Introduction to Gear and TermsWalking and talking

Today we are going to look at some of the standard equipment that we will be using throughout the course as well as some common terminology we will use.

We will look at …

CablesDevicesMicrophonesTerminology

Cables and Connections

We are going to look at the following cable types and some of there common uses .

Balanced and Unbalanced

TS and TRS

XLR

RCA

Musical Instrument Digital Interface

Universal Serial Bus

FireWire

Balanced vs Unbalanced

Cables are used to carry audio information in the form of electrical current through wire. This wire also functions as an antenna and can cause unwanted ‘line noise’.

Early phone companies discovered that over long distances this line noise increases. They developed a ‘shielded cable’ to combat these effects.

A shielded cable is built as follows…

Balanced vs Unbalanced

Unbalanced cables : can be shielded or not, and operate best with lengths of twenty feet or less. After twenty feet, there is a risk of picking up ‘hum’, ‘buzz’ or ‘hiss’, commonly called ‘line noise’.

Balanced cables: are shielded and allow for longer cable runs without creating noise.

They carry two signals 180 degrees out of phase, and when they reach the device it flips one signal and adds the two signals together eliminating noise built up.

Tip-Sleeve (TS) and Tip-Ring-Sleeve (TRS)

1. Sleeve: usually ground

2. Ring: Right-hand channel for stereo signals, negative polarity for balanced mono signals, power supply for power-requiring mono signal sources

3. Tip: Left-hand channel for stereo signals, positive polarity for balanced mono signals, signal line for unbalanced mono signals

4. Insulating rings

TS Cords

Also referred to as a ‘Mono’ cord because it carries only one channel or signal.

This cord is typically the cord connecting your instrument to you amplifier, your mixer to your power amp, etc.

The tip carries the signal while the sleeve carries the ground.

They come in different sizes. The two most common are ¼ inch(ex. guitar cable) and 1/8 inch cables (the size of an iPod cable).

TS Cables – Instrument vs Speaker

TS cables may look the same but can be wired different depending on their purpose.

Instrument cables carry a low amount of current and are susceptible to ground noise. They thus always have shield to help minimize this. They carry a ‘High Z’ or high impedance signal. Without getting scientific, long cable runs may result in noise and plugging into a low z input may result in distortion or loss of signal quality.

Speaker cables carry a larger amount of current and thus larger signal. They have two wires but no shield.

The large amount of signal covers any line noise.

TRS Cables

These cables are also called ‘Stereo’ cables because they carry two channels of signal.

They are generally wired with the left channel attached to the tip, the right channel to the ring, and the shield to the sleeve.

It is typically used to connect headphones or any device that plays back a left and right signal.

They come in different sizes. The two most common are ¼ inch(ex. guitar cable) and 1/8 inch cables (the size of an iPod cable).

XLR Cables

XLR Cables are most commonly used for connecting microphones, mixers, and speakers.

They have two ends, either male or female and carry a balanced signal.

They can also be called a ‘Low Z Cable’ as they carry a low-impedance signal. Without getting scientific this preserves the signal and reduces noise even at long cable runs.

XLR Cables

The left cable connector is a Female XLR, the right cable connector is the Male XLR.

The left pin ( pin1) carries the ground or shield.

The right pin (pin2) carries the Positive or Hot signal.

The bottom pin (pin3) carries the Negative or Cold signal. Cables can be made with any combination of

ends. You can have male to female, male to male, or female to female.

RCA Cables

Named for the Radio Corporation of America in the 1940’s

May also be referred to as ‘Phono plugs’

They are a very common connection on home audio equipment such as stereos and tv’s.

Our primary use will be using them to connect a tape deck to our mixer when needed.A

Musical Instrument Digital Interface

More commonly referred to as MIDI connections

They are 5-pin male to male connectors that exchange audio information between devices.

Common applications are synthesizers, drum machines, sequencers, sound modules, MIDI controllers, and even some guitars now.

Universal Serial Bus

Commonly called USB, it is a standard component in all computers and most computer hardware

USB has two different connectors: Rectangular Connector- called the A connector. This is for any

receiving device. Square Connector – called the B connector. This is for any sending

device.

USB 2.0 handles 480 Mbps

FireWire

Developed by apple and also referred to as iLink.

Used by many audio interfaces and hard drives for a very fast connection.

FireWire has the same connector on both ends.

FireWire 400 sends up to 400 Mbps while FireWire 800 handles up to 800 Mbps.

Devices

Next we will look at some of the devices we will use. Briefly we’ll describe the purpose of …

Mixers

Audio Interface

Direct Box or DI

Equalizers

Speakers

The Mixer

A Mixer is an audio device that controls the input, output, volume, and some parameters of audio sources for either playback or recording purposes.

There are several varieties of mixers: analogue desk, digital software, software with computer control surface, etc.

Think of a mixer as the ‘air traffic controller’ you would see at an airport. It communicates with all the signals to make sure they move quickly and efficiently so that they get to their destination without any problems.

