VDV Audio/Video Systems Installation 3 — Questions and Answers
Question 1: What does the term 'impedance bridging' mean in the context of connecting audio equipment?
- Connecting two speakers in series to double impedance
- The source impedance is much lower than the load impedance (Correct answer)
- Matching source and load impedance exactly at 75 ohms
- Using a transformer to isolate two audio circuits
Correct answer: The source impedance is much lower than the load impedance
Impedance bridging means the source (output) impedance is significantly lower than the load (input) impedance, maximizing voltage transfer between devices.
Question 2: When installing a distributed audio system using a 70V amplifier and speakers, what must be checked before connecting speakers in parallel?
- That all speakers have the same color code
- That the total wattage of all taps does not exceed the amplifier's rated output (Correct answer)
- That speaker wire gauge is 18 AWG or smaller
- That each speaker is no more than 50 feet from the amplifier
Correct answer: That the total wattage of all taps does not exceed the amplifier's rated output
In a 70V system, the sum of all speaker tap wattages must not exceed the amplifier's total rated power to prevent overload and distortion.
Question 3: Which connector type is used to terminate analog component video cables (YPbPr)?
- BNC
- XLR
- RCA (Correct answer)
- F-type
Correct answer: RCA
Analog component video (YPbPr) uses three RCA connectors, typically color-coded green, blue, and red.
Question 4: A technician needs to install a video display at a 15-degree tilt on a concrete wall. Which wall mount type should be selected?
- Fixed flat mount
- Tilting wall mount (Correct answer)
- Full-motion articulating arm
- Ceiling drop mount
Correct answer: Tilting wall mount
A tilting wall mount allows the display to be angled downward for optimal viewing, which is important when mounting above typical eye level.
Question 5: What is the primary function of a signal splitter in a video distribution system?
- To amplify a signal before sending it to a single display
- To convert analog video to digital format
- To distribute one source signal to multiple displays simultaneously (Correct answer)
- To switch between multiple source inputs
Correct answer: To distribute one source signal to multiple displays simultaneously
A signal splitter takes one source input and distributes it to multiple outputs so the same content appears on several displays at once.
Question 6: When pulling cable through conduit for an AV installation, what is the recommended maximum fill ratio to allow for heat dissipation and future cable additions?
- 25%
- 40% (Correct answer)
- 60%
- 80%
Correct answer: 40%
NEC guidelines recommend a maximum of 40% conduit fill to allow for adequate heat dissipation and ease of pulling additional cables in the future.
Question 7: A technician is asked to install a conferencing system that includes a ceiling microphone array. What is the primary advantage of this microphone type over a tabletop boundary microphone?
- It provides higher maximum SPL handling
- It captures audio from multiple directions without cluttering the table surface (Correct answer)
- It eliminates all HVAC noise automatically
- It only requires a single cable for power and audio
Correct answer: It captures audio from multiple directions without cluttering the table surface
Ceiling microphone arrays capture speech from multiple participants across the room without occupying table space or requiring participants to position themselves near a mic.
VDV Audio/Video Systems Installation 3
What does the term 'impedance bridging' mean in the context of connecting audio equipment?