5 More Pre Production Location Sound Recording Basics (Part 2)

As I am a generious guy I thought I would bash out part 2 of pre production basics (meaning essencials and at the very least)
read part one of 5 pre production basics part one

6. Double system 99% of the time
Unless this is a run and gun documentry or live broadcast location news then you probably have the freedom to easily slate and thus easily sync sound from a seperate sound recording device. The double system gets its name because you have one system for visuals and one for sound (according to my understanding)
This has many advantages such as easier capture for wildtracks, better quality recording due to higher quality specific sound recording electronics and wiring, more flexability to be out of the cameras way and less interference from longer cables, balanced or otherwise.

7. Order of priority
Equipment wise, your only as good as your weakest link and many other metephors a side, the equipment is of this importance as it works in a chain, obviously if anything in this chain is terrible then bring that up to the level of the others.
Your first link is the microphone/s its self, this will determine the amount of electronic current that needs amplifaction, the quality of the frequency response and how much other sound outside the polar pattern will be discrete (blocked).
Next is the mixer of some sort (please not just your camera!) Where it will be able to amplify the microphones electric voltage differences to acoustic energy and the better the pre amps and limiters the better the signal to noise ratio and the less your likley to peak and distort any unwanted, un expexted loud sounds.
Finally the recording device which is last because thankfully you have a good mixer doing most the leg work, dont you :-), this allows the freedome of the double system mentioned earlier.
Also dont forget to get balanced cables (refer to glossary) and the fewer cable to cable connections the lesser the chance of interference and noise being amplified with any recording. along with a good support for your microphone on a boom pole so you limit handling noise.

8. Information is only potencial power
Grab as much information on storyboards and floor plans and sizes of rooms and whats near by the location referring to the script. This could save you loads of time on the day in regards to descision making and mike placement, we both know its never exactly like the plan but better to have a guide!

9. Be ahead of the game
Referring to the edit, before hand you can draw up lists for wildtracks and sound effects which could be benificial to the troops in the edit. On another small note: REMEMBER ROOM TONE/ATMOSPHERE RECORDINGS FOR EVERY LOCATION. It's kind of useful, do at least 15 clean! seconds

Finally Number 10. Fail to plan, plan to fail
Not all these elements might be relevant to the situation but it does save you time in the long run and sets a good solid foundation for the edit. After we are part of a bigger creative team to achieve a great end result and just by reading articles like this you know it's more than a job but a lifestyle especially in independant low budget projects. :-) happy days.

Thanks.and comment or share below

Matt Price

Quick Note About Digital Microphones...

As we know, or should by now, analogue microphones are based on the same concept as our ears, this is the most effective way to actually hear because sound waves have no formula when it comes to multiple sources and are all added together depending on so many different circumstances that it is impossible to hear digitally, unless we get a chip in our brains to convert it some how it is a long long way off....

So what are digital microphones?

These beauties like the Shoeps SuperCMIT are really the future. They still are not completely digital for reasons above but have a digital transducer instead of going all the way down analogue cabling to be converted. This allows the signal effectively at source to be effectively set up so then your mixer/recorder can do even more with it in terms of collecting that sweet sweet sound.

So keep a look out for them because they will slowly become the norm, after all your not recording onto DAT tape i bet.

Thanks,

Matt

Microphone Polar Patterns...

This outlines the types of polar patterns. Polar patterns are the field of focus that the microphone will pick up due to the position of the diaphragm and other factors.

0 degrees is straight infront of the microphone, 180 degrees is directly behind the microphone

Omni Directional
This encompasses a field of all directions, or nondirectional. In theory it should be a perfect sphere but because the microphone its self is not infinitely small it gets in its own way, just like if it was on a persons body. So the smaller the body the better the polar pattern. The wave length of 10Khz is 3.4cm so small microphones are effective at even high frequencies.


Cardiod

This is the most common unidirectional microphone. There is a dip at the back due to the microphone casing and the direction of the diaphragm. A Sub cardiod is similar to the omnidirectional polar pattern but flatter. and Super and Hyper cardiod have tighter patterns compared to the basic cardiod pattern, but they add more sensitivity to the cardiod because of there higher sensitivity.

