They can be used on hard baffles between instruments, or on panels to make the mics directional.
A boundary mic has a mini-condenser mic capsule mounted very near a sound-reflecting plate or boundary. Because of the construction, the boundary mic picks up direct sound and reflected sound at the same time, in-phase at all frequencies. So you get a smooth response free of phase cancellations. A conventional mic near a surface sounds ‘coloured’ A boundary mic on a surface sounds more natural.
Other benefits are a wide, smooth frequency response free of phase cancellations, excellent clarity and reach, and the same tone quality anywhere around the mic. The pickup pattern is half-omni or hemispherical. Sound boundary mics have a half-cardioid or half-supercardioid polar pattern. They are great for placing on a conference table, or at the front edge of a stage floor to record drama or musicals.
Mini condenser mics can be attached to drum rims, flutes, horns, acoustic guitars, fiddles, etc. Their tone quality can be as good as larger studio microphones and the price is relatively low. With these tiny mics you can make a band in concert without cluttering the stage with mic stands, or you can mike up a drum set with two or three of these. Although you would lose individual control of each drum in the mix if you did this, the cost is lower than buying a full drum set and the sound is quite good with some bass and treble boost. Compared to large mics, mini mics do tend to have more noise (hiss) in distant-miking situations, so they really are best used close up.
A lavalier mic is a mini mic worn on a jacket lapel, tie or scarf, to record speech from a newscaster or lecturer. They are also perfect for recording good quality vocals when making talking head videos and hence are massively popular for YouTubers and video content creators.
A stereo mic contains two directional mic capsules in a single housing for convenient stereo recording. You just place the mic a suitable distance and height from the sound source and you will get a stereo recording.
Because there is no spacing between the mic capsules, there is also no delay or phase shift between their signals. Coincident stereo mics are mono-compatible – the frequency response is the same in mono and stereo – because there are no phase cancellations if the 2 channels are combined into one.
This condenser mic has a built-in analog to digital converter so it outputs a digital signal which is immune to pickup up hum.
Digital mics are usually side-addressed, have a large diaphragm, a flat response, and very low self-noise.
This mic is used for a live performance, or sometimes for conferences. It is a small condenser worn on the head, either omni- or unidirectional. This allows the performer freedom of movement on stage.
USB mics come in many types and guises, and have become for many the ultimate home recording studio mic for anyone on a budget, because no additional equipment is required to make a recording directly on your computer. You can get USB mics that work well on Mac, PC and iPad. They are easy to use (mostly they are plug and play) and very portable too.
The Perfect First Mic For A Home Recording Studio
You have covered a lot of ground in this article! You should now be in a fantastic position to compare the specs of all the different mics out there. But if you are buying your first mic, which is the best for a home recording studio situation?
For a home studio, first choice should probably be a cardioid condenser mic with a flat frequency response. This type of mic is particularly good for studio vocals, cymbals, percussion and acoustic instruments, and is a good all-rounder. You can get a USB version, or a standard mic to use with an audio interface.
Do remember that a condenser mic needs a power supply to operate. Some are battery or dual powered, but most will require a phantom power supply. Many audio interfaces have a phantom power switch so this shouldn’t be a problem now you are aware of it.
If you buy a USB condenser mic, then you do not need to worry about the phantom power issue – they are USB powered.
Your second choice of microphone for a home studio is a cardioid dynamic microphone with a presence peak in the frequency response. This is good for guitar amps and drums.
Why is cardioid better than omni for your home recording studio? Because this pickup pattern rejects the leakage, background noise and room reverb that you will almost certainly have in your home studio – although you can use acoustic treatment to mitigate this.
An omni mic can be very good, however if you mike close enough. Omni mics also tend to provide a more natural sound at a lower cost and they have no proximity effect.
Some would say that if you have no budget at all for room treatment, then a dynamic mic would be a better choice. I have found though, that by pinning up a couple of blankets and using a couple of well placed acoustic panels you can make a very fine home recording with a condenser mic, and you do benefit from the increased sensitivity. So my first mic would be a condenser. But if you are acoustically challenged in your recording space then you may get quicker and better results with a dynamic mic.
Your choice will depend on your budget and your main recording aim, and also where you are going to make most of your recordings.