How To Set Crossover Frequencies For Your Car Audio System

Crossovers are awesome for getting better sound from even cheap speakers. But what are crossovers, how are they helpful, and what are the best crossover settings for car audio?

In this article I’ll show you how to set crossover frequencies for your car audio system along with some other helpful info:

  • How crossovers work and why they make a big difference
  • The best car audio crossover frequency settings (table is provided)
  • Diagrams to show you how to set your car amp crossovers

…and much more, too. There’s a lot to cover so let’s get started!

What does a crossover do? Crossover frequency, slopes, and more explained

Crossovers and crossover frequencies explained diagram

People tend to talk about crossovers as if they totally “block” sounds you don’t want to go to your speakers. While they sort-of do, in reality, crossovers are filters that greatly reduce the amount of unwanted sound frequencies sent to speakers.

How are crossovers helpful for speakers?

Crossovers are very important for car audio as they help us deal with the poor enclosures they’re used in along with the weaknesses that small speakers have. Some of the most common speaker sizes installed from the factory or sold for aftermarket use like 3.5″, 4″, and 5.25″ sizes can be terrible for playing bass, resulting in bad sound and ugly distortion.

To make matters worse, speakers in cars, trucks, and even boats are often mounted in areas where it’s impossible to get great sound because they leak air and don’t form a good enclosure to deliver sound properly unlike home stereo speaker cabinets. That means they leak air badly and can “bottom out” easily if driven hard with bass sounds, for example.

One reason why crossovers are so helpful there is that we can use them to block terrible-sounding audio frequencies that ordinarily would cause these problems and others, too.

Understanding crossover basics

Car audio crossover examples

When we think about musical signals we don’t always realize the important things going on behind the scenes. In fact, you’ll almost never find a good-sounding speaker system that isn’t using one or more types of crossovers; that’s how important they are for great sound.

A crossover (audio crossover) is an electrical or electronic component circuit made up of parts that react to certain frequencies and designed to eliminate unwanted ranges of sound from reaching speakers.

Crossovers allow a desired range of sound to pass unaltered and effectively block ranges of sound past a limit called the cutoff frequency.

A crossover circuit can be used for only one single speaker channel or combined with another to separate and direct sound the best speakers suited to produce it. In car audio, the most common speaker crossovers are used in 2-way coaxial and component speakers.

Simple speaker crossovers can also be added inline with speakers to block lower-end bass as well.

What are the 3 types of crossovers in car audio?

There are 3 types of crossovers:

  1. Active (electronic) crossovers – work in the signal path (line-level signals)
  2. Passive (speaker) crossovers – work in the amplified speaker path after an amplifier
  3. Digital (software) crossovers – they work with sound in the digital music domain

1. Active (electronic) crossovers

Illustrated diagram of an electronic (active) crossover example

An example of an external (add-on) electronic (active) 2-way crossover. These are basically the same as the electronic crossovers built into many amps you can buy today. Some offer a few more options, but unlike years gone by, they’re less and less important these days. Most amps today include what you’ll need already.

Active crossovers use electrical components such as transistor-based chips called op-amps (operational amplifiers) to behave the same way as their much bigger and much less efficient speaker crossover counterparts.

They offer a lot of benefits (especially their compact size) and can be designed to allow you to choose between using no crossover, a high-pass, or a low-pass easily. Unlike passive crossovers, they do require power to work and change the signal, hence the name “active.”

Active crossovers work with a line-level (RCA) signal either before an amp’s RCA inputs (in add-on external crossovers you can buy) or inside the amp. The signal output of an electronic crossover has to be amplified, unlike speaker (passive) crossovers that you connect between an amp and speakers.

2. Passive (speaker) crossovers

Image showing speaker crossover examples and resistor, capacitor, and inductors

“Passive” crossovers are those that use inductor and capacitors, without a power source, to filter out sounds you don’t want to reach speakers. They’re usually used for smaller speakers like with tweeters, 2-way coaxial speakers, and component speaker systems because they’re relatively affordable in those situations.

