Active vs Passive Crossovers in a Car Audio System - What's the Difference?

Today we have a special guest from our partners at AudioControl. Josh Cramer, a Product Specialist, is here to give us the low down on active and passive crossovers in a car audio system. 

What is a Crossover

A crossover is a device or circuit that separates an audio signal into different frequency ranges, directing each range to the appropriate speaker.

The main function of a crossover is to prevent speakers from receiving frequencies they can't handle, which can damage them. For instance, sending subwoofer frequencies to a tweeter can "fry" it due to the incompatible low frequencies. Tweeters are meant to handle high frequencies. Crossovers ensure each speaker receives only the frequencies it's designed to play, enhancing sound quality and efficiency.

Crossovers are commonly used in multi-driver speaker systems like 2-way or 3-way component systems. In a 2-way system, a crossover typically splits the signal between a mid-range speaker for lower frequencies and a tweeter for higher frequencies.

Active Crossovers

Active crossovers use electronic components like operational amplifiers to divide audio signals before amplification. They offer more flexibility and precision but need more power.

Active crossovers offer several advantages over passive ones:

• Flexibility: Active crossovers provide more flexibility than passive crossovers, allowing for precise adjustments to crossover frequencies, slopes, and other settings. This customization lets you tailor the audio system to match specific speakers and your listening environment.
• Adjustability: Active crossovers often have adjustable crossover frequencies and slopes, allowing for precise tuning. This customization lets you fine-tune the sound to match your preferences or the needs of different audio sources.
• Signal Processing: Active crossovers offer advanced signal processing features like equalization, phase correction, and time alignment. These features can enhance audio system performance and compensate for speaker or room imperfections.
• Independent Amplification: Active crossover systems often use individual amplifiers for each driver (like woofers, midrange, or tweeters). This gives you more control over each driver and ensures they receive enough power for the best performance.
• Low Distortion: Active crossovers minimize distortion compared to passive crossovers, especially at high power levels. This is because they work on the audio signal before it's amplified, reducing the chance of signal quality issues.
• Bi-Amping and Tri-Amping: Bi-amping and tri-amping are techniques made possible by active crossovers. These techniques involve using separate amplifiers for different frequency ranges, offering more precise control over each. For example, bi-amping uses two amplifiers (one for low frequencies and one for high frequencies), while tri-amping uses three (for low, mid, and high frequencies).

Examples of active crossover devices include Digital Signal Processors (DSPs) like AudioControl D-Series amplifiers and DM-Series Processors. The D-6.1200 is one such example. AudioControl LC line amplifiers also have built-in active crossovers, offering a more affordable way to actively cross over amplifier outputs, similar to the D-Series.

Passive Crossovers

Passive crossovers use components like capacitors, inductors, and resistors to split the audio signal after it's amplified. They don't need external power but can introduce signal loss due to the components.

Unlike active crossovers, passive ones are placed after the amplifier, which is why signal loss occurs. AudioControl PNW Series 6.5” and 6x9” Component Speaker Kits include the PNW-LF1 & PNW-HF1, which have a single input and split the output into tweeter and woofer outputs.

Some passive crossovers also have adjustable tweeter output levels for easier amplifier gain matching. It's also important to note that passive crossovers have wattage limits. Exceeding these limits can damage the crossover or speakers.

Active vs. Passive Crossovers Summary:

To conclude, crossovers are essential for ensuring each speaker in a car audio system receives the correct frequencies, leading to a balanced and accurate sound across the full range of audible frequencies. Active crossovers make sense for those looking for more precision and control in their audio. Passive crossovers provide less fine-tuning but are cheaper to integrate.