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.

A remote starter, keyless entry or security system is a great way to enhance the functionality of your vehicle. A remote starter can make dealing with weather extremes much more comfortable. A properly installed security system can let you know if someone damages your vehicle or tries to steal it. If your car didn’t come with a remote control to unlock the doors, a keyless entry system can speed up the process of getting into your vehicle and locking it when you leave. An entire list of convenience options can be added to these systems to make them even more convenient and further improve the security of your vehicle.

Cellular Interface

Many companies sell smartphone interfaces for remote start and security systems. These systems work by interfacing between an app on your smartphone and the convenience system in your vehicle. Yes, you have to pay for a monthly (or yearly) service plan, so don’t be surprised by that aspect. These systems will allow you to lock and unlock your vehicle, start it remotely (if you have a remote starter installed), and pop the trunk if that is hooked up.

The best part is that if you have a security system, your phone will alert you with a message if your alarm goes off. Anywhere your car and your smartphone have access to a cellular connection, you can control the system.

Many smartphone interfaces include GPS receivers. Such a receiver can send the longitude and latitude of your vehicle to the app on your smartphone. This information will let you know exactly where your vehicle is and how fast it is traveling. The app also can let you know right away if the vehicle moves when it’s not supposed to.

Some of these systems include the ability to monitor battery voltage, advise you of vehicle diagnostic codes and tell you the temperature of the vehicle interior. A few of these systems include a built-in backup battery and will alert you if the unit is disconnected.

Power Window Control Interfaces

One of the “classic” convenience accessories is the power window interface. This module lets your convenience system roll your windows up and down with the press of a button on your remote. The system can be programmed to roll the windows up when the doors are locked. Many of these window control systems have the option of venting a window an inch or two with a short press of the button on your remote, then rolling the window down completely when you hold the button for a second or two.

Power window modules also can be used to control sliding doors or sun roofs.

Tilt and Motion Sensors

If you are worried about someone stealing your wheels or towing your vehicle, then a tilt and motion sensor would be a great addition. These sensors calibrate themselves each time the alarm is armed, then trigger the system when the vehicle angle changes by more than a couple degrees. These sensors should not trigger the alarm under normal wind conditions, thanks to integrated software that recognizes when the vehicle is rocking.

Backup Battery Siren

If you are concerned about someone cutting you the wire to your siren so they can work on bypassing the rest of a security system, ask your mobile electronics retailer about a battery backup siren. These sirens will go off if someone cuts the wiring to it. A key on the siren will turn it off.

Radar Sensors Boost Protection

If you have a convertible-top vehicle or like to leave your windows down, a radar or field disturbance sensor is a great way to keep your vehicle protected. These sensors usually have two stages of protection. The first will provide a warning to an intruder when something or someone enters the field. The second triggers the alarm right away. Your installer can fine-tune the size of the fields for a given sensor mounting location and vehicle type.

Keypads Add Convenience

Several companies offer convenience keypads that attach to the inside of your windshield. You can type in a code of your choice to arm or disarm the system.

Some keypads have the option of acting as a pager for an owner who has a two-way remote or smartphone interface. These systems use technology similar to what a smartphone uses with a glass screen uses to detect your finger presses.

Proximity Remote

Many new cars have proximity keys that unlock the doors when you walk up to the vehicle. Your installer can add similar technology to an aftermarket keyless entry system. You simply keep a fob in your pocket. When you walk up to the vehicle, it will disarm the alarm without your having to press a button.

High-output Sirens

If you want to get people’s attention when your alarm goes off, then the addition of a high-output siren is just for you. Some of these sirens are extremely loud, while others offer a sound that is truly ear-piercing! These high-frequency sirens are often called pain generators and are typically installed in the vehicle.

Protecting your vehicle from theft or vandalism is an art. Some installers take great pride in their security system installations. They conceal wiring in the dash very carefully and use wire protection that matches the factory look and feel. Split-loom, flexible-conduit, Tesa tape and vinyl tape are just some of the wire protection options. Installers route wires with factory wiring to further conceal their work.

Adding features and functionality to a security or convenience system is a great way to enhance its performance and usefulness. These are just a few of the possible additions available. Be sure to ask your local mobile electronics specialist retailer about the options they have available.

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.

When it comes to buying subwoofers, a lot of people have questions or make assumptions about the benefits and drawbacks of single voice coil and dual voice coil versions. Understanding the differences between them requires a slightly enhanced understanding of how an amplifier works. We cover both topics in this article.

How an Amplifier Works

An amplifier is a simple device that takes an audio signal (from your radio, for example) and increases the voltage. That’s it.

