Are Microphones Analog Or Digital Devices? (Mic Output Designs)

Microphones are used every single day to record both analog and digital audio. Hence, it makes sense that there is a bit of confusion about whether microphones are analog or digital devices or both.

Are microphones analog or digital? Microphones convert sound waves into AC electrical audio signals and are therefore analog devices. However, some microphones (like USB mics) are designed with built-in analog-to-digital converters and output digital audio, making them “digital microphones.”

Just because a microphone is analog or digital does not mean it can only record analog or digital. In fact, the vast majority of microphones today are analog, and the vast majority of modern audio recording is digital. Let's talk a bit more about microphones and their roles in digital and analog audio.

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Microphones Are Analog First And Digital Second (If At All)

This is the proper way of thinking about whether microphones are analog or digital. Microphones first produce analog audio signals (AC voltages). These analog signals can then be converted to digital signals if need be.

Microphones are transducers that convert mechanical wave energy (sound waves) into electrical energy (analog audio signals or AC voltage).

All microphones (excluding some marginal caveats) employ a vibrating diaphragm that moves in sympathy with the sound waves around it. The back-and-forth movement of this diaphragm then causes the creation of an AC voltage, often through electrostatic or electromagnetic principles.

So microphones create an analog audio signal first. In this regard, all microphones are technically analog first.

For more information on microphone audio signals, check out my article What Are Microphone Audio Signals, Electrically Speaking?

The differentiating factor, then, of analog and digital microphones is the output:

• Analog microphones output analog signals (measured in millivolts and commonly outputted through XLR or TRS connections).
• Digital microphones output digital signals (measured in bit-depth, sample rate, and dBFS and commonly outputted via USB).

A digital microphone is designed with a built-in analog-to-digital converter (ADC). The ADC takes the analog signal from the mic diaphragm/capsule at its input and converts that signal to digital information, which it then outputs.

This converted digital audio signal is ultimately outputted by the microphone's output, and thus the microphone is said to be “digital.”

There, of course, is some argument as to whether these USB microphones are actually “digital microphones” or not. I am of the opinion that if the microphone outputs digital audio, it can very well be considered and digital mic.

Recording Digital Audio With Analog Microphones

The vast majority of the audio recording that takes place today is done digitally. However, most microphones are analog. Surely we do not rely only on digital microphones for digital recording?

Absolutely not!

Analog microphones are still the status quo in today's digital recording. These microphones are able to be recorded into computers, digital audio workstations, and digital mixing consoles via analog-to-digital converters. ADCs are most common in audio interfaces, which are often designed to connect multiple microphones to a computer via a single USB, Firewire, Thunderbolt, or other digital connection.

In fact, audio ADCs were used to record analog microphones digitally well before they were ever designed to fit within digital microphones.

Are There Such Things As Dynamic, Condenser, And Ribbon Digital Microphones?

Microphones, as transducers, come in a variety of types. The main ones being dynamic (moving coil), condenser, and ribbon. Are there digital microphones with moving coil, condenser, and ribbon capsules, or are digital microphones restricted to one transducer type?

In theory, it is possible to turn any microphone into a digital microphone by including an ADC before the mic output. And because of that, there are digital dynamic, condenser, and ribbon mics on the market today.

As a quick example, here is one digital microphone for each transducer type:

• Digital moving coil dynamic microphone: Rode Podcaster USB.
• Digital condenser microphone: Blue Yeti USB.
• Digital dynamic ribbon microphone: MXL UR-1 USB

That being said, the great majority of commercial digital USB microphones are condensers. Why is this?

The reason why most digital/USB microphones are condensers is simply due to the nature of their application. USB mics are often used to capture one person speaking, and condensers tend to work best for this application.

Dynamics (both moving coil and ribbon) also work well for recording voice; it's just that condensers edge them out in that application.

Pros And Cons: Analog Vs. Digital Microphones

Let's do a bit of comparing and contrasting between analog and digital microphones.

