Power Amplifier Module For Subwoofer: Key Standards, Physical Properties, and Engineering Applications

Types of Power Amplifier Modules for Subwoofers

A power amplifier module for subwoofers is an essential electronic component that boosts low-level audio signals to a higher power level capable of driving a subwoofer and producing deep, impactful bass. These modules are crucial in car audio systems, home theaters, and professional sound setups. Based on amplification technology, they primarily fall into two categories: Class D and Class AB amplifier modules—each offering distinct advantages in efficiency, sound quality, and application suitability.

Class D Amplifier Modules

Class D amplifiers use pulse-width modulation (PWM) to deliver high-efficiency amplification, making them ideal for compact and power-sensitive applications.

Advantages

• High Efficiency (70–90%): Operates as a switching amplifier, minimizing power loss and heat generation, which enhances energy conservation.
• Compact & Lightweight: Smaller heat sinks and reduced component size allow for integration into tight spaces, such as in-car audio systems.
• High Power Output: Capable of delivering 200–400 watts RMS (and higher in advanced models), ideal for driving powerful subwoofers.
• Battery-Friendly: Consumes less current, preserving battery life in mobile and automotive applications.
• Advanced Signal Processing: Incorporates digital filtering and feedback circuits to reduce distortion and deliver clean low-frequency reproduction.

Limitations

• Complex Signal Path: May introduce subtle artifacts due to switching noise if not well-filtered.
• Less Nuanced Audio Detail: Some audiophiles argue that Class D lacks the warmth and micro-dynamics of analog amplifiers.
• EMI Sensitivity: Can generate electromagnetic interference, requiring proper shielding and layout design.

Best for: Car audio systems, portable sound systems, compact home theaters, and applications where space and efficiency are critical

Class AB Amplifier Modules

Class AB amplifiers combine the linear output of Class A with the efficiency of Class B, offering a balanced analog amplification solution prized for audio fidelity.

Advantages

• Superior Sound Quality: Provides smooth, natural bass response with excellent transient accuracy and warmth, favored by audiophiles.
• Low Distortion: Maintains high linearity and low harmonic distortion, especially at moderate power levels.
• Wide Power Range: Supports subwoofers from 100 watts up to 600+ watts RMS, suitable for both entry-level and high-end systems.
• Onboard Low-Pass Crossover: Enables precise frequency filtering, ensuring seamless integration with full-range speakers.
• Predictable Thermal Behavior: With proper heatsinking, maintains stable performance under continuous load.

Limitations

• Lower Efficiency (50–70%): Generates more heat, requiring larger heat sinks and better ventilation.
• Bulkier Design: Less suitable for space-constrained installations due to size and weight.
• Higher Power Consumption: Draws more current, which can strain electrical systems in vehicles.

Best for: High-fidelity home audio, studio monitors, premium car audio systems, and listeners prioritizing sound accuracy and warmth

Amplifier Type	Efficiency	Sound Quality	Power Output Range (RMS)	Heat Output	Best Use Case
Class D	70–90%	Very Good (modern models)	200–1000+ watts	Low to Moderate	Car audio, portable systems, space-limited setups
Class AB	50–70%	Excellent (analog warmth)	100–600+ watts	Moderate to High	Home theaters, audiophile systems, studio environments

Expert Tip: When choosing between Class D and Class AB, consider your priorities: efficiency and compactness favor Class D, while audio purity and dynamic range often make Class AB the preferred choice for critical listening. Hybrid designs are emerging that combine digital efficiency with analog refinement—worth exploring for balanced performance.

While Class D amplifiers were once considered inferior in sound quality compared to Class AB, rapid advancements in digital signal processing, filtering, and feedback topologies have significantly closed the gap. Modern Class D modules now offer audiophile-grade performance with exceptional efficiency. Conversely, Class AB remains the gold standard for analog warmth and musicality, though its higher heat output and power demands limit its use in compact or mobile systems.

Ultimately, the choice depends on your application, space constraints, power availability, and listening preferences. Understanding these two core technologies empowers you to select the ideal power amplifier module for a subwoofer that delivers both thunderous bass and faithful sound reproduction.

Functions and Features of Power Amplifier Modules for Subwoofers

A power amplifier module for subwoofer is a specialized audio component designed to deliver high-power, low-frequency signals to subwoofers with minimal distortion. Each channel of the amplifier is typically dedicated to driving a separate speaker load, ensuring precise control and optimal performance. The primary goal of a subwoofer amplifier is to reproduce deep bass frequencies—often below the range of standard speakers—with power, clarity, and accuracy.

