Even when you’ve replaced the factory audio system in your vehicle, there are chances that you’ll not get the best sound possible.
Because every vehicle has a different acoustic environment. There are different levels of engine noise, road noise, interior shape, and music preference in our cars. That is why some audio frequencies overpower others, and you get suboptimal sound.
You can try to solve this issue by using the head unit’s built-in equalizer (EQ). But this EQ only gives you bass and treble adjustment, and its preset curves are only suitable for factory speakers/subs.
Therefore, if you’ve already upgraded your factory audio components, you’ll need an external EQ to get the most out of your aftermarket amp, speakers, and sub.
Sound Storm Laboratories S4EQ – Best 4-Band Equalizer
- Dual Color Illumination
- Variable Subwoofer Filter, Subwoofer Level Control, Master Volume Control
- Switchable Phase Selector, Fader Control, Input Selector, 2 Source Input
The first equalizer we have is the S4EQ by Sound Storm Laboratories.
It’s a 4-band graphic EQ that gives a decent upgrade over your stereo’s EQ while not being heavier on your wallet.
These four bands represent the bass, midbass, mid, and high regions. The center frequencies of these regions are 30Hz, 150Hz, 1000Hz, and 20000Hz. The overall frequency range is 30-20000Hz.
It’s pretty simple in terms of design. All the controls are on the front side, while the inputs/outputs are on the back.
If we talk about the controls, you’ll get CD/radio selector on the left side. This selector allows you to switch between radio and CD/DVD players as your input source. Then, there’s a ‘master’ volume knob to control the overall system sound and a fader knob to adjust the balance between front and rear speakers.
Then, there are two controls dedicated to your subwoofer volume and frequency. While the volume control allows to increase/decrease of the output of the subwoofer channel, the frequency (30Hz-250Hz) knob acts as a variable low-pass filter and allows you to set the frequency limit for that output channel.
The remaining four controls are the frequency bands already discussed above.
In the rear area, you’ll get two inputs (one each for CD player and radio) and three outputs (two for front/rear speakers and one for sub).
On the top side, you’ll get radio/CD input gain controls and a phase shift selector. The phase shift feature is important because it allows you to synchronize the sound of the speakers and subwoofer.
This EQ also produces an above-average 7V preamp output which allows your amp to work without aggressive gain settings.
Overall, this EQ is great if you want something basic and quick to install.
Clarion EQS755 – Best 7-Band Equalizer
- 7-Band Graphic Equalizer 6-Channel / 7 Volt RCA Outputs (Front/Rear/Subwoofer)
- Adjustable Master Volume Level Control Adjustable Subwoofer Level Control
- 2-Channel RCA AUX Input with Adjustable Gain Selectable 12dB Low-Pass Crossover (60Hz or...
If you have a slightly higher budget for an equalizer, you can consider Clarion EQS755 as well.
It’s a 7-band EQ with six (front, rear, and sub) 8V RCA outputs and a 12dB low-Pass Filter (works at 60Hz and 90Hz frequencies).
These seven bands work at the center frequencies of 50Hz, 125Hz, 315Hz, 750Hz, 2200Hz, 6000Hz, and 16000Hz, respectively.
You can find these adjustment knobs on the front side, alongside other controls such as subwoofer volume, master volume, and fader controls.
The other important specs include 20Hz-30,000Hz frequency response and a 100 dB signal-to-noise ratio.
One good thing about EQS755 is the presence of speaker-level inputs that allow you to connect it to factory stereos without using any hi-lo converter in between.
To support more devices, this EQ has an aux RCA input to connect an mp3 player and a front-panel 3.5mm input to connect your phone or any other media player as the input source.
Lastly, all RCA connectors are gold-plated to ensure proper signal transfer.
Audiopipe EQ-909X – Best 9-Band Equalizer
- Audiopipe 9 Band Equalizer
The third EQ in our roundup is the EQ-909X by Audiopipe.
As suggested by its model number, it’s a 9-band equalizer. These additional bands allow you to have greater control over the sound frequencies.
These bands have center frequencies of 50Hz, 125Hz, 250hz, 500Hz, 1kHz, 2kHz, 4kHz, 8kHz, and 16kHz, respectively.
Other specs include 10Hz-50kHz frequency response range, main/aux input selector, and 100 dB S/N ratio.
The preamp signals produced by this EQ have 9 Volts which makes it an excellent line driver.
One thing I like about the 909X is that it’s more compact than other 9-band EQs which gives you more mounting options.
I didn’t like the crossover part as it only works at 60-90Hz. At this price, I believe there should’ve been a variable crossover. But this issue is subjective and doesn’t apply if you’re not going to to use this crossover feature.
Other than this, the knobs feel a little flimsy so you should handle them with care.
There’s no power switch, so you’ll have to make a remote wire connection to turn it on and off.
Why You Need a Car Equalizer
Some people argue that you don’t need any external car equalizer because built-in EQs are more than enough to handle this job.
But that’s not true for a few reasons.
Aftermarket EQs provide much greater control to the audio frequencies than the car stereo’s built-in EQ – no matter how premium they are.
And even if you’re satisfied with the EQ performance, car stereos don’t generally produce a strong preamp signal. It causes you to set the amp gain much higher, resulting in distortion and clipping.
The 3rd-party EQs solve this problem as many high-end models come with built-in line driver functionality. This functionality allows them to send a 6+ Volt signal to the amp.
Lastly, these EQs give you extra preamp outputs that can be handy if your car stereo doesn’t have many of those.
Things to Look for in a Car Equalizer
Below are some factors you should look for in a car equalizer before making any purchase.
Number of Frequency Bands
A frequency band is a small portion of the entire frequency range that an EQ can cover. For example, a 5-band EQ will have sub-bass, bass, midrange, upper-midrange, and treble regions as its bands. Each frequency band has a center frequency and a bandwidth.
While center frequency is the exact frequency point of that band (1000 Hz, for example), the bandwidth is the width/size of the band you’re adjusting.
The number of EQ bands will determine how much control you have over sound frequencies.
That is why budgets EQ will have 3-5 bands while high-end models can have as many as 15.
Graphic vs Parametric EQ
Graphic EQs are the basic EQs where you get different knobs or sliders as the graphical representation of frequency bands. These are predetermined frequency bands that cen be adjusted to boost/cut specific frequencies. These EQs have center frequency and bandwidth fixed.
On the other hand, parametric EQs are more advanced and allow you to tweak center frequency as well as the bandwidth. By doing so, you can minimize the effect of one band adjustment on its neighboring bands – something not possible in graphic EQs.
Number of RCA Outputs
You also need to consider the number of preamp outputs on an EQ. It becomes crucial if you have a large number of devices.
Lastly, there’s output voltage. This factor is important if you’re intending to use your EQ as a line driver and boost the voltage. As a general rule, EQ should give 5-6V output to the amplifier.