The Mixer

On a mixer you will find a variety of inputs:

Microphone XLR Inputs – 3 prong XLR connections

Line/Instrument – ¼ inch jacks to accept Low Z signals

Hi – Z or Guitar Jack – designed to accept a Hi –Z signal straight from your guitar or other hi-z source.

Stereo Inputs – for accepting stereo sources or creating stereo sounds

Tape or RCA Inputs – for inputs from a tape recorder or use with an iPod

The Mixer

The mixer also has several outputs:

Most mixers have main outs for the main speakers, auxiliary outs for monitors, a tape out, and headphones outs

We’ll explore the mixer in depth later in the course

Audio Interface

The soundcard on most computers is ill equipped to handle incoming audio signals.

An audio interface manages the incoming signals from instruments, microphones, etc. It processes these signals to a format that the computer can handle.

There is a huge variety of audio interfaces on the market today, one of the most popular is the m-box for use with ProTools.

The audio interface we will use is the Tascam US 1800

Audio Interface – Tascam at a glance

Audio Interface - Tascam

The Tascam 1800 can take in 8 XLR inputs, 2 Hi or Low – Z ¼ inch inputs, and 4 balanced mono inputs simultaneously

It is also capable of taking MIDI inputs

It has a stereo main out, 4 balanced mono outputs (these can be used as 2 stereo output pairs), a MIDI output, and a stereo headphones output.

It works with both MAC and PC software

Thirty One Band Equalizer

Referred to ask the ‘feedback buster’, it helps to remove or reduce harmful frequencies that can cause feedback during a live sound performance.

It can also be used to shape the sound of any speaker through manipulating frequencies.

Direct Box or DI

A Direct box is used to connect a High –Z, line level, unbalanced input source to a low-z, balanced, connection such as a mic input on a mixer or audio interface.

They may have a variety of outputs (XLR, TS, etc.) but most have a TS input

They help to reduce unwanted noise in a signal caused by bad grounding. Some have an optional ground lift switch.

Speakers

There are a variety of different speaker types and also a variety of names used to describe their purpose.

To understand speakers we need to understand hearing.

Sound waves cause our eardrums to vibrate, this vibration is converted to electrical nerve impulses and sent to the brain, the brain interprets this as sound.

Check out http://electronics.howstuffworks.com/speaker1.htm to see how sound waves travel.

Speakers

Speakers accept an electrical signal (not unlike our nerve signal) from something such as a microphone, CD player, etc.

The ‘brain’ of the speaker interprets this and recreates the sound waves using vibrations that would have caused such a signal.

The better the speaker…the more accurate the translation…the more authentic the sound!

Speakers- Cross Section

Speakers – Powered vs Unpowered

Powered speakers take their power from a regular outlet. They have their own volume control on the backside of the speaker.

Unpowered speakers require a device known as a power amp to provide power. The volume is not controlled by the speaker, and thus it is possible to harm or destroy the speaker by sending it more power than it can handle.

Both speakers types usually have XLR and ¼ inch inputs and outputs.

Speakers –VERY IMPORTANT

Two things…

1. Always make sure the volume on your speakers is turned down to its lowest point before powering them on (if using unpowered make sure the volume being sent to the speakers is down).

2. Always make sure your power your powered speakers after you’ve given power to the sound source and always shut your speakers off first when powering down.

Microphones

Later in the course we will explore microphones in depth but for now we will briefly discuss …

Dynamic, Condenser, and RibbonPolar PatternsHandling

Dynamic, Condenser, and Ribbon

Microphones convert sound waves to electrical impulses and send them to another device for interpretation.

Each of the three types captures the sound in a different way.

Within this course you will deal with primarily dynamic and condenser microphones.

Dynamic Microphones

Chances are, if you’ve ever spoken into a microphone it has been a dynamic microphone.

Dynamic microphones have a relatively thick diaphragm (responsible for picking up sound waves) and pick up the middle of the frequency spectrum.

They are capable of handling very high volumes or ‘sound pressure levels’ (SPL’s) and thus are excellent for live performances or picking up loud sources such as guitar amps or drums.

Because they don’t pick up the ends of the frequency spectrum as well they are not as accurate as condenser mics and add a ‘dirty’ quality to the sound.

Dynamic Microphones

SM 57

SM 58

Condensor Microphones

Condensor microphones are often used in recording studios and low source volume situations like micing an acoustic performance.

They pick up a very broad part of the frequency spectrum, accurately portraying the source sound.

They are very fragile and generally expensive and are not used for high volume situations (high SPL’s can break them).

Condenser microphones require ‘phantom power’, and extra amount of power (from 9 to 48 volts) supplied from the mixer or other power source.

Condenser Microphones – Rode NT1-A

Ribbon Microphones

Ribbon mics use a thin ribbon of aluminum as opposed to the diaphragm used by dynamic and condensers.

