This article was first written in 2013 and has been updated in 2024.
Once you own a portable audio recorder the next issue is obtaining a good set of microphones. This topic is complex, since there are hundreds of possible models. To make an informed choice you need to understand certain technical issues.
What types of microphones are there? Which are optimal for which tasks? What connectors do you need? Does the microphone require power and how do you provide this? In this article series I address these questions.
In this first article I will review how to choose an audio recorder before discussing certain limitations of built-in mics. In the second article I will discuss different types of microphones and discuss their power requirements. In the third article I will discuss the most appropriate microphones for several common recording tasks.
Your audio recorder
A decade ago I wrote many articles keeping pace with the profusion of portable digital recorders unleashed on the market. Since then several companies (Sony, Olympus, Marantz) exited this market and the pace of development has slowed.
I have recently summarised the state of the art as of July 2024. Check out this article for a handy table of available recorders. Choose your device based on its size, pre-amp quality, and required features.
Smaller and cheaper recorders (e.g. Zoom H series) tend to include a pair of built-in microphones for convenience. Larger units (e.g. Zoom F series, Sound Devices) are designed for experienced recordists who likely already own the specific external microphones they wish to use. So these devices do not include mics.
Are built-in microphones good enough?
Most pocket and hand-held units have integrated stereo microphones. (Some even have more than two mics.) But there are several reasons why you might wish to upgrade to external mics.
1. Handling noise. Holding the recorder and pointing it at your source leaves you vulnerable to noises transmitted through the body of the recorder. You can reduce this by using a padded grip, screwed to the tripod mount under the recorder. The image above shows a cheap solution.
But it's more ergonomic to use external microphones and run cables from the mics back to the recorder. You are now free to use the buttons and faders on the device without adding handling noise. If required the mics themselves can be cushioned in a cradle or other cushioning device.
2. Distance to the source. Sound pressure decreases by half for each doubling of distance from the source. So the number one way to get a louder, clearer signal is to get your mics closer to the sound source. This also reduces the amount of reverberation and extraneous environmental sounds.
For example, if you are conducting an interview you will want the mic to be proximal to your subject's mouth. If you are hunting for bird-song, you want the mic close to the avian subject. Even if you are gathering location soundscapes it is good to reduce sounds from "off-stage", depending on how you wish to define your area of interest. Having microphones on cables means you can stay at a moderate or even very long distance from them, if needs be.
3. Being inconspicuous. You can't hide a recorder in plain sight if you need to use the microphones welded to the end. But it's a lot easier to hide microphones. Indeed, some are even designed to be hidden. Nature recordists benefit from being able to position microphones and then move off into the distance, so as not to disturb the creatures of interest.
4. Audio quality. The microphones that come with recorders cost a fraction of the price of external microphones, and cannot be expected to achieve the same fidelity. An external mic can have reduced self-noise, improved ability to handle high SPL (volume), lower distortion, flatter frequency response, and so on.
5. Improved sound stage. The mics on a portable recorder come in a fixed topology, limited by the size of the device. Positioning the mics further apart can improve the stereo image, providing greater definition between left and right channels.
Manufacturers recognise this issue, which is why some recorders have "extra wide" menu settings. When used moderately these effects might improve the stereo field, but they are effects, involving mid-side processing or delay/phase tricks. I always turn off all such processing to ensure a clean recording of the source.
Certain recorders have microphones that can pivot out to support wider separation. But this is still limited compared to the possibilities afforded by external microphones.
6. Pick-up pattern. Sometimes you might want to use a shotgun microphone to "zoom in" on a sound. Other times you might prefer a pair of omnidirectional mics to gather a low-noise life-like soundscape. Or a pair of cardioid mics for some sort of a crossed configuration. Or... Well, there are lots of choices.
Given the above, I can be confident in claiming that for any given task, there is always a better choice than the built-in mics.
Conclusion
The second article in this series discusses different types of microphones and how they are powered.
Appendix
For reference, here's a list of my older articles discussing audio recorders.
Summary of Portable Digital Audio Recorders has been updated through 2012 (2009.11.08).
Which Portable Digital Audio Recorder? garnered 30 comments (2009.11.10).
Choosing An Audio Recorder For Ultimate Sound Quality -- which likely means it won't have a microphone (2009.11.12).
Sony PCM-M10 versus Olympus LS-10 / LS-11 compares my two favourite small units and spawned one of my most popular threads (2010.04.26).
Revisiting the Sony PCM-M10 versus Olympus LS-10 / LS-11 Discussion also has 60 comments (2010.09.16).
Sony PCM-M10 and Olympus LS-10 Sound Examples so you can use your ears to help decide (2010.12.15).
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