How To Connect Crossover To Car Amplifier?




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Many car audio enthusiasts use either active crossovers or passive crossovers. Crossovers we can find in the speakers, but also in the amplifiers.

They can be external or those built-in depending on the system, and how crossovers are connected directly affect the overall audio experience. But how should you connect crossover to the car sound system and get most of it? Let’s find out.

Depending on the type of crossover used, it has to be connected differently. Active crossovers and in-line passive crossovers have to be placed between the car stereo and amp. Passive component crossovers should be placed between the amplifier and the speakers.

In this article, I will in-depth cover all aspects related to the crossovers. What they are, how they work, the various types that there are and if you really need one, if your speakers need one, and if they really improve the quality of sound, if at all. 

You will also find out where each crossover is placed depending on its type, and I will show you how to connect it to your amplifier. 

What is a crossover in the car audio?

how to connect crossover with car amplifier

A crossover in terms of audio, whether for either car or home audio, is an electronics device that takes a single audio signal and splits it up into two or more audio signals. These signals are split up into different frequency bands of high, mid, and low frequencies.

These separated audio signals of different frequency bands power each specific driver (speaker) in your car audio system.

The low-frequency band signal will power your subwoofer, while the mid-range will power your woofers, and the high-frequency band signal will drive your tweeter.

Do I need a crossover for speakers?

This question has many factors that need to be considered before answering.

A better question will be to determine if a crossover improves each speaker’s sound quality and your car audio system as a whole. Then you could decide whether they would be beneficial to your circumstances.

However, we can also look at this question from the perspective of frequency balance and your speakers’ life expectancy (longevity). 

Furthermore, some speakers come with built-in crossovers, and some do not, but why not? So crossovers are there for a reason, and just because they are not built into specific speaker types does not mean that they should not be implemented somehow.

So, in short, crossover splits up one signal sending two or more specific signals (with separate frequency bands) to particular speakers. Without a crossover, all frequencies would go to all the drives, which is not optimal, to say the least.  

Keep in mind that each driver is designed and manufactured to handle specific frequencies. You can tell by the way they look (tweeters are small, midrange woofers are oval and medium in size, and subwoofers are typically large and round).

These drivers are built this way because sound waves look and act differently at various frequencies, and thus that is why they look the way they do. 

Hence, tweeters are not designed to handle low frequencies, and your subwoofer will never be able to handle high frequencies. Moreover, your midrange woofers and subwoofers duplicate many of the same frequencies.

Having many speakers play the same frequencies would cause booming, clipping, unwanted noise, low audio quality and could even cause them to blow (primarily because your speakers are all built to be separate entities).

If you don’t understand why these situations would occur, try to picture resonating soundwaves of various lengths.

When your subwoofer pushes out a low frequency, the sine wave is broad and wide, so the speaker resonates with a considerable forward and backward momentum. On the other hand, a tweeter deals with sine waves that are short and compressed and hence do not have to move to the degree that is comparable to a subwoofer. 

Now, if each of those speakers is receiving frequencies they are not built for, it is only a matter of time before some type of damage is incurred.

So, to answer the question, do you need a crossover for speakers? From a speaker’s life expectancy and frequency perspective, the answer is yes. 

Do coaxial speakers use and need crossovers?

Coaxial car speakers will usually have a built-in passive crossover already. The passive crossovers rely on specific circuitry components to filter and separate the frequencies sending the correct frequency to each driver.

Even if you add an amplifier, the passive crossovers in your speakers should be more than sufficient. These types of crossovers are pretty much always built into these types of speakers, and you would be hardpressed to find a pair that did not have them (this would be especially true for high-end quality aftermarket coaxial speakers).

Due to the drivers being built on top of each other, it is even more paramount that coaxial speakers implement a crossover so each driver can receive the appropriate frequencies. Otherwise, noise, clipping, and eventually blowing of the speakers can happen in no time.

What if I have an additional subwoofer for my coaxial speakers?

Some subwoofers may come with a built-in passive crossover, and some may not. Always consider using the high and low-pass frequencies on your amp if it comes equipped with them, and if not, I strongly recommend that you purchase an additional crossover (passive or active) for your subwoofer to work optimally and correctly. 

Do compoonent spekaers use and need crossovers?

Component speakers are car speakers that have the drivers separated from each other. For example, the tweeters will be on the dash and the woofers in the door panels.

