Crossovers are one of the single most helpful parts or features for getting great sound in car or home audio systems. However, using them the right way can leave you scratching your head if you don’t know the basics.
On that subject, what is a good crossover frequency for speakers in your car or home audio system? That’s what you’ll learn here.
In this article I’ll explain:
- How crossovers work and why they make a big difference
- The best crossover frequencies for car audio amps, speakers, and subwoofers
- Recommended crossover frequencies for small, medium, and large home stereo and home theater receiver speakers including subwoofers
- What to know about crossover slopes and which you should use
Let’s get started so you can enjoy better sound right away!
- The basics: What does a crossover do? What does crossover frequency mean?
- Crossover frequency vs music range chart
- What are good crossover frequencies for home audio?
- What are good crossover frequencies for car audio?
- What is a good crossover slope? Does it matter?
The basics: What does a crossover do? What does crossover frequency mean?
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 aren’t blocks but instead filters that greatly reduce the output level of certain sound frequencies sent to speakers.
How are crossovers helpful for speakers?
Crossovers are very important for audio as they help us deal with the weaknesses of commonly available speakers as well as poor installation environments. For example, some of the most common speaker sizes used in cars such as 3.5″, 4″, and 5.25″ sizes can be terrible for playing bass. They end up with bad sound and ugly distortion when driven with low-end bass and more power.
To make matters worse, many speakers aren’t used in proper enclosures. This ends up giving poor sound and distortion at higher volumes because they leak air and don’t properly trap sound waves like others. That means they can “bottom out” easily if driven hard with music with “thump” and hard bass.
An excellent solution to these and other problems is to completely remove that area of sound that causes poor sound quality. This lets you drive the speakers with more power yet get more clarity and volume from them – even cheap speakers!
2-way and 3-way speakers become possible
Additionally, 2-way and 3-way speakers rely on crossovers to act as a divider between the speakers, resulting in excellent sound thanks to limiting the range of sound each produces.
Understanding crossover basics
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 crossovers; that’s how important they are for great sound.
A crossover is an electrical or electronic component circuit made up of parts that react to certain frequencies and is designed to prevent 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 a single speaker channel or combined with others to separate and direct sound to others, too. In car and home audio, the most common speaker crossovers are used in 2-way coaxial speakers, component speakers, and 2-way speaker cabinets.
There are 3 types of crossovers you’ll find in home or car audio:
- Active (electronic) crossovers – work in the signal path (line-level signals)
- Passive (speaker) crossovers – work in the amplified speaker path after an amplifier
- Digital (software) crossovers – they work with sound in the digital music domain
Active (electronic) crossovers use tiny signal amplifier chips called op-amps (operational amplifiers) to act similar to much bigger and far less efficient speaker crossovers.
Not only are they much smaller in size, but they can also be designed to allow you to choose between using no crossover, a high-pass, or a low-pass filter easily using a slide switch. Unlike passive crossovers, they do require power to work and change the signal, hence the name “active.”
These types work with low-level (RCA) signals 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.
That means you’ll still need to use an amp to drive speakers with them.
Examples of car and home speaker “passive” (non-powered) crossovers. These are circuit boards using electrical components to block unwanted sound frequencies from going to speakers not best for producing them. This effectively separates splits the incoming sound signal into 2 or more and sends them to the speakers as needed.
“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 typically used for smaller speakers like with tweeters, 2-way coaxial speakers, and home theater 2-way speakers because they’re cost-effective and can deliver great sound.
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.
Electronic crossovers are typically used in subwoofer amps because of the cost and size savings – as well as better sound altogether.
Digital (software-based) crossovers
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.
Crossover frequency vs music range chart
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.
What are good crossover frequencies for home audio?
Since different people have different needs, I’ll cover the general best crossover frequencies for ome stereos and home theater receiver speakers in a table below.
One thing to remember is that these are general guidelines that should fit most people’s needs. However, just like anything else, what sounds good to one person or with one home audio system might not sound good for another.
Feel free to try out and adjust the crossover levels recommended here for what sounds best to you. Ideally, the crossover speaker frequencies (for example, for the main speakers and subwoofer) will blend seamlessly and there won’t be any “gaps” in the sound. If there are, you’ll need to keep tweaking it until that problem is removed.
