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How to choose a crossover

Send the right signal to your speakers and tweeters

Buck Pomerantz was born and raised in Philadelphia. His parents bought their first television set when he was born. He figured out how to run it by the time he was two. Besides athletics, his formative interests included electronics, amateur radio, music, and stage crew work. He got his BA in writing from Brown University. Then he joined a rock 'n roll band as their soundman and moved to Charlottesville, Virginia. After that venture failed, he spent time in Boston, New Orleans, and Berkeley. He worked in a music store in Austin manufacturing, installing, repairing, and operating sound systems for recording studios, clubs, and bands. He moved back to Charlottesville, ran a little recording studio and finally joined Crutchfield as a copywriter. He has 2 grown children and 3 grandchildren, but after a good nap he can still rock out.

More from Buck Pomerantz

AudioControl 6XS

AudioControl 6XS 6-channel crossover

A crossover is an electronics device that takes a single input signal and creates two or three output signals consisting of separated bands of high-, mid-, and low-range frequencies. The different bands of frequencies feed the different speakers, or “drivers,” in a sound system: tweeters, woofers, and subwoofers.

Think of a crossover network as an audio traffic cop, directing highs to your tweeters, midrange to your woofers, and low bass to your sub.

Without a crossover, a messy, sonic "traffic jam" results. Your midrange and sub duplicate too many of the same frequencies and your sub wastes time trying to put out high notes it wasn't meant to handle. A "fatal pile-up" could also occur, with your tweets being destroyed by some renegade tractor-trailer of a bass note thumping along in the wrong audio lane.

Because they're essential, you'll find crossovers in some form almost any time speakers are present. For instance, if your home stereo uses a pair of 2-way bookshelf speakers, it uses 2-way crossovers (inside the speaker boxes). Within each crossover, a high-pass filter blocks the lows but passes the high frequency notes to the tweeter, while a low-pass filter blocks the highs and passes low frequency notes on to the woofer.

Sound Ordnance P-67C component system

Sound Ordnance P-67C component system: woofers, tweeters, and crossovers

The crossover “networks” of coaxial, full-range car speakers are usually built into the speakers, and often consist of small electrical components like coils or capacitors. Crossovers for 3-way systems, those systems utilizing tweeters, midrange drivers, and subwoofers, include, besides high- and low-pass filters, “bandpass” filters which play frequencies between two points by utilizing both a high-pass and low-pass in the same filter network. So, for example you could have a midrange driver only playing 100 Hz to 2500 Hz.

Active or passive?

There are two basic kinds of crossovers: active and passive. Passive crossovers don’t need power to filter the signal as desired. Active crossovers require power and ground connections, but give you much more flexibility and fine-tuning control over your music.

Active systems

A sound system is termed “active” when 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.

Kicker KX2 2-way crossover

Kicker KX2 2-way active 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 you want to hear. 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.

The only potential disadvantage of an active crossover is that since it requires +12V, ground, and turn-on connections, it presents more of a challenge to install and set up than a passive crossover. But with a little time and care this shouldn't be a problem, and the rewards and advantages of an active crossover make it clear why you'll find one in virtually every competition-level car audio system. Likewise, stereo systems tuned for high-quality sound will make use of crossovers in order to keep the speakers playing clean and clear.

Passive crossovers

A passive crossover doesn’t need to get hooked up to a power source to work. There are two kinds of passive crossovers: component crossovers that connect between the amplifier and speakers, and in-line crossovers that fit in between the receiver and the amp.

Component crossovers

Passive component crossovers step into the signal path after the amplifier. They’re small networks of capacitors and coils usually installed near the speakers. Component speaker systems come with their crossovers set for optimum performance, and they are simple to install and set up. A full-range signal exits the amplifier and goes to the passive crossover which separates the signal into two parts and sends the high notes to the tweeter and the mid and low notes to the woofer. Most passive component crossovers have optional settings that let you turn down the tweeter some if it seems too loud for the woofer.