Passive speakers aren’t used to block midrange and treble (“highs”) from subwoofers because the size of the inductors needed would be really big – and expensive, too! They’re also much less efficient than electronic ones in that case.

That’s one reason the built-in low-pass subwoofer crossovers in amps are so great.

3. Digital (software-based) crossovers

In dash car stereo with equalizer shown

Software-based equalizers and crossovers use advanced software routines to alter sound in the “digital domain.” That means they can alter the sound (or filter it, as crossovers do) by working only with the digital musical signal. This makes them more complicated but saves spaces & money since it reduces size & the electronics required.

This type is implemented in the software code of home theater receivers, car stereo head units, or digital audio processors. Software-based crossovers usually work by implementing math-based functions that alter the signal output based on its frequency.

It’s a really complicated topic, but the basic concepts aren’t hard to understand. By using special formulas, not only different types of crossovers but also equalizers can be implemented and operate on the musical signal when its represented as a binary digital number.

This is a cost and space-saving feature as there are few, if any, parts needed to make it work. However, it usually takes more specialized microprocessors or digital signal processor (DSP) chips to do so.

What are good crossover frequencies for car audio?

Crossover audio range chart diagram

Within the range of sound your ears can hear, for most cases crossover frequencies typically fall into a small range you’ll likely use for tweeters (high-pass), full range speakers (high-pass), and subwoofers (low-pass).

The truth is, there’s not a “perfect” set of crossover frequencies that work for every speaker in every vehicle. That’s basically impossible because nearly everyone is using different speakers, a different setup, and so on.

However, here are some of the most common frequencies that work well in many cases. 

Recommended crossover frequency table

Speaker/System Type Crossover Freq. & Type Notes
Subwoofers 70-80 Hz (low pass)

Good low-pass frequency range for subwoofer bass & blocking midrange sounds. Best for pure, clear bass sound that "hits."

Car main (full range) speakers 56-60Hz (high pass)

Blocks low-end bass that causes distortion or speakers to "bottom out." Great compromise between full-range sound and midrange bass capability.

Tweeters or 2-way speakers 3-3.5KHz (high pass, or high/low-pass)

Most 2-way or 1-way (tweeter) crossovers use a frequency near this as most tweeters can't handle sounds below this range. Same for woofers above this range.

Midrange/woofer 1K-3.5KHz (low pass)

Woofers and many midrange speakers do not perform well above this general range. They're poor for treble and a tweeter should be added.

3-way system 500Hz & 3.5KHz (Woofer/tweeter crossover points)

Similar to 2-way systems the upper freq. would be the same. Midrange drivers in a 3-way system often do not perform well below 500Hz or 250Hz in many cases.

How to set the crossover frequency for speakers on your amp

How to set crossover frequency on car amp diagram

How to set high pass filter options on your amp (for main speakers)

Most people typically use a car amplifier for one of a few basic systems:

  1. Driving front and rear full range speakers, no subwoofer
  2. Driving front and rear full range speakers plus a subwoofer
  3. Driving a subwoofer

For cases #1 and 2, if your amplifier has a built-in crossover option you can use the high pass crossover to block low end bass that small speakers simply can’t produce well, if at all. The end result is that you’ll be able to drive your main speakers with more volume and lower distortion.

We only want to block that certain range of bass that subwoofers can handle. We don’t want to block bass found in the lower end of midrange like from the vocals in music (for example, around 100-120Hz or so). 60 to 70Hz or so are pretty common crossover frequencies that usually work well.

