Equalizers and Digital Sound Processors for Your Car

Both can improve car audio, but which is right for you?

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

Equalizers and digital sound processors (DSPs) are two kinds of devices that allow you to fine-tune the sound in your vehicle’s audio system. Both can improve the sound quality of an audio system so that it better matches the environmental conditions of your car.

Equalizers
  • Sits between the head unit and the amp.

  • Allows users to boost or reduce specific sound frequencies.

  • Generally cheaper than DSPs.

Digital Signal Processors
  • Can send specific frequencies to certain speakers.

  • Can fix preprocessing issues by fine-tuning the head unit to better match the interior of a vehicle.

  • Usually pricier than equalizers.

Car audio is inherently more complicated than home audio due to the irregular nature of vehicle 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 truck.

Equalizers Pros and Cons

Advantages
  • Cheaper than most DSPs.

  • Frequency-specific control of audio.

  • Versatile installation options.

Disadvantages
  • Cannot adjust output for individual speakers—affects the whole sound system.

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 reduce 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 are usually not as powerful as 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.

Digital Sound Processors Pros and Cons

Advantages
  • Most full-fledged solution for problematic interiors.

  • Adjust frequency performance for individual speakers.

Disadvantages
  • Pricier than most equalizers.

  • More complex installation.

Digital signal processors do the same job as equalizers, but many of them also perform crossover-like functions. That means they can be used for frequency issues, but they can also adjust which 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 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.