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Tuning your subs

How to make the bass in your car sound its best

Kenwood subs in a Sound Ordnance subwoofer box

In this article... I'll show you how to tune your amplifier to get your subwoofers to sound just the way you want them to. Just follow these simple steps for great bass:

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...

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.

Now you're ready for some bass

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.

First, turn the gain down

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

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.

low-pass filter

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.

Step 4: Bass boost and subsonic filter

If you have a bass boost, try carefully turning it up to hear what the bass drum sounds like when you do. Applying just a little bass boost will bring up the kick a lot. Be careful with the bass boost, if you choose to use it — this is where distortion is often introduced into a system. If you hear distortion, lower the sub amp's gain until it goes away. Use the bass boost to feel the beat in the air your sub moves.

bass boost

Now play with the bass boost.

For ported subwoofers, use a subsonic filter on your amplifier to tame any overly loud low notes. This will help decrease the levels of the notes at which the enclosure resonates. Fine-tune all the filters some more to make the bass drum sound tight and dry or loose and reverberant, according to your personal taste. I like reggae and soul, so my bass is plenty loud, but it's a bit drier than most people might like. The important thing is to keep adjusting your system until you hear something you like. When you're satisfied with the tone of your system's bass and kick, turn the sub amp's gain all the way down.

Blending all the frequencies

Now that each piece of the puzzle is set, it's time to bring all the music into focus.

Step 5: Matching the subwoofer level to the receiver volume

Turn up the receiver's volume to its maximum, distortion-free position. Then slowly turn up the subwoofer amp's gain until the bass sounds balanced with the rest of the music. That should do it.

Run your remote bass boost or level control up and down a little to hear what it does. Because of the size of the acoustic space in a car, subwoofers sometimes don't combine their sound constructively with the rest of a system's sound waves. If your bass has plenty of volume but seems to lack punch, you can sometimes help it by reversing your sub's speaker leads. This reverses the subwoofer cone's forward and backward movements, which might put all the sound waves together better than the other way. Whichever way sounds best is the right way.

Troubleshooting any problems

If you hear distortion coming from your subs, turn down the sub amp's gain. If, at this point, you cannot get enough bass out of your subwoofer to keep up with the other speakers without distorting, then you will need to get a bigger subwoofer and amplifier combination, with higher power-handling abilities.

You shouldn't lower the gain of your full-range amplifier to try and match your lack of subwoofer volume. Doing so could allow the amp to send out distorted, clipped signals to your full-range speakers, defeating your goal for clean, full sound, which is why you put in a subwoofer to begin with. More power, especially in the bass, is always better than not having enough.

Now you should be able to enjoy the robust fullness and beat of your music with your sub tuned up to match your system's capabilities and your ear's preference. Just remember to be polite, and turn your boom volume down when it might bother other people.

Learn more about sound tuning

For more information on how to tune your car sound stystem, see Adding a 4-Channel Amp. To learn more about getting the best sound out of your amplifier, take a look at our Amplifiers FAQ and Glossary articles.

  • Clifford from Glendale

    Posted on 11/22/2021

    I am running 2 15ow3 jl audio with a hifonics Gemini 2000w mono block, I hear distortion on da factory door speaker. Trying to tune it in

    Commenter image

    Buck Pomerantz from Crutchfield

    on 11/22/2021

    Clifford, I don't know what "da factory door speaker" is, but distortion is caused by overloading a speaker with too much volume from the source or poorly set amp gain.
  • Travon Price from Silver Spring

    Posted on 11/5/2021

    Thanks for the great tips, I have a question though. I have the JL Audi JD400/4 and your Sound Ordinace B8PTD, do I do ALL of these steps on the front and rear channels of the JL amp individually first and then the powered sub, or are there different steps for configuration. Thanks in advance.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 11/6/2021

    Travon, There are no reasons for skipping steps when it comes to fine-tuning the audio in your car.
  • John from Modesto

    Posted on 9/27/2021

    Thanks Buck. Follow up question on using a cross over. When I tune the amps should I set the amp gains and cross overs that are built in all to band pass or flat and not use any of those features built info the amps and do all my running with my crosse over which is a boss bx55?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 9/28/2021

    John, When using such a 3-way active crossover, you must first match the input and output levels on the crossover to produce the full-strength signal with no distortion. Then, you'll need to set the amplifier gains to produce the full-strength output with no distortion. Seeing as the amp is being fed signals that are already crossed-over, set the amp filters where they'll interact the least with each signal.
  • John from Modesto

