Crossovers FAQ
Answers to crossover questions

An active 2-way electronic crossover
» What's a crossover and do I need one?
» What's the difference between passive and active crossovers?
» How hard is it to install a crossover?
» What's the little selector switch on my passive crossover for?
Q: What's a crossover and do I need one?
A: For a more complete answer to the first part of this question, you'll want to check out our How to Choose a Crossover article. A crossover divides an input signal into two or more outputs of different ranges of frequencies, so tweeters, speakers, and subs will each get only the range of frequencies they were designed to play. Frequencies outside each designated range are attenuated or blocked.
Every speaker system needs a crossover of some type. Component speaker sets come with separate outboard crossovers, many with tweeter level selectors. Every full-range, coaxial speaker — with its tweeter mounted in front of the woofer cone — already has a tiny crossover network built into it somewhere.
If you want to run an "active" system, however, you'll need a more sophisticated crossover. In an active sound system each driver (tweeter, woofer, sub) has its own channel of amplification. This dramatically increases the available power, dynamic range (softest to loudest sounds), and your control of the system’s tonal response over the whole audio spectrum.
Almost all amplifiers come with built-in high- and low-pass filters that can serve as the crossovers in a component system. But these filters are small accessory features built into the amps and are often more inaccurate with less fidelity than a separate, dedicated electronic crossover.
An active crossover gets wired between the receiver and amplifier and cuts out the unwanted frequencies before the amp wastes energy boosting them, so the amp can focus on only the frequencies it's supposed to amplify. Active crossovers usually have volume controls on every channel or pair of channels so you can keep all the “voices” of the different drivers in balance. Some active crossovers include other sound-processing features like equalization for further tweaking of the sound to your personal satisfaction.
In a hypothetical 4-way active car audio system the original full-range audio signal might be crossed-over as follows:
- Low frequencies (say 100 Hz and lower) go to subwoofers.
- Midbass speakers get frequencies between 100 and 250 Hz.
- Midrange speakers would see frequencies between 250 and 3,000 Hz.
- All frequencies above 3,000 Hz are handled by the tweeters.
Keep in mind that the crossover points listed here are for example only and do not apply to every car or speaker system out there. The best crossover points for one vehicle might not be the best for another. It all depends on the speakers being used and the acoustic properties of the car. Most electronic crossovers allow you to choose from several crossover points.

The passive crossover from a set of high-end component speakers
Q: What's the difference between passive and active crossovers?
A: Short answer: an active crossover needs power — a passive crossover does not.
Passive crossovers go between the amplifier and the drivers (tweeters, speakers, and subs). A passive crossover circuit is built with coils, capacitors, and resisters beefy enough to handle the high output power of most amplifiers. Some passive crossovers include a tweeter level switch, which gives you some control over how loud the tweeter plays relative to the woofer. A disadvantage of using passive crossovers is that they filter out frequencies already amplified, creating extra heat and lowering speaker efficiency.
An active, or electronic crossover goes between the receiver and the amp. It handles low-level preamp signals with its solid-state circuitry to cleanly divide the signal and send each band of frequencies in the right direction. Active crossovers are usually adjustable (you can select the crossover points) and often have other features like bass boost circuits for subwoofers. Another bonus when using an electronic crossover is that you can independently control the relative volumes of all your different drivers.

Audiofrog passive crossovers are designed to work with specific Audiofrog drivers
Q: How hard is it to install a crossover?
A: Passive crossovers are very simple to install. They do not require a power connection, a turn-on lead, or grounding. You connect the speaker wire coming from your amp to the crossover's input. Then the tweeter gets wired to the tweeter output, and the woofer to the woofer output. That's it. The most challenging part of installing a passive crossover may be where to mount it, but most crossovers are small enough to fit inside your car door near the woofer's location.
Active crossovers require a bit more planning and time, but with a little effort, almost anyone can get the job done. You'll need to provide 12-volt power from your car battery to operate the crossover just as you must provide a 12-volt source of power to your amp or amps. A distribution block is a good way to get power for your crossover via the same main power cable as the amp does. You'll also need a solid, noise-free grounding point — it's generally best to ground your crossover at the same place as your amp.
Your electronic crossover also requires a turn-on lead to trigger it to turn on when you power up the receiver, and you can either run that wire to the receiver or daisy-chain it to the amp's remote terminal. You'll route the audio signal from your receiver to the inputs on the crossover via RCA patch cables. You then run more patch cables from the crossover outputs to the amplifier inputs — highs to the tweeter amp, mids to the woofer amp, and bass to the subwoofer amp, for example.

The 3dB switch lets you take the edge off the highs
Q: What's the little selector switch on my passive crossover for?
A: Many component systems have passive crossovers with 2- or 3-way tweeter level switches included. Ideally, a crossover will put out the same level of signal, or volume, to the tweeter as it does to the woofer. But many people find that sounds unbalanced and too shrill and bright. Many speaker manufacturers recognize that and put tweeter attenuators in their crossovers. The settings should include "0 dB," when the tweeter level is the same as the woofer; "-3 dB," for a little attenuation; sometimes "-6 dB," for a lower tweeter level; and sometimes even "+3 dB," for those who like it brighter.

