Installing a mobile audio system involves much more than just hooking up some wires and driving in a few screws. Almost all vehicle manufacturers have realized that some amount of audio system tuning will dramatically improve their customers’ experience. When you decide it’s time to upgrade your factory audio system, we need to take into account any tuning that may have been done by the factory. It’s not easy, but at the same time, it’s not impossible. This article provides a brief look at what is involved in connecting a new amplifier and speakers to your factory source unit or amplifier, or as it is called, OEM integration.

It’s Not Flat

No, we aren’t talking about the Earth. One of the first steps in designing a premium audio system upgrade is to measure the electrical signal that is being sent to each of your speakers. Why? As we mentioned, more and more factory source units and amplifiers include advanced signal processing. Even some of the most basic audio systems with only four speakers have custom equalization for each speaker. Once our installers know what they are dealing with, they use that information in designing your new system.

The signal measurement process should be done before system design. If the signal is flat (no equalization), then the system design may take a different direction from when the signal is equalized. Compensating for factory equalization requires that some kind of equalizer be installed in the new system. Either way, we have to allot time to measure the acoustical response of the new system and make appropriate adjustments.

Think of this process as though your installer were a surgeon preparing to solve a medical problem for you. The surgeon will order x-rays, scans and many tests long before you’re on the operating table. Nobody wants to start work on a project without knowing what they are dealing with. Modern car audio systems are no different.

Front and Center

Automobile manufacturers strive to make all their customers happy – within a certain budget. This goal includes providing an enjoyable audio experience for everyone in the vehicle. Many mid- and high-level factory audio systems use a center channel to help create a listening experience that is enjoyable for both occupants of the front seats. Configured properly, a center channel can help create a realistic soundstage from both seating positions. Trust us when we say that some of the people who tune these factory audio systems have a lot of experience doing what they do.

When we want to upgrade the audio system in a vehicle with a center channel, we have to reverse-engineer how that speaker is functioning. Is it a mono signal that is the sum of the left and right signals? Is it an up-mixed signal that plays sounds that are not reproduced by the left and right speakers? It could also be a little bit of both. Your installer will have to do some tests to decide what is happening and how to deal with it.

Do We Undo or Up-do?

If you have a vehicle with a genuine up-mixed center channel, one of the best ways to upgrade the audio system is to leave the processing alone and add better speakers, amplifiers and signal processing. With this method, we can create a sound system that sounds amazing from both the driver and passenger seats.

The basic concept is to take the left, center and right signals; recombine any frequency filtering; then send those three signals to whatever speakers you choose for each side of the vehicle and the new center channel. Often, the new system will be a three-way speaker set in the doors and maybe the A-pillars, and a two-way system in the center. We will most certainly use a digital signal processor and/or an integration processor to do the signal filtering and tuning for the new system.

How We Undo What They Do

Several processors on the market can sum filtered channels together and undo factory equalization and time alignment. Some of these processors require manual adjustments and some work automatically with a custom setup track. After using one of these processors to provide a full bandwidth signal, we can then use digital signal processing to set up the new system and compensate for the vehicle acoustics. Just as the vehicle manufacturer chose to equalize the signal going to each speaker, we need to do this to maximize the performance of your new system.

What if We Don’t Undo What They Did?

Imagine a simple scenario: You have a car, perhaps a Nissan Altima. Even the base model audio system has equalization in this vehicle. Equalization is based on the speaker that is being used, location of the speaker and acoustic effects of the vehicle on the signal from that speaker relative to the listening position. If we change the speaker to one that is better, the factory equalization can – and most likely will – work against us. That nice new speaker may sound worse than the cheap factory speaker. After all, the manufacturer tried to make what was likely a low-quality speaker sound OK.

Trust Your Local OEM Integration Experts

When it comes time to upgrade the audio system in a fairly new vehicle, make sure you are working with a mobile electronics retailer that knows how to evaluate the existing audio system properly. If you are changing the source unit, then it’s no big deal. But if you are using the factory radio and/or amplifier, proper testing is crucial. Don’t be scared or discouraged. A well-trained retailer can transform any audio system into something truly amazing! Drop in and see what they can do for you.
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 you head to your local mobile electronics specialist in search of new speakers, there are a few criteria to keep in mind. Choosing a speaker size can go one of two ways: You can pick something that fits a specific mounting location or you can choose based on the characteristics of the speaker relative to its size. Are you interested in knowing why speakers come in different sizes? Good! You’ve come to the right place.

What Does a Speaker Do?

It is the job of a speaker to convert the electrical signal from your amplifier into motion. The motion of the speaker cone excites the air around it. As the cone moves forward, the air in front of the cone is pressurized. As the cone moves rearward, the air is rarefied. These pressure waves extend out from the speaker and our ears detect these minute changes in pressure as sound. Pretty simple, isn’t it?

Things to Consider in Terms of Reproducing Sound

When it comes to reproducing sounds, the lower the frequency, the harder it is to produce the sound. For every doubling of frequency, the speaker cone has to move a quarter the distance to produce the same level of output. As example, if your subwoofer has to move 2 mm to produce 95 dB of output and 40 Hz, it only has to move 0.5 mm to reproduce 95 dB at 80 Hz. To reproduce 95 dB of output at 160 Hz, the cone only has to move 0.125 mm.