When selecting a subwoofer amplifier, several key technical specifications must be evaluated to ensure compatibility with your audio system and performance expectations. These include power output, frequency response, total harmonic distortion (THD), and impedance handling. Understanding these parameters helps in choosing an amplifier that matches your subwoofer’s requirements and delivers rich, dynamic bass.

Core Technical Specifications

Power Output (RMS)

Power output measures the continuous wattage an amplifier can deliver to a subwoofer at low frequencies, typically expressed in RMS (Root Mean Square) watts. This is a more accurate indicator of real-world performance than peak power ratings.

For most car audio or home theater subwoofers, a suitable power range is between 200 and 400 watts RMS per channel. Matching this output to your subwoofer’s power handling capacity ensures efficient operation without underpowering or risking damage from clipping and overheating.

Frequency Response

This specification defines the range of frequencies the amplifier can effectively amplify without significant signal loss or distortion. Since subwoofers are designed to reproduce bass, the ideal frequency response for a subwoofer amplifier is typically between 20 Hz and 200 Hz.

A well-tuned frequency response ensures that only low-frequency signals are amplified, reducing strain on the amplifier and preventing unwanted midrange or high-frequency sounds from reaching the subwoofer, which could degrade sound quality.

Total Harmonic Distortion (THD)

THD measures the amount of unwanted harmonic content added by the amplifier during signal amplification. Lower THD values indicate cleaner, more accurate sound reproduction.

Contrary to the original statement, a **good THD value is *below* 0.1%**, not above. Amplifiers with THD levels under 0.1% are considered high-fidelity and suitable for premium audio systems. Higher distortion levels can result in muddy or harsh bass, especially at high volumes.

Impedance Compatibility

Impedance refers to the electrical resistance a subwoofer presents to the amplifier, measured in ohms (Ω). Common subwoofer impedances are 2Ω, 4Ω, and sometimes 8Ω. The amplifier must be capable of safely driving the connected load without overheating or shutting down.

Most subwoofer amplifiers are designed to handle 2Ω or 4Ω loads, with some supporting stable operation at 1Ω when multiple subwoofers are wired in parallel. Ensuring impedance compatibility prevents damage and allows the amplifier to deliver its rated power efficiently.

Specification	Ideal Range	Performance Impact
Power Output (RMS)	200–400 W per channel	Ensures strong, clean bass without underpowering or distortion
Frequency Response	20 Hz – 200 Hz	Optimized for deep bass; avoids unnecessary amplification of higher frequencies
Total Harmonic Distortion (THD)	< 0.1%	Delivers clean, accurate sound; lower distortion enhances audio fidelity
Impedance Support	2Ω to 4Ω (some down to 1Ω)	Enables flexible wiring configurations and safe operation

Key Features That Enhance Subwoofer Performance

Beyond technical specifications, modern subwoofer amplifiers come equipped with advanced features that improve integration, control, and customization within an audio system. These features make it easier to fine-tune bass response and adapt to different listening environments.

Low-Pass Crossover: Filters out high-frequency signals above a set point (e.g., 80–120 Hz), ensuring only low frequencies are sent to the subwoofer. This prevents muddiness and improves overall system clarity.

Subsonic Filter: Blocks extremely low frequencies (below 20–30 Hz) that are inaudible but can waste amplifier power and damage subwoofers due to excessive cone movement.

Remote Level Control: Allows real-time adjustment of subwoofer volume from the driver’s seat or listening position via a wired knob or wireless remote, eliminating the need to access the amplifier directly.

RCA Inputs & Outputs: Provide high-quality, low-noise signal transfer from the head unit or processor. Many amps also include pass-through RCA outputs to daisy-chain additional amplifiers.

Bass Boost / Equalization: Offers adjustable frequency bands (e.g., +6 dB at 45 Hz) to tailor bass response based on room acoustics, vehicle type, or personal preference.

Gain & Phase Controls: Gain adjusts input sensitivity to match source levels, while phase control (0° or 180°) aligns the subwoofer’s output with main speakers for smoother integration.

