What is Class-D Amplification?

Class-D amplifiers (also called "switching amplifiers" or "digital amplifiers") represent a fundamental departure from traditional analog Class AB designs. Instead of continuously varying transistor conduction to reproduce audio signals, Class-D amplifiers rapidly switch transistors on and off at high frequencies (typically 200kHz-500kHz), modulating the switch timing (pulse-width modulation or PWM) to recreate the audio waveform.

This switching operation offers critical advantages:

• High Efficiency (>85%): Transistors operate in either fully-on or fully-off states, minimizing resistive losses that generate heat in Class AB designs. This means more of your electrical system's power reaches the subwoofer as usable output.
• Reduced Heat Generation: With 85%+ efficiency, only 15% of input power is wasted as heat compared to 40-50% in Class AB amplifiers. This enables smaller heatsinks and more compact chassis designs.
• Lower Electrical System Stress: Drawing less current from your vehicle's alternator and battery for equivalent output power reduces voltage drop, extends battery life, and minimizes the need for expensive electrical system upgrades.
• Compact Form Factor: Smaller heatsink requirements and efficient power supply design enable ultra-compact amplifier chassis that fit in spaces impossible for equivalent Class AB designs.

Class-D for Subwoofer Applications

While early Class-D amplifiers faced criticism for high-frequency switching noise and potential EMI issues, modern implementations like the AL-800.1 have largely overcome these limitations through:

1. Advanced Output Filtering: Multi-stage low-pass filters remove switching frequency artifacts while preserving audio bandwidth. The AL-800.1's 10Hz-250Hz frequency response confirms effective filtering without audible artifacts in the subwoofer range.

2. Optimized PCB Layout: Careful circuit board design minimizes electromagnetic interference (EMI) that can cause noise in adjacent audio equipment or vehicle electronics. Modern Class-D amplifiers rarely cause the alternator whine or radio interference common with early designs.

3. Thermal Stability: Unlike Class AB amplifiers that experience power compression as heatsink temperatures rise (reducing output as thermal limits are reached), Class-D amplifiers maintain consistent output power across wide temperature ranges due to inherently low heat generation.

4. Cost-Effective Manufacturing: Class-D topology requires fewer output transistors and smaller passive components compared to Class AB designs, enabling manufacturers like Feelart to deliver high power output at competitive price points without sacrificing reliability.

Real-World Performance Advantages

For the AL-800.1 user, Class-D efficiency translates into tangible benefits:

Electrical System Impact: At full 800W @ 1Ω output, the AL-800.1 draws approximately 70-75A from your vehicle's electrical system (assuming 85% efficiency and 14.4V supply). A comparable 800W Class AB amplifier would draw 100-110A for the same output—a 30-35A difference that significantly reduces alternator load and voltage drop.

Installation Flexibility: The compact 11″ × 7.5″ × 2″ chassis fits locations impossible for traditional amplifiers: under rear seats, behind kick panels, in spare tire wells, or minimal trunk corners. This space efficiency preserves cargo capacity while delivering full-power performance.

Thermal Management: During extended high-volume listening or competition burps, the AL-800.1's low heat generation maintains stable output without thermal protection activation. Class AB amplifiers often enter thermal protection after 30-60 seconds of sustained high power, requiring cool-down periods that interrupt listening.

Battery-Friendly Operation: Lower current draw extends battery runtime during engine-off demonstrations or tailgating sessions. Systems powered by Class-D amplifiers can play 30-50% longer on battery power before requiring engine restart to recharge.

Input Sensitivity & Gain Structure

The AL-800.1's 0.15V-6V adjustable input sensitivity accommodates virtually any source equipment configuration:

Low-Sensitivity Settings (0.15V-0.5V): Match aftermarket head units with high-voltage preamp outputs (4-5V RMS). Setting sensitivity too high with strong source signals causes premature clipping and distortion.

Mid-Range Settings (0.5V-2V): Accommodate typical aftermarket head units (2-4V preamp output) and most DSP processor outputs. This range provides optimal signal-to-noise ratio for most installations.

High-Sensitivity Settings (2V-6V): Enable integration with factory head units via line output converters (LOCs), which typically provide 0.5-2V output. High sensitivity allows full amplifier output from weak source signals without excessive noise amplification.

Proper Gain Setting Procedure:

• Start with sensitivity control at minimum (fully counterclockwise)
• Play dynamic music at 75-80% head unit volume
• Slowly increase amplifier sensitivity until bass reaches desired level
• Verify no audible distortion at maximum listening volume
• For precise calibration, use oscilloscope or distortion detection tool (DD-1, SMD DD-1+)

Low-Pass Crossover Configuration

The 40Hz-250Hz variable low-pass crossover defines the upper frequency limit sent to subwoofers:

40-60Hz (Ultra-Low Setting): Reserved for systems with dedicated midbass drivers (6.5″-8″ component woofers) handling 60-200Hz. Minimizes subwoofer excursion above fundamental bass notes, reducing distortion and power compression.

