Let’s face it, most of us aren’t really happy with the stereo system that comes in our car. Sure, if you bought a Lexus with a top-of-the-line Mark Levinson system, you’re more than likely content. For the rest of us, the good news is that for a very reasonable investment, you can upgrade the performance of your sound system quickly and easily. In this article, we’ll look at 10 upgrades that will result in better car audio and a dramatic improvement to the enjoyability of your sound system.

1. Add a Subwoofer

Even the most exotic of factory-installed sound systems cannot produce amazing bass. For most of us, the speakers in the doors don’t play much below about 50Hz. This means we are missing out on more than an octave of the most fun part of our music.

Adding a subwoofer does more than just improve the bass in your car, it eliminates the need for your smaller speakers to try to produce bass. The result is that they will sound better, play louder and likely last a lot longer.

Subwoofer upgrades range from pre-fab enclosures that will sit in your trunk or cargo area to custom-built systems that are optimized for the space in your vehicle and the subwoofers you choose.

2. Add an Amplifier

Beyond not having enough bass in a factory audio system, the next most common complaint is that the system won’t play loudly enough. While the speakers in your car are limited in their capabilities, the most common issue is a lack of power from the radio or amplifier. Your local mobile electronics specialist can add an amplifier to your system that will let you crank up your tunes without the system distorting.

Compact amplifiers that will produce a good, clean 50 watts per channel are a great starting point. You can easily find an amp that produces 75 to 100 watts per channel if you really want to blast your tunes.

3. Upgrade Your Speakers

If you have read any number of our articles here at BestCarAudio.com, then you will undoubtedly know the importance of using high-quality speakers in your vehicle, or in any sound system. Speakers are the only link between the electronics in your audio system and your ears. Even the highest-resolution FLAC or DSD files and the best amplifiers known to man will sound mediocre if you don’t use high quality, low-distortion speakers.

While you are having those speakers upgraded, make sure they are being installed properly. The shop should be using plastic speaker-mounting adapters where required. Everything should be solid and secure to allow the speakers to do their job without causing buzzes or rattles.

4. Add a Digital Signal Processor

For too long, adding a signal processor has been considered the icing on the cake when it comes to premium audio system design. The reality is, as soon as your budget allows for it, adding a processor can dramatically improve the performance of even a modest installation.

In the hands of the properly trained technician, the signal delay and equalization capabilities of a good processor can smooth the frequency response of the speakers in your car, truck or SUV to make your music sound lifelike. Adjustments to output levels and signal delay can create a realistic listening experience that sounds as though you were front row at your favorite concert or sitting in a living room, listening to an exotic sound system.

Processors are available as stand-alone solutions that can be inserted into your audio system between the head unit and the amplifier. If you are building a system from scratch, many companies offer high-quality amplifiers with integrated digital signal processors.

5. Add Sound Deadening

If you have ever upgraded a sound system by switching from an inexpensive amp to a great one, you may have noticed there is less background noise or hiss. When listening to music in our vehicles, we need to try and ignore wind and road noise and sound from the engine and exhaust system. Having your local car audio specialist retailer add a layer of sound deadening to your doors, the firewall, the floor or the roof will dramatically reduce the noise in your vehicle. If the doors are sealed properly with deadening, the performance of the speakers in them will also improve significantly.

When shopping for sound deadening, the number one priority is to pick a product that will remain adhered to the vehicle. We’ve seen many damping products that turn gooey and melt when hot. Ask to see a sample of the damping material and heat it up with a lighter to see if it melts before you let someone cover the inside of your car with it.

6. Listen to Better Music

No, we aren’t dissing your gangster rap or John Fogerty CDs. There has been a trend of late to focus on high-resolution audio files like FLAC and DSD. While the mechanical limits of these file formats dramatically exceed the listening limits of all humans, the improvement in recording and mastering equipment required to create these recordings is of excellent quality. In short, even within the standard 20Hz to the 20kHz range, high-res audio files sound better because they are created better.

