This is a report regarding the AKG 'C 4000 B' multi polar pattern microphone...Make: AKG
Price: £229
Application: Concert hall, strings, vocal, brass, acoustic and general music recording.
Dynamic: We can apply uses in different types of recording to this microphone judging by it's polar pattern. The variable polar patterns of this microphone being omnidirectional, cardioid and hyper-cardioid means that this microphone can pick up general sound from all angles (omnidirectional), specific to one angle (cardioid) and extremely accurate to one angle (hyper-cardioid).
This means that this microphone can be used for almost all types of recording, it is however usually advised to be used when recording instruments or voice. This is due to it's polar pattern being able to pick up sound from all angles and the ability to hone in to one direction (recording a single instrument or voice).
Polar Pattern and Frequency Response Curves of the 'AKG C 4000 B'
(Diagrams from the unit's user manual)
Polar Pattern
A microphone's directionality or polar pattern indicates how sensitive it is to sounds arriving at different angles about its central axis. How the physical body of the microphone is oriented relative to the diagrams depends on the microphone design.
Some microphone designs combine several principles in creating the desired polar pattern. This ranges from shielding (meaning diffraction/dissipation/absorption) by the housing itself to electronically combining dual membranes.
An omnidirectional microphone's response is generally considered to be a perfect sphere in three dimensions. In the real world, this is not the case. As with directional microphones, the polar pattern for an "omnidirectional" microphone is a function of frequency. The body of the microphone is not infinitely small and, as a consequence, it tends to get in its own way with respect to sounds arriving from the rear, causing a slight flattening of the polar response.
A unidirectional microphone is sensitive to sounds from only one direction. The sound intensity for a particular frequency is plotted for angles radially from 0 to 360°. (Professional diagrams show these scales and include multiple plots at different frequencies. These diagrams just provide an overview of the typical shapes and their names.)
The most common unidirectional microphone is a cardioid microphone, so named because the sensitivity pattern is heart-shaped. A hyper-cardioid is similar but with a tighter area of front sensitivity and a tiny lobe of rear sensitivity. These two patterns are commonly used as vocal or speech microphones, since they are good at rejecting sounds from other directions.
(Wikipedia)
This source, like all wikipedia information is only semi reliable. We can only assume that the author know what they are talking about in regards to the Microphone's polar pattern. The source does however match information I have collected from other sources, we can therefore assume that it is truthful.
“A microphone that is equally sensitive to sounds coming from every direction is called an omni-directional pick up pattern. The smaller the microphone barrel is, the higher would be the frequencies up to which it would tend to remain omnidirectional. An infinitely small microphone of this type would be omni at all frequencies.
The other basic design, the original "classic" ribbon microphone, placed the ribbon within a magnetic gap. Of course any sound approaching it from either the front or back would cause the ribbon to vibrate in-sync with the sound. Sounds approaching the ribbon from anywhere in the plane across its middle would tend to encounter the ribbon with equal effect on both sides causing little or not motion of the ribbon and hence little or no electrical output."
(Live Sound Reinforcement. by Scott Hunter Stark. 9th edition 2004)
I'm confident that this source is accurate as it came directly from a book regarding sound recording and what equipment to use.
“The AKG C 4000 B is affordably priced to make it attractive mainly for small home and project studios. Its design provides 3 different polar patterns (omni, cardioid, and hyper cardioid) selectable on the microphone, making it suitable for many applications, even live sound.”
(Musician's Friend Website)
This source is taken from the above website. Being a company who specialize in instruments and recording equipment, we can assume that their information is factual. This website has been awarded 45/45 on satisfaction and low prices.
Frequency Response
This Microphone's Frequency Response is: 20 to 20,000 Hz
Frequency response is the measure of any system's response at the output to a signal of varying frequency (but constant amplitude) at its input. In the audible range it usually referred to in connection with Electronic amplifiers, microphones and loudspeakers. Radio spectrum frequency response can refer to measurements of coaxial cables, category cables, video switchers and wireless communications devices. Subsonic frequency response measurements can include earthquakes and electroencephalography (brain waves). The frequency response is typically characterized by the magnitude of the system's response, measured in dB, and the phase, measured in radians, versus frequency. The frequency response of a system can be measured by:
applying an impulse to the system and measuring its response.
sweeping a constant-amplitude pure tone through the bandwidth of interest and measuring the output level and phase shift relative to the input
applying a signal with a wide frequency spectrum (e.g., maximum length sequence, white noise, or pink noise), and calculating the impulse response by deconvolution of this input signal and the output signal of the system.
simply measuring the output of a system where an input signal isn't practical.
If a system is demonstrated to have a poor frequency response, a digital or analogue filter can be applied to the signals prior to their reproduction to compensate for these deficiencies.
Frequency response curves are often used to indicate the accuracy of amplifiers and speakers for reproducing audio. As an example, a high fidelity amplifier may be said to have a frequency response of 20 Hz - 20,000 Hz ±1 dB. This means that the system amplifies all frequencies within that range within the limits quoted. 'Good frequency response' therefore does not guarantee a specific fidelity, but only indicates that a piece of equipment meets the basic frequency response requirements.
(Wikipedia)
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