Adjusting an amp’s high pass crossover

For amplifiers with adjustable crossovers, use the following steps:

  • Turn off equalizer or bass boost functions
  • Set the front channel or front and rear (if using both) crossover switches to “HP” or however they’re labeled for the high pass function.
  • Adjust the crossover frequency control to the lowest setting (this is usually around 50Hz for most amps).
  • Using a small screwdriver, turn it up slightly – about 1/8 of a turn. This should be around the 60-70Hz range.
Note: Not all amplifiers offer an adjustable control. Some (especially ultra-compact models) use fixed frequencies and switches only. In that case, try using the switch position closest to the 60-70Hz high pass frequency range.

How to set subwoofer crossover frequency options

Similarly, do the following to adjust the subwoofer frequency & crossover:

  • Turn off equalizer or bass boost functions
  • Set the crossover switch to “LP” or however it’s labeled for the low pass
  • Adjust the crossover frequency control to the lowest setting (this is usually around 50Hz for most amps).
  • Using a small screwdriver, turn it up slightly – about 1/8 of a turn. This should be around the 70Hz range
  • Adjust as needed: if you’re not happy with the low-end range (the range of bass sound produced), don’t be afraid to adjust the frequency control a bit.
TIP: With decent power and a good speaker enclosure properly matched to the sub, you should have clean, pure bass at this point.

However, I’ve seen many cases where a subwoofer installed in the wrong type of subwoofer enclosure produces bland, poor sound. A crossover can’t fix that problem.

What crossover slope do I need? Does it make a difference?

What crossover slope do you need image of man thinking

In some cases, you’ll be able to choose from a number of crossover slopes (the steepness of the cutoff) on your amplifier or other components. As I mentioned earlier, the slope how effective a crossover is at allowing fewer unwanted sounds to reach your speakers, with higher numbers being more effective.

And as I mentioned ealier, -12dB per octave (“-12dB/octave”) is very common in car audio. While it may seem like the rule of “more is better” applies here, the truth is that most of the time a 12dB or 18dB/octave crossover slope is all you’ll need.

Why do some electronics offer more crossover slopes?

Some amps, head units, and digital processors/equalizers for car audio offer more crossover options for people who want advanced control – especially if you’re working on a high-end sound system. For example, when bi-amping speakers (using an electronic crossover and separate amp channels for the tweeter, the midrange speaker, and so on), you can take advantage of each speaker’s natural behavior and get super-detailed control over the signals you send to them.

That’s a much more advanced topic and worth its own article, by the way.

However here are the basic rules for crossover slopes that will work for 90% of people:

  • A 12/dB setting is good and will do the job in most cases for subwoofers (low-pass) and full-range speakers (high-pass).
  • However, 18dB/octave can be better for some subwoofers depending on your particular subwoofer, the enclosure, and how your vehicle alters the sound. In that case, experiment using the -18dB setting and see how it sounds.
  • 6dB/octave is a bit poor and will allow sounds to pass that can “muddy” the sound and just isn’t good enough for bass speakers. I don’t recommend that in most cases.

Most of the time, the main goal is to have the same cutoff at the same frequency. The goal, in perfect conditions, is that the speakers match up just right so there’s not much overlap in their sound as well as no gaps in the sound.

However, it’s definitely a lot harder in the real world. In my experience, however, 12dB/octave works well and is effective enough to make a big difference in how your system sounds.


About the author

Marty is an experienced electrical, electronics, and embedded firmware design engineer passionate about audio and DIY. He worked professionally as an MECP-certified mobile installer for years before moving into the engineering field. Read more »

Your comments are welcome.
  1. I have two amps. 1 with all 4 door speakers connected to it. 2nd only has subwoofer connected to it. With a crossover accepting all signals from radio. But I have no front speaker sound. I know the speakers work and the wires are good since I I switch the front/rear rear input button on crossover. I’m wondering what else am I missing. To get front/rear to work together.
    Thank you

    • Hi, well if some troubleshooting at the amp shows that all front and rear speakers are working (for example, by swapping front & rear inputs to the amp to test it), then it sounds like a signal issue.