Starting with the pros of digital microphones:

• Easy to use with computers: Simply plug-and-play (or at the very most download a driver).
• Often have zero-latency headphone monitoring also built-into the microphone.
• Converting the analog signal to digital information in close proximity (within the mic) will reduce the likelihood and effects of electromagnetic interference in the mic signal (less length for the electrical analog signal to travel).

The cons of digital microphones:

• Are often limited to recording one microphone at a time.
• Cannot be easily used with analog gear or even analog-to-digital gear (audio interfaces, etc.)

Compared to digital microphones, the pros of classic analog microphones are:

• Compatibility with analog gear and easy use with external ADCs and audio interfaces.
• Wider variety of microphones.

And finally, the cons of analog microphones:

• The need for an audio interface or analog-to-digital converter to record digitally (though these are easy to use).

Recording Audio With Digital Microphones

Though analog recording could be achieved using digital microphones, there's really no point in doing so. There would be extra steps and conversions in order to do so that are not worth the effort.

In fact, it's much easier to use analog microphones in practically any recording situation (analog or digital) unless you're connecting directly to a computer.

Because digital USB microphones have their own built-in ADCs, computers will communicate with them as their own audio interfaces. Digital audio workstations and other computer-based recording software will only accept one input interface and one output interface at a time. This means that when using a digital USB microphone, we're limited to one microphone at a time. Of course, there are ways around this, but these workarounds are not obvious.

We would then have to convert the mic's digital data into an analog signal, which is an extra step.

Finally, converting back and forth between analog and digital audio does introduce latency (delay) in the signal. Though typically not a big deal, this is yet another completely avoidable issue if we simply recorded analog audio with analog microphones.

A Note On MEMS Microphones And Analog/Digital Outputs

To wrap up our discussion on analog and digital microphones, let's talk about MEMS (MicroElectrical-Mechanical System) microphones.

MEMS mics are the tiny microphone chips often found in laptops, smartphones, and personal voice assistants like Apple’s Siri, the Amazon Echo, and Google Home. These small microphones offer stable performance that does not drift over time and have begun phasing out the tiny electret microphones in computer technology.

Whereas the above dynamic, condenser, and ribbon mics are not typically referred to as “digital microphones” (rather as USB mics), MEMS microphones come distinctly as either analog or digital. The audio signal chain design within MEMS microphones is fairly similar to the aforementioned dynamic, condenser, and ribbon “digital” mics.

Let's look quickly at how a MEMS microphone works.

The MEMS silicon-machined transducer has two plates and works practically the same as an electret condenser. Varying the distance between a movable diaphragm and stationary backplate causes a change in capacitance between the two plates and a sympathetic AC voltage (analog signal).

This analog signal has extremely high impedance and is unusable as an audio signal. Therefore, an amplifier is designed immediately after the transducer. The amplifier boosts the signal but, more importantly, reduces the signal's impedance so it can be effectively used as an audio signal. At this point, the MEMS mic is still analog.

Designers then have the choice of either integrating an analog-to-digital converter immediately after the amplifier or not. An integrated ADC would produce a digital MEMS mic, whereas skipping this step would produce an analog MEMS mic.

Digital MEMS mics are very popular since MEMS microphone technology is mostly driven by smartphones, laptop computers, and voice-activated digital technologies.

So this is the same idea as we've discussed earlier. The big difference being that MEMS microphones are actually described as being either analog or digital.

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Related Questions

Is wireless microphone technology analog or digital? Wireless microphone technology can be analog or digital. Analog wireless mic signals are transmitted through AM or FM analog radio waves modulated continuously across the bandwidth. Digital wireless mic signals are transmitted through digitized RF frequencies, which modulate between two set values.

To learn more about wireless microphones, check out my article How Do Wireless Microphones Work?

Do all digital microphones have USB connections? Though any digital connection could be used to connect digital microphones to computers, USB connections are the most popular commercial connection for digital microphones on the market.

To learn more about USB microphones, check out my articles Best USB Podcasting Microphones and Top 9 Best USB Microphones (Streaming, PC Audio, Etc.).