Depending on the types of component speakers you purchase, they will come with a separate outboard crossover

crossover with component speakers
Set of component speakers with passive crossover

Does a crossover improve sound quality?

You already know that a crossover is needed to send the correct frequencies to the valid speakers. Due to this, the audio quality will be improved tenfold. Each driver can now react independently and function correctly with the frequencies that it is receiving.

In turn, the speakers don’t have to struggle by trying to play frequencies they are not built to cope with, and they will produce a clean and clear sound. 

Crossovers improve sound quality so much, that you will not see a competition-level car audio system without them even incorporating various types and more than one crossover. Listening to audio from a speaker that is tuned correctly with a crossover is like night and day compared to one without. 

What types of crossovers can I get?

Different types of crossovers affect sound differently, so let’s consider the three main types and discuss the type of quality they provide to speakers. 

Active crossovers

When each speaker has its own amplification channel, it is then termed “active.” This significantly increases the dynamic range and tonal response of your audio system.

Now, an active crossover is placed between the stereo and the amplifier, cutting out the unwanted frequencies before they reach the amplifier, so the amp then does not have to waste precious energy trying to boos those signals.

An active crossover will typically have volume (gain) controls for each driver, so you can tweak each speaker’s volume (voice), enabling you to balance them out to a sufficient degree. In addition to that, some will feature an equalizer for additional delicate touches.

The only possible downside to an active crossover you can see is that it may prove a challenge to install because it is powered and requires to be grounded.

However, it will not be a problem for any car audio professional. So when you are prompted to choose either active or passive, the active option is usually a better bet providing better audio quality and more refined adjustments to said audio. 

A few years ago I have installed in my car two DS18 DS-XM3 active crossovers. They were extremely easy to set-up and until today I am happy with the choice. They are available on Amazon, so if you are looking for a high-quality yet simple crossover, check the recent price on Amazon.

Passive crossovers

Passive crossovers do not need to be connected up to any type of power source to work. There are two types of passive crossovers that you get, and they work in slightly different ways. 

Passive component crossovers

These types of crossovers are placed in the pather after the amplifier. The circuitry consists of a small network of coils and capacitors, which are usually installed near the speakers. Due to it filtering a signal that has already left the amplifier, this type of crossover wastes power, releasing unwanted parts of the audio signal as heat. 

One I strongly recommend is the DS18 PRO-CFX. I have found it really useful when setting the loudness of the tweeters, that thanks to the adjustable octaves from -6 dB up to 3 dB, I found the perfect balance between bass and heights from the dash.

PRO-CFX is worth every cent, and is really cheap for its functionality, so why do not check the latest price on Amazon and save some money?

Passive in-line crossovers

Unlike component crossovers, passive in-line crossovers are placed before the amplifier. This means that they separate the signal before it reaches the amplifier, so the amplifier does not have to waste any energy on boosting unwanted frequencies. An active crossover is this form of a crossover, yet it is powered.

An amazing example of the in-line crossover is the PAC BB-6PR. So if you have a separate amplifier for the tweeters, check PAC BB-6PR on Amazon to ensure your tweeters will get only the high frequencies.

Can I use a crossover without an amp?

When you are thinking about installing crossovers without an amplifier, there is one thing you have to consider.

Every audio situation, no matter what it is, requires an amplifier. An amplifier takes a line-level signal usually acquired from the preamp and boosts it through to your speakers so they are able o play.

Remember that your stereo has a small built-in amplifier and some standard OEM audio systems come with external amplifiers. Without an amplifier, there would be no audio coming from your speakers.

Hence no matter what situation you find yourself in, there will always be some sort of amplification. However, depending on the type of crossovers being used, you may not require additional amplification, such as an external aftermarket amplifier.  

Crossovers that are built into speakers and component crossovers (that may or may not come with component speakers) may not need an additional aftermarket amplifier. These types of crossovers are more than capable of handling the amplification from your car stereo. 

In-line crossovers are designed to sit between the stereo and the amplifier, cutting the frequencies before they reach the amp so that the amplifier once again does not have to boost unnecessary signals. 

Therefore you can imagine if you do not have an aftermarket amplifier, it would be quite difficult to try to implement this type of crossover in your car audio setup. 

Active crossovers definitely need to have an additional aftermarket amplifier and will not work correctly, if at all, if an aftermarket or some other type of external amplifier does not sit between it and the speakers.

This is especially true if you are looking to build complicated car audio systems where you would need multiple amplifiers. A two-way active crossover would need two amplifiers: one for each set of tweeters and woofers and sit between the amplifiers and the car stereo or head unit. 