You can find high-res audio files at websites like Tidal, HDtracks, iTrax and 7Digital.

7. Upgrade Your Electrical System

If you want your amplifier to produce power, it needs to be fed power. After all, that energy needs to come from somewhere, right? The electrical systems in modern cars and trucks are designed to only “just” supply the vehicle with the power it needs to operate the engine, lights, climate control system and the radio that came with the car. If you add a 1,000-watt amplifier, you will tax the electrical system.

The easiest upgrade is a high-quality battery. Look for an absorbed glass mat (AGM) battery from a reputable brand. These batteries are more rugged than conventional flooded lead-acid cells and can produce a little extra voltage. Always choose the largest battery possible for your application. More capacity will provide increased play time when the vehicle is turned off and more current to your amplifier when the volume is cranked.

If you are considering adding anything more than a few thousand watts of power to your sound system, then investigate upgrading the alternator in the vehicle. An automotive electrical system runs off the alternator when the vehicle is on. Most are rated for anything from 65 to 180 amps. Remember, though: Your vehicle wants to use some of that power for itself. If the vehicle is using 80 amps, and you need another 150 amps for your stereo, well, you need an upgraded alternator.

8. Have Your System Set Up by a Pro

Lots of us like to install car audio equipment at home in our driveway. Do-it-yourself car audio has been popular since the 1970s and always will be. The problem is, it takes more than a solid understanding of electrical theory and physics to install and configure a modern audio system. Qualified installers use tools like real-time analyzers to set crossovers and adjust polarity. They use oscilloscopes to match the amplifier sensitivity settings to the source unit. Investing in this gear is often out of reach for most do-it-yourselfers and often overlooked. If every aspect of your audio system isn’t optimized, you are short-changing yourself on performance.

Your local car audio specialist retailer can help you get your system set up and optimized. Drop by and talk to them. In most cases, it will only take an hour or two – a small investment to improve the sound of your audio system.

9. Upgrade Your Source Unit

It’s no accident that our suggestion to upgrade the radio in your car is almost last on our list. These days, changing the radio in the dash of our vehicles is often impossible. Climate controls, vehicle information displays and configuration options and complex ergonomic creations make installing a new double-DIN radio impossible.

If you can replace your radio, not only will you find you get an improvement in sound (if you pick a high-quality source), but you’ll also get a lot more features. One of the most popular reasons to upgrade your radio is to add smartphone connectivity solutions like Android Auto and Apple CarPlay. Drop by the local stereo shop and see what’s available for your vehicle.

10. Upgrade Your Upgrades

How’s that for a confusing idea? What we are talking about is replacing your existing audio equipment with even better products. Let’s say you had a set of $250 components installed in the doors of your car a few years ago, and the system is tuned to optimize those speakers with a digital signal processor. If you upgrade those to a set of $1,600 components and have the system retuned, the difference will be night and day. Your music will be clearer and more detailed. You’ll be able to pick out subtleties that were otherwise lost. Think of upgrading to amazing speakers like cleaning your glasses: Everything will suddenly become crystal clear. The same applies to upgrading your subwoofers. There is a lot of information in the bottom few octaves of your music. A better sub will recreate your bass with dramatically improved realism.

Where to Go for Better Car Audio

No matter what upgrade path you choose for your audio system, be sure to hire a reputable and qualified professional to do the work. Picking the right installer is like choosing an artist to do a tattoo or paint a portrait. You don’t want the cheapest; you want the person or team that will do the best work so you can be happy with the results.

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.

In the ’80s, ’90s and early part of the 2000s, upgrading the car stereo system in your vehicle was a relatively simple process. You’d start by picking out a new radio that offered the features you wanted and add a set of speakers to improve the sound of the system. Pretty much anyone with a basic understanding of electrical systems could use a wire harness adapter to install the radio, and the speaker installation was usually a drop-in upgrade, save for having to crimp on some spade connectors.

