Condenser Mics
Technology
Condenser microphones work on the principle of a variable capacitance (condenser is another word for capacitor). The condenser mic has a thin film membrane, the diaphragm, stretched across a metal disk, the backplate. The membrane is coated with a very thin layer of gold. A voltage is applied across the capacitor formed by the gold plated membrane and the backplate. This voltage is why condenser mics require "phantom power". The phantom power supplies this voltage charge across the membrane, and the sound is produced by movements of the membrane creating a change in capacitnace that results in an audio signal. Condenser micrphones are very sensitive and able to respond well to a broad range of frequencies. This is why they are the type of mics associated with the highest quality microphones.
Examples:
The sensitivity and wide frequency response of condenser microphones allow them to be considered as the universal choice for recording. Many venerable designs have been used on recordings for many decades. Mics, such as the Neumann U87, are icons of the recording industry, and are the go-to mics in many situations.
In our current times, with global manufacturing, prices have come down on condenser mics in general, and there are many affordable options for recording, such as the Rode NT1, AudioTechnica AT4040, and the Lewitt LCT 440.
And for very demanding applications, there are mics such as the Earthworks QTC30, and QTC40, which offer precision, high resolution, audio recording where no compromises are desired.
In 1967, Neumann introduced a new version of their U67 tube condenser microphone, the solid-state U87, which uses an FET (Field Effect Transistor) circuit and is phantom powered. Engineers, producers, and artists all feel in love with the U87. Consequently, by the mid 1970s the U87 was already a defacto standard in the recording industry. It can be found in every commercial recording studio.
Note:
In the 1970's, the Neumann U87 was so popular and desireable that they ran the following simple ad in recording industry publications.
Affordable Mics
Not everyone can afford a Neumann U87. Luckily, there are quite a few microphones available that provide very good quality for significantly less. In fact, you can pay as little as $100 for a large diaphragm condenser microphone. One example if the Audio-Technica AT2020, which gives repectable results at a modest price. A step up from there is the Lewitt LCT 440 PURE, which gives a more nuanced sound while still being affordable.And, if your budget allows for $1000, there is the AKG C414, which is possibly the second most desireable microphone in any studio. Similar to the U87, the C414 will work well on almost any source! It is great for vocals, instruments, room mics, overheads, etc. So, naturally, the C414 has been very popular since introduced around 1971. It has had several iterations, but all of them have been staples in most studios, and are always near the top of the list when engineers pick their "desert island" mics.