Equalizers and Digital Sound Processors for Your Car

Graphic equalizers shown on car head unit
Steven Puetzer / Photolibrary / Getty

Equalizers and digital sound processors are two kinds of devices that can allow you to fine-tune the sound in your vehicle’s audio system. Car audio is inherently more complicated than home audio due to the irregular nature of car and truck interiors, so even great automotive sound systems can end up sounding bad right out of the box. The interior of your car is full of materials that absorb or reflect sound, which can result in some frequencies getting muffled while others hit your eardrums like a mac truck.

Leveling the Playing Field

Some head units include simple bass, treble, and mid-range adjustments, but equalizers take it a step further than that. In a system that includes an amplifier, the equalizer sits between the head unit and the amp, and it allows you to boost or cut back on specific sound frequencies.

There are several different types of equalizers, each of which has its own benefits:

  • Graphic equalizers have fixed bandwidths, but they provide sliders that can be adjusted precisely.
  • Parametric equalizers provide even greater control, as they allow you to adjust the width and center point of each frequency band.
  • EQ boosters are powered, which means they are essentially a combination of an equalizer and an amp. They aren’t typically as powerful as most good amps, but using one is simpler than using both a passive equalizer and a standalone amplifier.
  • Analog equalizers use physical dials or sliders to provide precise control over frequency settings.
  • Digital equalizers don’t have physical controls, so they can often store settings for a variety of frequency profiles.

The Cure for the OEM Head Unit Blues

Digital signal processors do the same job as equalizers, but many of them also perform crossover-like functions. That means they can frequency issues, but they can also adjust what frequencies are sent to which speakers.

There are a number of uses for a digital sound processor, but one of the most remarkable is to fix problems that you may have noticed with your OEM head unit. Most factory stereos are designed to compensate for low-quality speakers, which is accomplished by artificially manipulating the frequency profile. When you replace your inferior original equipment speakers with high-quality aftermarket units, this manipulation is often very easy to pick up on. If you also install an amp, the problem will only get worse.

That’s where a digital signal processor can come to the rescue. The processor sits between the head unit and the amp, and it can literally undo the factory unit’s monkey business. Some digital signal processors even have custom profiles that can be downloaded from the Internet, which will automatically fix the preprocessing issue and improve the overall listening experience by fine-tuning the unit for the interior of the specific vehicle.

What's Involved in the Installation of an Equalizer or Sound Processor?

Since there are so many different kinds of equalizers and sound processors, the installation process varies from one situation to another. Some equalizers are built right into head units, some standalone units come in a single-DIN profile, and others are designed to be mounted near your amplifier. Similarly, most sound processors are designed to be tucked away in the same location as your amplifier.

The wiring process usually isn’t any more complex than installing an amplifier or a crossover, but it’s a more involved operation than just dropping in a couple direct-fit full range speakers. Equalizers are typically installed between your head unit and amp, while sound processors can be installed between the head unit and amp or directly between the head unit and the speakers. Some sound processor kits will even plug seamlessly into your head unit and existing harness.