To optimize the performance capabilities of a speaker, it should operate within the frequency range for which it was designed. A woofer or subwoofer won’t be able to reproduce high frequencies accurately. A tweeter will self-destruct if you ask it to try to play bass frequencies. For this reason, we use three- and four-way speaker systems in most vehicles. That means using crossover networks.

The purpose of a crossover is to split up the frequencies that pass through it. We are going to delve waist-deep into the benefits and drawbacks of the crossovers commonly used in car audio system component speaker sets.

How a Passive Crossover Network Works

A passive crossover network is a component or group of components that is installed on the speaker wires between an amplifier and a speaker. The behavior of these components attenuates portions of the signal going to the speaker itself. Four components are commonly used in passive networks: capacitors, inductors, resistors and protection devices.

The combination and configuration of these components are used to create a low-pass, high-pass or band-pass filter network. Resistors are used to attenuate the output of devices, or sometimes used as part of a frequency-dependent impedance correction circuit called a Zobel network. Some manufacturers include light bulbs, diodes or some form of positive temperature resistors to limit how much voltage a tweeter receives. Completely passive active networks have been available (but that was a long time ago).

How an Active Crossover Functions

An active crossover is a device that modifies an audio signal before the amplifier. It works on line-level or preamp signals only. Active crossovers combine op-amps, resistors and capacitors to alter different frequency ranges of the signal. Unlike passive networks, active crossovers can be designed to increase the level of the signal, but only in the case of powered filters. Active networks are often include other functions, such as remote level controls and bass boost circuits.

Benefits of Passive Crossovers

It is worth noting that each passive network is designed to work at a specific frequency for a specific speaker. If you change the speaker, the filter will not respond in the same way. In some cases, if the impedance of the speaker is significantly different from the one the network was designed for, the speaker may be damaged, or portions of the network may become damaged.

Passive networks are easy to use. You run a wire from your amplifier to the input of the network, then connect each speaker to the output. Other than mounting the network in a dry location that is free from vibration, that’s about all you have to consider.

Some passive networks include some form of output level attenuation. Most use a two- or three-position switch. Some use jumpers. An extremely high-end network may include a variable L-pad or potentiometer for extreme fine-tuning capabilities.

Passive crossovers allow you to split the power of a single amplifier channel to drive two different speakers. Fewer amplifier channels can dramatically reduce the system cost, since you only need a pair of amplifier channels to run a full set of speakers.

Limitations of Passive Crossovers

Since a passive crossover network is designed for a specific frequency, once the parts are chosen and assembled, there is no way to change that frequency without introducing new or additional parts.

Designing a passive crossover can be somewhat complex. The simplest of networks rely on some basic assumptions about the impedance of each speaker at the crossover frequency. Designing a network that compensates for the complex reactive load that speakers create as they move is difficult. It requires computerized modeling software and a way to measure the impedance and frequency response of the speaker at varying drive levels.

High-quality passive crossovers are designed for a specific distance and angle between the woofer and the tweeter. If the network is designed for the speakers to be far apart, moving the speakers close together will cause the signals to sum incorrectly. Even changing the angle of a speaker can have a dramatic effect on the frequency response at the crossover point.

Passive crossover networks have limitations in how much power they can handle. The magnetic fields created in an inductor have a limit. The voltage applied to a capacitor also has a limit. Crossover networks can and do overheat and fail if too much power is sent to them.

Passive crossover networks consume energy. Using a speaker system with a passive network is not quite as efficient as one using an active filter network. The overall efficiency of the crossover network depends on its complexity and the quality of the components used in the network.

Passive crossover networks are somewhat susceptible to noise. If you run a wire with an AC signal on it past the inductor in a passive network, the network can easily pick up that signal and add it to the audio signal. Choosing a safe location to mount passive crossover networks is important.

Benefits of Active Crossovers

Most active crossover networks are adjustable. That means by turning a knob or moving a switch, you can change the crossover frequency. This flexibility makes active crossovers suitable for use with almost any speaker system. Most active crossovers also include level controls, so you can easily fine-tune the level of the midrange and tweeter to compensate for different mounting locations.

