• A
• B
• C
• D
• E
• F
• H
• I
• L
• P
• R
• S
• T
• W
• X

A

Active Subwoofer

A subwoofer with a built-in amplifier. The amp, driver, and electronics are engineered as one system, often including DSP and protection circuits.

Common misconception: An external amplifier is automatically “better.” In most cases, integrated designs are more precisely matched.

B

Bass Reflex

An enclosure design with a port that reinforces low frequencies using rear radiation from the driver. It increases output and low-end extension.

Common misconception: Ported subs are always less precise than sealed ones. Precision depends more on tuning and room interaction than enclosure type alone.

C

Class D

A highly efficient amplifier technology capable of delivering substantial power with minimal heat. It is the dominant topology in modern subwoofers.

Common misconception: Class D sounds “digital” or harsh. Properly designed Class D amplifiers are extremely linear and transparent.

Crossover / Crossover Frequency

The frequency at which the signal is divided between the main speakers and the subwoofer, typically between 60 and 120 Hz. Proper adjustment ensures seamless integration.

Common misconception: Lower is always better. The correct crossover depends on how low the main speakers can cleanly operate.

D

DBA (Double Bass Array)

A configuration using multiple subwoofers at the front and rear of a room, time-aligned to reduce standing waves and create even bass distribution.

Common misconception: More subs mean more bass. The goal is uniformity and control, not sheer loudness.

Down-Firing

A design where the driver radiates downward toward the floor. The floor becomes part of the acoustic loading.

Common misconception: Down-firing spreads bass more evenly. At low frequencies, directionality is minimal; placement matters far more.

DSP (Digital Signal Processing)

Digital processing used to shape frequency response, apply filters, manage protection, and optimize performance for the room.

Common misconception: DSP “colors” the sound. In reality, it is often used to correct physical and acoustic limitations.

E

Enclosure Q (Q Factor)

Describes the damping characteristics of a system or filter. Higher Q values produce narrower, more pronounced peaks; lower Q values result in broader, smoother behavior.

Common misconception: Higher Q means tighter bass. Excessive Q can create boominess.

F

Frequency Response

A graph showing output level across frequencies. A smooth response indicates balanced reproduction.

Common misconception: A deeper published number guarantees better bass. Measurement conditions matter greatly.

Front-Firing

A design where the driver faces forward into the room. Predictable and common in most systems.

Common misconception: Front-firing is inherently more accurate than down-firing. Room acoustics dominate either way.

H

High-Level Input

A connection that takes the signal directly from speaker terminals. Often used with stereo amplifiers that lack a dedicated subwoofer output.

Common misconception: High-level connections sound inferior. When properly implemented, there is no inherent sonic penalty.

I

Impulse Response / Transient Accuracy

The ability to reproduce sudden changes in signal quickly and cleanly. Important for punch and realism.

Common misconception: Only sealed subwoofers have good transient response. System design and tuning matter more than enclosure type alone.

L

LFE (Low Frequency Effects)

A dedicated bass channel in surround sound formats, intended for special low-frequency effects. Represented as the “.1” in systems like 5.1.

Common misconception: The LFE channel contains all bass. Low frequencies exist in every channel.

LFE Channel vs. Bass from Main Speakers

In home theater systems, bass management routes low frequencies from all speakers to the subwoofer when speakers are set to “Small,” in addition to the LFE channel.

Common misconception: Large floorstanding speakers eliminate the need for a subwoofer in home theater.

Limiter

A protection circuit that reduces output before distortion or damage occurs.

Common misconception: A limiter always degrades sound quality. Without it, distortion or mechanical stress would occur sooner.

Low-Level Input (RCA / Line-Level)

A connection using preamp outputs, standard on AV receivers and many modern stereo amplifiers.

Common misconception: RCA connections are inherently low quality. In typical subwoofer cable lengths, they are fully adequate.

P

Passive Subwoofer

A subwoofer without an internal amplifier. Requires an external power amplifier.

Common misconception: Passive designs are more “audiophile.” Integration is often more complex and less optimized.

Phase and Phase Adjustment

Describes the timing relationship between subwoofer and main speakers. Adjustable phase helps prevent cancellation at the crossover region.

Common misconception: 0° is always correct. Proper phase depends on placement and distance.

R

Room Gain

Natural low-frequency amplification caused by room boundaries. Smaller rooms reinforce deep bass more strongly.

Common misconception: More room gain is always beneficial. Excessive reinforcement can cause boominess.

S

SBA (Single Bass Array)

Multiple subwoofers placed along one wall to improve bass consistency across the room.

Common misconception: One very large subwoofer is always superior to several smaller ones. Multiple sources often improve distribution.

Signal-to-Noise Ratio (SNR)

The ratio between desired audio signal and background noise. Higher numbers indicate cleaner operation.

Common misconception: Small numerical differences are always audible. In real rooms, ambient noise often dominates.

SPL (Sound Pressure Level)

A measurement of loudness expressed in decibels (dB). Indicates maximum output capability.

Common misconception: Higher SPL automatically means better sound quality.

Stereo Subwoofer Integration

The integration of a subwoofer into a two-channel music system to extend low-frequency performance without disturbing imaging.

Common misconception: A subwoofer ruins stereo imaging. Poor setup does; proper integration enhances scale and depth.

Sub-Out

A dedicated subwoofer output on an amplifier or receiver, typically filtered and level-controlled.

Common misconception: Without a sub-out, a subwoofer cannot be properly used.

Subsonic Filter

A filter that removes extremely low, inaudible frequencies to protect the driver from excessive excursion.

Common misconception: Anything below 20 Hz is irrelevant. Infrasonic content can still stress the system.

T

THD (Total Harmonic Distortion)

A measurement of harmonic distortion added to the original signal. Lower values generally indicate cleaner reproduction.

Common misconception: A slightly lower THD figure is always audibly superior, especially in the bass range.

Transient Response

See Impulse Response / Transient Accuracy.

Tuning Frequency

The frequency at which a ported enclosure is acoustically reinforced.

Common misconception: Lower tuning automatically means deeper usable bass.

W

Wattage / Amplifier Power

The electrical output capability of the amplifier.

Common misconception: More watts always mean more bass. Output depends on the entire system: driver size, excursion capability, enclosure design, and power supply robustness.

X

Xmax (Maximum Linear Excursion)

The maximum distance a driver can move while remaining within its linear operating range. Greater excursion allows more air displacement and deeper bass capability.

Common misconception: Cone size alone determines output. Excursion and surface area work together.