CAT Technical Skills 3

Question 1

What is the purpose of a delay line in a distributed audio system with multiple speaker zones?

Accepted Answer

Synchronize audio with distant speakers to avoid echo

Answer

Delay lines time-align audio signals so that sound from distant speakers arrives at listeners simultaneously with nearby speakers, preventing echo or comb filtering.

Question 2

In a 70V distributed speaker system, what is the advantage of using a step-down transformer at each speaker?

Accepted Answer

It allows multiple speakers to be wired in parallel without impedance issues

Answer

70V transformers allow many speakers to be wired in parallel on a single amplifier output while maintaining a manageable load impedance.

Question 3

What is 'feedback' in an audio system and what is its primary cause?

Accepted Answer

A howling sound caused by a microphone picking up its own amplified output

Answer

Acoustic feedback occurs when a microphone picks up sound from a speaker and re-amplifies it in a continuous loop, creating a howl or squeal.

Question 4

What does 'THD' measure in an audio amplifier?

Accepted Answer

Total Harmonic Distortion

Answer

Total Harmonic Distortion (THD) measures the ratio of harmonic overtones added by the amplifier to the original signal, expressed as a percentage.

Question 5

A commercial audio technician is troubleshooting a 60 Hz hum in a system. What is the most likely cause?

Accepted Answer

Ground loop between two pieces of equipment

Answer

A 60 Hz hum (matching AC power frequency in the US) is a classic symptom of a ground loop caused by multiple ground paths between equipment.

(CAT) Commercial Audio Technician Practice Test

(CAT) Commercial Audio Technician Practice Test

CAT Technical Skills 3