      You’ll need to go backwards from the amp to the crossover to the radio to narrow it down. It’s hard for me to comment more without more specific information. It also depends on the crossover as some models behave differently than others. Best regards.

  2. Thank you so much for this information!!!! It greatly helped and solved my sound issue with my stereo!!!! Finally got it all dialed in using your info and it sounds 100 times better than how i had it set before!! Totally appreciate it!!!!

    • Hi Erik. Thank you so much for letting me know how my info helped you. It’s very flattering to hear plus it makes the hard work worthwhile.

      I hope you enjoy your music and have a great week! :)

  3. really very well explained. Earlier I had sent both the front and rear set of speakers at HP pass with frequency set at 50hz in both. And had set the Sub frequency at LP pass with 80Hz. Now have Set Sub at 60Hz, Front component sets at 99Hz from radio at HP, and rear set of speakers at 60Hz at HP. I am using all Sony ES 9500 series from Radio, Amp, SPeakers. Though sound had been clearer after these changes, but the impact of the drum beats and quality is not as expected. In radio the Cross over frequency could be set between 0 to 250 Hz, but in Amp the frequency set range starts from 0 to 5000 Hz. In Amp also HP is set for both front and rear Speakers and LP for Sub. Do we need to make further changes of crossover in amp also. How can we relate the 0-250hz crossover setting range in Radio Vs. 0-5000hz range in Amp ?

    • Hello there. Are you using the crossovers of *both* the head unit and the amplifier? Because you should use just one or the other. If you’re using the radio’s crossover(s), turn if off on the amplifier to avoid having too many variables affecting sound.

      The crossover range on your amp is simply a larger one than that of the head unit’s built-in one. Otherwise, they should be essentially the same (both likely are 12dB/octave slopes, perhaps 18dB). If the subwoofer can produce good bass below 100Hz, the 60Hz low-pass frequency for it may be too low.

      The interior of your vehicle will affect the bass sound so it’s pretty common to do trial and error adjustments to find out sounds best to you. But it’s typically around the crossover frequencies I listed in the article. Subwoofers (often) have a good low-pass point of around 70-80Hz or so.

      I would try lowering it back to 50-60Hz high pass for the front speakers and you may need to adjust the bass EQ/boost if there’s a lack of bass. Best regards.

  4. Thanks Dear for your help… In The amp, both front and rear Crossover set on ‘HP’, with minimum 500Hz . HP selected in amp because all 4 channels have Tweeters (with crossovers). Front 2 components(6″) and rear 2 (6*9″) , While selecting HP in amp, the LP section of below 500Hz doesnt work. It remains off until LP is selected on Amp. The HP Crossover ajdustment starts from 500 to 5k Hz.
    So that ways, we can say, In case, crossovers in the Amp is set to “Off”, then I can listen 60Hz to 500Hz (if head unit both rear and back are set to 60Hz), which it will be absent while HP is on in Amp.
    There are 4 options in amp for front and rear speakers i.e. HP/LP/BP/Off. So, by your suggestions, I should keep front and rear crossovers as “Off” of in the Amp. But in that case, will I get that quality HP effects on my 4 tweeters? Because the physical crossovers of tweeters could find it difficult to filter High frequencies from 60Hz + signal supply from Head Unit. It was easier in case HEad unit HP filter was set to 100 or 150 Hz or 250Hz (max). The slope here is 12/octave. My Head unit/ Amp and speakers are High Resolution ES series ones, Sony Xav 9500 ES, ES amp and ES speakers. So please consider that also while guiding me. I am again raising a Query, hope you dont mind it :-)
    I am a little bit enthusiast of quality music like you, but not well trained like you. I want the best possible details in my music so I keep on researching and doing experiments on my own:-)

    • Hi, if your tweeters already have crossovers in place you won’t need to use the high-pass feature of the amp for that. Just for blocking low bass to the smaller speakers if you like.

