How To Install And Wire Car Speaker Crossovers The Right Way

If you want more power & volume, less distortion, or simply to enjoy your music with better sound, you’re going to need to know how to connect speaker crossovers. I’d love to help!

In this article, I’ll cover how to install and wire car speaker crossovers with great results. 

Here’s what you’ll find inside:

  • Car speaker crossover wiring diagrams
  • How to install tweeters with crossovers (including tweeters with built-in crossovers already)
  • How to install a crossover in your car like a pro – tips on installation and mounting
  • Additional helpful info about speakers, impedance, crossovers, and more

There’s a lot to cover so let’s get started!

How to wire car speaker crossovers (diagram and info)

How to wire car speaker crossovers diagram

How-to and tips for wiring car speakers to crossovers

In order to correctly wire speaker crossovers, you’ll want to do the following:

  • Be sure to plan for having enough speaker wire on hand. Many speakers do come with speaker wire, but more often than not (1) it’s fairly short in length or (2) it’s not great quality. I recommend picking up a roll of 25 feet, 50 feet, or even more to make sure you have enough if running wire from speakers to the crossovers.
  • When connecting the wire, strip about 3/8″ wire from each wire and twist the bare conductors tightly to prepare them for the speaker wire terminals or connectors you’ll be using
  • Be sure to carefully follow the crossover & speaker wire polarity markings. That’s because if one speaker is wired backward vs another, this creates a condition called being “out of phase.” That just means one speaker is working to make sound in the opposite direction of another and can cause some sounds to cancel out, in addition to sounding weird and not as it should.
  • Always use the correct speaker impedance for the crossover. Crossovers are designed to work only with one speaker impedance (Ohms) in most cases. Changing this causes crossover shift which means the crossover’s frequency cutoff changes dramatically and your speakers won’t sound right at all.

Crossovers are normally marked with the correct speaker wire polarity to connect to as well as which speaker you should connect. Often you’ll find an abbreviation like “TW” for the tweeter and “Wf” or “Md” for woofers and midrange/midbass speakers.

Do crossovers have to be wired close to speakers?

Diagram showing crossover wired close to or far away from the speaker

You can install & wire speaker crossover close to the amp or car radio. They don’t have to be installed close to the speakers.

The good news is that yes, you can wire speaker crossovers close to your amp or car stereo if it’s less work. While it’s usually easier to do it where the speakers are when upgrading factory 2-way component speaker systems (since they’re often close to each other in the doors, for example), it’s not important.

example of component speakers installed in car door

It’s generally easier to put a crossover near the component speakers when upgrading (or adding your own) 2-way speaker systems. However, there’s no reason you have to most of the time. When it’s convenient, you might find it helpful to keep the crossover closer to the car stereo or amp, saving the need to do more work or run new speaker wire to go to it.

For example, if you’re upgrading factory-installed tweeters but don’t want to have to hunt down and modify the factory wiring, normally it would require running new speaker wire to them. Instead, you can avoid all that time & headache by wiring them inline behind the head unit, then connecting the new tweeters in place of the old ones.

As long as the speaker wiring is reasonably short (less than 50 feet for each speaker, for example), in the real world it’s not a problem. This is especially helpful for situations like adding bass blockers (inline high-pass crossovers) from an amp to your main speakers.

Just be aware that some vehicles may have factory crossovers installed on the speaker itself (very common for factory tweeters) or somewhere else in the speaker system. It pays to be sure before connecting your own.

How to mount & install car speaker crossovers – 2 great ideas

How to install and mount car speaker crossovers diagram

Once you’ve wired your speaker crossovers, you’ll want to make sure they’re installed and mounted securely. That avoids a lot of problems with them bouncing around and even potentially having a short-circuit if the terminals come close to metal.

As you can see from the diagram above, I’ve provided 2 practical ways:

  1. Mounting crossovers using wire (“zip”) ties: this is definitely one of the easiest and best ways to make sure your crossovers stay put. Not only that, but it saves a lot of time, too. This also works in nearly all vehicles (even boats in many cases!).
  2. Using self-adhesive Velcro tape: Using sticky-back Velcro tape is pretty fast as well, although in hot temperatures the adhesive can lose its strength over time. However, it’s really easy and if you have some Velcro already handy it’s a great way to make good use of it. You can also remove the crossovers without having to cut anything unlike with wire ties.

car speaker crossover installation example using wire ties to mount it

Shown: an example of how I used wire ties to mount a 2-way speaker crossover to the car’s wiring harnesses in the trunk. It’s not “fancy” looking, but still one of the easiest – and best – ways to install crossovers with a lot less hassle.

If you’ve ever bought wire ties you may have noticed that they’re often way too short to wrap around speaker installation parts. One of the installation tricks I use to solve this is by connecting wire ties to each other end-to-end for extra length.