60-80Hz (Optimal for Most Systems): Standard setting for component speaker systems. 80Hz crossover point (most common) allows subwoofer to handle deep bass while main speakers focus on midrange clarity. Provides smooth transition with minimal overlap.

80-120Hz (Full-Range Subwoofer Operation): Useful when main speakers are small (4″ or less) with limited low-frequency capability. Subwoofer handles wider bass range, compensating for satellite speaker limitations. Requires proper subwoofer positioning for cohesive imaging.

120-250Hz (Special Applications): Rarely used except for unique installations (bandpass enclosures, pro audio applications, or intentionally overlapping frequency ranges for maximum output).

Subsonic Filter & Excursion Protection

The 15Hz-40Hz adjustable subsonic filter (also called infrasonic or high-pass filter) protects subwoofers from excessive excursion below their operating range:

Why Subsonic Filtering is Critical:

• Ported Enclosure Protection: Below port tuning frequency, subwoofer excursion increases dramatically without producing audible output. Unfiltered infrasonic content causes mechanical damage (voice coil bottoming, surround tearing).
• Power Efficiency: Amplifier power wasted on inaudible infrasonic frequencies is unavailable for producing clean, loud bass in the audible range. Proper subsonic filtering maximizes usable SPL output.
• Cone Control: Rapid, large-amplitude excursion at infrasonic frequencies stresses suspension components and generates distortion products (Doppler distortion, intermodulation) that degrade midrange clarity.

Subsonic Filter Setting Guidelines:

• Sealed Enclosures: Set 5-10Hz below system's -3dB rolloff frequency (typically 25-30Hz for most 10-12″ sealed systems)
• Ported Enclosures: Set 3-5Hz below port tuning frequency. Example: 35Hz-tuned ported box → 30Hz subsonic filter
• Competition Systems: Disable subsonic filter or set to minimum (15Hz) to maximize output at tuning frequency during burp competitions

Bass Boost: Uses & Abuses

The 0-12dB bass boost @ 45Hz provides frequency-specific output enhancement:

Legitimate Bass Boost Applications:

• Cabin Acoustic Compensation: Compensate for vehicle cabin gain/cancellation nodes that create uneven bass response. Modest boost (3-6dB) can flatten response in weak-output frequency zones.
• Enclosure Tuning Correction: Sealed enclosures naturally roll off below resonance. Carefully applied boost can extend perceived low-frequency response without excessive excursion.
• Musical Preference: Some listeners prefer exaggerated deep bass for genres like reggae, dubstep, or modern hip-hop. Moderate boost (4-6dB) enhances impact without overwhelming midrange.

Bass Boost Warnings & Best Practices:

• Never Compensate for Inadequate Power: Bass boost is NOT a substitute for insufficient amplifier power. Using boost to increase volume causes premature clipping, distortion, and potential subwoofer damage.
• Start with 0dB (Boost Off): Set system levels and crossover points with bass boost disabled. Only add boost after system is properly tuned and levels are balanced.
• Use Sparingly: Maximum 12dB boost dramatically increases power demand and cone excursion. Excessive boost causes amplifier clipping, voice coil overheating, and mechanical failure.
• Monitor for Distortion: Any audible distortion (flapping, buzzing, popping) at high volumes indicates excessive boost. Reduce boost immediately to prevent damage.

Power Wire & Fusing Requirements

Minimum Wire Gauge: 4 AWG OFC (Oxygen-Free Copper)

At full 800W @ 1Ω output with 85% efficiency, the AL-800.1 draws approximately 70-75A from your vehicle's electrical system. Proper wire gauge selection ensures safe, efficient power delivery:

4 AWG OFC Power Wire (REQUIRED):

• Current Capacity: 120-140A (sufficient for 800W continuous operation with headroom)
• Voltage Drop: <0.5V @ 75A over typical 15-20 foot run from battery to amplifier
• Resistance: ~0.25Ω per 100 feet (enables efficient power transfer)
• Cost vs. Performance: Optimal balance between wire cost and electrical performance

DO NOT Use 8 AWG Wire: Despite some installer claims, 8 AWG wire (40-60A capacity) is dangerously undersized for 800W amplifiers. Undersized wire causes excessive voltage drop (reducing output power), overheating (fire risk), and premature amplifier protection mode activation.

