A Quick Guide To The World Of Sound

Contents:

· Handling Audio Gear

· Catalogue Of Gear

· Microphones

· Audio recording equipment

· Mixing hardware

· Accessories

· How To Use The Edirol Recorders

Handling Audio Gear

The fundamental rule to audio equipment is NEVER DROP IT.

-Cables-

Usually cables are more durable nowadays and can combat being beaten up a little as long as they aren’t coming into contact with any sharp objects that can slice into the protective casing or completely cut the cable. Cables should not be tightly wrapped as this can snap the inside wiring, this is commonly seen with chargers as the user has wrapped the cable tightly around the power pack.

Two Cable Pro Tips:

1. When wrapping a charger, on the first wrap, let the wire have a little bit of slack this will stop the protective wrapping from breaking.

2. One of the most common wires in audio is the XLR cable known by the 3 pins in the adapter. The best way to wrap these cables is to hold one of the ends in your fist, then assume a power grab position. Proceed to wrap the cable under your elbow back to your fist, and repeat.

-Microphones-

No microphone should never be dropped, however some microphones are more sensitive than others. The two types of microphones are Dynamic and Condenser. The main difference is that dynamic microphones don’t need power from a pre amp. However condenser microphones need an additional 48 volts of power to allow the microphone to pick up signal. Microphones rely on movement of a magnet and coil that vibrates when sound interacts with it, producing a small electrical signal. Dropping the mic damages the magnet and coil causing issues with sound.

When recording its best to understand polar pattern. A polar pattern is a diagram explaining where the microphone will pick up sound from.

The three most common polar patterns are:

· Cardioid

· Omnidirectional

· Figure of 8

Cardioid is the most basic type of microphone and will usually only pick up sound in front of the microphone. Whilst there are different types of cardioid microphones the only difference is usually how good they are at rejecting feedback and ambient noise.

Omnidirectional is the polar pattern used to capture sound all the way around the microphone in a 360 degree field. These are usually the most sensitive are are usually condenser microphones. The issue with omnidirectional mics is that they are very prone to feedbacking and you can’t really aim this mic away from unwanted sound sources.

The best way to explain figure 8 microphones is to imagine two cardioid mics attached together back to back, facing away from each other. This a great way to capture audio for an interview video for example, allowing the recording of multiple sound sources whilst cancelling environmental sounds.

Our Rode NTG-1 is a shotgun microphone so it's more sensitive to sound sources in front of it. Due to its polar pattern, it can negate quite a lot of background noise. Paired with the “Dead Cat” wind diffuser it can cut out a lot of sound.

Common uses of shotgun microphones are for talks or speeches in meetings, conferences, and lectures. In scenarios such as these, the speaker does not need to hold a microphone and speak into it or wire a microphone on his body in order to record his speech or lecture. He can just stand and talk at a distance as long as he talks to the front of the shotgun microphone. This way, the speaker can just focus on talking during his lecture without the cumbersomeness of having to have a microphone on him.

The microphone is connected via an XLR cable, the XLR is most commonly seen with a 3 pin connector, The three pins are positive, negative and earth. The earth wraps around the positive and negative to reduce interference into the wire and loss of signal.

-Optimal Mic Placement-

Obviously the mic needs to be pointed at the sound source you want to record but different mics can pick up sound sources in more than one way.

Shotgun mics need to be concentrated onto the sound source, distance is required otherwise they are prone to peaking, this is why they are usually used as boom mics.

The edirol and tascams have stereo microphones for left and right. This is often used for those 3D sound experiences on the internet. They also record mono. Having a mono recorder with two microphones allows you to record table interviews clearly and layering the audio with say audio of say the NTG-1 gives the audio depth.

Mic placement highly depends on the sensitivity of the mic and its directional sensitivity and this can range from brand to brand so i highly suggest studying the polar patterns on the mics we have.

-Environments-

Choice of environment is very important. Is the recording is taking place in a public place expect unwanted noise. Establishing where you want to record the audio for a film will tell you what audio equipment you should used.

For example if you were recording in a church, there’s two scenarios. You want the setting of a church but clear audio (music video), or you want the environment of the church and pick up the ambience.

For the first scenario you would want microphones that don’t pick up sound sources other than the sound from in front of the microphone, much like the Rode NT1 and the Lavaliere microphones.

For capturing the natural reverb of the building i would recommend using a lavalier mic to pick up the main sound source and then have the tascams near the sound source but they will pick up the ambience. In the editing have the tascam tracks lower than the source to add body to the sound.

-Feedback, Bleed and How To Stop It-

Feedback happens when a microphone picks up its own signal when it’s amplified. To stop this point the mic away from the amplified sound source.