Important: Always match your amplifier’s power output and impedance rating to your subwoofer’s specifications. Using an underpowered or incompatible amplifier can lead to distorted sound, clipping, and potential damage to both the amp and subwoofer. Additionally, ensure proper ventilation and wiring gauge to support high-current operation and maintain long-term reliability.

Applications of Power Amplifier Modules

Power amplifier modules are versatile components that play a crucial role in enhancing audio performance across a wide range of environments. From entertainment to safety, their ability to boost signal strength, minimize distortion, and deliver clean, powerful sound makes them indispensable in modern audio systems. Below are key application scenarios where power amplifier modules deliver significant value.

🎵 Musical Instruments and Karaoke Systems

Compact yet powerful, amplifier modules are ideal for musical instruments such as electric guitars, keyboards, and digital pianos. They provide the necessary gain to drive speakers efficiently while enabling tonal shaping through effects like overdrive and distortion. In karaoke machines and portable music players, these modules enhance volume output and audio clarity, ensuring rich sound reproduction even in small or acoustically challenging spaces.

Key benefit: Enables high-fidelity sound from compact devices without compromising on loudness or clarity.

📢 Public Address (PA) Systems

In schools, airports, train stations, and corporate buildings, power amplifier modules are essential for public address systems. They amplify microphone and audio source signals to levels sufficient for large-area coverage, ensuring announcements are intelligible over ambient noise. With reliable signal boosting and stable output, they support clear communication in emergency and routine scenarios alike.

Pro insight: Modern modules often include protection circuits to prevent speaker damage during prolonged use.

🎙️ Broadcasting and Audio/Video Production

In professional studios and broadcast environments, amplifier modules ensure that microphone and instrument signals are amplified with minimal noise and distortion. This is critical for capturing clean audio during recording sessions, live streaming, or television production. High signal-to-noise ratios and consistent output quality make them a trusted component in the signal chain.

Technical note: Precision amplification preserves dynamic range and detail, essential for post-production editing.

🎬 Home Theater and Surround Sound Systems

For immersive cinematic experiences, power amplifier modules drive multiple speakers and subwoofers with precision. They deliver the high current needed to reproduce deep bass and explosive sound effects while maintaining clarity during dialogue and subtle audio cues. Whether used in 5.1, 7.1, or Dolby Atmos setups, these modules ensure dynamic, theater-quality audio at home.

Upgrade tip: Pairing a dedicated subwoofer amplifier module enhances low-frequency response and reduces strain on the main receiver.

🎤 Live Sound Reinforcement

At concerts, conferences, and outdoor events, power amplifier modules provide the robust output required to drive large speaker arrays and stage monitors. Their ability to handle high power demands and resist thermal overload ensures consistent performance during extended use. Many are designed with cooling systems and feedback suppression to maintain clarity in live environments.

Critical factor: Matching amplifier power to speaker impedance ensures optimal performance and longevity.

🎧 High-Fidelity (Hi-Fi) Home Audio Systems

Audiophiles rely on power amplifier modules to extract the full detail and emotional depth from high-resolution audio recordings. These modules offer precise control over speaker drivers, resulting in accurate sound staging, tight bass, and transparent midrange. When integrated into a subwoofer or stereo amplifier, they elevate the listening experience to professional standards.

Value insight: Even in compact form factors, modern modules can rival traditional amplifiers in performance.

🚗 In-Car Audio Systems

Vehicles present unique acoustic challenges, including road noise, limited space, and electrical interference. Power amplifier modules overcome these by providing clean, high-power output to car speakers and subwoofers. This results in clearer music, deeper bass, and improved overall sound quality—especially important for enthusiasts seeking premium in-cabin audio experiences.

Installation tip: Use shielded cables and proper grounding to minimize noise in automotive environments.

🎸 Instrument Amplification and Effects

Beyond basic amplification, power modules are used in instrument amplifiers to shape tone and enable effects processing. Guitarists, for example, use them to achieve overdrive, distortion, or clean boost—key elements in rock, blues, and jazz genres. Their responsiveness to input dynamics makes them ideal for expressive musical performance.

Creative use: Modules can be integrated into custom pedalboards or DIY amp builds for personalized sound design.

🚨 Emergency Warning and Notification Systems

In fire alarms, civil defense sirens, and public safety systems, power amplifier modules ensure that warning messages and alerts are delivered with maximum audibility and clarity. Their reliability under stress and ability to operate continuously make them suitable for life-critical applications where audio must be heard across large areas or noisy environments.

