Choosing an Electret Condenser Microphone

An electret condenser microphone has a permanently charged element in its capsule, so it does not need the high polarizing voltage of a traditional condenser. It does need a small amount of power for the preamplifier built into the capsule, which is usually a JFET. Electrets are common in lavalier, headset, desktop and built-in laptop mics. Choosing one mostly means matching the capsule, connector and power source to the device you record with.

Before you start

You can choose and test the microphone locally. You need the mic, the device it connects to, and that device's sound settings, and no online service is required. Some people use a browser-based microphone test. If you do, read what that page says about how it processes and stores audio, and don't assume the audio stays on your device.

• What you will record: voice for calls, streaming or voice-over, interviews, instruments or room sound.
• Which input your device has: a 3.5 mm jack (a separate mic jack or a combined headset jack), USB, or XLR on an audio interface or mixer.
• Whether that input supplies power: plug-in power on 3.5 mm mic inputs, phantom power on XLR inputs, or neither.
• The manufacturer's manual or spec sheet for each microphone you are considering.

Step-by-step instructions

1. Match the connector to your input device

Electret mics with a 3.5 mm plug come in two types. TRS plugs have three contacts and TRRS plugs have four. Combined headset jacks on most laptops, phones and tablets expect TRRS. A separate microphone jack on a desktop computer or recorder usually expects TRS. If the plug doesn't match the jack, the mic may not be detected, may stay silent or may buzz, and an adapter of the correct type fixes this. A USB electret mic has its own converter and shows up as a separate input device, so it bypasses the computer's analog input. An XLR electret mic is meant for audio interfaces and mixers.

2. Confirm how the microphone is powered

The capsule's preamplifier has to get power from somewhere. Most computer, phone and recorder mic inputs supply low-voltage plug-in power through the 3.5 mm jack. Line inputs do not, and not every camera does, so check the device manual. Other mics get power from an internal battery or belt pack, from phantom power on an XLR input, or from the USB connection. If a mic needs plug-in power and your device can't provide it, choose a battery-powered model or a USB or XLR version instead.

3. Pick a polar pattern

An omnidirectional mic picks up sound equally from all directions. It tolerates head movement and is common on lavaliers, but it also captures more room echo and background noise unless it sits close to the mouth. A cardioid mic rejects sound from behind. It suits a desk in a noisy room, but you need to speak toward its front. Distance often matters more than the pattern: the closer the mic is to your mouth, the louder your voice is compared with the room.

4. Read the specifications that matter

Only compare figures that were measured the same way. Spec sheets from different brands don't always use the same reference conditions.

• Sensitivity: how much signal the mic produces at a given sound pressure. It is often quoted as a negative dBV/Pa value, and a number closer to zero means more output, so you need less gain.
• Self-noise (equivalent noise level) or signal-to-noise ratio: lower self-noise or a higher SNR means less hiss in quiet passages.
• Maximum SPL: the loudest sound the mic handles before it distorts. This matters for loud singing, instruments and close placement.
• Frequency response: the range and shape of the response. A gentle presence lift can make speech clearer on calls.
• Operating voltage and output impedance: these must suit the input you plan to use.

5. Choose a form factor and accessories

Lavaliers keep your hands free for video and interviews, but clothing rubbing on the cable and capsule can be audible. Headsets keep the mic at the same distance from your mouth, which helps on calls and while gaming. Desktop and boundary mics suit meetings around a table. A foam windscreen reduces plosives and wind noise, and a shock mount or proper clip reduces handling noise.

6. Connect, select and set the level

Select the microphone as the input device in your system sound settings. Select it again in each app you use, because video-call and recording apps often have their own selector. Before you change the input level, write down the current value so you can go back to it. Speak at your normal distance and adjust the level until peaks stay clearly below the top of the meter. For a USB mic, set the device and the recording app to the same sample rate. 44.1 kHz and 48 kHz are common, and 48 kHz is the usual choice for video.

Check the output

Make a short test recording: speak normally for a while, then stay silent for a few seconds. Play it back on headphones as the output device. Hiss and hum are much easier to hear on headphones than on laptop speakers.

• Peaks: speech should never hit the top of the meter. Clipping sounds harsh and can't be removed afterwards.
• Silent section: a steady hiss points to gain or self-noise, a low hum points to electrical interference, and occasional clicks usually come from the cable or from handling.
• Channels: many electret mics are mono, so on a stereo input your voice may appear in the left channel only. Record in mono or duplicate the channel in your editor.
• In the app itself: video-call apps often apply noise suppression and automatic gain, so the result in a call can differ from your test recording.
• Input hardware: a 3.5 mm mic is limited by the device's built-in preamp and converter. A noisy laptop input adds hiss that no choice of microphone can remove.

Common problems and next steps

• No sound at all: check that the right input device is selected and that the operating system allows the app to use the microphone. Then check the TRS versus TRRS plug type, whether the input supplies plug-in power, the battery and power switch on battery models, and phantom power on XLR inputs.
• Very quiet signal: move the mic closer before you raise the input level. Also check that it is plugged into a mic input, not a line input. Low-sensitivity mics need more gain, and more gain also brings up more noise.
• Constant hiss: lower the gain and move closer. If hiss remains at a usable level, the built-in input may be the limit.
• Hum or buzz: unplug the laptop charger or try another USB port. Keep the mic cable away from power supplies, or use battery power if the mic supports it.
• Distortion: lower the input level, move the mic back slightly, add a windscreen or pop filter, and confirm the source isn't louder than the mic's maximum SPL.
• Thin or warbling voice on calls: test with the app's noise suppression and the system audio enhancements turned off, then turn them back on one at a time.

If the computer's built-in input still adds noise after these corrections, a USB microphone or a USB audio interface is the main upgrade. For a camera, look up in its manual whether the mic input supplies power and whether you can set the recording level manually, and do this before you buy a microphone.