In the previous delivery it was possible to appreciate the difference between the elements the dynamic and the condenser. I recommend studying the microphones of tape (ribbon, ribbon), piezoelectric (used in electric guitars) and contact microphones.
Juan Tamayo, CTS *
Dynamic microphones and condenser have many applications, both in the professional music industry and in the professional installation industry. But, undoubtedly, the most used capsule is the capacitor.
The polar pattern defines the intensity with which the sound is captured in a microphone depending on the angle with which it arrives, basically it is the way the microphone listens depending on where the sound comes from. There are several types of polar patterns, the most common are: omnidirectional, cardioid, hypercardiode, line + gradient and figure in eight. Due to a marketing issue, a sub-type of sub-patterns such as the sub-cardioid or semi-cardioid among others have been created. But basically these are patterns that try to be cardioid, but do not reach to meet the technical requirement.
The names of the polar patterns are applied according to the acquisition angle generally given in the 1 KHz frequency. Omnidirectional corresponds to a listener of 360 °, cardioid to 120 °, hypercardioid to 100 °, line plus gradient 90 ° and figure in 8 listens to both sides of the capsule, generally 120 ° each, but there is no or I do not know a definition of your coverage in degrees. The reader should be very careful since the information provided by some manufacturers may not include the polar pattern at other frequencies. For example, a cardioid microphone in 1 kHz can be omnidirectional at frequencies close to 250 Hz and hyper cardioid at frequencies close to 8 KHz.
The polar pattern has associated physical phenomena. One of the most important is the rear capture angle, this means that the narrower the angle of capture of a microphone, it is possible that behind the capsule enter sound. A cardioid microphone does not have this problem, but a hypercardioid does. A clear example of this occurs when in a scenario they put a return right in front of the singer and this has a hyper cardioid microphone, there is a great possibility that there is the phenomenon of feedback or feed back, so it is recommended to put the angled monitors on the stage. On installation systems I have seen this problem a lot when they install sky microphones just below a sky speaker.
A physical phenomenon that can be useful when using a microphone is the distance factor (DF). The DF refers to the comparison of sound pressure according to two similar capsules with different polar patterns. Everything is done in comparison to omnidirectional and tells us about how equal in volume captures a microphone with another capsule if you move it away from the initial omnidirectional microphone location.
For example, I have two microphones with similar sensitivity and impedance, but one is omnidirectional and the other hypercardioid. If the sound source is one meter away from the omnidirectional microphone, so that it sounds as hard as the hypercardioid microphone should be at 2 meters away. In other words, if I bring the hypercardioid microphone close to a meter away, I can attenuate the gain to equalize the volume. In conclusion, with a more closed pattern it is possible to use less gain, which will optimize the process of adjusting the chain during the transmission of the audio signal.
Polar pattern construction
There are two ways to create a polar pattern, a mechanical and an electronic form (the ambisonic microphones are a mixture of these in several stages). The mechanical form has different techniques, but basically they are given by the difference of sound pressure in the capsule. The electronic form is a technique widely used in microphones with a variable polar pattern, such as the AT4050. Two capsules or more, that by changing the feeding of these, changes the capture form of the pattern.
* Juan Tamayo is a senior applications engineer for Audio-Technica Latin America, with more than 10 years of experience making audiovisual projects as a designer, integrator, consultant, among other functions. You can write to email@example.com