Shopping for a new car audio amplifier is tricky. There are thousands of amplifiers available from at least a hundred car audio companies. Picking the right amp for your system requires balancing an expectation of performance with the cost and features of the amp in question. In this issue of Bang for Your Buck, we are going to talk about car audio amplifier features that will make your audio system sound better and more enjoyable while maximizing your investment.

Amplifier Channels

Decades ago, you could choose from two- or four-channel amplifiers to power your audio system. Most people used a four-channel amp for the front and rear speakers and a high-power stereo amp bridged to drive a subwoofer or two. The rise in popularity of class D monoblock amplifiers in the ’90s replaced the big stereo amp on the subs with something more efficient, and often more powerful.

No matter how you divvy up the work, you are going to need multiple amplifier channels. Let’s look at two amplifier options for a starting point. A four-channel amplifier is extremely flexible. It can power your front and rear speakers, a set of components and a subwoofer or be dedicated to a set of components using active filters instead of passive networks. It’s rare that a high-quality four-channel amp can’t remain an important part of your system.

Another alternative for an amplifier is a five-channel model. In most cases, these amplifiers provide between 50 and 100 watts of power from the four main channels and 300 to 600 watts from the subwoofer channel. A significant advantage of these amplifiers is that they are housed in a single chassis. This design reduces the need for power and ground distribution blocks and simplifies installation.

Built-in Crossovers

When you are starting out on an audio system upgrade, you will want to take a close look at the crossovers built into the amplifier you are looking at. Assuming you go with a four channel amp, each channel pair will likely include crossovers that can be configured in a high- or low-pass mode. This crossover design makes the amp suitable to drive speakers or a subwoofer. If you plan on using the amp to drive a set of components in an active configuration (something that you should aspire to), then look for crossovers that can reach higher frequencies – in the 4 to 5 kHz range. If you are planning on using a digital signal processor to handle crossovers (another wise aspiration), then the crossover frequencies matter less.

Vehicle Integration Features

Upgrading a modern factory sound system can be tricky. In many applications, the source unit can’t be replaced. This means we need to connect to the radio or the amplifier. If you are planning on keeping your factory source unit in the system, then you will want to choose an amplifier that provides OEM integration features. First and foremost, the amplifier needs to be able to accept a speaker-level signal. Some amplifiers have dedicated connections for high-voltage signals. Other designs allow you to connect the factory speaker wires to the RCA inputs, then press a button to reduce the voltage to something that the amp can handle. A third popular option is amplifiers that include an RCA adapter that has circuitry built into it that reduces voltage.

The second feature you are going to want to look for is remote turn-on detection. Different companies have different names for this feature. In a nutshell, you want the amplifier to turn on when the factory stereo turns on. Amplifiers with automatic remote turn-on detection monitor the input connection for an audio signal or the presence of a DC voltage generated by BTL-type amplifiers in head units.

Remote Level Controls

If you are going to use the amp you have chosen to drive a subwoofer, then choose something that includes or has the provision for a remote level control. A remote level control is typically a small metal or plastic box with a knob sticking out of it. You can turn this knob up or down to increase or decrease the level of the subwoofer relative to the rest of the speakers in your car.

The best designs are attenuators. This means that at the maximum position, the amp behaves as though the knob isn’t connected. You can turn down the bass level by turning the knob counterclockwise. The reason this design is best lies in the process of how systems are tuned.

Ideally, try to avoid bass boost controls. If you want more bass, then you should want more of ALL your bass, not just those frequencies around 50Hz. Deep bass (below 30Hz) is a lot of fun!

Amplifier Power

Here’s another tricky subject that requires balancing a lot criteria. First, you can never have too much power available. With that said, depending on your speakers, you may have more power than you’ll ever be able to use. In almost every case, maximum amplifier power determines the size of the amplifier, and vice versa. A 1,500-watt subwoofer amplifier that will operate reliably on a hot summer day isn’t going to fit in the palm of your hand. If you are hoping to upgrade your audio system while keeping the equipment out of sight, then you will need to choose an amplifier that will fit under a seat or in a storage compartment.

In terms of speaker longevity, choose an amplifier that is rated at the same (real) power ratings as your speakers. If the system is set up properly, you shouldn’t have any reliability problems.

Amplifier Installation Accessories

The second-to-last step in choosing an amplifier for your vehicle is to choose the right installation accessories for it. No, we aren’t talking about chrome shrouds or lighting kits. Your choice of power wire can have a dramatic effect on the performance and reliability of your amplifier. It might sound like a sales pitch, but don’t be stingy with the wiring you choose. A $40 amp kit with 1,000-watts printed on the package may look like a deal, but do you think it will supply power to your amp the same way a $100 kit will?