The Reality of Modern Car Audio

Fast-forward to 2010 and beyond, and the world of car audio has changed dramatically. Even the most basic of new cars and trucks include Bluetooth hands-free calling and audio streaming technologies, and most will play your MP3 digital audio files from a USB stick. For many people, the only reason to want to upgrade their vehicle is to add a smartphone integration technology like Android Auto or Apple CarPlay.

When it comes to the sound of modern stereo systems, there is still room for improvement. Basic audio systems can still benefit from upgraded speakers, and most vehicles could use a high-quality subwoofer upgrade. The problem with modern sound systems is that the companies like Bose and Harman (the people behind JBL, Infinity, Mark Levinson and Lexicon) are pretty good at what they do. They use powerful digital signal processors to optimize the amplifiers that power these systems to make the most of the speakers in the car. If you upgrade to new speakers, the processing that made cheap speakers sound OK can make your good speakers sound mediocre. In essence, the days of going to a stereo shop to buy a new set of speakers to upgrade the sound in your car are gone.

How Stereo Shops Handle Stereo Upgrades

When you take your new car to a shop for a sound system upgrade, there are a few steps required to ensure you will get the performance you want from the system. The first should be a series of questions from the salesperson about how you enjoy your music. Do you listen at high volume levels? Do you like lots of bass? Some will ask you what kind of music you listen to to help understand your goals for your audio system. For the truly dedicated, the questions should include a query about what you hope to improve by upgrading the system. A visit to your vehicle can often provide valuable insight into what’s missing. If you have the bass turned up on the factory radio, you may benefit from a subwoofer. If you have boosted high frequencies, a speaker upgrade may be in order.

Your job is to let them know what you have, and what you want. Their job is to determine how to achieve that goal.

Understanding Your Stereo System

Where the expertise of a mobile electronics specialist retailer shines is in knowing how your factory stereo works and, subsequently, how to upgrade it. Remember the signal processing we talked about at the beginning of the article? If a shop sells you a new set of speakers without addressing this tuning, you may not like the results. There are three options available to deal with this processing. If you can, a new radio and potentially a new amplifier will eliminate the tuning. Audio interfaces include the PAC AmpPRO, iDatalink AR, Axxess AX-DSP or one of the many ZEN-Audio solutions from Nav-TV. Finally, you can add an amplifier with a digital signal processor to correct the tuning for the new speakers. There’s no “best” answer to your upgrade needs, as each vehicle and client’s goals differ.

The Importance of Signal Processing

Before you balk at the cost of adding a DSP and amp to your factory stereo, keep in mind that the vehicle manufacturer and its audio system supplier used this very process for making the speakers in your car perform as well as they did.

System tuning is a critical part of any installation. It can be as basic as setting the crossovers and sensitivity controls on an amp to configuring crossovers, equalization settings and signal delay on a DSP. In either case, an acoustic analyzer can give the installation technician valuable insights to produce a predictable result.

Coping with Sticker Shock

Let’s go back to the late ’90s and work out the speaker upgrade costs. You might have a budget of $200 for a nice set of components for your doors. The shop would likely charge one to two hours to install the speakers, depending on the complexity of the vehicle. In ’90s labor rates, you’d likely be out the door for around $400, including shop supplies and whatever taxes applied in your state or province.

Dealing with a new car is a different story. You can maintain your $200 speaker budget if you want, and chances are, labor rates have increased a little. The basic speaker upgrade and speaker installation is now going to run around $450 to $500. Not too bad, right?

Let’s look at how we handle the tuning in the vehicle. You’ll need an amplifier with a built-in DSP. There are lots of compact solutions available from companies like JL Audio, Mosconi, Helix, Audison, AudioControl, Sony, Alpine and Kicker. A suitable amp will run anywhere from $600 to over $1,000, depending on the features, power capabilities and quality of the unit. Add in speaker wire and power wire for another hundred or so. Depending on how your factory audio system works, you may need one of those vehicle interfaces we talked about. They cost between $250 to almost $1,300 for some of the complex MOST150 interfaces for Mercedes-Benz vehicles.