Active crossovers don’t care how powerful your amplifiers are because they process the signal before it enters the amplifier. Active crossovers are also not very sensitive to temperature variations, so they can be very accurate, all the time. If one of the amplifiers channels in an active crossover system clips, the distortion only affects that single channel.

Challenges of Active Crossovers

Because active crossovers are universal in design, being able to set crossover frequencies accurately can be challenging. Labels on potentiometers are notoriously inaccurate. Most active crossovers have fixed attenuation slopes. You can’t change these slopes to compensate for response characteristics or placement variations. Unless the speaker manufacturer provides it, or you have extensive experience in measuring the electro-mechanical and acoustic response of the set of speakers, knowing what frequency to cross speakers over at can be difficult. Too low and you risk damage to the tweeter. Too high and you get distortion from the midrange. Many speaker combinations also require the over- or under-lap of the crossover frequencies to produce a flat response.

An active crossover requires a dedicated amplifier channel for each speaker. These extra channel requirements can increase the cost of designing a system.

The Perfect Solution

If there is no limit to your budget, the ideal crossover solution for a set of speakers is an active crossover with a Digital Sound Processor performing the filtering. A DSP will offer adjustable crossover frequencies, and most offer adjustable crossover slopes and alignments.

No matter what you choose, it’s a good idea to spend some time with a high-resolution RTA to make sure your system is set up for the smoothest, flattest response possible at the crossover frequency.

This article is written and produced by the team at www.BestCarAudio.com. Reproduction or use of any kind is prohibited without the express written permission of 1sixty8 media.

Developing a speaker requires that the designer and engineer balance many different aspects, such as the application, cost and desired performance level of the end product. For the consumer, navigating the thousands of different speaker offerings on the market can be difficult. Two speakers can measure similarly regarding efficiency, power handling and frequency response, but still perform completely differently because of different distortion characteristics. Cone, dust cap and suspension resonance, motor non-linearity, and enclosure/application requirements play a crucial role in determining how the end-product will sound once installed in the listening environment. This article scratches the surface of looking at the benefits and drawbacks of choosing speakers by comparing coaxial and component speaker designs.

When Choosing Speakers, Define the Design

Component (or separate) speakers are a set of speakers that includes a set of dedicated midrange drivers and dedicated tweeters. Each of those four speakers requires a dedicated mounting location. By contrast, a coaxial speaker features a midrange driver with a tweeter mounted in the center of it. In most cases, the tweeter is on top of an extension post connected to the pole piece. Other coaxial designs use a bridge or mesh grille to suspend the tweeter over the midrange. These are sometimes called coaxially mounted components by marketing departments.

Benefits of Coaxial Speakers

In most cases, coaxial speakers are the less-expensive options in a product lineup. This pricing is due to the chosen target customer and not because you can’t make a high-quality coaxial speaker. Less-expensive magnets, baskets, cone materials and suspension components, and wider tolerances that allow for faster production with fewer rejected assemblies, all help reduce cost. The benefit is, if you need an inexpensive speaker, coaxials are a good solution.

Coaxial speakers can be installed faster, so they are less expensive to install. The integrated tweeter saves a lot of time during the installation process. Most coaxial speakers have integrated crossovers of some sort that don’t require special wiring or mounting. The net result is that your installer can get them up and running in your vehicle in about half the time it takes to install a component set, which means your labor charges will be reduced.

Benefits of Component Speakers

Most component speakers are made from better materials and have higher performance goals. High-end components can cost more than $5,000 for a set and often include premium passive crossover networks, elaborate installation accessories and – of course – amazing speakers. The sound that component speakers produce, when installed and tuned properly, can be amazing!

When a good set of components is tuned properly, most of the sound can appear to come from the tweeters. Having a separate tweeter allows your installer to mount it high in the vehicle – at the top of the door, on the dash or in the A-pillar. The combination of proper tuning and placement puts the music out in front of you, essentially at eye level. This higher soundstage is similar to what you would experience at a concert, listening to the band performing in front of you.

