Speaker Systems & Amplification Flashcards
7 cards from real CEA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Speaker Systems & Amplification flashcards as text
Line array speaker systems are designed to produce what type of wave front, and what is its key distance advantage?
Answer: A cylindrical wave front that loses only 3 dB of SPL per doubling of distance
Line arrays produce a cylindrical wave front that follows the inverse-distance law (3 dB loss per doubling of distance), compared to 6 dB for a point source, making them ideal for large venues.
Four 8-ohm speakers are wired in series. What is the total impedance?
Answer: 32 ohms
Series-connected impedances add directly: 8 + 8 + 8 + 8 = 32 ohms.
Why is a limiter placed in a speaker-system signal chain before the power amplifier?
Answer: To prevent amplifier clipping and protect drivers from excessive or distorted power
A limiter caps signal levels so the amplifier never clips; clipping creates harmonic distortion with DC-like content that rapidly destroys tweeters and compression drivers.
A compression driver used in a high-efficiency PA horn employs which transducer mechanism?
Answer: Moving-coil (dynamic) with a phase plug
Compression drivers are moving-coil transducers that couple a rigid diaphragm to a horn via a phase plug, yielding high efficiency and controlled high-frequency dispersion.
In a properly set gain structure, the amplifier's input sensitivity control should be adjusted so that:
Answer: The amplifier reaches full rated output exactly when the mixer outputs its maximum clean level
Proper gain structure aligns every stage so the amplifier hits full clean output when the console delivers its highest undistorted signal, maximizing headroom and signal-to-noise ratio throughout the chain.
How does speaker efficiency differ conceptually from speaker sensitivity?
Answer: Efficiency is the ratio of acoustic output power to electrical input power; sensitivity is a standardized SPL reading at 1W/1m
Efficiency is a dimensionless power ratio (acoustic out ÷ electrical in, typically less than 5%), while sensitivity is a dB SPL measurement under defined conditions of 1 watt at 1 meter.
When two identical subwoofers are placed side by side on the floor facing the audience, the primary acoustic result compared to a single subwoofer is:
Answer: Up to 6 dB more on-axis SPL with narrowed horizontal dispersion
Two coupled subwoofers yield up to 6 dB of additional SPL on axis (3 dB from doubling amplifier power plus 3 dB from mutual coupling) while narrowing horizontal dispersion due to array effects.