Needless to say, attempting to upgrade one of these premium sound systems is, in fact, opening a moderately expensive can of worms. On the low side, you’ll be $1,500 and exceeding $4,000 wouldn’t take long.

Is the Upgrade Worth It?

Take a deep breath. Talking about spending thousands of dollars on a speaker upgrade might scare a lot of people. The question is, are the upgrades worthwhile? When executed by a properly trained technician, the answer is unquestionably yes! Not only will new speakers play louder, they produce less distortion to make your music clearer and more detailed. The signal processor can be used to fine-tune the system to provide the overall sound balance you want. Most people enjoy smooth and natural midrange with some accentuation in the midbass region and a little more in the bass region. Your technician can fine-tune the high-frequency response of the system to your preferences and the kind of music you enjoy.

Think of upgrading your stereo like buying a new suit or a dress. You can walk into a store and pick something off the rack. It will fit and do its job, but it might not be perfect in every area. The alternative is to commission someone to create a garment specifically for your needs and the occasion. They’ll measure you, discuss fabric options and consult on the overall design. You end up with something that is exactly what you want and is a joy to wear.

An upgraded audio system is the same. We’ve heard countless stories of clients who enjoy spending time in their vehicle so much, they find themselves looking for excuses to go for a drive. Hearing your music on a reference-quality sound system is indeed like hearing it for the first time. New sounds, new voices and amazing realism are just the starting point. To experience a taste of just how great a mobile audio system can sound, drop by your local car audio specialist retailer and ask to listen to one of their demo vehicles or displays.

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.

In 1982, Michael Knight was able to talk to his 1982 Pontiac Firebird and ask it for navigation directions. Of course, watching “Knight Rider” meant that we understood that KITT was make-believe. Fast-forward 35 years, and talking to our vehicles is now a reality, thanks to our smartphone.

The modern smartphone, be it an iPhone or a device running the Android operating system, is more of a computer than a phone. Sure, it has a speaker and a microphone, and you can indeed make phone calls with it. But more people spend time browsing Facebook, playing Candy Crush or texting their friends than making phone calls. Our society is simply addicted to the modern smartphone, and most of us can’t go more than a few minutes without having it at our sides.

Cell Phones in Automobiles

Early mobile phones were more of a walkie-talkie than a phone. You had to press a button to talk, then wait for the party on the other end to reply. This was called single-duplex communication. After a few years, full-duplex communication meant that you could talk at the same time as the person you were calling. As phones evolved, providers increased the number of communication channels available so that multiple phones could be used in one area. It wasn’t until the early ’80s that a standardized communication network dedicated specifically for phone use was put into place.

Fast-forward a few decades and the communication between our phones and the service provider is all based on digital communication. As important as voice calls are, data communication has become the top priority for many phone users. Cell phone service providers are constantly upgrading their cellular towers and technologies to increase communication speed and decrease latency.

Hands-Free Calling

Long before we had to worry about looking at maps on our phones, we had to deal with the issue of people talking on their phones while driving. Distracted driving is a serious issue and is the cause of many accidents and fatalities. In 2013, more than 3,000 people were killed because of distracted driving. In 2015, more than 391,000 injuries were caused by driver distraction.

The simplest way to prevent distraction is to not talk on or look at your phone while driving. Several global companies have strict rules about communication while in the car and strictly forbid any kind of phone usage.

If you have to talk, then a hands-free system that uses Bluetooth is a good solution. Bluetooth is a short-range digital radio communication protocol that works with a speaker and microphone to let you talk and hear the response from a caller without the need to hold on to your phone. Even the cheapest new cars include Bluetooth hands-free calling.