The size of a speaker cone affects how much sound the speaker will create for a given amount of input signal. Let’s generalize things a little (because a lot of external factors affect this statement): A 12-inch speaker cone has to move twice as far as a 15-inch speaker cone to produce the same amount of output at a given frequency. That also means the 12-inch speaker requires more power to produce the same sound as the 15-inch.

Bigger is Always Better, Right?

Based on this logic, you should simply select the biggest possible speaker for every application, right? Well, it’s not quite that easy. When we get into midrange and high frequencies, the speaker cone has to move back and forth very fast. A 1,000 Hz tone requires that the speaker move forward and backward 1,000 times a second. A 10 kHz tone requires 10,000 of these same motions per second. If we use a big speaker with a relatively heavy cone, it’s very hard to keep up with the input signal. Why? Inertia.

Let’s use an analogy to help explain this. Imagine that you are at a parade and waving a flag. The pole is 6 feet long and the flag on the end is 3×5-foot. You wave the flag back and forth as fast as you can. Even if you are really strong, the fastest you can wave it back and forth is once, maybe twice a second. Now, look at the little kid standing beside you at the parade. He has a little paper flag that’s 2×3 inches on a 5-inch-long plastic stick. His little hands can wave that flag back and forth five or six times a second.

Speaker engineers have to balance several characteristics to achieve specific goals for a given design. Let’s compare the weight of a speaker cone for a 10-inch subwoofer to that of a 10-inch midrange used in concerts and public address systems. A typical 10-inch sub that is designed to play frequencies below 150 Hz has a cone assembly (cone, voice coil, former, half the spider and half the surround) that weighs around 150 grams. A 10-inch speaker designed to be used for midrange frequencies (150 to 1 kHz) has a cone mass assembly of around 40 grams.

Clearly, the lighter assembly can move faster and keep up with the reproduction of higher frequencies.

Is Lighter Better?

Now we face the conundrum of balancing low- vs. high-frequency output. A lighter cone will move faster and is capable of producing extended high-frequency output. A heavier cone has a lower resonant frequency and thus, can produce more low-frequency output. Combine these generalizations with electrical issues affecting voice coil inductance, and we further hinder high-frequency output. It starts to become clear that we need different-sized speakers for different applications.

Subwoofers

Most subwoofers are sized from 8 to 18 inches. Since subwoofers are designed to play frequencies below 100 Hz in car audio applications, they need a lot of excursion capability and a low resonant frequency. This means subwoofers will have relatively heavy cones. At high excursion levels, cones are exposed to significant stresses, so the cone has to be strong, and this further contributes to their weight. Subwoofers have to handle a lot of power. This power allows us to move the cone over relatively large distances. Power handling requires bigger components in the form of large-diameter voice-coil formers and windings.

Midbass Drivers

A dedicated midbass driver is typically designed to play from around 50 to 500 Hz. Sizes are typically 6.5 to 8 inches in size, but some people have used 10- and 12-inch drivers. The cone has to be heavier than that of a midrange, but not heavy enough to slow it down for higher frequencies.

If you look at the frequency content of a performer, you will see that many voices extend down to 100 Hz. Accuracy in speed is important in this frequency range. Resonances and non-linear behavior causes harmonic distortion. This is often perceived as “warmth” in the midbass region. We do not want anything extra in our music, so accuracy is what matters.

Midrange Speakers

Midrange speakers become a balancing act of several different characteristics. Of course, the cone has to be relatively light, but managing linearity and distortion becomes an even higher priority. It’s easier to hear distortion at midrange frequencies. The cone has to balance mass, damping and strength to prevent deforming and cause harmonics. The suspension has to be very linear.

Managing inductance also becomes a more significant issue because it can reduce high frequency output. Midrange drivers for typical car audio applications vary in size from 6.5 inches and 6×9 inches on the large side down to as small as 2.5 inches. Many midrange drivers try to do double-duty as midbass drivers for use in two- or three-way audio systems. While this is a minor compromise, it is a necessity. We consider midrange speakers to cover the range from 100 Hz to 3,000 or 4,000 Hz.

Tweeters

To reproduce frequencies above 2.5 kHz, tweeters need very light cones. Tweeter cones don’t move very far, so they don’t require much excursion, but there still has to be a suspension. Resonances in the cone can wreak havoc with frequency response. Premium tweeters may make use of features like ferrofluid in the gap to improve power handling. Premium tweeters may also include a copper pole-piece cap to reduce inductance and distortion.

Directivity Considerations

Another consideration when choosing speakers is that all speakers above a certain frequency start to become directional. Directivity refers to a reduction in high-frequency output as you move off-axis to the speaker. If you choose your speakers and design your system carefully, you can minimize the effect of directivity. The only real consideration would be to have your tweeters pointed at you.

The Balancing Act

The applications for the information in this article vary, depending on your overall goal for your audio system upgrade. A simple set of coaxial replacement speakers will be chosen by the size application. If you are building a high-end audio system with multiple amplifiers, channels, digital signal processing and custom speaker mounting locations, then choosing the right speakers in terms of their quality and intended application becomes more important.

Learn More about Speakers and Their Different Sizes at Your Local Retailer

Your local mobile electronics specialist retailer can help you choose the right speakers for your application and performance goals. Drop in at a local shop today and have a listen to their demo board or demo vehicle. It’s an amazing experience!

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.