Focal Performance PS 165AS crossover

Crossover for a Focal Performance PS 165AS component system

Since it is filtering a signal that has already been amplified, a passive crossover wastes power, releasing the unwanted parts of the amplified signal as heat. Also, speakers actually change their impedances when playing which also changes a passive crossover’s crossover point, or frequency response, leading to inconsistent sound definition, especially around the vocal regions. (This is another advantage to using an active crossover, which is unaffected by speaker impedance.)

In-line crossover

Besides passive crossovers that operate on speaker-level signals and connect between your amp and your speaker components, there are also in-line crossovers that connect before the amplifier. They look like little cylinders with RCA connectors on each end and simply plug into your amplifier’s inputs. In-line crossovers make sure your amplifiers don’t waste energy amplifying signals you don’t want — like high frequencies to a subwoofer amp. Installing an in-line crossover is a great and inexpensive way to sharpen the sounds of your system, especially in a component speaker system.

F Mods

Examples of in-line crossovers

In-line crossovers each come set to a specific frequency and can’t be adjusted. Another disadvantage of using in-line crossovers is that they react differently to different amplifiers, possibly changing their crossover points unpredictably.

For future upgrades and expansion, go active

If you plan on expanding your system in the future, it's wisest to go with a separate outboard crossover, instead of relying on the ones built into your receiver and amplifier. While these built-in crossovers work well, they don't offer the total system control of an outboard unit. Also, if you ever upgrade your amp, you don't have to give up your crossover.

Tuning your system

Varying your crossover points is one approach to "tuning" your speakers. You can expect this adjustability from just about any active crossover. Setting crossover points also helps define the overall tonality of your system.

Setting your low-pass filter above 100 Hz gives you the type of boom many rap fans are looking for, while pushing it down to 80 Hz tightens up your bass and improves front soundstaging. Because each output channel on an active crossover usually has its own level control, you can even use this component to compensate for varying efficiency or sensitivity ratings among your speakers.

Stereo 3-way crossover

How a stereo 3-way crossover fits into a system

Let there be music

Let's look at an example. Take a simple three-way crossover network:

  • lowpass filter with a crossover point at 80 Hz;
  • highpass filter with a crossover point at 3,000 Hz;
  • bandpass filter with a low crossover point at 80 Hz and a high crossover point at 3,000 Hz.

You hop into your ride, slip in a CD and suddenly a hefty dose of unadulterated Dave Matthews Band is headed straight for your speakers. The lowpass cleans up Carter Beauford's kick drum and the low notes on Stefan Lessard's bass, and passes these tones below 80 Hz to your subwoofer system.

Meanwhile, your highpass sends cymbal crashes and acoustic guitar harmonics to your tweeter, while limiting frequencies below 3,000 Hz. And Dave's vocals, Boyd Tinsley's violin, and other sounds between 80 and 3,000 Hz find their way through the bandpass crossover to your midrange drivers.

The crossover assigns the proper frequencies and levels to the various speakers in your vehicle, the pieces of the sonic puzzle fit together perfectly, and DMB sounds righteous. It's all good.

Get Everything You Need

You'll need patch cables and power wires to connect an active crossover.
Check out all of the crossovers and other sound processors available at Crutchfield.

  • James from Qatar

    Posted on 6/22/2015 5:30:52 AM

    What are inbiuld crossover

  • Buck Pomerantz from Crutchfield

    Posted on 6/22/2015 4:13:25 PM

    James, A crossover will be describes as 'built-in" when it's located inside a device, like a component speaker or an amplifier.

  • Phill from Texas

    Posted on 7/6/2015 9:57:28 PM

    On point and very helpful. Thanks for the info. I have the Rockford Fosgate BP300 12 which has it's own settings in addition to my Kenwood 501 Head unit. Currently I've set the speakers controls to minimum and using only the Kenwoods settings. Is this the best use of this setup?

  • Buck Pomerantz from Crutchfield

    Posted on 7/7/2015 3:54:35 PM

    Phil, Normally it wouldn't matter, except to say you should use the controls of either one but not both at the same time. But because the low-pass filter of your powered subwoofer can't be turned off, I suggest you turn off all the subwoofer tone controls on your receiver and use only the tone controls (bass boost and X-over) of the subwoofer.