Existing Mobile Smartphone Navigation Applications

We started talking about asking our phones for directions. Portable navigation devices with voice recognition have been available for more than a decade. Where using your smartphone differs is in the ability to retrieve real-time mapping and traffic flow information. Google Maps, Waze and Apple Maps all provide navigation directions based on accident, road closure and flow information to help you reach your destination as efficiently as possible.

Map information is big business. Google has invested millions of dollars into developing its mapping information. Google claims coverage of 99 percent of the world, with an impressive 25 million updates each day. It has further enhanced that mapping information with data on businesses to make getting where you want to go even easier. Gone are the days of needing to purchase new maps to get the latest information.

Voice Recognition Systems

Unlike the voice recognition system built into portable navigation devices that listened for specific phrases or requests, Apple’s Siri and Google’s Voice Assistant can interpret common language communication to perform commands or execute requests. “Navigate to” has been replaced with “find me a,” “take me to” or “get directions to” whatever address or location you want. These systems capture what you say, analyze the content on their servers, then send the required commands back to the phone.

Smartphone Integration Solutions

Apple CarPlay and Android smartphone integration solutions were developed to make using your smartphone safer while you drive. These software solutions run on the multimedia receiver in the dash of your vehicle and use your phone’s cellular data connection to listen to your requests and provide you with the information or entertainment you want. Asking for directions will launch Apple Maps or Google Maps. Asking to call a phone number or a business will initiate a hands-free phone call. You can send text messages and even have the systems read you the response from your friends, co-workers or family.

Control Your Vehicle with Your Smartphone

Another popular use for a modern smartphone is as a remote control for your vehicle’s convenience system. In the most basic of functions, you can use an application on your phone to send a command to your vehicle to lock or unlock the doors, pop the trunk or remote start the engine. Of course, hardware needs to be installed in your vehicle to perform these functions.

In a premium solution, these smartphone cellular communication solutions include telematics solutions. When the vehicle hardware is equipped with a GPS receiver, the location and speed of the vehicle can be communicated back to your smartphone. Business owners can track their fleet of company vehicles, and parents will know where their kids are a few seconds after pushing a button in an app.

The Future of Mobile Communication

Automakers are working to allow our vehicles to talk to each other in order to reduce traffic congestion and the chance of accidents. For this to happen, your car or truck needs to know where all the vehicles around it are located and where they are going. The hardware exists today to make this happen, but the communication networks aren’t fast enough to implement the system.

In 2020, the fifth generation of mobile communication protocols (called 5G) will launch. Cell companies already have 5G hardware and are busy testing and configuring it to provide communication rates as fast as 20 gigabits per second with less than one millisecond of latency. Interestingly enough, the desire to have automobiles communicate efficiently with one another is driving this technology.

Latency is the time it takes for a message to travel between two devices. Right now, cell phones take 20 to 30 milliseconds to communicate to a server. For a vehicle traveling at 65 miles an hour, this delay means that a vehicle could have travelled more than 3 feet between when the message was sent and when it was received.

Add to that the time it would take to transmit that information to another vehicle, plus any computer processing time, and our accuracy based on communication speed is greater than 10 feet. That’s not adequate for an intelligent collision prevention system. If we can reduce the latency to 5 milliseconds, we’d have an accuracy of about 7 inches – more than enough to prevent vehicles from colliding.

Stay Safe Behind the Wheel

Until our primary mode of transportation is no longer our personal vehicles, the need and desire to communicate while behind the wheel will remain an important safety consideration. If you are interested in upgrading the smartphone technology in your car, truck or SUV, we invite you to visit your local specialist mobile electronics retailer. Be sure to bring your smartphone with you, so you’ll know exactly how the features and functions they demonstrate will work.

(KITT photo: By Shane K from Mississauga, Canada (KITT) [CC BY-SA 2.0 (https://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons)

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.