Consider 2 AWG OFC for Optimal Performance:

• Reduces voltage drop to <0.3V @ 75A for improved power delivery
• Provides headroom for future system expansion (additional amplifiers)
• Maintains cooler wire temperatures during sustained high-power operation
• Recommended for electrical systems with multiple high-power amplifiers

Fuse Selection & Placement

Recommended Fuse: 80A ANL or MIDI Fuse

The AL-800.1 specifications suggest 40A × 2 fusing, totaling 80A primary fuse rating. Proper fuse selection protects against catastrophic wire damage during short-circuit conditions:

Fuse Placement Critical Rule: Install primary fuse within 18 inches of battery positive terminal. This protects the entire power wire run from battery to amplifier. Wire damage anywhere along this run could cause electrical fire; the fuse disconnects power before wire insulation melts.

ANL vs. MIDI vs. AGU Fuses:

• ANL Fuses (Recommended): Industry-standard for car audio, fast-blow characteristics, widely available, reliable protection. Use 80A ANL fuse in fuse holder near battery.
• MIDI Fuses: Automotive-style blade fuses, compact, often pre-installed in distribution blocks. Equivalent protection to ANL in smaller package.
• AGU Fuses (Avoid): Glass tube style, inferior vibration resistance, prone to intermittent connection issues. Not recommended for modern installations.

Fuse Rating Guidelines: Total primary fuse rating should be 100-125% of maximum expected current draw. For 800W @ 1Ω (75A draw), 80-100A fuse provides protection without nuisance blowing. Never exceed 100A fuse with 4 AWG wire.

Grounding Best Practices

Ground Wire = Power Wire Gauge: Always use same gauge wire for ground as power wire (4 AWG OFC minimum). Undersized ground wire causes voltage drop identical to undersized power wire, reducing amplifier performance and causing protection issues.

Optimal Ground Connection Points:

• Direct Metal-to-Metal Contact: Remove paint, rust, and undercoating to expose bare metal at ground point
• Structural Chassis Members: Ground to thick frame rails, seat mounting points, or structural brackets—NOT thin body panels that flex
• Short Ground Wire: Keep ground wire length <3 feet from amplifier to ground point. Shorter = lower resistance = better performance
• Multiple Contact Points: Use ring terminal with multiple mounting bolts or screws for redundant connection security

Ground Loop Noise Prevention: If installing multiple amplifiers, ground all amplifiers to the same point (common ground) within 12-18 inches of each other. This minimizes ground potential differences that cause alternator whine and other electrical noise.

Electrical System Considerations

Stock Electrical System Capability (800W Amplifier):

Most factory electrical systems (100-140A alternators, 60-75Ah batteries) can support one 800W amplifier without upgrades, provided:

• Proper wire gauge (4 AWG minimum) minimizes voltage drop
• Battery is healthy with good cranking amps (400+ CCA)
• Alternator maintains 13.5-14.5V at idle with audio system playing
• Vehicle is driven regularly (not prolonged engine-off listening)

Symptoms of Electrical System Inadequacy:

• Headlight dimming during bass hits (indicates excessive voltage drop)
• Amplifier protection mode activation at high volumes (low voltage protection)
• Audible distortion at max volume that wasn't present at moderate levels
• Battery dies after 10-15 minutes of engine-off listening

Electrical Upgrades for Improved Performance:

• Big Three Upgrade: Replace/supplement three primary ground cables with 1/0 AWG or 4 AWG OFC: (1) battery negative to chassis, (2) chassis to engine block, (3) alternator positive to battery positive. Cost: $50-100 parts, dramatically reduces voltage drop.
• AGM Battery Upgrade: Replace flooded lead-acid battery with Absorbed Glass Mat (AGM) battery. AGM batteries handle high current draw/recharge cycles better, maintain voltage under load, and provide more power per pound. Brands: Odyssey, XS Power, Kinetik. Cost: $200-400.
• High-Output Alternator: Only necessary for multi-amp systems or sustained high-power competition. Quality high-output alternators (180-250A) cost $300-800 installed.

Overall Assessment

The Feelart AL-800.1 earns a 4.0 out of 5.0 rating, representing solid value in the budget monoblock amplifier category. This rating reflects exceptional price-to-performance ratio, genuine 1Ω stability, and ultra-compact Class-D design, balanced against lack of CEA-2006 verification, limited brand recognition, and basic feature set compared to premium alternatives.

Strengths: The AL-800.1's greatest asset is its $399.99 price point delivering features and capabilities typically reserved for $400-600 amplifiers. The compact 11″ × 7.5″ × 2″ chassis enables installation flexibility impossible with traditional amplifiers, while Class-D efficiency minimizes electrical system demands. Comprehensive adjustability (variable crossover, subsonic filter, bass boost, input sensitivity) provides tuning flexibility for diverse system architectures. For budget-conscious enthusiasts seeking maximum power output without premium pricing, the AL-800.1 delivers tangible performance.