Shotgun

These are the highest directional microphones. They have small fields of sensitivity to the left, right and rear. This is still significantly smaller than other directional microphones. This is the most common on film sets for booming over subjects.

See Also: Condenser Microphones, Dynamic Microphones and Carbon Microphones.


images are free to reuse via wikipedia

Thanks,

- Matt Price

Parabolic Refectors

A Parabolic microphone is a microphone with a parabolic reflector fitted to it. This collects and focuses sound on the microphones head like a TV dish picks up satellite signals. This has many advantages for picking up and amplifying distant sounds that you want to isolate from the rest of the environment. A classic example is bird song because parabolic reflectors are very good at picking up high frequencies. this is also used in sports broadcasting, eavesdropping and espionage. 

The high frequencies are picked up more due to the direct physical laws of sound waves. This is because they only focus waves with a wave length much smaller than the diameter of the parabola. To obtain hi-fidelity sounds including the lower end frequencies (down to 20Hz) you need a parabola around 17 metres. This is because if we say the speed of sound is 342 m/s through the air (speed of sound) 342 ms / 20 Hz = 17 metres. Parabolic reflectors will sacrifice the lower end frequencies to be more manageable sizes.

Representation of how a reflector works with microphone facing the central point  for maximum pickup.

Thanks,

- Matt Price

Q+A: How Do Carbon Microphones Work?

• The carbon microphone is seen as a simple device to turn sound into electronic signal. Some examples of their use where in telephones, radio broadcast systems and the popularity was at a peak around the 80's. These where eventually replaced by more powerful and less noisy microphones. Some are still used today due to their durability and working in low power environments.

  The tapping of microphones came from this microphone as the carbon atoms would get stuck together sometimes and so needed to be hit to separate them to ensure the microphone worked properly, this is still carried on today even though there is no advantage compared to just talking into it.

• With reference to the diagram below. Carbon is a resistor, which isn't very efficient at conducting electricity as it tends to resist, hence being a resistor. A current runs from the diaphragm which is the first plate, through the carbon to the other plate. The carbon molecules normally resist it somewhat, lowering the power flow. When a sound wave pushes down on the top plate, however, it squeezes the carbon molecules more tightly between the two plates. This increases their conductivity, creating more electric current. As the plate moves up and down with the sound wave, the current increases and decreases, creating an electric wave in the shape of the sound wave.
  
  
  

  

  Grey Circles = Carbon Granules - Diaphragm (flexible electrode) moves, changing signal output strength

  If you feel i have missed anything or want to comment feel free.

• • Thanks,

    - Matt Price

Q+A: How Do Dynamic Microphones Work?

With reference to the diagram below a dynamic microphone has a thin diaphragm attached to a coil of wire, which in turn is surrounding a magnet. When sound waves vibrate the diaphragm this vibrates the coil and the difference on the magnet translate to current in the wire and then goes to an external device or speaker. The speed of vibration determines the current and the resulting sound.

Dynamic microphones are generally used for live events such as concerts. This is due to the fact unlike the condenser microphone, it has a low sensitivity and can handle a lot louder environments.

Any questions or feel i have missed anything please comment below,

Thanks

-Matt Price

Q+A: How Do Condenser Microphones Work?

The word condenser actually means capacitor. A capacitor is a common electrical component which stores energy in the form of an electrostatic field. The capacitor allows acoustical energy to be converted to electrical energy.


The electrostatic field needs external or battery power to be created, the image below illustrates that this field is created between the two plates of the diaphragm and the back plate. As the diaphragm is moved from sound waves the change in the electrostatic field information is sent to an external recording device and then amplified as the initial voltage differences are so small.

The resulting audio signal is stronger signal than that from a dynamic. Condensers also tend to be more sensitive and responsive than dynamics, making them well-suited to capturing subtle nuances in a sound. They are not ideal for high-volume work, as their sensitivity makes them prone to distort.

Feel free to comment for more information to be added or made more clear.

Thanks,

Matt Price