Not too long ago, we saw a discussion about an article called “The 12 Best Tweeters (Reviews & Ultimate Buying Guide 2018).” Being curious, we decided to check the article out to see what criteria they used to choose the products and how they tested them. Much to our dismay, there were no criteria, nor was there any testing or a simple performance review. So, what was going on? Read on and we’ll explain why you should be wary of Top 10 lists.

Keep Your Story Straight

We’ve read hundreds, if not thousands, of product reviews in our decades in this industry. A member of the Best Car Audio staff used to review car audio products for one of the top mobile electronics magazines. We showed him the article above, and he’s still curled up in the fetal position, rocking back and forth, mumbling stuff about pink noise, microphones and distortion.

In a formal product review, the goal is to explain the features and benefits of a product. In the case of a tweeter, a review would include a detailed explanation of the product design, an explanation of the materials used to build the device, lab-based measurements of the output and a listening test. Of course, a summary of the key benefits and drawbacks of the design would give readers the opportunity to decide for themselves, based on their application and budget, if that product was suitable for their application.

In the article we were looking at, the only “review” was a restating of the product features from Amazon.com. Even when they did decide to get creative and provide some insight into the “quality” of the design, their comments conflicted with the ranking of the products. The number two product included a comment of “The materials used in construction are not so great,” and the number three offered “With the silk dome and metal construction od the speaker it is not the most advanced product on the market.” Yes, there is a typo in the text.

Wait, isn’t this the Top 12 tweeters? Why choose to rank products number two and three if there are better solutions available?

What is Clickbait?

The formal definition of clickbait is content or a title that encourages visitors to click on a link to a particular page or video. A few examples would be “How to get free beer” or “You won’t believe how great these speakers sound.”

Of course, anyone who writes articles wants people to read them, and at times, a little creative license or enthusiasm is OK to draw attention to the work.

In the case of the Top 12 tweeter article, and all the other articles on that website, all you are getting is a list. Yes, they have put some effort into compiling the list, writing somewhat useless text and stealing photos from manufacturer websites (yeah, you can’t just take those and do whatever you want with them). Using the “Top 5,” “Top 10,” “The Best” or any other type of clickbait title is designed purely to get you to read the article, even though the content doesn’t offer any quantification of the performance of value of the product.

So, Why Make at Top 10 List?

Now that you know what should be in a product review, or in this case, a product comparison, and clearly, that hasn’t been provided, why did they go to all the trouble of making the website and the article? The answer is to make money. You see, each product includes a link to “check the latest price on Amazon.” If you hover your mouse over the link, you’ll see that the website name is included as a tag in the link. This is called an associate link. If you follow the link and purchase the product, the website that provided the link gets a kickback from Amazon. Depending on the category, the kickback can be anywhere from 1 percent to 10 percent of the selling price. In terms of the website making money, it’s well worth the effort.

Why Do We Care?

When it comes to helping you choose the best possible products for your car audio system, the goal of a reputable specialist mobile electronics retailer is to quantify your goals, understand your application and then suggest a solution that will fulfill those requirements. Internet articles that purport to offer this information are doomed from the outset because they haven’t fulfilled the two most important tasks: qualification and application.

Imagine you are looking for a tweeter that will fit into the factory location in the doors of your Honda Civic. A large bullet tweeter simply won’t fit. Conversely, in a scenario where you have a wall of subwoofers in the back of your SUV and you want a dozen tweeters to mount around them, a reputable retailer might not suggest a small silk-dome solution. The “best” tweeter is the one that fits in your application, sounds the way you want and works with your budget.

Rather than waste time with clickbait articles that lack any substance, the next time you want to upgrade the sound system in your vehicle, drop by your local specialist mobile electronics retailer and ask them for some help. They will likely have products on display for you to audition and may even have a demo vehicle to check out. Most importantly, they are there to make sure you get the right solution and to install and configure it to provide the best performance possible.

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.

