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The popular "electret" microphones of today are inexpensive and provide very good performance for just a few dollars. Often times they come with a fixed load resistor but I have discovered that by making that load resistor variable, the gain can be adjusted.
Below is a good description of condenser and electret microphones:
Condenser Microphones
Principle of Operation:
Condenser microphones operate on the principle of variable capacitance.
They consist of a thin diaphragm placed very close to a backplate. When sound waves hit the diaphragm, it moves, causing a change in the capacitance between the diaphragm and the backplate.
This change in capacitance is converted into an electrical signal.
Power Requirements:
Condenser microphones require an external power source, often referred to as phantom power (typically 48V) or a battery, to maintain the electrical charge between the diaphragm and the backplate.
The power source is necessary for both the capsule and the internal preamplifier.
Sensitivity and Sound Quality:
Condenser mics are known for their high sensitivity and excellent frequency response, making them ideal for capturing detailed and accurate sound.
They are often used in studio recordings for vocals, acoustic instruments, and other applications where sound quality is paramount.
Cost and Durability:
Generally, condenser microphones can be more expensive due to their complex construction and high-quality sound reproduction.
They are more delicate and less durable than dynamic microphones, requiring careful handling.
Electret Microphones
Principle of Operation:
Electret microphones are a type of condenser microphone but with a significant difference in how they are powered.
In electret mics, the diaphragm or backplate is permanently charged due to a material called an electret (a dielectric material with a quasi-permanent electric charge).
This eliminates the need for a continuous external power source to maintain the charge on the diaphragm and backplate.
Power Requirements:
While electret microphones do not require phantom power for the capsule, they still need a small amount of power (usually provided by a battery or a low-voltage power supply) for the internal preamplifier.
This makes them more convenient for portable applications.
Sensitivity and Sound Quality:
Electret microphones are also quite sensitive and have a good frequency response, though they are typically not as high-end as true condenser microphones.
They are widely used in applications where space and power constraints are important, such as in lavalier (lapel) mics, headset mics, and various consumer electronics.
Cost and Durability:
Electret microphones are generally less expensive than true condenser microphones.
They are durable and can be made very compact, making them ideal for use in portable and consumer devices.
Summary
Condenser Microphones: High sensitivity and excellent sound quality, require external power (phantom power or battery), often used in professional audio settings, and are typically more expensive and delicate.
Electret Microphones: A subset of condenser microphones with a permanently charged element, require less power, commonly used in portable and consumer applications, more affordable, and durable.
Both types of microphones have their specific uses and advantages, making them suitable for different audio recording scenarios.