As someone with experience working in a music studio trying to stop audio bleed from mics (especially drums) becomes quite difficult. This leads to some crude looking but great improvisation techniques like using polystyrene cups to isolate the heads of mics, making standard microphones into a more directed microphone.

-Mixers-

The issue with mixers is that most mixers are made with very cheap plastic knobs, these if not kept in its bag that it came in or in a suitable position on a desk, the will inevitably come off. Try not to spill any liquids on the equipment.

When using the separate recorders like we do with them each having separate SD cards there’s no point using a live mixer. It is going to limit the placement of microphones, the only reason i would consider using a mixer would be if we had recording devices that didn't save, id run the mics through the mixer and then record the audio from the mixer. But since we use the Tascams, they work perfectly separately. The mixer would just do what we do in post editing anyway.

Id recommend using the mixers during the sound editing process but even then this is really not needed. The mixers we have are pretty much luxury items, only adding more work to something that was simple to start with.

Catalogue Of Audio Equipment

· 2x flip cameras

· 2x edirol recorders

· Behringer xenyx mixing desk

· Rode NTG-1

· Rode Shotgun Mic

· 2 Tascams

How to use the edirol recorders

The back of the edirol removes to reveal two AA battery ports. However the edirol can work with DC power. On the back of the recorder you can switch it to work on either the batteries or the DC power.

The hold switch stops any pressable buttons from working. This is so no buttons can be accidentally pressed when recording etc.

Limiter/AGC is the auto gain control meaning the device will automatically cater to low level sound and boost it, while reducing loud sound.

Low cut refers to the process of cutting frequencies from the audio spectrum. We can hear 20Hz - 20KHz however audio that falls between 20 Hz - 200 Hz in general sounds very muddy so low cut helps when recording music or singing, but can also clean up speech. There is an option in the settings menu to change the low cut to up to 400 Hz but this is usually unnecessary.

Mic gain adjusts the general sensitivity of the microphone.

Before starting a recording ensure that the batteries have enough battery life and ensure that you have enough free space on the SD card. Insert SD card

In the settings make sure you’re using the correct sample rate, this is found in the recorder setup menu. The standard sample rate is 44.1kHz, this is to do with how sound waves are processed, because the average max frequency a human can hear is 20 kHz we sample it at double the Hz to capture the peaks and troughs. (Up and down bits of a wave)

It’s important to match the recording sample rate to the audio processing sample rate in the audio editor. A miss matched audio sample rate can stretch or squash the audio file making it sound slower of faster and trying to delete any artifacting in the audio is a lot of work that could have been avoided. This is the same for bit rate matching, bit rate affects the processing of amplitude of a wave. Just a quick check that the audio sample and bitrate is matching is gonna save hours of work...

48kHz is the industry standard sample rate anything higher is usually for mixing high quality sound files. You can go to up to 192 kHz but that’s generally for mixing movie orchestral soundtracks. Not saying you can't record at a 192kHz you will just need a lot of processing power and a lot of storage. I mean a lot.

RodeLink Receiver and Transmitter Lavalier Microphone:

Transmitter:

The transmitter takes two double A batteries. To take the back off the transmitter to insert the batteries press the button on the back, at the bottom of the transmitter and slide down. Note; the back does not come all the way off. Insert the batteries at a 10 degree angle and inserting them at an angle greater than this damages the springs.

THE FRONT DOES NOT COME OFF.

When the back of the transmitter is slid down you have access to the gain control and sync button. The gain control allows you to add +10DB and +20DB. The sync button (red) is used for pairing the transmitter to the receiver.

Connect the microphone to the transmitter using the 3.5mm jack port.

To power on the device hold the power button down until the number 1 is shown. To mute the device tap the power button once, the led on the power button will go red indicating that you have muted the device (this will be shown on the receiver as well). The number will flash if it the transmitter is not connected to the receiver.

To power off, hold the power button.

Receiver:

The receiver has the same power up procedure and the same buttons when the back is removed.. The receiver has a dedicated mute button and has a channel button. We won't need to use the channel button because we only have one transmitter.

On its side it has the line out that will connect to the DSLR camera.

You can attach the receiver to the DSLR camera using the shoe mount on the back of the receiver.

Lapel MIc Placement.:

The mic is very sensitive, meaning it will pick up ambient noise, try and position the mic as close to the sound source as possible as the receiver has an auto gain function that confuses the ambient sound as another speaker. As it tries to adjust the ambient noise the main sound source you try to record increases and decreases in level, this is not good.

Position the microphone on the person so nothing is going to hit or touch the mic. Especially beards...