As we move toward the end of our discussion of car audio electrical theory, we need to talk about capacitance and inductance and how the characteristics of those phenomena interact with AC and DC signals. There’s no doubt that these are advanced concepts, but even a basic understanding of how capacitors and inductors work is fundamental to a thorough understanding of mobile electronics systems.

What Is a Capacitor?

A capacitor is a two-terminal electronic component that stores energy. Capacitors are made of two metallic plates that are separated by an electrical insulator. When we apply a voltage to one terminal of the capacitor, the electrons on one plate will impose a force on the opposite plate to create an opposite charge. The result is that the plates have equal and opposite charges and thus, maintain an electric field. Because the plates in a capacitor are very close together, they can store a large amount of energy for their overall size.

Capacitors are quantified in units of farads. A farad is defined as one coulomb of charge on each plate, resulting in a voltage of one volt across the terminals.

Capacitors in DC Circuits

Capacitors are, at their most basic function, a device that stores a microscopic magnetic field between its plates. When we apply a DC voltage to a discharged capacitor, it appears as a short circuit for an instant as the magnetic and electric fields start to form between its plates. As the capacitor starts to store energy, it increases in effective resistance, and the amount of current flowing through the device is reduced. Once the capacitor has equalized with the supply voltage, almost no current passes through the device.

When we remove the supply voltage from a capacitor, it will attempt to maintain the voltage across the terminals. It is this characteristic that makes capacitors an ideal solution to reduce variations in voltage. Capacitors resist changes in voltage.

Inside the amplifiers in our car audio systems, capacitors are used to store large amounts of energy at the rail voltage. When there is a sudden demand for current that exceeds the capability of the power supply, the capacitors will release energy to maintain their initial voltage. This characteristic helps to stabilize the voltage of the amp during dynamic transients. This same concept applies to “stiffening capacitors” used on the 12V feed to your amplifier. When implemented using high-quality components, the addition of a large capacitor can help to provide transient current to the amp.

The Capacitor in AC circuits

In alternating current circuits, capacitors take on an interesting phenomenon of “virtual resistance.” As we know, capacitors don’t like to change voltage, yet an AC signal is one that is defined as ever-changing. Depending on the relationship between the capacitor value and the frequency of the AC signal, some amount of the current is allowed to pass through the cap.

If we attempt to measure the resistance of a capacitor with a conventional multimeter, we’ll find it shows an extremely high value. For AC signals, we use the formula Xc = 1 / (2 x 3.1416 x F x C) to calculate the effective resistance, where F is the frequency of the signal and the C is the value of the capacitor in farads. Because this resistance is not present in DC signals, we call it capacitive reactance.

If we wanted to create a simple filter circuit to limit the amount of low-frequency signal going to a speaker, we could wire a non-polarized capacitor in series with the speaker. To calculate the frequency at which the cap starts to reduce bass going to the speaker, we can rearrange the above equation to F = 1 / (2 x 3.1416 x R x C), where R is the same value as the speaker resistance. For a four-ohm speaker and a capacitor with a value of 200 uF (microfarads), we get a frequency of 198.9 Hz. At this frequency, the capacitor appears to have the same reactance as the speaker, and the signal that is going to the speaker is reduced by 50 percent. Because capacitance is inversely proportional to frequency, the impedance of the capacitor increases as frequency decreases. At 99 Hz, the reactance is 8 ohms, at 50 Hz, it’s 16 ohms, and so on. This phenomenon simultaneously reduces the current supplied by the amplifier and acts as a voltage divider between the cap and the speaker.

A capacitor in series with a speaker is known as a first-order high-pass filter. It reduces the output of the speaker at a rate of -6dB per octave as you move away from the crossover frequency as defined above. Capacitors are suitable as filters for midrange and high-frequency drivers in passive designs and as protection devices for tweeters in active designs.

What Is an Inductor?

