Live Sound Quiz #2

Front 1

What is the purpose of a block diagram?

Back 1

A block diagram represents the principal parts or functions of a system through blocks connected by lines that show the relationships of the blocks.

Front 2

What is the difference between a block diagram and a schematic?

Back 2

Block diagrams are efficient at providing a concise overview of a complicated system.

Schematic diagrams provide the detailed explanations of all the parts that the system holds.

Front 3

How can block diagrams be useful to you?

Back 3

Block diagrams show the signal flow of a system, which can help us isolate a problem in an audio setup.

Front 4

What is the difference between pink noise and white noise?

Back 4

White noise is equal energy per frequency and pink noise is equal energy per octave.

Front 5

Why is pink noise used to test audio equipment rather than white noise?

Back 5

Because pink noise is calibrated to how we hear, which is an increase of one octave ever time the frequency doubles.

Front 6

What is the importance of using good cables and connectors?

Back 6

Poorly made cables can allow noise and interference to compromise the signals coming from your source.

Front 7

What kind of conductors are in a balanced connection vs. an unbalanced connection?

Back 7

An unbalanced cable consists of two connectors with two conductors each, connected by two wires inside the cable: a signal wire and a ground wire.

A balanced cable, by contrast, has three conductors in the connector and three wires in the cable: two signals wires plus a separate ground wire.

Front 8

What is four conductor quad/star quad cable, and how do you wire it?

Back 8

There are four cores in star-quad cable plus an overall screen. The arrangement of the four cores provides greatly improved rejection of electromagnetic interference compared to standard two‑core mic cables.

The screen helps to prevent electrostatic interference from reaching the signal cores.

The four cores are arranged in a cross formation, and the opposite cores are wired in parallel to form a single balanced pair. There is also a shield.

XLR: 123

Quad: Shield, R/B, G/W

Front 9

What is the purpose of audio snakes?

Back 9

Audio snakes are used to

-save time & money

-eliminate clutter

-limit the length in which microphone cables carry signals to their final destination

Front 10

What are the three types of cables used in an audio system?

Back 10

Mic/line, speaker, power

Front 11

What are some types of audio connectors?

Back 11

XLR, TRS 1/4", TS 1/4", RCA, 3.5mm.

Front 12

What are some mass pin speaker connectors?

Back 12

SpeakOn NL-2, NL-4, NL-8.

Front 13

How do you properly wire XLR?

Back 13

1-Ground, 2-Positive, 3-Negative

Front 14

How do you wire XLR to TRS 1/4"?

Back 14

1-S, 2-T, 3-R

Front 15

What is a Direct Injection Box used for?

Back 15

Their main purpose is to convert unbalanced and/or high impedance instrument signals into a format suitable for direct connection to a mixing console's mic input - without the use of a microphone.

Front 16

What does a the ground lift switch do on a DI box?

Back 16

The ground lift switch eliminates unwanted hum and buzz by interrupting the ground loops between equipment, preventing current flow along the cable shield between two devices.

Front 17

What is an insert cable used for?

Back 17

A cable that splits a TRS plug to two TS plugs, with separate signals carried on the two split plugs.

Often used to access the send/return on a mixer insert, but have other uses as well, such as splitting a stereo output carried on a single TRS jack to separate left/right signals on TS plugs.

Front 18

How is an insert cable made and wired?

Back 18

Tip = send

Ring = return

Ground = ground

Front 19

What is the basic principle of balanced audio circuits?

Back 19

Carries two copies of the same audio signal. The two signals are reversed in polarity. If the cable picks up noise along the way, the noise added to both of those cables is not reversed in polarity. So when the cold signal flips in polarity to match the polarity of the hot signal, any noise carried along the cold signal cancels out with noise in the hot signal.

Front 20

How do balanced circuits differ from unbalanced circuits (other than cable differences)?

Back 20

Balanced cables are less susceptible to noise and provide a more reliable signal that is stronger over long distances.

Front 21

How far can you run cable in an unbalanced circuit vs. a balanced circuit?

Back 21

Balanced: 100s of feet

Unbalanced: 25 feet

Front 22

What is the voltage level found on an electrical outlet?

Back 22

120 V

Front 23

What is a ground loop?

Back 23

When two separate devices are connected to ground separately, and then also connected to each other through some kind of communication cable with a ground, creating a loop.

Front 24

What are the three types of grounds in audio?

Back 24

Signal, chassis, and earth

Front 25

What are the locations of electrical power, neutral, and earth ground on an electrical outlet?

Back 25

Front 26

How do you interface an unbalanced device with a balanced device?

Back 26

Through a cable in which the positive input is fed the signal from the device while the negative input is connect to ground. (Floating negative input can be a source of noise.)

Front 27

What are the dangers of disconnected earth grounds?

Back 27

When a device has no proper grounding, high voltage may flow into the metal case of the device, and touching the case may shock you and cause injury or death.

Front 28

Why is grounding important?

Back 28

In the event of an electrical fault which brings dangerous high voltage to the case of an appliance, the current should flow into the ground wire and trip the breaker.

Front 29

How do the three audio grounds interconnect with one another?

Back 29

Signal ground is for the very low voltage signals within a device, chassis ground for the device itself, and earth ground is for a power system which powers the device.

Front 30

How do you prevent ground loops?

Back 30

-Lift the ground

-use an isolation transformer

-don't let devices share grounds

-use twisted pair wiring

Front 31

Drawing of a ground loop?

Back 31

Front 32

How do you remove a ground loop from an audio system during a set up?

Back 32

-disconnect the ground from the input end

-OR if you have a ground lift switch just use that

-OR put an isolation transformer in the signal path

Front 33

Back 33

Amplifier symbol

Front 34

Battery symbol

Back 34

Front 35

Switch (SPST) symbol

Back 35

Front 36

Resistor symbol

Back 36

Front 37

Capacitor symbol

Back 37

Front 38

Diode symbol

Back 38

Front 39

Transformer symbol

Back 39

Front 40

Ground symbol

Back 40