How an active stereo 3-way crossover fits into a system
Check out all our crossovers at crutchfield.com/crossovers.
Ken Simmons from Nashville
Posted on 2/12/2023
For any novice readers out there just trying to learn, I noticed the statement "...coming from your amp to the crossover's input." in the opening paragraph when it is discussing connecting the crossover in an active system. I believe it should be the crossover's outputs you want to connect from going into your amplifiers. Any experts please correct me if I am misunderstanding the words and block diagram.
Buck Pomerantz from Crutchfield
on 2/13/2023
Bruce
Posted on 2/1/2023
How can you advise about crossovers when you don't understand basic electronics. Buck answered one person saying he didn't know maybe the manufacturer used a step up transformer to amplify. A step up transformer only steps up the secondary voltage not the wattage. Input wattage equals output wattage minus heat loss etc.
Buck Pomerantz from Crutchfield
on 2/1/2023
A. Maldonado from Puerto Rico
Posted on 5/28/2022
I bought from Crutchfield two set of Infinity Kappa 6.5 speakers (front and rear), running on an Alpine MRP-F240 which I bought some time ago but there are still running great. Recently, I bought a Clarion MCD-3660 Crossover and a Clarion EQS755. My son gave me a set of 6X9 Rockford Fosgate (RF) P1692. I am installing it on a 1997 RAV4 4door. The Kappa speakers have their own crossover. I plan to install the Kappa speakers with the Alpine AMP, and the RF speakers on an extra AMP. Which AMP should I buy, for the RF speakers and since the Kappa speakers bring their own crossover, can I omit the Infinity Crossover and use the Clarion MCD-3006 crossover instead?
Buck Pomerantz from Crutchfield
on 5/31/2022
Kaleb Jones from Waynesville
Posted on 8/24/2021
I just purchased a set of component speakers. My question is my head unit has active crossover built in if I put it in network mode I can control each speaker separately. Could I use this instead of the passive crossover that came with the component? I would like to tame down the tweeters and the passive crossover -3db is not enough for me. Would this negatively affect my tweeters or woofer's in away?
Bruce Southall from Crutchfield
on 8/24/2021
jack m from houston
Posted on 3/12/2021
How can a passive crossover "boost" the tweeter signal +3dB? It's just resistors capacitors and inductors, how is it possible to amplify?
Buck Pomerantz from Crutchfield
on 3/30/2021
Bill Young from TRENTON
Posted on 11/10/2020
Not sure if my previous question went through so sorry if this is a duplicate. I just purchased an RF T1675S speaker system for my 2018 Chevy Silverado. I downloaded the instructions and they don't have any info on the crossovers that are included. Do I not use them as I am replacing factory speakers to factory locations with no AMP? If not how/where do they go? It looks like all the extra connectors and brackets included are for the speaker install not the crossovers.
Henry from NYC
Posted on 11/5/2020
Hello, I have a BMW e46 with HiFi system (non-HK) with stock 10 channel amplifier. I plan to replace the stock speakers with aftermarket speakers that match closely to the specs of the OEM speakers, but with slightly better specs. The BMW system has in it active crossover points from the stock amp (23.6Hz @ -6dB/oct slope input high-pass filter for all front channels, then 23.6Hz to 430Hz@-12dB with added notch filters at 190Hz and 550Hz for Woofer output; then 1.25kHz to 5.5kHz @ -12dB for Mids; and then 6 kHz @ 12dB upwards for Tweeter highs). So without changing out the stock amp, do I exclude the inline crossovers that come with the speakers, or is there a way to help streamline or compliment the current crossover points with them, as you can see the stock filter points have "holes" between each range? The stock BMW amp handles 40W @ 2ohms for the woofer channels and 35W @ 4 ohms for all else. Is there a good replacement amplifier/crossover combo that can be used to replace the stock amp (looking for specifications such as RMS rating, number of channels and ohms per channel; not brand names, they can be matched to the specs later), without going too extreme (would prefer good audio, but not over the top; that is why thinking of keeping stock system except for the speakers)? If I put 4 ohm woofers on the 2 ohm channels, would this cause issues with the stock system so long as the speaker RMS is above the rated RMS of the channel from the amp (such as heat or wear)?
tony doan from miami
Posted on 8/14/2020
I recently installed the morel ccwr254 in a 2010 accord. I am using the supplied capacitor which has an crossover point of approximately 265hz. I have a pioneer avh2700bs and have the hpf at 200hz 12db slope. I've noticed that if I change the slope or lower the hpf to 100hz or so, it affects the sound of the morel, as if there is the capacitor was not connected. Is this normal? Is the slope from the head unit adding up with the morel capacitor slope?
Buck Pomerantz from Crutchfield
on 8/18/2020
Jay
Posted on 8/12/2020
Is it safe to use the included crossover from a component set with only one of the components? i.e. with just the tweeter
Buck Pomerantz from Crutchfield
on 8/13/2020
Eric from Granite Bay
Posted on 8/11/2020
I recently purchased a component speaker system that includes a passive crossover box but also has an "integrated crossover" built into the wires of both the tweeters and speakers. Am I supposed to use both or are they just including both for different setups? My though was that I should only be using the passive crossover box as it seems that it would be redundant to use that as well as a built-in crossover.
Buck Pomerantz from Crutchfield
on 8/11/2020