In the simplest of terms, an inductor is a coil of wire that creates a magnetic field based on the amount of current flowing through it. Many inductors feature iron cores to increase the intensity of the magnetic field. Where a capacitor resists changes in voltage, an inductor resists changes in current flow. We know from our previous article on magnetism that current flowing through a conductor creates a magnetic field around that conductor. If we wrap the conductor in a loop, the proximity of the loops to one another intensifies the magnetic field.

Also from our previous article, we also know that a magnetic field can impose a voltage on a conductor. If the current in an inductor tries to change, the magnetic field attempts to create a voltage across the device to maintain the current flow.

A good analogy for an inductor is a flywheel on a motor. Once you have established a specific rotational speed, it takes a large amount of work to increase or decrease its speed. Inductors work the same way with current. They resist changes in current flow. Inductors are rated using the unit henry (H). A henry is defined as the opposition to electrical current flow through a device that results in one volt of electromotive force to appear across the terminals.

Inductors in Electrical Circuits

In most applications, we don’t want inductors in a 12V DC circuit because they resist changes in current flow. For a variable load such as an amplifier, a large amount of inductance in the supply wiring would result in an unstable supply voltage as the current requirements change.

There are some cases where inductors are used in combination with a capacitor to act as a noise filter.

In an AC circuit, inductors allow low-frequency signals to pass through the device with little to no effect. If we wire an inductor in series with a speaker, it acts as a high-pass filter. Unlike a capacitor, in a DC circuit, an inductor appears as a short circuit with very little resistance. To an AC signal, we can calculate the reactive inductance of a capacitor using the equation Xl = 1 x 3.1416 x F x L, where F is frequency and L is inductance in henries.

If we want to use an inductor as a high-pass filter, we can determine the effective crossover point by swapping the Xl for the resistance of the speaker. In this example, we’ll use an inductor with a value of 6 mH (millihenries) and a speaker with a nominal impedance of 4 ohms. There, the -3dB point of the filter circuit would be F = 4 / (2 x 3.1416 x 0.006), or 106.1 Hz. This value of inductor would make a good low-pass filter for a woofer. Just as with a capacitor in series with a speaker, an inductor acts as a first-order filter and reduces output at a rate of -12dB per octave as frequency increases from the crossover point.

Other Cases of Inductance and Capacitance

Anytime two conductors are parallel to each other and in close proximity, there will some level of capacitance. Many overly exuberant enthusiasts talk about capacitance in interconnect cables. While this is a factor, the microscopic changes (if indeed any are perceptible) can be compensated for during the tuning process of the system. When it comes to buying high-quality interconnects, noise rejection and overall design durability should be your top goals.

The voice coil winding in the speakers we use has a certain amount of inductance. This characteristic reduces high-frequency output by reducing current flow at high frequencies. Because speakers are dynamic, their parameters change as the speaker cone moves. In the same way that having an iron core in an inductor increases inductance as compared to an air-core design, the inductance of a speaker voice coil increases when the cone assembly moves rearward into the basket. The T-yoke in the center of the speaker increases the strength of the magnetic field created by the current in the voice coil. Likewise, as the speaker moves forward, the inductance decreases. These position-based inductance distortions can cause a high-frequency warbling effect that can be detrimental to the reproduction of your music. One solution is to implement an under-hung voice coil design where the gap is taller than the coil winding. The drawback to this design is that the voice coil is often small and lacks power handling. Another option is to include a copper pole piece cap to reduce the magnetic field and minimize distortion. A copper cap is an expensive option but offers excellent performance benefits.

Car Audio Electrical Theory

For now, this is the end of our series of articles on car audio electrical theory. We hope you’ve enjoyed learning about the physics behind how your car audio system works. Our goal is to educate enthusiasts so that they can make educated purchases and upgrades to their mobile sound system. If you have any questions, drop by your local mobile electronic specialist retailer. They can help you design an upgrade that will truly transform your commute into an enjoyable listening experience.

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