Think of your power wire like the tires on your car. Inexpensive skinny tires work fine when you are cruising through town on the way to get the groceries. When it’s time to crank up the excitement, these tires fail to provide premium performance. A high-quality tire simply sticks to the road better, and in many cases, lasts longer. Power wire is the same.

Quality Installation and Configuration

Last and certainly not least is your choice of who will install your amplifier. Cars and trucks aren’t as simple as they used to be. Composite construction, aluminum, high-strength adhesives, computer data networks and BCM-controlled charging systems require that someone with extensive experience work on your vehicle. Assuming that your new car or truck is like every other vehicle they have worked on is a recipe for disaster.

A properly trained and qualified installation technician understands how to mount equipment safely and reliably. They understand the proper process to make electrical connections so that they are efficient and safe. Finally, they have a tried-and-true process that ensures every amplifier is configured to provide maximum performance and reliability. Choose whom you let work on your car very carefully.

Local Help With Car Audio Amplifier Features

When it comes time to upgrade your stereo system, drop into your local mobile enhancement retailer and ask about the latest car audio amplifier features. They will work with you to choose a solution that includes the features you want and provides the performance you desire.

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.

We recently talked about the difference between good and great speakers. In a nutshell, when you choose great speakers, you get more power handling, the potential for more output and dramatically improved clarity, thanks to a reduction in distortion. In this issue of Bang for Your Buck, we are going to look at two car audio speaker technologies that reduce distortion. This article will be a true behind-the-scenes look at how speakers work.

Current Flow and Magnetic Fields

According to Lenz’s law, when current flows through a conductor, a magnetic field is created around the conductor. At the same time, when we move a conductor through a magnetic field, a current is created in the conductor.

The diagram above shows a conductor (in grey) with a current flowing through it. The green lines show the direction of the magnetic field around the conductor.

In a speaker, the voice coil is a coil of wire wrapped around a bobbin or former. Current from our amplifier flows through this conductor and sets up a magnetic field around the voice coil. We use this property to move the speaker in and out of the basket. When the polarity of the magnetic field is the same as that of the fixed magnet, the similar magnetic fields repel each other, and the speaker moves forward. When the polarity of the magnetic field reverses, the speaker is attracted to the magnetic field and the speaker moves rearwards.

Unfortunately, when it comes to dealing with alternating current, the behavior of magnetic fields can work against you. When the polarity of the current reverses, it has to fight against the magnetic field it created. You can think of it as momentum. If marbles are rolling across the floor, it takes energy to make them change direction. This opposition to the change in the flow of current is called inductance. The electrical momentum resists the desire to set up a new magnetic field of the opposite polarity.

Managing Voice Coil Inductance

The amount of inductance in a speaker voice coil is determined by several factors. The size of the voice coil conductor, the geometry of the conductor, the number of layers in the voice coil and the proximity of the voice coil to the top plate and the pole piece – just to name a few.

So, how does inductance cause distortion in a speaker? As you can see in the diagram above when the voice coil winding (in red) is at rest, it is centered on the top plate (in green). As the cone moves down, more of the voice coil is beside the magnet (in blue) and the pole piece (in pink). Conversely, as the come moves outward, less of the cone is near the pole. In a conventional speaker design, the changes in proximity to the steel pole piece cause changes in inductance. As the inductance decreases, there is less opposition to the flow of high-frequency current and an increase in high-frequency performance. Changes in performance based on the position of the speaker cone result in distortion.

The image above shows the inductance of a voice coil relative to its position in the speaker. The red curve is the inductance graph of a conventional speaker. The blue curve is the inductance graph of a speaker that includes an aluminum shorting ring at the bottom of the T-yoke. As you can see in the image above, without the shorting ring, the speaker has dramatically different inductive characteristics depending on the position of the cone.The graph above shows the frequency response of a speaker without a shorting ring (in red) and that of a very similar speaker with a shorting ring (in blue). As is clearly evident, the inclusion of a shorting ring dramatically improves the high-frequency performance of a speaker. Further improvements in linearity can be achieved by including a copper cap on top of the T-yoke.

When you are shopping for great speakers, look for inductance-reducing caps on all speakers (subwoofers, midrange drivers and tweeters), and in larger speakers (subwoofers and midrange drivers) where the room is available in the motor assembly, look for the presence of a shorting ring.

Comparing Inductance Numbers

If we can’t determine whether a speaker has a design that mitigates changes in inductive characteristics, can we simply look at the specifications? They most certainly do provide a hint. A 6.5-inch woofer without a cap or shorting ring may have an inductance of 0.7 to 1.1 mH (millihenries), whereas a speaker with these technologies will be closer to 0.1 or 0.2mH. In terms of how they sound, all other design criteria being equal, the driver with the lower inductance will have better high-frequency performance and produce less distortion.