They tend to take away some of the higher frequencies and lesson the attach or ‘punch’ of the source sound. This produces a smooth, silky, and rich sound.

Ribbon mics are extremely fragile, a strong breath blown into the ribbon is all it takes to break them.

Ribbon Microphones

Polar Patterns

Within the different types of mics there are also a variety of “polar patterns”. These refer to where a mic picks up its sound from.

Omnidirectional: pick up sound from all around the microphone

Cardioid: pick up sound from the front of the microphone but have a ‘blind spot’ in the back.

Figure 8: pick up sound from both the front and back but not all the way around.

Polar Patterns

Notes On Handling

Microphones are susceptible to damage from moisture or dust and should be put away or covered when not in use.

A condenser microphone should ALWAYS be connected before turning on phantom power and ALWAYS turn off phantom power before disconnecting.

Microphones are fragile and expensive …handle them with care.

Terminology

One of the outcomes of this course is for you to be able to describe audio using correct terminology.

We will look at the ideas behind…

Sound Wave Frequency Amplitude and Volume Equalization Reverb Pan

Soundwaves

As mentioned earlier, sound can be thought of as vibrations causing changes in air pressure. These waves can bounce, be absorbed or a combination of both. The study of how sound behaves is known as acoustics.

Visually, sound takes the shape of a wave.

Frequency

Frequency (of a sound wave) refers to how often the particles of the medium the sound is travelling through vibrate.

It is measure in hertz (Hz) and 1 Hertz = 1 vibration/second

Each wave has a characteristic called a period, the time it takes to complete one full cycle. The frequency of the wave is the reciprocal of the period.

Frequency

There are infinite frequencies, and these create the frequency spectrum.

Much like the color spectrum, there are only certain frequencies we can hear without help from technology.

Humans, typically, can hear from 20 Hz to 20 kHZ (20 000 Hz). This is know as our audible range.

We will explore common frequencies later in this course.

SPL’s and Loudness or Volume

Sound Pressure Level’s refer to the change in pressure created by sound. They are measured using a logarithmic scale with unit Decibels (dB).

Loudness or Volume is a less specific way of describing the SPL of a source without units. It is a ‘qualitative’ term.

Hearing audio safely requires a knowledge of harmful SPL’s which we will learn shortly.

There is a relationship between the visual representation of a sound wave and the SPL and Loudness or volume.

SPL, Loudness or Volume - Amplitude

Each wave also has a characteristic know as it’s amplitude. This is the distance it travels away from it’s axis of symmetry or equilibrium.

Consider the diagram

The Jet has a larger amplitude

The jet is ‘Louder’

Equalization

Equalization refers to the process of adjusting the balance of a sounds frequency parts. The device that does this is known as an equalizer.

Common kinds of equalizers are graphic, parametric, shelving, and filter.

Although the initial purpose of equalization was to make the input source faithfully reproduced in the output, we now use equalization to enhance the sound.

Equalization-Graphic Equalization

Graphic EQ - Graphic EQ is where the faders are arranged from low to high frequency.

The are set to a specific frequency.

We will use a 31-band graphic equalizer to try and ‘shape’ our sound as well as eliminate feedback.

The next slide shows how a graphic equalizer may look in a software program.

Graphic Equalizer

Equalization - Parametric

Parametric EQ - They allow you to choose the frequency that you want to change as well as the range of frequencies around it (called the Q control).

A wide Q will center your frequency around a broad group of frequencies which will all be affected. A narrow Q will only affect the frequencies close to the set frequency.

Most mixers use a three band parametric EQ (we see it as “bass, mid, treble”).

Parametric Equalizer

Equalization - Shelving

Shelving EQ’s affect all frequencies above or below a set frequency.

Most stereos have a shelving EQ, an example would be the ‘bass boost’.

Two main kinds of shelving EQ are high shelf and low shelf

Shelving EQ – Low Shelf

Low shelf - functions like a bass control knob on a stereo. Low Shelf EQ's adjust the level of signal at the set frequency and all frequencies below it

Shelving EQ – High Shelf

High shelf - functions like a treble control knob on a stereo.

High Shelf EQ's adjust the level of signal at the set frequency and all frequencies above it.

Equalization- Filter EQ’s

Sometimes your track just sounds better if you eliminate few carefully chosen frequencies. This type of EQ is actually called a filter.

Low pass (high-cut) - filters out frequencies higher than the set frequency.

High pass (low cut) - filters out frequencies lower than the set frequency.

High pass (low cut) - filters out frequencies lower than the set frequency.

Filter EQ’s - Diagrams

Reverb and Pan

When we hear sounds, we not only hear them from the source, we hear the reflection of sound from walls and other nearby surfaces.

This ‘reverberation’ is a natural part of what we hear and we can notice when it is not in a sound. We can simulate this will an audio processor.

Pan, refers to the ‘left-right’ placement of a sound.

We can also tell this naturally and can replicate it using audio processors.