Many factors contribute to where and how your installer mounts the tweeters – your budget, your performance goals, and how much modification you want or will allow to your vehicle. All locations have their benefits and drawbacks. For example, a tweeter mounted on the dash or A-pillar is very near the windshield. The hard surface of the windshield can cause significant reflections. Alternatively, a mounting location in the upper section of the door may reduce these reflections, but may not raise the soundstage as high, or could make it appear to come from somewhere closer to you than the dash or pillar location.

A component speaker doesn’t have any of its output blocked by the tweeter, which eliminates some minor reflections . Likewise, with a coaxial speaker that uses a tweeter post, a component speaker can have a full dust cap. The dust cap moves with the cone and increases the driver cone area. Additional cone area increases the driver’s efficiency.

The Huge Role of Crossovers

Whether you choose a coaxial or component speaker set, you are going to need a crossover to handle splitting up the frequencies. In the most basic of speakers, a capacitor is used on the wire going to the tweeter to block low and midrange information. The midrange driver is allowed to roll off naturally – ideally, there are no significant high frequencies resonances that will affect the sound.

As you progress up through the quality of a speaker set, you will see steeper filter networks on tweeters. These steeper networks allow the tweeter to play to a lower frequency and then be stopped to protect it from excursion damage. At the same time, filtering the high-frequency output of the midrange is common in mid- to high-end crossover networks. Speaker manufacturers construct the most elaborate of crossover networks with premium components for both the high- and low-pass portions of the network. Adjustability is often built into the crossover for tweeter level. Small components can be overdriven and saturated, reducing their effectiveness. Large amounts of distortion can cause the tweeter cap to overload and explode.

The Option of Coincident-mounted Coaxial Speakers

The radiation pattern of a speaker is a sphere in its standard operating range. As frequency increases, this output pattern becomes more directional. When a tweeter is mounted at the base of a midrange, a phenomenon occurs called Intermodulation Distortion. As the cone of the midrange moves up and down to reproduce music, this moving surface modulates the reflections of the tweeter.

It is worth noting that the same thing happens when a single speaker cone is asked to reproduce high frequencies: The source of the high-frequency sounds moves forward and rearward as the speaker cone attempts to reproduce lower frequencies. This modulating effect is known as Doppler Distortion. These distortions, combined with the narrowing of the radiation pattern as frequency increases, are some of the many reasons why we have to use different-sized speakers to reproduce music accurately.

When shopping for a coaxial speaker, you will want to choose one that has the tweeter mounted low enough not to interfere with the installation of a grille or trim panel over top of the speaker. You should also look for a tweeter that has a small waveguide that prevents the output from bouncing off the midrange cone.

Shopping for Speakers

We could spend years discussing the different aspects of speaker design and performance. Suffice it to say that you should seek out the assistance of a seasoned and reputable professional for purchase and installation. Be sure to quantify as much of the purchase process as possible – your financial limits, cosmetic preferences regarding installation and performance goals for the system. You will want to use music you have listened to many times when auditioning speakers.

You may want to listen to both a set of more- and less-expensive speakers to help quantify the price point you have chosen. Finally, talk with the salesperson and, if possible, the installer about how and where the speakers will be installed. Be sure to ask about sound deadening, spacers, wiring and anything else that can affect the performance of the installed speaker.

Speaker shopping is a lot of fun, and getting new speakers for your car, truck, boat or motorcycle can be very exciting. Be patient – take your time and be thorough. You will enjoy your new purchase all that much more when you choose a great-sounding speaker and a skilled installer.

This article is written and produced by the team at www.BestCarAudio.com. Reproduction or use of any kind is prohibited without the express written permission of 1sixty8 media.

The speakers in your mobile entertainment system are one of the most critical components in determining how your system sounds. If you choose poorly designed speakers that have distortion issues from poor cone, suspension or motor design, no amount of signal processing can make your system sound great. The methods used to install your speakers are as important as the design of the speakers themselves. In this article, we are going to look into some of the common mistakes that occur during speaker installation and how to maximize the performance of your speakers.

Speakers Need A Stable Foundation

If you want to listen to a record player, you want the unit to be on a solid table or stand. You’d never try to hold the turntable on your lap – the needle would jump and bound all over the place. When it comes to speakers, you want all the energy from the motor to move the speaker cone and not the basket. Why would the basket move? Newton’s Third Law of Motion states: When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.

