What Is An Audio Crossover- Terms defined and explained

If you’re new to speaker systems, you’ve probably heard the term “crossover” mentioned a lot. But what does it mean? Is it even necessary? Well, simply put, yes! The crossover is an essential item for sound systems. If you use it incorrectly, it can negatively impact the overall sound quality of the system.

Here is a simple guide that will tell you more about crossovers, as well as the different types of crossovers.

What Is a Crossover in a Speaker?

Put simply, a crossover is an electronic device which is wired between the amplifier and the car speaker to ensure bass frequencies are sent to bass speakers and treble frequencies are sent to treble speakers. Inappropriate frequencies are removed to ensure the speaker does not play distorted sounds.

For example, low (bass) frequencies will be removed/filtered from the music (audio signals) being sent to a tweeter, because tweeters are designed only to play high (treble) frequencies. If the low frequencies were not removed the tweeter would play distorted sounds as it doesn’t have the capability to play low (bass) sounds. The same is true for a large bass speaker or subwoofer. If the audio being sent to a bass speaker did not pass through a crossover for bass speakers to remove the high treble frequencies then the bass speaker would play distorted treble sounds as it has not been designed to play high frequencies.

The crossover is designed to stop certain frequencies from traveling through to the speaker/output.

The audio crossover plays a critical role in a sound system since it stops the signal’s full range from reaching the speaker. Basically, it acts as a traffic police cop; it allows some frequencies to travel through and stops others so that there isn’t an accident on the road or distorted sounds in speaker land. The crossover is essential for any sound system because it compensates for the natural electrical components of the drivers in the sound system.

There are many different applications of this electronic filter. The crossover breaks the signals into different audio frequencies and sends them to the right driver (speaker). You can split the full range audio signal into two (bass and treble) or three (bass, mid range and treble) bands, which will greatly improve the quality of the sound.

Audio crossovers are mostly used when a speaker can’t cover the entire audio spectrum, ie a subwoofer (bass) or tweeter (treble) speaker. If you pass the entire audio range through, it will cause distortion and a strange relative volume. This is because the driver (speaker) can’t handle all frequencies from high to low.

Most sound systems or multi-frequency speaker systems have multiple different sized speakers. Since every speaker is designed to operate on a different frequency band, you will need an audio crossover system to separate the frequencies accordingly.

For example, let’s say you have a PA system cabinet. It contains woofers for mid to low frequencies, as well as a tweeter for high range frequencies. Whether you’re listening to a live band on stage or playing recorded music from a CD, you will need an audio crossover installed to make the sound clear.

The crossover will be used to split all the different frequencies from high to low. The signal will be routed accordingly to the tweeter or woofer of the PA system cabinet, ensuring the highest quality sound.

Do You Need a Crossover for Speakers

Yes. Crossovers are generally used in car speaker systems, but they can also be used for other sound systems. You can use crossovers for:

  • Loudspeaker cabinets
  • Professional audio systems
  • Power amplifiers
  • Musical instruments
  • Home cinema sounds
  • Consumer electronics

If you’re planning on going for professional audio where you need a proper sound system, you will need two things: crossovers and a sound reinforcement system. The former is used for keyboards or bass amplifiers and enclosures. The latter is used for monitor speakers, PA speakers, subwoofer systems, etc.

What Is an Active Crossover

Active audio crossovers are installed before the amplifier. They have active components in their filters, and the most common type is the op-amp. They are used for amplifiers inputs to curb the noise that can be created when signals are amplified. These crossovers need power amplifiers on every output band. This is why people usually install 2-way crossovers for both the tweeter and woofer.

What is a Passive Crossover

Passive crossovers are used after the amplifier rather than on the input. They work well in cases with high current and high voltage. Since they don’t require two types of amplifiers, they are cheaper than active crossovers. Passive crossovers also don’t need any power connections to filter the signals to a desirable level. On the other hand, active crossovers need ground and power connections.

Active vs. Passive Crossovers

There are some advantages that active audio crossovers have over passive types. Firstly, they respond to frequencies detached from any changes that occur due to the driver’s electrical components. This allows you some control and flexibility over your music.

Secondly, you will find that active crossovers are an easy way to fine-tune different frequency bands according to the drivers used. You will also be able to reduce the effects of overdriving and distortion since you can easily isolate the signals from each driver. This can drastically improve the quality of your sound and give you room to fine-tune it according to your personal preferences.

Moreover, when you install active crossovers, the speaker drivers are connected directly to the power amplifiers. This maximizes the damping control of the amplifier over the voice coil of the speaker. It reduces the effects of the electrical components of the driver, which can easily improve the system’s transient response.

Lastly, you will see a solid reduction in the output requirement of the power amplifier. The active crossover ensures that no energy is lost in any of the passive components of the amplifier. This can increase the quality of the sound as well as reduce costs for you.

Other Types of Crossovers

There are other crossovers that you may need for different sound systems. They all have different functions that may be beneficial in certain situations.