Speaker Suspension Nonlinearities

The purpose of the spider (also known as a damper) is to keep the voice coil laterally centered in the air gap between the top plate and the pole piece and to help return the cone to the resting position when the audio signal is removed.

Picking the perfect damper stiffness (compliance) for a given cone mass and desired resonant frequency is one of the biggest balancing acts involved in designing a speaker. If the spider is too stiff, the resonant frequency of the speaker may be too high for the desired application and its efficiency may suffer.

A variety of materials are available, as well as different sizes and different geometries. A spider is a spring. Some spiders are designed for linear compliance and some are progressive. More importantly, because of variances in voice coil winding height and basket design, some spiders include an offset mounting lip. This is called a cupped spider. This cup or spacer allows the spider to attach to the voice coil former above the winding, then connect to the chassis while keeping the voice coil vertically centered in the magnetic gap.

The above graph shows the suspension compliance of two different 6.5-inch diameter speakers based on the position of the cone. The graph in red shows the compliance of a speaker that uses a cupped spider. You can see that at 6.5mm of inward travel, the suspension is 25 percent stiffer than at 6.5mm of outward travel. The blue graph shows a similarly sized speaker with a flat spider. Though the overall compliance is different, the behavior in the forward and rearward directions is nearly identical.

What To Look For in a Spider

Ultimately, we want the spider to exert the same amount of force on the cone and voice coil as it moves forward or backward from the rest position. The amount of force should not change based on the direction of cone travel. Imagine the distortion created by a speaker playing a sine wave where the cone doesn’t move as far rearward for a given amount of current as it moves forward. As such, try to avoid speakers that use cupped spiders.

Hear Different Car Audio Speaker Technologies In Person

The next time you head to your local mobile enhancement retailer to listen to new speakers, choose two wildly different price points and listen to the same portion of a song on each speaker. Listen to them at a reasonably loud volume level, and position yourself across the room. Switch back and forth until you determine the differences.

Then, add a third speaker option, priced and featured somewhere in the middle. Make the same comparison with this new speaker and the expensive speakers. Once you have listened to the speakers, ask to look at a sample of each and see if you can correlate some of the design characteristics we have discussed with their performance. It’s not only a great way to audition products but to learn about what makes one car audio speaker technology or design better than another.

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.

It should be no surprise that your choice of speakers has the biggest impact on the sound quality of your car audio system. With that said, many consumers simply don’t understand what separates one speaker from another in terms of performance and value. In this installment of Bang for Your Buck, we are going to talk about car audio speaker upgrades and the performance benefits of buying premium speakers.

How Do Speakers Work?

In the simplest terms, a speaker has a cone, a motor and a suspension. The cone is a rigid surface that moves to produce sound. The motor is a voice coil and a fixed magnet. When alternating current from your amplifier creates a magnetic field in the voice coil, the assembly attracts itself toward or repels itself away from the magnet. Finally, the suspension’s job is to keep the voice coil and cone centered in the speaker basket and control how far the cone moves at low frequencies.

Many engineers have made it their life’s work to try to perfect the performance of a loudspeaker. Advances in computer simulation are responsible for great leaps in performance, thanks to models of magnetic fields and finite element analysis of cone and suspension assemblies.

Why Aren’t All Speakers Perfect?

It’s simply impossible to design a perfect speaker. Just as with a source unit or amplifier, each component in a speaker is responsible for some minute amount of non-linear behavior that changes the way a speaker sounds. Cone and dust cap resonances cause distortions at mid and upper frequencies. Non-linear suspension geometry can cause harmonics at low frequencies and high excursion levels. Uncontrolled magnetic field changes in the voice coil, top plate, magnet and T-yoke increase inductance and cause distortion at higher frequencies.

In spite of this, don’t think for a second that the speakers available for your car, truck or SUV aren’t great upgrades over what came from the factory. Remember: Better speakers offer better performance.

The Speaker Quality Analogy

Cameras are a good analogy for speaker performance. An inexpensive digital camera hanging on a peg in a big-box store will take a picture of anything. You’ll be able to discern the content of the photo without any problem.

When you move up to a premium point-and-shoot camera in the $400 range, the photos the camera takes will be more accurate. The focus will be improved, and the images will have more detail. It’s still the same picture, but the accuracy is better.

Finally, if you move to a digital SLR camera with a premium lens, the accuracy and detail increase even more. The subtlest of nuances in the content are captured with exemplary detail. You can see each hair in a person’s eyebrow or the smoothness of the finish on an automobile.