Safety note: Amplifiers in emergency systems often feature redundancy and fail-safe operation protocols.

Professional Insight: When selecting a power amplifier module for any application, consider key specifications such as output power (watts RMS), impedance compatibility (4Ω, 8Ω), signal-to-noise ratio, total harmonic distortion (THD), and thermal management. Matching these to the speaker system and environment ensures optimal performance, longevity, and user satisfaction.

Application	Key Requirement	Recommended Module Feature	Typical Power Range
Home Theater	High dynamic range	Low THD, multi-channel support	50–200W per channel
Live Sound	High power output	Durable build, thermal protection	200–1000W per channel
Car Audio	Noise immunity	DC-DC regulation, compact size	30–300W RMS
Public Address	Speech clarity	High SNR, built-in DSP options	25–250W
Hi-Fi Audio	Precision amplification	Class A/AB, wide frequency response	30–150W

Additional Considerations

• Efficiency: Class D amplifier modules offer high efficiency and compact size, ideal for battery-powered or space-constrained applications.
• Connectivity: Modern modules support digital inputs (e.g., I²S, SPDIF) and analog sources, ensuring compatibility with diverse audio systems.
• Thermal Management: Look for modules with heat sinks or fanless designs for silent and reliable operation.
• Protection Features: Over-current, over-temperature, and short-circuit protection enhance reliability and safety.
• Scalability: Modular designs allow for easy integration and expansion in multi-speaker or distributed audio systems.

How to Choose Power Amplifier Modules for Subwoofers

Selecting the right power amplifier module for your subwoofer is crucial for achieving deep, clean, and distortion-free bass. Whether you're building a custom audio system for your car, home theater, or outdoor setup, understanding the technical and practical factors involved will ensure optimal performance and longevity of your components. This comprehensive guide walks you through the essential considerations when choosing a subwoofer amplifier module.

Important Note: Mismatching amplifier power and subwoofer specifications can lead to permanent damage. Always verify compatibility before making a purchase or installation.

Key Factors in Selecting a Subwoofer Amplifier Module

1. Match Subwoofer Power Handling (RMS)
   • The subwoofer’s RMS (Root Mean Square) power rating indicates the continuous power it can handle without overheating or failing. This is more important than peak power ratings.
   • The amplifier module’s RMS output should closely match the subwoofer’s RMS handling—ideally within 75% to 100% of the sub’s rating.
   • Example: A subwoofer rated at 400W RMS works best with an amplifier delivering 300–400W RMS to avoid underpowering or clipping, which causes distortion and potential damage.
2. Consider Subwoofer Sensitivity (dB)
   • Sensitivity measures how efficiently a subwoofer converts power into sound, expressed in decibels (dB) at 1 watt from 1 meter away.
   • Higher sensitivity (e.g., 88–92 dB) means the sub produces more volume with less power, allowing a lower-powered amp to perform well.
   • Lower sensitivity subs (below 85 dB) require more amplifier power to achieve the same output, so pairing them with a high-output amp is essential.
3. Impedance Compatibility (Ohms)
   • Impedance, measured in ohms (Ω), affects how much electrical load the subwoofer presents to the amplifier.
   • Common subwoofer impedances are 2Ω, 4Ω, or dual voice coils (DVC) offering multiple wiring options.
   • The amplifier must be stable at the subwoofer’s final impedance. For example, a 2Ω sub requires a 2Ω-stable amp; otherwise, the amp may overheat or shut down.
   • Many modern amplifier modules are multi-ohm stable, supporting both 2Ω and 4Ω loads, providing flexibility in configuration.
4. Space and Installation Type
   • Determine whether you need a built-in amplifier module (integrated into the sub enclosure) or an external standalone amplifier.
   • Built-in modules save space and offer a clean, compact solution ideal for tight installations like under seats or in dash compartments.
   • External amplifiers offer greater power, cooling, and tuning flexibility but require more space and careful mounting.
   • Consider heat dissipation—ensure adequate ventilation, especially in enclosed spaces.
5. Connectivity and Input Options
   • Look for amplifiers with versatile input options: RCA line-level inputs for clean signal transfer from head units, and speaker-level inputs for systems without RCA outputs.
   • High-level inputs allow connection to factory stereos by tapping into existing speaker wires.
   • Ensure the amplifier has proper output terminals (binding posts or spring clips) compatible with your subwoofer wiring gauge (typically 12–16 AWG).
6. Tuning and Control Features
   • Essential controls include:
     • Gain/Level Control – Matches the amp’s input sensitivity to the source signal.
     • Low-Pass Filter (LPF) – Blocks high frequencies, sending only bass to the subwoofer (adjustable between 50–150 Hz).
     • Subsonic Filter – Removes ultra-low frequencies below the sub’s effective range, reducing strain.
     • Phase Control (0°/180°) – Aligns the sub’s output with main speakers for coherent sound.
   • Advanced models may include remote level controls, digital displays, or Bluetooth tuning via smartphone apps.
7. Build Quality and Environmental Protection
   • Opt for amplifiers with a solid metal chassis for durability and heat dissipation.
   • For marine, outdoor, or vehicle applications, choose weather-resistant or waterproof amplifier modules with conformal-coated circuitry to resist moisture and corrosion.
   • Check for protective features like thermal shutdown, short-circuit protection, and overload prevention.
8. Performance Specifications
   • Signal-to-Noise Ratio (SNR): Should be 80 dB or higher—higher values mean cleaner audio with less background hiss.
   • Total Harmonic Distortion (THD): Should be below 1%—lower THD ensures accurate, undistorted bass reproduction.
   • Frequency Response: Look for a range that matches your subwoofer (e.g., 20–200 Hz) for optimal low-end extension.
   • Efficiency: Class D amplifiers are preferred for subwoofers due to high efficiency, compact size, and minimal heat generation.
9. Brand Reputation and Value
   • Stick with reputable brands known for reliability and customer support (e.g., JL Audio, Rockford Fosgate, Alpine, Kenwood, Monoprice).
   • Compare warranty length and service availability.
   • Balance cost with features—sometimes a slightly higher investment yields better long-term performance and durability.

