Of the many types of microphone that are available to buy, condenser microphones are considered among the best in terms of quality and value for money. Since their introduction almost a hundred years ago, condenser microphones have gained a reputation as microphones with impressive specifications. In general, they have excellent response, sensitivity, and are capable of high-quality reproduction.
Conventional Condenser Microphones
Condenser microphones function by allowing incoming sound waves to vary the capacitance of the microphone's internal element assembly. This in turn varies an existing steady voltage supplied by batteries or by so-called phantom power supplied via the microphone cable from another device such as a mixing desk. In this way, the original pattern of the sound waves is preserved. The output is a varying audio-frequency signal which is sent to any other device, such as an amplifier, mixer, transmitter or recording device via the microphone's cable, or by radio in the case of wireless versions.
Electret Condenser Microphones
Electret condenser microphones are a special type of condenser microphone that became available over fifty years ago. Their simpler construction enables them to be produced and sold at affordable prices. Electret condenser microphones are now the most commonly used microphone type, especially in applications where sound quality isn't critical, such as mobile phones. In terms of quality, electret condenser microphones have lagged well behind more expensive conventional condenser microphones and focused on mass production of cheaper, low quality microphones. More recent advances, however, have seen the production of higher quality electret condenser microphones that can match even high-end conventional condenser microphones.
USB Condenser Microphones
Condenser microphones intended for direct connection to a computer have become increasingly available in recent years. USB condenser microphones, so-called because they connect to any available USB port on a computer, carry additional circuitry to convert the audio signal to digital data. At first of rather doubtful quality, USB microphones have improved significantly over their relatively short history, and professional-quality models are now available.
Choosing a Condenser Microphone
Condenser microphones, although generally of similar specifications in terms of sensitivity and frequency response for a given price range, nevertheless have design variations that make some models better than others for specific applications. As every condenser microphone buying guide stresses, the intended use of any particular condenser microphone should be the main factor in deciding which particular model to buy. So-called small-diaphragm condenser microphones, for example, have a good and even frequency response over the whole audio spectrum and are suitable for situations in which a variety of different sound sources are to be recorded. Large diaphragm microphones, on the other hand, are the preferred choice where a warmer bass response is required.
Understanding the Provided Specifications
Manufacturers of microphones publish specifications for each model that they produce. A basic understanding of what those specifications mean can make it easier to choose a model that is suitable for its intended use.
Frequency response is shown as a graph in which the microphone's sensitivity over the entire audible range of sound frequencies can be seen. Normal human hearing ranges from around 20 hertz (vibrations per second) at the low-frequency end of the audio spectrum to 20,000 hertz at the higher end. It should be kept in mind that, although most musical instruments' tones usually lie well within this range, there are also naturally produced harmonics and other overtones at the upper end of the frequency range that need to be picked up as well. Most overtones aren't audibly noticeable as musical tones, but they combine to produce the distinctive sound of any instrument. If the microphone's frequency response is too limited to capture most of those overtones, it will result in an inferior tone. This is exactly the case with mobile phone microphones. They can receive and transmit speech with enough clarity, but music is heard as thin and harsh. That's because the phone's microphone (usually an inexpensive electret condenser microphone) is designed only to capture the relatively narrow band of frequencies that speech requires in order to be intelligible. It's not designed to capture the very high and low frequencies that music requires. For high-quality music recording, good frequency response is essential.
Transient response refers to how responsive a particular microphone is to abrupt changes in sound. For example, striking a piano key will cause a microphone's diaphragm to respond almost instantaneously. There's always an avoidable delay, however. The longer the delay, the less accurately the microphone captures the rich initial transient sounds of the piano key. These transients are brief and fleeting, but they give the piano tone its distinctive initial attack, which is an essential component of its sound. This applies equally to many other instruments too. Vocals have rich transients too, especially when sibilant sounds are sung or spoken. A microphone with poor transient response will be unable to capture those transient sounds accurately. The result is a vocal tone that is less rich and lacking presence. Small-diaphragm condenser microphones have the best transient response of all standard microphone types. In some situations, their high transient response may be unwanted if it emphasises sibilant sounds too much.
Most standard, general purpose condenser microphones are omnidirectional. They pick up sounds approaching the microphone from any direction. While this may be useful in certain situations, there are many more situations where it's a disadvantage. Using an omnidirectional microphone to record a musician performing in a pub, for example, will produce disappointing results as it will pick up as much crowd noise as music from the performer. Unidirectional condenser microphones by contrast are designed to be significantly more responsive to sounds approaching from in front of them than from the sides or from behind. They can literally be aimed at the performer and cut out much of the extraneous background noise. Unidirectional microphones, whether condenser or another type, are often referred to by the term cardioid. This refers to the heart-shaped diagram that shows how sensitive a particular microphone is to sounds coming from any direction relative to its axis.
Negative Aspects of Condenser Microphones
No microphone type is perfect and that includes condenser microphones, despite the high praise often lavished upon them. They are not the most robust of microphones and are sensitive to moisture. That means they are better-suited to operating in controlled environments such as recording studios. They are less well-suited to live stage performances where more robust designs are advisable. Dynamic microphones tend to be preferred over condenser microphones for live performance work not only because of their more robust design, but also due to their resistance to moisture and their lower susceptibility to unwanted feedback.
Condenser Microphone Reviews
Printed specifications present the cold, hard facts about a condenser microphone's technical characteristics. Personal reviews from owners of a particular model, however, can often give a more insightful opinion gained through experience of using a particular microphone in a variety of situations. There are many review sites online where current and previous owners of any model of microphone are happy to give their opinion on it. These can be very useful, especially for someone wanting to know how well a particular model of condenser microphone performs in very specific situations. Reviews for any particular microphone can, in most cases, be found by entering the manufacturer's name and the model number followed by the word "review" into any search engine.
A high-quality condenser microphone that has been kept in good condition can be expected to perform as well as it did when it was new. This makes buying a used condenser microphone an attractive option as they will be more affordable. Anyone buying a used microphone should try to ensure that it actually has been handled with reasonable care and no intermittent faults are present as a result of damaged connectors or loose components.
How to Find Condenser Microphones on eBay
There's usually no shortage of condenser microphones available on eBay. Finding them is a simple matter of delving into eBay's Pro Audio Equipment category, which is a subcategory of their Musical Instruments main category. The option to filter the list of all but condenser microphones will appear as a check-box under Types. The list can be further tailored to group condenser microphones by manufacturer, price range, condition and more.
New microphone technologies are constantly being tested and developed, and some promising new designs featuring lasers and fibre optics are already available. It may well be that one such design will beat all others but, for now, condenser microphones are the dominant type. Their excellent characteristics and stability make them the microphone of choice for high-quality professional use in studios and in many other situations.