This way, you can use any wire ties (6″, 8″, and other standard lengths stores may have) to get the job done. 

Installer tip: Be sure to get enough wire ties before starting your installation! I recommend buying a standard pack of at least 100 6″ or 8″ zip ties. However, my advice is to buy extra. Having 200 or more is much better especially as you’ll have enough to neaten up your bundled amp or speaker wire runs.

I don’t recommend you bother with the small packs of 25 – 50 or so as you’ll run out of them quickly.

How to wire tweeters with built-in crossovers to speaker crossovers

How to use tweeters with built in crossovers with 2-way speaker crossover diagram

What about using different tweeters with an existing component set or making your own component speaker set using some speakers & crossovers you bought.

The good news is that in most cases if the tweeter impedance matches that of the 2-way crossover this can work.

However, the most important thing here is that you don’t use the built-in tweeter crossovers. You’ll have to remove and/or bypass those.

Generally speaking, most add-on tweeters have one of 3 kinds of built-in or external crossover:

  1. Low-cost 6dB/octave crossover (capacitor) mounted right on the tweeter.
  2. A single capacitor wired inline on one wire.
  3. A 2nd order (12dB/octave) crossover is wired in line with the tweeter wiring or connects to it.

For #2 & #3, you’ll just need to either bypass it and connect the tweeter to speaker wiring & the crossover directly. Case #1 is a bit trickier. You’ll need to either remove the capacitor and solder the speaker wire to the positive tweeter terminal, bypassing it, or solder a jumper wire around it.

Soldering a jumper wire around it will act as a short and the capacitor will no longer be seen by the crossover you’d like to use.

Note that you shouldn’t use existing crossovers on speakers when connecting them to a new crossover. The crossover you’d like to use will behave differently and the sound won’t be correct. (The crossover frequency can change and other kinds of problems pop up)

What happens if I use a different impedance speaker on a crossover?

Crossover shift due to speaker impedance change explained diagram

Diagram showing what happens when you change the speaker Ohm load connected to a crossover: crossover shift occurs. That’s because the crossover frequency is very dependent on the speaker load used. When that changes, the crossover frequency moves (“shifts”) accordingly.

Crossover shift when using different impedance speakers

As I showed earlier, crossovers are based on parts (capacitors and inductors) that work as filters according to the speaker load they’re connected to. Because of this, when you change the speaker impedance you change the crossover frequency and the sound.

You’ll likely notice some sound problems if you do it:

  • A “harsh” sound from woofers or midrange speakers. Tweeters may sound distorted and begin to “break up” at a lower volume than they used to.
  • A “thin”, weak quality to the music.
  • Gaps in the sound ranges you should be hearing.

Speaker crossovers can only be used with the speaker impedance they’re designed for or they won’t sound the same.

As an example, wiring an 8 ohm home speaker to a 4 ohm car speaker crossover won’t work right. In that case the crossover frequency would shift downward 2 x the original value (example: a 3.5kHz crossover frequency would shift to 1.75kHz). That’s because the crossover is designed using math & parts based on using a 4Ω speaker load.

What happens to a crossover when I half the speaker impedance?

When you change the speaker impedance connected to a speaker crossover it can significantly shift the crossover’s cutoff frequency. As a general rule:

  • Halving the speaker impedance (ex.: 8ohms to 4 ohms) doubles the crossover frequency (Ex.: 3.5kHz goes to 7kHz)
  • Doubling the speaker impedance (ex: 8 ohms to 16 ohms) halves the crossover frequency (Ex. 3.5kHz goes to 1.75kHz)

We don’t want this because it allows the wrong range of sound frequencies to pass to the speakers. In the case of tweeters, bass & midrange are bad because they can’t produce it properly. In fact, after a certain power level tweeters can be damaged when driven hard by bass frequencies.

Likewise, many woofers can’t produce high frequency sounds well and often sound really bad when producing it.

If you change the speaker Ohms you’ll have to replace the speaker crossover as well to match.

More great articles to help

You’re in luck! As it turns out, I’ve more fantastic AND free info about tweeters & speakers for you:

Got questions or comments?

Feel free to leave a comment below or you can reach me via my Contact page. Thanks for reading!

Your comments are welcome!

  1. I have a question. My tweeter in dash and sub woofers in door and back seat.do I run it to the tweeter in dash then also run it to the sub woofers? What do I do with door speakers wiring then.?because I would come from the crossover in dash by tweeters then ran to sub woofers in door.I am basically gonna have extra wires.

    Reply
    • You mean the woofers in the doors? Subwoofer aren’t normally in doors. It depends on what you’re trying to connect/wire up (you didn’t say specifically).

      Normally you’d wire a 2-way crossover to the tweeters and woofer if you’re referring to component speakers. I am not clear on what you’re asking.