Selection Factor	Ideal Range / Recommendation	Why It Matters	What to Avoid
Amplifier RMS Output	75%–100% of subwoofer RMS	Prevents underpowering and clipping	Matching peak power instead of RMS
Impedance Match	Amp stable at sub’s final load (2Ω or 4Ω)	Ensures safe and efficient operation	Using 1Ω loads on non-stable amps
Signal-to-Noise Ratio	≥ 80 dB	Reduces background noise	Low SNR causing audible hiss
Total Harmonic Distortion	< 1%	Pure, accurate bass reproduction	High THD causing muddy sound
Low-Pass Filter Range	50–150 Hz, adjustable	Smooth integration with main speakers	Fixed or missing crossover

Expert Tip: When in doubt, slightly underpowering a subwoofer is safer than overpowering it. Clipping from an overdriven amp causes more damage than clean, moderate power. Always set gain properly using a multimeter or test tones to avoid distortion.

Final Recommendations

• Always consult your subwoofer’s manual for exact power, impedance, and wiring specifications.
• Use high-quality power and ground cables (4-gauge for high-power systems) to prevent voltage drops.
• Consider future upgrades—choose an amplifier with headroom or expandability if you plan to add more subs.
• Test the system at moderate volumes first, then gradually increase while listening for rattles, distortion, or overheating.
• Keep firmware updated if using a digitally controlled amplifier module.

By carefully evaluating power ratings, impedance, physical constraints, and performance features, you can select a power amplifier module that not only matches your subwoofer but enhances your entire audio experience. A well-matched amplifier ensures powerful, clean bass that brings music, movies, and games to life—without risking component failure. When properly chosen and configured, your subwoofer system will deliver years of reliable, high-impact performance.

Frequently Asked Questions About Subwoofer Power Amplifier Modules

Q: How is a subwoofer power amplifier module installed?

Installing a subwoofer power amplifier module involves several key steps to ensure safe and optimal performance. While the exact process may vary depending on the amplifier type and vehicle or audio system setup, the general installation procedure includes:

• Power Connection: Connect the amplifier to a reliable power source—typically the battery—using an appropriately gauged power wire. A fuse should be installed near the battery for safety.
• Grounding: Secure a low-resistance ground connection by attaching a ground wire from the amplifier to a clean, unpainted metal surface on the vehicle chassis.
• Signal Input: Route an RCA cable from the head unit (or audio source) to the amplifier’s input to carry the audio signal.
• Subwoofer Connection: Use speaker wire to connect the amplifier’s output terminals to the subwoofer, ensuring correct polarity (positive to positive, negative to negative).
• Remote Turn-On Wire: Connect the blue remote wire from the head unit to the amplifier so it powers on automatically when the audio system is activated.

