Saturday 20 October 2007

The Audio Technica BP4027














As part of my Media Broadcast course, I was required to find out about a microphone of my choice.
My group chose the Audio Technica BP4027.
Audio Technica BP4027 Stereo Shotgun Microphone

Name, Make, Model, Price and cost?

Audio Technica BP4027

$734.63 : Full compass

$1000.00 : Audio Technica direct

$852 : Performance Audio

*This particular model does not seem to be readily available in the UK.

What type of Microphone is it?

The AT BP4027 is a variation on the classic ‘shotgun’ - type microphone.

The ‘Shotgun’ microphone is so-called due to the shape and size of it’s body. The classic shotgun microphone uses two key features to achieve a very focused ‘pick up’ or ‘polar pattern’. The first is the way in which the ‘in-line’ element (this mic has two elements) is housed in the centre of the long, tube-like body. Grooves are placed along both sides of the Mics body, this allows the process called ‘wave cancellation’ to take place. Through wave cancellation, sound that has been picked up from the rear and side of the microphone will be mostly eliminated or reduced to be so faint as to not be audible to the human ear.

This microphone is condenser microphone, which means that it needs an external power source, Phantom power is the most likely to be used. The 4027 can be switched between ‘Stereo Wide’ and ‘Stereo Narrow’ modes. As the names suggest, this allows the pick-up range to be modified to some degree when the microphone is being used as a shotgun microphone.

The BP 4027 contains two elements, the second being an omni-directional (or ‘figure of eight’) type. A ‘bass roll-off’ switch is present on this microphone. This is used to cut off lower (hence ‘bass’) frequencies.

Application(s)

When the 4027 is switched into its in-line element, it is then best used in the same manner as a classic shotgun microphone. Any situation that requires the recording of a very specific sound source will benefit from the use of a microphone of this type. Common uses are outside recording projects, such as wildlife/animal programs where a lot of external, background noise such as wind and rain is present. The shotgun microphone allows focused recording from a distance, this can be very useful when working with video, and you are taking a wide, open shot - the shotgun will let the operator focus the audio recording, while keeping the camera out of view. This situation would be very common in the movie industry. As was mentioned earlier, this microphone can be switched between ‘wide’ and ‘narrow’ modes when being used as a shotgun mic. This allows greater flexibility and more potential uses.

As mentioned earlier, the BP4027 has two elements which are defined using the built-in switch. When this microphone is set to ‘omni-directional’ mode, it allows the operator to use the 4027 in a wide range of situations, where a stereo microphone is prefered; field acquisition, sound effect recording, live events, news gathering and one-on-one interviews (as both parties will be equally picked up without moving the mic during the session).

Connectors
This microphone uses a 3-pin XLR connector type. This type of connector is almost always ‘balanced’. The use of balanced audio connectors allows for a (potentially) better quality recording, as background noise that is picked up during its ‘signal flow’ is greatly reduced by using a process known as ‘Phase Cancellation’.
A common XLR cable has both a male and female connector. The male connector is comprised of three pins. The female connector has 3 sockets. On virtually all microphones that use the XLR connector type, the microphones connection is of the male type.

There are several variants of the XLR connector. However it is the 3-pin variety that is most commonly found in the audio world. The 4-pin XLR is often used in the telecommunications industry. The 5-pin version is most commonly found in Pro-Lighting equipment.

Polar Pattern

In regards to microphones, the ‘Polar Pattern’ is a representation of a microphone sensitivity to sounds arriving at differing angles around it’s central axis point. Different types of microphones will have different polar patterns - each relative to the job(s) it is intended for.

Cardioid









Shotgun









Omni-Directional









*The circle in the centre of the diagram represents the central axis of the microphone. The further from the centre of the graph is, the stronger the mic signal is from that direction.

It is important to note, that the above examples of polar patterns are ‘perfect world’ scenarios.
In reality, a microphones polar pattern is very likely to be much more uneven and disjointed than those above. Below is the polar patterns for the BP4027 - taken directly from Audio Technica’s website.



















Pro’s and Con’s of its Design V.s Application.

The BP4027 allows much more possibilities than your normal shotgun microphone. It is solidly designed, and its manufacturer is very well known in the Pro-Audio world for producing good quality, well built microphones.
However, it’s polar pattern shows that it is not the best uni-directional microphone on the market. It does have a large amount of ‘bleed’, this could be a very serious issue if you really need a tightly focused shotgun mic.
It may very well be a better idea to purchase a cheaper Uni-Directional mic, and a Omni/Cardioid microphone seperately.
Frequency Response.

The “Frequency Response”, as the term suggests, is the name given to the way in which a microphone responds to particular frequencies.

To find out the frequency response of a microphone, “white noise” is used. White noise is a sound which consists of equal quantities of all frequencies.
The microphone in question, is used to record white noise from a single source. The output of the microphone is then fed into a type of oscilloscope called a “Spectral Analyzer”. This machine is used to help the user examine spectral composition of a signal that has been routed into it. The results of the Spectral Analyzer are then used to produce a ‘frequency response table’.

Below, is the frequency response table for the BP4027;














As can be from seen from the above example, the frequency response table has two axis.
The ‘x’ axis represents the microphones response, which is measured in decibels (dB). The ‘y’ axis represents the frequency range that the microphones response was tested against.

The frequency response table allows the user to quickly and easily see what a microphones particular strengths (if any) are. And is one way of telling if a microphone is going to be a good choice for the job in hand.

A lot of microphones (including the 4027) have “bass roll-off” switches, which allow the user to define wether the microphone picks up frequencies of below a certain point. This is usually shown in the frequency response table as it is above - with a dotted line (as the Legend suggests).

Some people/sources say that the perfect frequency response would show on the table as a straight line - that is to say that the microphone responded to all frequencies in the same manner.

Others say that the ‘perfect’ frequency response is a myth, as the perfect response all depends on the job in hand.

SOURCES
Price;

Using “froogle”, which is a Google based shopping search engine. I have given prices, and links to those prices under the title “Name, Make and Model”



A Future Music (popular UK music production magazine) web-Blog review

Audio Technica’s own website

PerformanceAudio.com

Wikipedia; XLR connectors

Microphones

Wave cancellation

I got a lot of information on Microphones by using one of Paul Whites books “Studio Recording Basics B” (non-internet source)


Synthopia

Crown Audio

Record Producer.com

I also used notes that i had taken from my previous Music Production course.

I thought the above sources were good to use, as they have a good reputation in the audio world. Having said that , I always make sure that I take care to cross-check anything I find on Wikipedia, as it sometimes can be very wrong. It is always a good idea to check the ‘Discussion’ page, to see if there is any areas of disagreement.
With microphones, the basic information is very often presented in the form of a ‘data sheet’, which gives the microphones technical specifications. Using these, it is very easy to cross-check information, so you can be sure that the information you have is correct.
For a non-internet information source, I used the book by Paul White “Studio recording Basics B”. Paul White is a very well known figure in the music technology industry and has written many books on the subject. I have always found his work to be very good, and hold a lot of confidence in that what he writes is correct.






1 comment:

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