    Posted on 9/24/2021

    Hello Buck. Great article. I am getting ready to install a multi amp system in my ride. If I understand correctly, if my amps have cross overs and gain control then I shouldn't use a seperate 3 way cross over?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 9/27/2021

    John, If you have a 3-way component speaker system that came with 3-way crossovers, use them. Most amplifiers don't have the necessary bandpass crossover filters for mid-range speakers, nor high-pass filters crossed-over high enough for tweeters.
  • Brian from Johnson city, TN

    Posted on 9/20/2021

    I just purchased a Rockford Fosgate p300-10 powered sub. I have a Kenwood excelon aftermarket head unit already. I'm wondering what you would suggest would be good settings on the amp? Thanks.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 9/21/2021

    Brian, This article goes trough all the steps you need to adjust the settings for good bass. If re-reading the article doesn't help, you should hire a professional installer to make the adjustments.
  • JohnP from Worcester

    Posted on 8/2/2021

    Hi Buck, I wanted to thank you for your advice. All the years I have had some kinda system in my car I never realized how much it was defeating the purpose of have the frequency settings on the sub amp and HU set the same. So i tested it both ways and disabled the HU(set the Freq to 200 and slope to -6, which is as much as disabled I can make this HU) I used the sub amp xover set to 80-90 and sounds way better than having both the HU and Amp do the same thing. Thank you again for your help. My previous question: You mention "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." If I have an amp and a head unit that neither can be completely shut off, how should I set them? My HU is a Pioneer DEH-P980BT, amp is a Kicker ZX 400.1. The HU has the ability to adjust Freq and slope(slope-6,-12,-18) Should I set the Xover on the HU to -6 and 200hz and adjust at the amp or set the amp to 200Hz and adjust at the HU?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 8/3/2021

    John, I recommend using the 24 dB/octave low-pass filter of that amplifier as the main crossover for your sub, set around 80-100 Hz. So, set the receiver's sub channel low-pass filter at 200 Hz with a slope of 6 dB/octave for the least interaction between the two active crossovers.
  • K Hill from Carrollton TX

    Posted on 7/17/2021

    Buck, I posed a question about what voltage is high gain and what voltage is low gain since my Pioneer GM-DX874 amplifier I got from Crutchfield has voltages of 6.5v on the left and 0.2v on the right rather than "max" and "min". It is hooked up to my stock 2002 Chevrolet Silverado 1500 HD crewcab radio. But browsing other sites I found that 6.5v is actually low gain and 0.2v, relatively low voltage compared to 6.5v, is actually high gain like Buck says. That can be confusing to people new to car amplifiers.

  • K Hill from Carrollton TX

    Posted on 7/16/2021

    And thanks Buck for obviously spending much time answering so many of these questions from all of us noobs!

  • K Hill

    Posted on 7/16/2021

    I have a Pioneer GM-DX874 from Crutchfield and your article could clarify what a high gain setting is and what a low gain setting is voltage wise. The article says to turn the gain counter clockwise to set it to it's lowest. If I turned it counter clockwise I would be setting it to 6.5 volts, the highest voltage, and clockwise all the way would be 0.2 volts, the lowest setting. So to set the gain to the lowest I would turn mine clockwise rather than counter clockwise right? This isn't like wire gauge where higher number is smaller wire or higher voltage is lower gain and lower number is larger wire or lower voltage is higher gain right?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 7/17/2021

    K, The best way to deal with the markings for an amp gain setting is to ignore them. They are confusing, to say the least. They don't correspond to the amp input capability, but to the maximum output of the receiver or other source. Counter-clockwise to 6.5V means the receiver is blasting so loud the amp gain needs to be set to minimum. The 0.2V setting means the source is weak and the gain needs to be maximized.
  • Mike from Portland

    Posted on 7/12/2021

    "You shouldn't lower the gain of your full-range amplifier to try and match your lack of subwoofer volume. Doing so could allow the amp to send out distorted, clipped signals to your full-range speakers, defeating your goal for clean, full sound, which is why you put in a subwoofer to begin with. More power, especially in the bass, is always better than not having enough." I don't understand this - if anything all this will do will reduce how loud you hear the output from your main speakers at a given volume control setting. It WILL NOT increase clipping since you're not changing the amplifier power rail voltage levels - all you're doing is changing the amp's negative feedback to reduce the output gain. The only way you could introduce clipping would be to reduce voltage rails or turn your gain UP at a specific volume so that you're now hitting rail voltage which is the root cause of clipping.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 7/14/2021

    Mike, The operative word in the quote you mention is "could" when describing a particular scenario's outcome. Many people blow up their speakers or subs by trying to match highs to lows while increasing the general level.