      The 60Hz range is very, very far from the frequency range of the tweeters so it’s not normally a problem. I would recommend that since you have a very nice quality head unit to use my recommendations from the previous comment & the article. Best regards!

  5. thanks dear, as guided, turned off amplifier crossover. applied your settings as recommended, now enjoying my music like never before. Thanks once again …

  6. Hello, one help required w.r.t. car battery. My car battery is of 35 AH capacity. Have installed the 1000 watts RMS amp with load of “200 watts RMS” total on 4 components and “500 watts RMS ” of Subwoofer. 4 Guage wire power supply to amp. Do I need to upgrade the battery with higher AH power for more powerful and accurate sound and How much AH? I listen to music Only while driving and alternator on.

    • Hello. What model amplifier and speakers do you have? You can use the fuse rating on the amp as an approximate guide for its maximum current draw.

      As long as the alternator can keep up with the amplifier’s current draw it should be fine. The sound quality won’t change based on the battery or alternator. Power & max. volume can be affected sometimes but for average listening it’s not normally a problem.

  7. Hello, I have a Deaf Bonce 180.4 4 channel with 4 deaf Bonce Sylvester mid range speakers. In the speaker owners manual it says to use a high pass filter of 250 to 350 hz @ 12db octave but also gives a low pass filter setting of 8k to 12k. 12db octave. Am I to adjust high & low pass crossovers on the amp for these speakers?

    • Hi, if they’re true midrange speakers then they’re typically used with a bandpass filter or as part of a 2-way component speaker setup. The low pass recommendation may be referring to that low-pass crossover point used for that reason.

      However, 8-12kHz is much higher than is typically used. How are you using the speakers?

  8. Hello Marty, I have already taken help previously which was fuitful.
    Have a problem with my Car music system setup. I have Car receiver Sony 9500 ES, Car Amp Sony 5ES, Speakers connected 4 Sony ES series total 180 RMS, Subwoofer of 500 RMS Sony ES series XS-W122ES. Car Battery of 55 AH, keeping in mind Subwoofer load. Car to Amplifier power cable and earthing cable both of 4 Guage Blaukpunkt OFC. All CAr speaker cables of 16 Guage OFC and 3 RC cables of Blaukpunkt OFC. Car receiver Crossover Front and rear both at 63Hz and Sub crossover at 79Hz. In Amplifier, all crossovers are Set to “Off” position.
    My issue is that Subwoofer power output(boom and effects) had suddenly gone down by 80%. Simultaneously, the output QUALITY from 4 component speakers had also gone down by more than 50%. By QUALITY I mean to say that the CLARITY of sound , SEPERATION of instruments and DETAILS and EFFECTS of the Sound And DEPTH in the Instruments in the Song, they all are gone down more than 50%. Overall Bass has gone down all of a sudden.
    This used to happen in all my previous Sony set ups, and in this one also, but the quality improved everytime in 10 days or so, for further some time. This used to happen frequently. But this time, this issue has not improved for 1 month now. Its looking like I am listening music on a very basic and cheapest music setup available in the market.
    Please help and guide…

    • Hello Mayank. It sometimes is difficult to troubleshoot problems like this. But my first thought is that perhaps it is a problem with the amplifier or power or ground connection(s).

      One thing to do would be to check power connections & voltage at the amplifier’s +12V battery terminal with a test meter to be sure it is good. You can also check to be sure the main fuse near the battery is not close to failing, as sometimes those can appear good but can be slightly melted/blown, causing problems with voltage & power.

      If you don’t find any problems that way, I would remove it from the vehicle to “bench test” it from a +12V power source, test speakers, and an audio source to see if you still have the same problem. Best regards!

      • Hello MArty, thanks for your response. However, sound was little bit improving by itself. But, before checking the incoming current at 12V terminals of Amplifier, I opened and re connected the wire connections on both sides of fuse. Connected them back very tightly. Now the sound quality had improved at it should be. Thanks a ton for guidance again…

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