This could even be split up into a three-way crossover. Then each amplifier would power each set of speakers (tweeters, woofers, and subwoofers).

How to set up a crossover in my car?

Setting up a crossover in your car is pretty straightforward, even if you have no experience in doing so. The first thing you need to do is figure out what type of speakers you have and what crossover system you want to integrate into your car stereo system. 

How to set up an active crossover in my car?

As we said, an active crossover needs to be placed between the stereo and the amplifier. By saying that, I assume that you already have or are going to purchase an aftermarket stereo.

With this in mind, the active crossover will have low-level (RCA) or high level (speaker wire) inputs or perhaps both depending on the model.

The inputs are where the signal from your stereo will go. Considering you have an aftermarket amplifier, you would need to install your crossover relatively close to it, so you would not require additional wire.

Furthermore, you could use the same power source cabling and utilize the same grounding area that the amplifier does. Some active crossovers may even come with a remote connection, and then you could use your amplifier remote connection point for this.   

All you would need to do is to connect the low-pass and high-pass terminals to your amplifier’s correct terminals. The crossover will typically have an RCA output, and your aftermarket amplifier will definitely have an RCA input.

For example, consider your subs were on channels 1 and 2, and your standard coaxial or component speakers were on channels 3 and 4 of your amplifier. Then you would send the low-pass channel of the crossover to your subs and the high-pass channel of the crossover to your coaxial or component speakers channel. It’s as simple as that.

Keep in mind and consider that you are using the correct gauge wire for all connection types. Also, you have grounded both your amplifier and crossover correctly, and that they are powered up correctly. Then you should be good to go. 

How to set up a passive crossover in my car?

Setup of component crossovers

Passive crossovers are into coaxial speakers, so you do not need to worry about connecting up those crossovers. You either connect them straight up to your amplifier according to the speaker terminals, or connect them to your car stereo according to the correct colored wiring or harness.

If you do not know the correct wiring setup of a car stereo and harness, check out my article How To Wire Car Speakers To The Radio Without The Harness, where I go over the speakers and car stereo harnesses in detail.

External component passive crossovers come with an instruction manual, and the steps will be easy to follow. It would be the same concept as wiring up your amplifier to your speakers just with a device (the passive crossover) in between them. 

Setup of in-line passive crossovers

In-line crossovers are connected between your head unit and the amplifier. You would determine which wires would be the low-pass and which would be for the high-pass connecting them to the appropriate terminals (just as you would do for an active crossover set up).

The principles of combining the proper crossovers to the correct driver terminals would apply in all cases of any crossover situation. 

How to set crossover frequency for a car audio system?

Passive crossovers will not allow you to configure the high-pass or low-pass filters for the most part. This includes both in-line and component crossovers. Some external component crossovers may have optional settings that will let you turn the tweeter or woofer up or down slightly, however for the most part, all passive crossovers are set and optimized prior to your purchase, so you do not need to worry about them.

Active crossovers come with a gain knob (volume), and then they will also have some sort of knob or type of screwdriver turnkey that you can set for the high and low-pass filters for all the channels or each channel, depending on the crossover model you have.

All you would do is turn these knobs and cut off the frequencies you wish. I know it may sound easy, but in the case of active crossovers, to set them correctly, you have to hear the sounds they pass through.

What frequencies should each driver be set to?

If you do not know what frequencies to set your high pass middle, and low-pass filters to on your crossover, don’t worry because you could use the best general settings below.

Depending on your taste and the music type you listen to, you can adjust these settings accordingly however, these settings are an excellent place to start. 

  • Low-pass filter set to 80 Hz;
  • A high-pass set to 3,000 Hz;
  • A Midrange filter would have a low setting to 80Hz and a high setting to 3000Hz.


To summarize, a crossover is an integral part of any audio system, whether it is for car or home audio. A crossover enables the drivers of a speaker to receive the correct frequencies, and thus, those drivers are able to perform and produce higher quality audio.

There are different types of crossovers, including active and passive, and they can be inserted into your car audio setup at various points in the chain. This allows the frequencies to be cut either before or after the amplifier, depending on your needs.

Furthermore, it is relatively straightforward to understand what a crossover is, what it does, and how to install it considering different types of car audio systems.

Whatever your preference or car audio system setup is, you should be considering a crossover of any type to improve your overall sound quality.