You may (logically) be asking yourself, “Why do we call it a power amplifier?” We get an increase in power because the speakers we connect to the outputs of the amplifier have a low impedance. In car audio, we typically see loads between 1 and 4 ohms. This low impedance, combined with the increased voltage of the audio signal in the amplifier, causes relatively large amounts of current to flow through the voice coil of the speaker. This current flow causes a magnetic field and, subsequently, the voice coil moves toward or away from the magnetic field created by the stationary magnet on the speaker.

(OK, maybe this didn’t stay as simple as originally planned.)

Amplifier Load Determines Amplifier Power

Let’s use an example of an amplifier that has a peak output voltage of 20 V. We don’t need to worry about the fact that this is an alternating current signal – we will examine this at a single point in time. With 20 V applied to our voice coil, let’s say we have a 4 ohm impedance on this coil. Ohm’s law states that a potential of 20 volts applied across a resistance of 4 ohms will result in 5 amp of current to flow. Using the equation P (Power) = Voltage x Current, we get 20 x 5, or 100 watts of power. If we change the impedance of the load to 2 ohms, we double the current to 10 amps, for a resulting power level of 200 watts.

If you look at the specifications for an amplifier, especially a subwoofer amplifier, you will see power ratings at different load impedances. In most cases, unless the voltage of the power supply in the amplifier is adjustable, amplifiers will make more power as the load impedance decreases.

What About These Subs?

Deciding which subwoofers to buy depends on the amp you are using and the number of subwoofers you are going to use. You want to choose a combination of subwoofers that will let you wire the voice coils together to an impedance that will allow the amp to make the power you want. Let’s look at several examples.

Example 1

We have the option of two different fictional subwoofers, each rated for 750 watts of continuous power handling. One subwoofer has a single 4 ohm voice coil. The other subwoofer has dual 4 ohm voice coils.

The dual voice coil subwoofer can have its coils wired in series to produce an 8 ohm load, or in parallel to produce a 2 ohm load. To complete this fictional example, we have an amplifier that will produce 400 watts into a 4 ohm load and 700 watts into a 2 ohm load. We have a small car and want to use a single 12 inch subwoofer in a large vented enclosure to get maximum low-frequency output. What sub should we use?

If we use the single voice coil subwoofer, the amplifier will not make full power in the 4 ohm load. We should use the dual voice coil subwoofer and wire the voice coils in parallel to present the amp with a 2 ohm load.

Example 2

In this example, we have the same electronic equipment, but the vehicle is a large SUV. There is a lot of room for subwoofers, and the owner wants to list to reggae, loudly. The owner has listened to a friend’s system and found out that a pair of subs matches his listening preferences perfectly. Which subs should we use?

If we use the dual voice coil subs, we have three options for wiring the four (two on each sub) voice coils together. We could wire all the coils in parallel. Parallel wiring will present the amp with a 1 ohm load. Most likely, the amp will go into protection because the load is too low. We could wire all the coils in series to present the amp with a 16 ohm load – but that’s not going to happen. We could wire the voice coils on each subwoofer in series, then parallel the pair of subwoofers to get a 4 ohm load. A 4 ohm load is not ideal.

If we use a pair of single voice coil subwoofers, however, and wire the subs in parallel, we get a 2 ohm load. Happy amp and happy customer!

Choosing and Wiring Subwoofers

• You can use as many subwoofers as you want on a single amplifier.
• You must use all the voice coils on each sub. If you need a 4 ohm load but have a dual 4 ohm sub, using only one coil is going to cause issues. Bad issues.
• Wire all the subwoofers you choose so the current going through each subwoofer is the same. In most cases, this means using pairs of subs. In the past, several companies offered dual 6 ohm voice coil subs that could be wired in groups of three to present amplifiers with standard load impedances of 1 or 4 ohms.

Do not wire one dual voice coil subs in series and one in parallel before connecting the subs together in parallel. You will get more current through the (parallel) low-impedance subwoofer. This imbalance will upset the performance of the enclosure and wreak havoc with the reliability and quality of your system. This is unrelated to the wiring of multiple subwoofers, but: Don’t mix and match different subwoofers. Each has its enclosure requirements and response characteristics. There is no way to guarantee that the output of two different subwoofers will sum positively at all frequencies.

So, Which Voice Coil Configuration Is Better?

The answer to the question “which is better” is neither. SVC and DVC subwoofers are simply two different options when buying. They are analogous to a tire manufacturer offering different-sized tires for different vehicles – there is an application for each.

Adding a subwoofer system should be one of the very first things you do to upgrade a factory audio system. When you are ready to make the leap into the realism, impact and dynamics that a great subwoofer can add, drop by your local car audio specialist retailer. They would be happy to work with you to design a system that meets your performance expectations.

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.