Amplifier Ratings Explained

When it comes to car audio, amplifiers play a crucial role in delivering the power needed to drive your speakers and subwoofers. But with so many technical terms and ratings on the spec sheet, it can be overwhelming to determine which amplifier is right for your system. This guide will break down the most important amplifier ratings to help you make an informed decision. ABOVE IS THE AUDIO DYNAMICS Model SD1200.1v2

1. RMS Power vs. Peak Power

  • RMS Power: This stands for "Root Mean Square" and represents the continuous power an amplifier can deliver without distortion. RMS is the most accurate reflection of an amplifier's real-world performance.

  • Peak Power: This indicates the maximum power an amplifier can deliver for short bursts. While it may sound impressive, it’s less relevant for daily use since music and audio signals rarely operate at peak levels.

Tip: Always prioritize RMS power over peak power when evaluating an amplifier.

2. Total Harmonic Distortion (THD)

THD measures the amount of distortion an amplifier introduces to the signal. It’s expressed as a percentage, with lower values indicating cleaner sound. A THD below 1% is generally acceptable, but audiophiles often look for values under 0.1%.

3. Signal-to-Noise Ratio (SNR)

SNR measures the level of the audio signal compared to background noise, expressed in decibels (dB). A higher SNR means less noise and a clearer signal. Aim for an SNR of 90 dB or higher for optimal performance.

4. Class of Amplifier

Amplifiers are categorized into different classes based on their design, efficiency, and sound quality:

  • Class A: Known for the best sound quality due to its continuous operation over the entire audio waveform. However, it’s highly inefficient and generates significant heat.

  • Class AB: Combines the sound quality of Class A with improved efficiency, making it the most common choice for car audio systems.

  • Class D: Operates with high efficiency using a switching design. It’s compact and ideal for driving subwoofers but may lack the precision of Class A/AB for full-range applications.

  • Class G/H: Variants of Class AB that utilize multiple voltage rails or a tracking power supply to improve efficiency during higher output levels.

  • Push-Pull: A specific configuration often used in Class A and AB designs. It involves two transistors (or tubes) working alternately to amplify the positive and negative halves of the audio signal. This configuration reduces distortion and improves efficiency while maintaining excellent sound quality. Push-pull designs are especially valued for their ability to deliver clean power in demanding setups.

Choosing the Right Class: Class A is ideal for audiophiles prioritizing sound fidelity, while Class D suits those focused on high power and efficiency.

See Mosconi ZERO pictured below - CLASS A

AUDIOFROG AMPS PICTURED BELOW - CLASS D

5. Impedance (Ohms)

Impedance is the resistance an amplifier encounters when driving a speaker, measured in ohms (Ω). Most car audio amplifiers are designed for 4-ohm loads, but many can handle 2-ohm or even 1-ohm loads for higher output. Always match your amplifier’s impedance capability with your speakers to avoid damaging the equipment.

6. Efficiency

Efficiency refers to how much of the input power is converted into audio output versus wasted as heat. Class D amplifiers are the most efficient, often exceeding 90% (with a Sign Wave), while Class A amplifiers typically have efficiencies below 30%.

7. Damping Factor

The damping factor measures the amplifier’s control over the movement of the speaker cone, particularly at low frequencies. A higher damping factor usually translates to tighter and more accurate bass.

8. Input Sensitivity

Input sensitivity defines the voltage level required to drive the amplifier to full power. Matching this to your head unit’s output voltage ensures optimal performance and prevents distortion.

9. Heat Management

Amplifiers generate heat, and effective heat dissipation is critical for longevity and performance. Look for amplifiers with adequate heat sinks, cooling fans, or thermal protection.

10. Power Supply Types

The type of power supply in an amplifier is critical to its performance and efficiency. Here are the common types:

  • Linear Power Supplies: These use large transformers and capacitors to convert DC power. They are reliable and deliver clean power but are bulky and less efficient. Linear supplies are often found in older or high-end audiophile-grade amplifiers.

  • Switching Power Supplies: Also known as SMPS (Switch Mode Power Supplies), these are compact and highly efficient. They convert DC power using high-frequency switching, which allows for a lighter and more compact design. Most modern car amplifiers use switching power supplies due to their space-saving benefits and ability to handle high power demands.

  • Push-Pull Power Supplies: A common configuration in car amplifiers, push-pull power supplies use two transistors to alternately drive current through a transformer. This design steps up the 12V DC from the car’s electrical system to higher voltages needed by the amplifier. The push-pull mechanism is efficient and ensures stable power delivery, making it essential for high-performance audio systems.

  • Regulated Power Supplies: These maintain a consistent output voltage regardless of fluctuations in the car’s electrical system, ensuring stable performance even under heavy load.

Mosconi Pro Amp pictured below comes in different classes
A, AB and d, depending on the number of channels & type

Final Thoughts

Understanding amplifier ratings is key to building a car audio system that meets your expectations. By focusing on essential specs like RMS power, THD, and impedance, you can choose an amplifier that provides the power and clarity your system deserves. Whether you’re upgrading for better bass or audiophile-grade sound, these ratings will guide you to the perfect amplifier.

Still have questions? Contact us at Advanced Car Audio Solutions for expert advice tailored to your car audio needs.