  • israel hall from brooklyn, ny

    Posted on 7/14/2015 2:13:32 AM

    I would like to speak to someone about installing a crossover to my home theater system your help in one's choosing a crossover is quite good

  • Buck Pomerantz from Crutchfield

    Posted on 7/14/2015 1:40:56 PM

    Israel, I don't know why, how, or where a crossover could possibly be utilized in a home theater system. The speakers have crossovers built in, designed by the manufacturer to match the individual drivers. Receivers have built-in crossovers so the subwoofer output will just be bass. This article discusses crossovers used in car audio applications. If you're putting together a home theater system with separate PA-style horns, speakers, and subwoofers, each with its own amp, then you may need to look at a Pro Audio crossover. Give us a call, for help in deciding.

  • Michael

    Posted on 8/10/2015 8:02:41 PM

    Is the epicentre a crossover? How will it affect audio quality?

  • Buck Pomerantz from Crutchfield

    Posted on 8/11/2015 12:21:28 PM

    Michael, The Epicenter by Audio Control is a bass-restoration processor, not a crossover. It uses sophisticated processing to analyze the incoming signal, restore low bass fundamental tones, and increase the bass response.

  • Julius from NAIROBI

    Posted on 8/13/2015 11:57:55 PM

    Does a crossover help to distribute sound to every corner of your experiencing that problem right now my subwoofer loses sound rather the impact its supposed to please

  • Buck Pomerantz from Crutchfield

    Posted on 8/14/2015 12:43:50 PM

    Julius, Crossovers are used to shape signals to match a speaker's ability to reproduce the sound. For example, a tweeter would be destroyed by low-frequencies if a crossover didn't prevent them from playing. For help improving the sound of your bass, check out this article.

  • Ryan McPherson from Fallon, NV

    Posted on 8/22/2015 4:26:58 PM

    What if I have some 3 way crossovers but only have speakers for a 2 way application...woofer and tweeter with no midrange? If I only connect the woofer and tweeter I'll have a gap in my audio range? Can I convert my 3 way to a 2 way?

  • Buck Pomerantz from Crutchfield

    Posted on 8/24/2015 10:58:42 AM

    Ryan, If you're talking about passive crossovers, then I don't think you can convert them from 3- to 2-way. Passive crossovers have fixed separate frequency bands for outputs and there's no easy way to recombine them. There are active crossovers that can switch from one mode to the other. But I've never seen a passive crossover that can do that.

  • Jorge from Caguas

    Posted on 8/31/2015 11:39:46 PM

    Is possible to hook a 30 watts RMS tweeter with a 200 watts RMS midbass speaker in same channel? I heard that only speakers with same size, watts RMS and ohm can be together in same channel cause they need to have the same voice coil to receive equal wattage, in this case the tweeter or the mibass speaker one of them will receive more power (in wattage) than the other and will burn or blown, help me out

  • Buck Pomerantz from Crutchfield

    Posted on 9/1/2015 12:35:24 PM

    Jorge, Assuming there is a crossover to keep low notes away from the tweeter and high notes away from the woofer, you can hook both components to the same amp channel, as long as the amp doesn't put out more than about 50 watts RMS per channel or it'll blow the tweeter.

  • Ronny Mathew from Atlanta, GA

    Posted on 12/1/2015 11:40:01 PM

    I'm having the hardest time finding just a passive crossover. I bought a set of component speakers that came with tweeters, 6.5" speakers, and crossovers, but one of the crossovers has gone bad. Where would I be able to find just the passive crossover? I can't seem to find any here on crutchfield, or anywhere else.

  • Buck Pomerantz from Crutchfield

    Posted on 12/2/2015 4:03:35 PM

    Ronny, Crutchfield does sell some passive crossovers, but they're designed to go with specific woofers and tweeters and you didn't identify yours so we can't tell if any of them would work for you. I suggest contacting your component's seller or manufacturer to see if replacement parts are available.

  • Sahand from Tehran, Iran

    Posted on 1/21/2016 1:22:15 PM

    tnq so much, it was so useful for me, by this information i can install my car audio system myself :)

  • Sean

    Posted on 2/27/2016 9:45:56 PM

    Love the DMB reference. Righteous.