Considerations: The 1.0-point rating deduction primarily reflects absence of CEA-2006 power verification and limited real-world testing data. Without independent power testing, actual output may differ from 800W @ 1Ω specification. Additionally, minimal brand presence outside Southeast Asia creates uncertainty regarding long-term reliability, warranty support, and resale value. Users prioritizing documented performance and established brand reputation may prefer alternatives despite higher cost.

💰 Value Analysis

Price Point: At $399.99, the AL-800.1 occupies the sweet spot between entry-level offerings ($150-$250) and established mid-tier brands ($400-$600). This pricing delivers 800W @ 1Ω Class-D amplification at 40-50% cost savings compared to comparable amplifiers from Rockford Fosgate, Kicker, or JL Audio.

Performance-Per-Dollar: Exceptional. Comparable 800W @ 1Ω Class-D amplifiers from established brands typically cost $400-600. Even accounting for potential power specification optimism, the AL-800.1 likely delivers 600-700W actual output—still excellent value at $399.99.

Total System Cost Consideration: Budget $750-$1000 total system investment: amplifier ($399.99), subwoofer ($200-400), enclosure ($100-200), wiring kit ($75-150). This positions the AL-800.1 as foundation for capable daily-driven bass systems without premium-component pricing.

🎯 Recommended For

• Budget-Conscious Enthusiasts: First-time upgraders or value-oriented buyers seeking maximum power output per dollar without sacrificing essential features or 1Ω stability
• Space-Constrained Installations: Vehicle owners requiring compact amplifier dimensions for under-seat mounting, minimal trunk corners, or creative installation locations impossible with traditional amplifiers
• Daily-Driven Bass Systems: Users building practical 800W subwoofer systems for modern bass-heavy music (hip-hop, EDM, trap) without competition-level power demands or budget
• Multi-Amplifier Systems: Installers seeking dedicated subwoofer amplification for complex systems with separate component speaker amplifiers and DSP processing
• Factory Head Unit Integration: Owners retaining factory head units who need wide input sensitivity range (0.15-6V) to accommodate line output converter signals
• Electrical System Limited Vehicles: Situations where stock electrical system must support audio system, benefiting from Class-D efficiency and reduced current draw

⚠️ Less Suitable For

• Power-Obsessed Competitors: SPL competition enthusiasts demanding verified CEA-2006 ratings, dyno testing results, and maximum power extraction should consider premium alternatives with documented performance
• Brand-Conscious Consumers: Users prioritizing established brand reputation, comprehensive warranty support, and proven long-term reliability over cost savings
• Sound Quality Purists: Audiophiles seeking minimum measurable distortion, extensive technical specifications, and premium component quality may prefer higher-end amplifiers despite cost premium
• Professional Installation Shops: Businesses requiring predictable warranty support and customer service may hesitate due to limited Feelart brand presence and uncertain parts availability

📝 Final Verdict

RECOMMENDED: STRONG BUY for Budget & Space-Conscious Applications

The Feelart AL-800.1 represents exceptional value proposition, delivering Class-D efficiency, 1Ω stability, and ultra-compact dimensions at a highly competitive $399.99 price point. While absence of CEA-2006 verification and limited brand recognition introduce uncertainty compared to established alternatives, the combination of comprehensive adjustability, flexible power scaling (300W @ 4Ω to 800W @ 1Ω), and installation-friendly compact chassis make this amplifier compelling for budget-conscious enthusiasts.

Users prioritizing maximum power output per dollar, space-efficient installation, and Class-D electrical efficiency will find the AL-800.1 exceeds expectations. The wide input sensitivity range (0.15-6V) and variable crossover/subsonic controls provide tuning flexibility matching amplifiers costing twice as much.

For daily-driven bass systems, space-constrained vehicles, or multi-amplifier configurations, the AL-800.1 earns its 4.0/5.0 rating and strong buy recommendation. When properly installed with adequate power/ground wiring (4 AWG OFC minimum), this compact monoblock delivers impressive performance rivaling established brands at 40-50% cost savings—cementing its position as one of the best value propositions in the budget 800W amplifier category.

Official Product Information

Manufacturer: Feelart AL-800.1 Official Product Page

Access official specifications, technical documentation, and manufacturer contact information.

Alternative Sources:

• Feelart Vietnam Official Site - Regional distributor with detailed product information
• Online Retailers: Check eBay, Amazon, AliExpress for availability and customer reviews