Proper installation ensures maximum efficiency, prevents electrical hazards, and enhances sound quality. Always refer to the manufacturer’s manual for model-specific instructions.

Q: Can a power amplifier module for a subwoofer be used with any type of subwoofer?

While many power amplifier modules are designed for broad compatibility, they are not universally interchangeable with all subwoofers. Compatibility depends on several technical factors:

• Impedance Matching: The amplifier must support the subwoofer’s impedance (measured in ohms, e.g., 2Ω, 4Ω). Mismatched impedance can lead to overheating or underperformance.
• Power Rating: Ensure the amplifier’s RMS (Root Mean Square) output matches or slightly exceeds the subwoofer’s RMS power handling. Avoid pairing a significantly overpowered amp without proper control settings.
• Configuration: Monoblock amplifiers are ideal for single subwoofers, while stereo amps may be used in bridged mode depending on design.
• Wiring Options: Some subwoofers have dual voice coils, requiring specific wiring setups that the amplifier must accommodate.

To guarantee optimal performance and avoid damage, always cross-check the specifications of both the amplifier module and the subwoofer before integration.

Q: How to maintain a power amplifier module for a subwoofer?

Regular maintenance extends the lifespan of your amplifier and ensures consistent audio performance. Key maintenance practices include:

• Inspect Connections: Periodically check power, ground, and signal cables for looseness, corrosion, or wear. Tighten terminals as needed.
• Clean Dust and Debris: Gently clean the amplifier’s heat sink and vents using compressed air to prevent overheating. Avoid using liquids or abrasive materials.
• Avoid Overloading: Do not exceed the amplifier’s rated power output or connect incompatible speakers, as this can cause clipping, distortion, or permanent damage.
• Monitor for Warning Signs: Watch for unusual sounds (distortion, buzzing), frequent shutdowns, or excessive heat, which may indicate internal issues.
• Firmware Updates (if applicable): For digital amplifiers, check for firmware updates from the manufacturer to improve stability and features.

With proper care, a well-maintained amplifier can deliver powerful, clean bass for years.

Q: Does a power amplifier module for a subwoofer need ventilation?

Yes, proper ventilation is essential for the reliable operation and longevity of a power amplifier module. Amplifiers generate significant heat during operation, especially when driving low-frequency signals at high volumes. Without adequate airflow:

• Thermal Shutdown: Many amplifiers have built-in protection that automatically turns them off when overheating, disrupting audio playback.
• Component Degradation: Prolonged exposure to high temperatures can damage internal electronics, capacitors, and transistors.
• Reduced Efficiency: Heat buildup decreases power output and increases distortion.

Best practices for ventilation include:

• Install the amplifier in an upright position to allow natural convection cooling.
• Avoid enclosing it in sealed compartments or covering it with fabric or carpet.
• Ensure at least 2–3 inches of clearance around the unit, especially near the heat sink.
• Consider models with built-in cooling fans for high-power applications.

Proper placement and airflow management help maintain peak performance and prevent premature failure.

Q: What is the difference between a subwoofer and a power amplifier?

Although they work together, a subwoofer and a power amplifier serve distinct roles in an audio system:

Feature	Subwoofer	Power Amplifier
Primary Function	Reproduces low-frequency audio signals (typically 20–200 Hz), such as bass and sub-bass tones.	Increases the power of an audio signal to drive speakers or subwoofers effectively.
Component Type	Electroacoustic transducer (a type of loudspeaker).	Electronic device that boosts line-level signals to speaker-level power.
Input Source	Receives amplified signal from the power amplifier.	Receives low-level signal from a preamp, head unit, or audio processor.
Power Handling	Rated in RMS watts it can handle; converts electrical energy into sound.	Rated in output power (e.g., 500W RMS); supplies energy to the speaker.
Physical Design	Includes a cone, voice coil, magnet, and enclosure (sealed, ported, etc.).	Contains circuitry (analog or digital), heat sinks, and input/output terminals.

In short, the amplifier provides the power, while the subwoofer produces the deep bass sound. They are complementary components: one cannot function effectively without the other in a high-performance audio setup.