Home stereo crossover frequency table
|Speaker/System Type||Crossover Freq. & Type||Notes|
|Subwoofer||80 Hz (low pass)||
Good low-pass frequency range for subwoofer bass & blocking midrange sounds. Best for pure, clear bass sound that "hits." *For THX Certified/non THX Certified 80 Hz is advised, but test 80-120H for the best sound.
|Tower/main front speakers [4", 5.25", or 6" woofers]||60-80Hz (high pass)||
Blocks low-end bass that causes distortion & speakers to "bottom out." Great compromise between full-range sound and midrange bass capability. Works best complimented with a subwoofer.
|Tower/main front speakers [8", 10" or larger woofers]||40Hz (high pass) or "flat" (full-range)||
Larger woofer cones are usually much better at handling deeper bass. Also, home theater surround systems normally send very low bass to the subwoofer as well.
|Small center, surround, or bookshelf||100-120H (high pass)||
Many surround or center speakers use drivers not suited for lower bass - only midrange and above.
|Mid-sized center, surround, or bookshelf||80-100Hz (high pass)||
Better suited for playing bass notes slightly below vocals and notes around 100Hz, but not good for lower bass.
|Large sized center, surround, or bookshelf||50 or 60-80Hz (high pass)||
Larger speakers of this type can often handle a bit more bass nearly down to, but not including, the subwoofer range. Try 50Hz for larger woofers and 60-80Hz for others if unsure.
|On-wall or mini satellite/surround type speakers||150-200Hz (high pass)||
Many can't produce much bass but instead midrange and above. May distort badly if sent low bass notes so be sure to use a HPF as recommended.
What are good crossover frequencies for car audio?
Car audio speakers are somewhat different from home audio in that they often suffer from terrible enclosures which aggravates the problems they have when producing certain sounds. The crossover frequencies below are general guidelines that work well in most cases but be aware you may need to tweak them.
For example, small speakers with no real enclosure may have horribly “thin” sound – in that case you may need to raise the high-pass filter (HPF) frequency even higher to minimize sound problems. Use these as a starting point, see what you get, and go from there.
Car audio speaker & amp 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.
What is a good crossover slope? Does it matter?
In some cases, you can choose from a number of slopes (the steepness of the cutoff) on your amplifier or other components. As I mentioned earlier, the slope controls the steepness of a crossover filter, or how strongly it reduces & blocks sounds you don’t want to reach your speakers.
And as I mentioned earlier, -12dB per octave (“-12dB/octave”) is very common for both car and home audio systems. While it may seem like the rule of “more is better” applies here, the truth is that most of the time a 12dB/octave crossover slope is all you’ll need.
I’d had some success using an 18dB/octave slope with subwoofers, but aside from that, it won’t usually make much of a difference – at least not enough you’ll take notice of.
Here are a few tips to help:
- I don’t recommend a -6dB/octave crossover for speakers, especially small main ones. That’s because a 6dB slope still allows a lot of bass to pass when using tweeters and small speakers.
- 12dB is almost always fine. 18dB is fine too, but you likely won’t notice much difference in most speaker systems.
- Don’t spend extra money, time, or effort for a more advanced crossover unless you really need the features. The majority of the time, even for amplified speaker installations at home or in the car, a standard crossover works great when properly set up.
Why do some car or home audio components have different slope settings?
Example of a car amplifier without crossover slope options. If it’s not labeled near the controls, it’s nearly always a 12dB/octave and you’ll be fine.
It’s not unusual for home & car audio stereos and amps to offer 6dB, 12dB, 18dB, and even steeper (ex.: 24dB) crossover slopes you can choose. That’s especially true for mid to high-end equipment. The extra selectable crossover slope options allow more advanced control and flexibility when working with custom audio systems.
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 eliminating waste and any audio interference a speaker crossover may cause by driving them directly without a crossover.
That can give you some of the best sound possible if you’re really wanting to pursue high-end sound using more advanced techniques.
What is a good crossover slope for car audio and home audio?
However here the best crossover slopes for most 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 it in most cases.
The main goal is to have the same sound filtering at the same crossover frequency. The goal is to have the sound put out by the speakers match up perfectly so there’s neither much overlap nor gaps in the sound between the speakers.
I don’t think I’ve installed a home or car audio speaker system yet where the -12dB per octave wasn’t able to do the job well.