Skills Flashcards

What is the correct procedure for calculating amplifier power requirements for a loudspeaker system that must achieve 100 dB SPL at 10 meters, using a loudspeaker rated at 97 dB sensitivity (1W/1m)?

Answer: Sensitivity at 10m = 97 − 20 = 77 dB; need 100 − 77 = 23 dB above 1W; 23 dB = 200W; answer: approx. 200W

First, find SPL at 10m at 1W: 97 dB − 20×log10(10) = 97 − 20 = 77 dB. Then find power needed to reach 100 dB: 100 − 77 = 23 dB. Power = 10^(23/10) = 10^2.3 ≈ 200W.

An AV technician is configuring an EDID (Extended Display Identification Data) emulator in a matrix switcher installation. What problem does EDID management solve?

Answer: EDID emulation provides a stable handshake signal to the source device, preventing it from defaulting to a lower resolution or losing sync when displays are switched

When a display is switched away from a source, the EDID handshake is broken, causing the source to renegotiate and potentially output a lower-common-denominator resolution. An EDID emulator maintains a stable EDID to the source at all times, preventing resolution drops during switching.

What is the function of a delay line in a distributed audio system, and when must it be applied?

Answer: A delay line introduces a time offset to loudspeakers further from the source, aligning them with the primary speaker so listeners hear a single, coherent sound source

In distributed audio, delayed fill speakers must be time-aligned to the primary speaker. Without delay, a listener near a fill speaker hears it before the main system, creating an echo and destroying intelligibility. Haas effect alignment requires the fill speaker to arrive 0–25ms after the primary source.

A CTS technician is setting up a multi-camera videoconferencing system and needs to configure correct white balance on all cameras. What does white balance achieve, and what is the standard procedure?

Answer: White balance calibrates the camera's color channels so that a white object under the room's lighting appears neutral white on screen — set by pointing the camera at a white reference card under actual room lighting

White balance ensures the camera renders the room's color temperature correctly. Under tungsten lighting (2,700–3,200K) without white balance, an image appears orange; under fluorescent lighting (4,000–5,000K), it may appear green. Manual white balance using a reference card under actual room lighting gives the most accurate result.

In AV control system programming, what is the difference between a 'set' command and a 'get' (query) command sent to a controlled device?

Answer: 'Set' commands instruct a device to change state (e.g., power on, volume to 50%); 'get' or query commands request the device to report its current state

Control system programming uses 'set' commands to send configuration changes to devices (output state, input selection, volume) and 'get' or query commands to retrieve the current device state for feedback to the control interface, enabling accurate status displays.

What is throw ratio in projection, and how do you calculate the required projector throw distance for a 120-inch wide screen using a lens with a throw ratio of 1.5:1?

Answer: Throw ratio = throw distance ÷ screen width; distance = throw ratio × screen width = 1.5 × 120 = 180 inches

Throw ratio = throw distance ÷ screen width (or image width). Rearranging: throw distance = throw ratio × screen width = 1.5 × 120 inches = 180 inches (15 feet). This tells you how far from the screen to mount the projector.