      Reply
  2. Why can’t I run my passive crossover directly to the head unit using factory speaker wires? I haven’t seen 1 video anywhere explaining.

    Reply
    • You can, it’s just not very common. 1) cut the factory speaker wiring, 2) connect additional speaker wire to extend it, and 3) connect to the crossovers on the input side. It’ll have to be the correct speaker Ohms load/type of course.

      Reply
  3. I would like to connect my Pioneer deh-s4250 to my Clarion eqs755. Then connect the eq to my 4 Pioneer TS-A6880F speakers. OR Do i have to have to have a amp?

    Reply
      • With the clarion, can I use a Blitz BZK-4 audio crossover, I have 2 of them I also have a gravity gr-eq9, a 1604 blaubunk amp and a pioneer GM-D8604 amp. I don’t want to blow my speakers and the pioneer amp is rated 400 RMS. THE BLAUBUNK IS ONLY 50 RMS FOR A 1600 WATT AMP. I plan on having the system done by a pro not myself, I just want a kick a__ system.

        Reply
  4. Hello there.I want to ask something. I have an old car with broken speakers.I put in front doors a 16.5cm adapters and i have place for the tweeters in the front dash.I want to put Hertz DSK 165.3 2-Way Compo.Problem is i dont have money to pay someone to wire up things and i have to do it myself.I have 2 cables + and – for the front left door speaker and 2 for the front left dash tweeter.I know that crossover needs 1 + input and 1 – input from my CD Unit and then it splits to Door and tweeter.My question is about the cables coming out from the Unit.Are there 1 pair + and – for each front doors and dash tweeters and it splits to 2 + and – or its 2 + and – for each speaker?I want to use my original wires but just to put the crossover before them.

    Reply
    • Hi Erik. Most likely you can’t use the original wiring to the factory tweeters (if there are any installed). You’ll need to wire it like this:

      1. CD player -> crossover + & – inputs.
      2. Crossover woofer out -> door speakers (can use the factory wiring if you like).
      3. Crossover tweeter out -> run wire to the new tweeters in the dash.

      Reply
      • Thanks for the fast reply Marty. Now there is only 1 pair + and – for the front left tweeter and woofer and 1 pair + and – for the front right tweeter and woofer right? i just have to figure out which ones are for the left and for the right.I can use both factory wires right? just apply them to the Crossover and then input from the CD to the crossover and thats it?

        Reply
  5. Hi Marty I have an EQ and Crossover connected to my system, which is one bass with it’s amp and a 4 channel amp and 4 PRV mid range speakers 6MR250B-4 SLIM to be exact, I would like to add front tweeters, how would I do it and what type of crossover would I need. Thanks in advance.

    Reply
    • Well, most tweeters already include crossovers, but if you’re using midrange it sounds like you’ll need to get some 2-way crossovers to connect to the midrange and tweeters. You can then just use the same amp channels to go to the inputs on the crossovers.

      The crossovers are usually tend to have a crossover frequency around 3.5KHz, but you select those based on the recommend range of the tweeters & midrange.

      Reply
  6. Good morning Marty,
    Question about a system configuration.
    First of all great article, some of the best details I’ve ever seen!
    I will be installing the following into a 2021 Chevy Silverado and want some advice or just understanding.
    Mephis Mclass 6.5 & 6×9 components
    Powering them with an audiocontrol d4 800.
    My question is the amp has a dsp and wanted to understand how the crossovers come into play with the dsp. I think have a general idea, but really am seeking better understanding.

    Reply
    • Good morning, Doug. I’m glad you like my article. In the case of the D-4.800 for standard speakers like yours you can optionally use the high-pass crossover functions to block very low bass if you like.

      However since you don’t have have a subwoofer as far as I know, I wouldn’t since there’s nothing to make up the difference for the low end bass. So you’re probably fine using all speakers in full range mode and work on setting up your equalizers for the best sound. In a more complex system (adding a subwoofer, bi-amping speakers, etc) it’s a different situation and crossovers are helpful.

      Reply
      • Ahhh I accidentally left out I will be adding in a 8” mephis mojo with the lc1500. That might have been good information. Really appreciate the forts cut of feedback. Maybe you can elaborate so I have a strong understanding of what you mean about the passive crossovers the components come with.

        Reply
        • Hello Doug. In that case you’ll benefit by using the high-pass crossovers on your main speakers (say 50-60Hz or so is usually good) and a low pass for the subwoofer channel(s). That way you’ll have the lower bass being handled by the subwoofer only for less distortion for the main speakers.

          If you’re using component speakers with passive crossovers there’s nothing to worry about there. The passive crossovers are separate from built-in crossover functions and will separate highs/lows as needed for the tweeters and midbass speakers.

          Reply

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