Whether we’re talking about great photographs or great music, the resulting experience has as much to do with the equipment as it does with how it’s used. A good photographer knows how to compose an image to evoke emotion and tell a story. It’s not just a matter of pointing the camera at an object and pressing the shutter release. In our cars and trucks, how equipment is installed and configured plays a huge roll in the quality of the listening experience. We’ve talked about the importance of proper equipment installation in the past. When it comes to speakers, doing things right is crucial.

Better Speakers Can Play Louder

Let’s compare 6.5-inch component woofers designed for use in the door of your vehicle. Right off the bat, we can look at the Xmax specification to determine how far the cone can move. Cone excursion directly relates to the maximum output possible from a speaker. The Xmax specification describes the geometry of the motor assembly. A speaker with a rating of 5mm (one-way) can move forward or rearward 5mm without any changes in the amount of voice coil winding that is within the magnetic gap. Beyond this measurement, distortion in the output increases quickly.

A basic 6.5-inch speaker may have 2 or 3mm of one-way excursion. A better speaker will have numbers in the 4 to 5 mm range. Finally, the very best designs may offer as much as 9mm of one-way excursion. Though not deliberately included in this discussion, many 6.5-inch subwoofers have an Xmax specification around 9mm.

Better Speakers Handle More Power

As you spend more money on a speaker set, their power handling capabilities increase. We should make it clear: More power handling does not relate to better performance from a speaker. It’s just one of the many aspects that need to be considered during the evaluation and purchasing process.

Power handling in a speaker is determined almost exclusively by the diameter of the voice coil. Just as with a radiator or intercooler in a car, more surface area allows for the dissipation of more heat. If you overheat a voice coil, the adhesives used to bond the winding to the former will fail and the winding will unravel – usually with smelly and crunchy consequences.

With some exceptions, there are some general guidelines for the relationship between voice coil diameter and power handling. A 1-inch (25mm) voice coil can usually handle about 60 watts of continuous power. Moving up to a 1.25-inch coil (32mm) increases continuous power handling to about 80 watts. Finally, 1.5- to 2-inch voice coils can handle between 100 and 150 watts of power.

The absolute power handling numbers depend on many factors, including the diameter of the voice coil winding conductor, the proximity of the voice coil to the T-yoke and top plate, and the presence of any cooling vents in the motor design.

Why Is Power Handling Important?

For years, high-quality speakers were considered fragile. They were made with lightweight components, supposedly to help improve their transient performance. The problem was, many people like to listen to their music at high volume levels. It was unfair that speakers that sound great couldn’t handle large amounts of power. In the last decade or so, this contradiction has gone away. Premium speakers not only sound great, but they also offer good excursion capabilities and can handle lots of power.

Better Speakers Produce Less Distortion

Sadly, very few companies talk about distortion when it comes to speakers. In fact, the entire topic of distortion in the mobile electronics industry is often overlooked because it often reveals that products people think are great actually aren’t. A manufacturer needs to be confident in his (or her) product design to reveal every detail of its performance.

While output capabilities and power handling are important aspects of speaker design, distortion, or the lack of it, is the most important of all. To the untrained eye, it’s difficult to determine the quality of a speaker by looking at it, but there are often some hints. More information can be provided by looking at a high-resolution frequency response graph of a speaker. Here, cone, dust cap and surround resonances reveal themselves to give some insight into the design of the speaker and how it should be integrated into a system.

How is Distortion Measured?

Speaker distortion is easy to measure, for those with the right equipment. Just as with an amplifier or signal processor, a known signal is sent to the device under test. The output of the device – in this case, the speaker – is compared to the input signal.

A concept that is hard for many to grasp is how distortion manifests itself. If you feed a 1kHz, 2-volt RMS sine wave to a well-designed speaker, you get a 1kHz tone back. In a speaker with design issues, you get that 1kHz tone, plus other sounds. These extra sounds are distortion. Sometimes the sounds are harmonics of the 1kHz frequency.

Better speakers produce less distortion. That is to say, less additional information is added to your music. As such, your music sounds clearer, instruments and performers are easier to identify and the sound is more realistic. The most important thing to consider – once that distortion is created, it can’t be removed from the system.

How to Shop For Car Audio Speaker Upgrades

It can take years to train yourself to identify subtle differences in speaker performance. With that said, listening to two or three music tracks again and again on different sound systems will help you identify the benefits and drawbacks of those system designs and installations.

When it’s time to go speaker shopping, visit your local mobile enhancement retailer and ask for a demonstration. Whether the source is on a display board or in a demo vehicle, listening is the fastest way to quantify the performance differences between speakers.

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.