When the voice coil pushes the speaker cone out, the inertia of the cone is also pushing back on the fixed magnet. If the speaker isn’t mounted securely, it will buzz, vibrate and otherwise move around. These vibrations cause all manner of distortion.

Look at a set of high-end home audio speakers. Years ago, Linn had a set of narrow floor-standing speakers that used a pair of small midrange drivers, roughly 4.5 inches in diameter. The front baffle of the speaker enclosure was 1.5-inch thick MDF. If you knocked on it with your knuckles, it sounded like concrete. And yes, those speakers sounded excellent!

Speaker Installation – Consider Mass

To combat the forces generated by the moving speaker cone, you will want to consider beefing up the mounting surface. In the case of a subwoofer enclosure, an extra-thick front panel can help. Vertical braces on either side of the speaker mounting surface help even more. The best solution is to run full-size braces from the front of the enclosure to the rear. Full depth braces lock the front and rear panels together and add dramatic strength to the speaker mounting surface. These braces also control vibrations in the rear panel to improve performance further.

For a smaller speaker such as midrange or midbass driver in a door, adding strength is a little more difficult. The most common practice is to add a layer or two of butyl damping material (sound deadening) to the metal around the speaker. You can even add a layer or two on the inside of the door skin if you are concerned about thickness. Damping materials with an aluminum layer add a little extra mass.

If your installer is constructing a set of speaker mounting adapters, then ask if they are using a material that has some mass to it. HDPE and ABS are good; acrylic is even better. A material like Corian – the DuPont countertop material – is fantastic. You can easily cut and shape Corian and glue parts together with Cyanoacrylate (Crazy Glue). You may want to use thread inserts or t-nuts with all of these materials. While it is readily available and easy to work with, don’t use wood for speaker adapters inside doors – it will get wet, swell up and deform. It can also hold water and get moldy.

Speaker Installation – Location Matters

If your audio system is going to use factory speaker locations, most of the time these are acceptable to provide an unobstructed output path to the listening area. The last thing you want to do is block the output of the speaker by putting something in front of it. Keep magazines, books, paper and other objects from piling up in front of, or on top of, your speakers.

For subwoofers, the location of the sub has a dramatic effect on how it sounds. You want the energy from the subwoofer to be able to mix with the sound from your midbass speakers as easily as possible. For this reason, hatchbacks and SUVs are great for bass. If you have a sedan, then firing the output of your subwoofer through a ski pass-through works well. You can get away with firing subs into the trunk of a sedan, but you will want to ensure that your midbass drivers can play fairly low – say 75 Hertz or so – to ensure that you don’t lose impact and dynamics.

Back-Wave Cancellation Problems

We use speaker enclosures for two primary reasons – to limit the movement of the speaker cone and to prevent the sound coming from the rear of the speaker cone from canceling out the sound coming from the front. You need to prevent the rearward sound from mixing with the front. For midrange speakers, this means building good quality mounting adapters. Your installer can also use sound-deadening materials to seal up openings in the interior skin of your door panels. You will get better speaker performance with proper back-wave management than you will just buying better speakers.

Weather Protection Ensures Longevity

When mounting speakers in a door panel, it is inevitable that the back of the speaker will get wet. The interior of doors are not completely watertight, and this poses a challenge for installers. Creating an enclosure out of a water-resistant material would be the perfect option, but there is rarely enough mounting depth and it is difficult to create an enclosure that is large enough not to affect the performance of the speaker. For many years, installers have used foam ‘hats,’ cut in half to protect the top of the speaker from direct exposure to drops from the window seal. These are a good option. A thick foam gasket mounted behind the speaker mounting surface can also help. Companies like SoundSkins and F.A.S.T. Rings have ready to apply pre-cut solutions.

There are dozens of other considerations when it comes to having your speakers installed. The most important task for you is to partner with a retailer that does high-quality work and has an excellent reputation. Choosing great speakers for your car audio system is a lot of fun. Hearing them perform up to their potential is even better.

This article is written and produced by the team at www.BestCarAudio.com. Reproduction or use of any kind is prohibited without the express written permission of 1sixty8 media.