Component Crossovers

Passive component audio crossovers work by essentially stepping into the path of the signal after it has passed through the amplifier. They are installed near the speakers with a small network of coils and capacitors. If you’re using a component speaker system, you will get a component crossover with it. They help you achieve optimum performance from the speakers and are easy to install.

The way component crossovers work is by first receiving a full-range signal from the amplifier. This signal passes through the component crossover and gets divided into two. The low notes are sent to the woofer system while the high notes are passed on to the tweeter. You will be able to use the settings to turn the tweeter down if you think it’s louder than the woofer.

However, you should know that the passive component crossover does waste power. The signal has already been amplified by the power amplifier. The crossover releases unwanted notes from the amplified signal in the form of heat. You will also have to be careful about the changes that the speakers make while playing; they can create a change in the crossover point of the component crossover or even the frequency response. This can lead to an inconsistency in the sound definitions and vocal regions.

In-Line Crossovers

In-line crossovers are installed before the signal passes through the amplifier. They have RCA connectors at every end and resemble little cylinders. All you need to do is to plug them into the amplifier’s input. The best thing about in-line crossovers is that they ensure that energy is not wasted. In-line crossovers make sure that the amplifier doesn’t amplify signals that you don’t want to be amplified. It is an inexpensive and efficient way to make sure that you have a high quality of sound. They work well with component speaker systems.

However, in-line audio crossovers aren’t flexible since they come with a set frequency. There might also be an unpredictable change in crossover points since they react differently to every amplifier.

What Is a 3-Way Crossover for Speakers?

If you want accurate hi-fi output, the 3-way crossover system is a perfect option. A 3-way speaker system is able to handle the three different levels of frequency in an efficient manner. The tweeter takes care of the highest frequencies while the woofer and mid-range handle the low frequencies and speech parts, respectively. The 3-way crossover can help create an effective result by dividing the frequencies accordingly. The capacitors and inductors are really important in this system. The inductor restricts frequency increase while the capacitor prevents frequency decrease.

A 3-Way Crossover isn’t the same as a Low Pass Crossover, but a lot of people may confuse the two systems. So, what’s a low pass crossover? A low pass crossover makes sure that any frequencies under the cut-off level are still passed through to the speaker. On the other hand, the 3-way crossover system has three types of filters installed in the system: Low Pass, High Pass, and Band Pass. There can be overlaps in the crossover points, but you will have to calculate all of this to make sure the output is distinct and smooth.

Low Pass Filter

Some systems come with selected cut-off frequency levels. The Low Pass Filter (LPF) helps by reducing the strength of signals that have high frequencies and sending through frequencies lower than the cut-off frequency. The LPF design will impact the response you get from your frequencies. It complements High Pass Filters and creates an efficient system. It allows the shorter wavelengths through and comes in different forms. You can get hiss filters, anti-aliasing filters, acoustic barriers, digital filters, and more for your sound system.

Low Pass Filters ensure a smoother signal and remove any short-term fluctuations from the sound quality.  LPFs are sometimes used by professional filter designers as a prototype filter for the system they are handling. It allows them to check the bandwidth of the unit as well as the impedance of the sound. This can help them achieve the desired level of quality.

High Pass Filter

A High-Pass Filter (HPF) essentially reduces the strength of the signals that emit lower frequencies than the cut-off while allowing frequencies higher than the cut-off level to pass through. This electronic filter needs to have an accurate filter design so that it passes the frequencies according to your needs. An HPF is usually great for bass-cut and low-cut filtration.

It helps to block the DC signals coming from the circuit as well as manages radio frequencies and average non-zero voltages. When used with Low Pass Filters, they also act as Band Pass Filters. HPFs pass longer wavelengths through the systems, basically acting as the opposite of LPFs.

Band Pass Filter

A Band Pass Filter (BPF) can be tailored to pass certain frequencies through the system and stop any frequencies that fall outside that range. They are mostly used in receivers and wireless transmitters. The main purpose of the BPF is to make sure that the bandwidth in the output signal is limited to the band you want. This makes sure that the transmitter will not interfere with any other stations.

The Band Pass Filter prevents any unwanted frequencies in signals to go through while allowing a certain range of frequencies to pass through. This filter is crucial when it comes to optimizing the receiver’s sensitivity and noise-to-signal ratio. 

Tuning

When using audio crossovers, you also have to deal with tuning the speakers according to different crossover points. If you’re using an active crossover, you will have more room to adjust according to your needs. When you set all the crossovers at different points, it can positively impact the tonality of the speaker system.

For example, rap music needs the Low Pass Filter set at above 100Hz to give you the boom that rap needs. Pushing the LPF down to a mere 80Hz will improve the front sound staging and tighten the bass. Output channels have their own level of control on an active crossover, so you can use different components to adjust the sensitivity and efficiency of your speakers.

Summary

You will be able to get optimized and high-quality audio from your speaker system if you use a crossover in the right way. There are many types of crossovers, and each comes with their own set of benefits. You should check your sound system to see which audio crossover will suit your needs the most. For beginners, it may seem hard to adjust the crossovers in the sound system, but you’ll improve with practice. As long as you keep working at it, you’ll be able to get the most out of your sound system.

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