Apr 24

Question 1

What is the difference between a condenser microphone and a dynamic microphone?

Answer 1

Condenser mic requires power source 9-48v

Dynamic is more durable.

Question 2

What can cause “hum” noise in a sound system?

Answer 2

Induced A/C, power supply failure

Question 3

What converts electrical energy into acoustic energy?

Answer 3

loud speaker - transducer

Question 4

What converts acoustic energy into electrical energy?

Answer 4

microphone

Question 5

With respect to cabling, magnetic fields are only canceled by two things. What are they?

Answer 5

Balanced cable

Distance from source

Question 6

What is the typical impedance of a balanced, low-impedance line input?

Answer 6

600 Ω

Question 7

What is the maximum current output of a 600W amplifier connected to a 16 Ω load?

Answer 7

6.12A 600/16Ω

Question 8

What is the best shielding you can use in a permanent install, or within a rack or piece of equipment?

Answer 8

foil shielding

Question 9

When distributing sound, what is the main objective?

Answer 9

Create a uniform sound field.

Question 10

What is the function of a mixer?

Answer 10

Combines multiple signals, provides input selection, and allows signal control.

Question 11

What can be used to convert a conventional speaker into a speaker compatible with a constant voltage system?

Answer 11

Transformer 8 Ω output at secondary

Question 12

There are two methods to distribute sound for a paging system. What are they and how do they work?

Answer 12

Constant amp systems: 70V and 25V

Self-amp systems: 24V

Question 13

On it s secondary, a paging transformer will produce how many Ω?

Answer 13

8 Ω

Question 14

In a self-amplified system, each speaker acts as its own ___ at ___ volts ___.

Answer 14

amp at 24 volts DC

Question 15

A self-amplified system uses two pairs of conductors. What is each pair for?

Answer 15

1 pair for 24V power; 1 pair used for audio signal.

Question 16

Why are constant voltage systems preferred for bigger installs?

Answer 16

One central amp can power a great number of speakers over a long distance; cheaper for scalability.

Question 17

A balanced mic cable has three connections. What are they?

Answer 17

2 for balanced signal; 1 for ground (tip, ring, ground)

Question 18

What type of mics can utilize phantom power from a mixer?

Answer 18

condenser

Question 19

P = I2 R - - so what happens to the power when current flow is increased by a factor or two?

Answer 19

Voltage is increased by a factor of 4

Question 20

With respect to self-amplified systems, the audio signal is the same as one you would find where?

Answer 20

analog telephone line

Question 21

What type of output is used with low impedance speakers?

Answer 21

direct output

Question 22

What is the proper amount of overhead to build into a paging system with regards to the amplifier’s capability

Answer 22

20%

Question 23

What would you use to electronically adjust the level of a page background music in applications where noise levels are continuously changing?

Answer 23

ambient noise sensor

Question 24

AUX inputs accept what kinds of signals?

Answer 24

Hi-Z, high impedance inputs, line level cables, about 6ft. cables

Question 25

What output is not affected by an amplifier's master volume control?

Answer 25

Tape out

Question 26

If you are connecting speakers to a direct output, what is the most likely problem to occur?

Answer 26

impedance mismatch

Question 27

What is the purpose of a digital feedback terminal?

Answer 27

To eliminate feedback (acoustic)

Question 28

What is the purpose of a voice over IP gateway?

Answer 28

To make remote announcements sent over the internet, It converts analog telephony signals to digital

Question 29

For direct connected systems, what types of wire should be used and when?

Answer 29

16 over 100ft | 18 under 100ft

Question 30

Transformer power loss is stated in what?

Answer 30

DB insertion loss

Question 31

Say you have two speakers. The cone on the first moves out and at the same time, the cone on the second moves in. What is this condition known as?

Answer 31

Out of phase

Question 32

When speakers are out of phase, what typically happens?

Answer 32

Lose up to 1/2 of their normal volume and will not sound nearly as well.

Question 33

Line matching transformers and associated speakers are connected in ___ across the amplifier's output

Answer 33

parallel

Question 34

When installing a paging system, care should be taken to keep as much separation as possible between two things. What are they?

Answer 34

Mic and speaker

Question 35

Amplifiers with output circuits carrying audio signals can use Class 1, 2, or 3 wiring as long as they are what?

Answer 35

listed and marked

Question 36

Define the term temporary equipment as it relates to audio equipment

Answer 36

it's taken down after the event

Question 37

Define rated outage power.

Answer 37

output voltage when delivering full power

Question 38

Ambient noise level is best found how?

Answer 38

SPL meter (tester)

Question 39

What is the most practical approach to wiring for multiple speakers?

Answer 39

zoning

Question 40

What must be done to a sound masking system so that all frequencies fall within the preferred masking curve?

Answer 40

calibrate for the environment

Question 41

Define white noise

Answer 41

unfiltered, unaltered thermal noise

Question 42

What are a transformer's taps rated in?

Answer 42

Watts

Question 43

A sound masking system level should be how many dB louder than speech

Answer 43

1 - 5 dB