Car audio Tuning Guide

One of the things I like most about subwoofers is that I can feel the musical emotion directly with my body. The low frequency beat often forces me to dance around, or, at the very least, nod my head along with the rhythm. That's why we all like music in the first place — it moves us.

It can take a little time and effort to get the exact bass sound you want from your subs, but the rewards of a well-tuned subwoofer system are overwhelmingly cool and physically satisfying.

Before we get started...

This article discusses how to tune your subs and amp to get the best sound you can. If you are looking for information about buying subwoofers, please read our Subwoofer Buying Guide and check out our selection of top-rated subwoofers, then come back here to learn more about setting them up to deliver great sound.

First, set your speaker level

Keep in mind, distortion is the enemy: it destroys speakers, subs, and eardrums. Distortion sounds like crackling, flapping, crunching, or hissing that interferes with the distinct sound of a musical instrument. If you power your full-range car speakers with an amplifier, it is crucial that the amp's gain is properly set to prevent distortion. [Need an amplifier? See our full selection.]

Step 1: Remove the distortion

With the amp gain set low, play some music and turn up your receiver's volume until you hear the music distorting; then back off the volume until the music sounds clean again. Note or mark where the receiver's volume is. This setting is the maximum volume your receiver can go to and still play cleanly.

Now, turn the amp's gain up until you hear distortion again; then back off the gain slightly until the distortion goes away. The amp gain is now set, so you can lower the receiver volume to a more comfortable level. Even if your speaker system does not have an amplifier, you still need to find that maximum volume point on your receiver by turning it up to just below distortion level.

Step 2: Flatten the signal, open the low-pass filter

Turn your sub amp's gain to its lowest, most counter-clockwise position. Switch its low-pass filter on and set it as high, clockwise, as it will go. If it has a bass boost, turn it off. If it has a remote level control, set it to its middle position so, later, you have the choice of boosting or cutting the bass on an individual song.

Adjust your receiver's bass tone control to its middle, zero, or "flat" setting, whichever it's called on your stereo. If it has a subwoofer level control, set it, also, to its middle, or "no gain" setting. Sometimes receivers have a crossover, low-pass filter, or bass boost on their subwoofer output. Make sure those are all turned off, too.

Start by turning the gain down, and turn off your filters and bass boost.

Note: Do not use the low-pass filters, crossovers, or bass boosts on the receiver and the amplifier at the same time. Use one or the other, but not both. The reason is that something called phase distortion generates around each filter or boost's crossover frequency, muddying up the sound.

Step 3: Adjust the subwoofer gain and low-pass filter

Play music through your receiver at about one-quarter volume. Turn up the gain of the subwoofer amp until the sound from your subwoofer completely overpowers the other speakers, without distorting.

Turn the gain up until it distorts, then back it off until the sound is clean again.

While listening to the music coming out of your sub, slowly adjust the sub amp's low-pass filter downward until all the high- and mid-frequency notes disappear.

Adjust the low-pass filter downward to eliminate high- and mid-frequency notes.

The low-pass filter eliminates the notes you don't want your subwoofer to play. It also acts like a tone control to capture the "edges" of the kick drum's sound; the attack and release of its boom. Filter out the cymbals, strings, vocals, and guitars. Leave the bass and the low drums.