In the past, we’ve looked at Class AB and Class D amplifier classes, the two most popular configurations in the mobile electronics industry. With that said, a few other classes deserve some explanation, as they can deliver improvements in amplifier efficiency without altering the sound quality. This article will review Class AB and Class D and then talk about G and H designs. We’ll also dispel some myths about device topology and how these amplifiers work.

How Does the Amp Output Stage Work?

Before we talk about output device configurations, we need to explain how the output stage of an amplifier works. When your installer connects a speaker to an amplifier, they expect a voltage proportional to the input signal to be supplied. The amplifier power supply determines the maximum voltage that can be provided to the speaker and the impedance of the speaker determines how much current will flow. Our limits are the voltage of the power supply and its current delivery capabilities.

Almost every amplifier uses what’s known as a Class B output device configuration in car audio systems. This circuit design uses two switching devices (transistors or MOSFETS) to alternate between the amp’s positive and negative voltage supplies. When both are off, no voltage is supplied to the signal. When the positive device is on, a positive voltage is supplied to the speaker, and it moves outward. When the negative device is on, the speaker moves inward. The level of our audio signal determines how “on” each device is. This configuration is often referred to as a push-pull design.

Class AB Car Audio Amplifiers

A Class AB amplifier is a Class B amp adjusted to make the transition between the positive and negative switching devices smooth and effectively distortion-free. Most amplifiers switch from one device to the other with as little overlap as possible so the amplifier can be as efficient as possible.

A few high-end amplifiers allow both devices to overlap their operation a little more than normal to ensure that the transition is even smoother and less crossover distortion is created. This configuration reduces distortion at the expense of increasing how much current the amp draws. When appropriately executed, the results can be quite astonishing. The ARC Audio SE-Series and D’Amore Engineering A-Series amplifiers are great examples of these high-bias designs.

For a more scientific look at how A, B and AB stages are configured, check out this BestCarAudio.com article.

Class G and Class H Amplifiers

A few companies that truly understand what genuine enthusiasts expect from a high-end car audio amplifier have implemented what are known as Class G and Class H designs. Unlike Class B, G and H don’t refer to an output device configuration at all. G and H are different methods of adjusting the power supply’s output to improve an amplifier’s efficiency. As such, Class G and Class H amplifiers are subsets of a Class B amp.

The power supply may be configured in a Class G amplifier to deliver two more output voltages. The amp operates typically at a lower-than-maximum rail voltage so that less heat is generated in the output devices. When you crank up the music, the amp will dynamically switch the power supply output to a high-voltage mode, so the output signal doesn’t get clipped. Some amps’ switching is based on average power level requirements, and others can change based on the audio signal’s immediate needs. A Class G amplifier’s output devices are configured in a standard Class B topology and, with proper biasing, deliver the same amazing sound quality.

Class H amplifiers are very similar to Class G, except that the power supply voltage tracks the audio waveform at high output levels. So, rather than low- and high-voltage modes, the voltage is variable. This configuration offers further improvement in amp efficiency of Class G with the same sound quality as B.

Class D Amplifiers Deliver Efficiency

A Class D amplifier still uses the same Class B output device configuration, with separate positive and negative switching devices. Where it differs is in how the devices are driven. The analog audio waveform is processed by a controller IC into a series of pulses with different widths. The pulses switch the positive or negative output devices all the way on or off very quickly. A large filter network between the output devices and the speaker smooths these pulses to recreate the original analog waveform.

The efficiency benefit comes from the output devices acting as switches rather than resistors. With little time being partially on or off, very little heat is generated.

Modern Class D driver ICs operate at impressively high frequencies. Some run as fast as 600 kHz, so delivering good high-frequency audio performance is less of an issue than for amplifiers designed a few decades ago. These same ICs include low-voltage operation features to help amplifiers work in vehicles with stop-start electrical systems.

It’s All About Amplifier Efficiency

These days, installers want the smallest and most efficient amplifiers they can find. These criteria make installations more manageable. For those who are genuinely passionate about their listening experience, the larger amplifiers with Class AB output stages still deliver the best performance. If you’re shopping for an amplifier for your car audio system, drop by your local specialty mobile enhancement retailer and ask them about the amplifier classes they offer. Based on your vehicle, power needs and performance expectations, they’ll help you choose a solution that will ensure that the music you listen to sounds great!

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.

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 all know that having sound deadening installed in your car or truck is a great way to improve its comfort while allowing your stereo upgrades to sound better. In this article, we’ll look at some of the strategies for adding sound deadening. We’ll talk about different areas of the vehicle and the benefits associated with treating those surfaces. Based on this, you can decide how to get as much value and performance from a damping material investment.

Why Add Sound Deadening

Sound deadening comes in several solutions. For this article, we will focus on what’s known as constrained-layer damping (CLD). In short, these are sheets of dense butyl rubber that are bonded to a flexible layer of aluminum. The CLD is intended to be applied to your vehicle’s metal panels to add mass and reduce the panels’ ability to vibrate and transmit sound from outside the car or truck to the interior.

Sound deadening can be applied to almost any surface to help prevent noise from the engine, exhaust, transmission, tires or wind from getting into the vehicle.

Some damping materials like SoundShield add a layer of closed-cell foam to the aluminum layer for additional energy absorption. This foam also reduces the chances of wiring harnesses or door actuator rods from rattling and making noise as you drive.

Sound Deadening Car Doors

One of the most dramatic upgrades you can make to your vehicle’s comfort is to have the doors treated with sound deadening. Here, two approaches offer different benefits. The outer door skin, the one you see when you look at your car or truck from outside the vehicle, is a large and relatively flat surface. If you tap on it, you can feel that the metal is somewhat flimsy. Having damping material added to the back of this panel will dramatically reduce noise transfer. Since you sit close to the door, the results are quite noticeable.

The second surface that can benefit from deadening is the inner door skin. This is the metal you’d see when the technician working on your car or truck removes the plastic trim panel from the interior side. This is another large surface and is often very flat.

Aside from keeping road noise out of the interior, sealing the door skin can have a dramatic effect on the performance of a door-mounted speaker. Typically, large openings in the metal allow access to the window regulator (the mechanism that raises and lowers the window), the door handle and the latch parts. Left open, the sound coming from the back of the speaker will mix with the sound coming from the front and cancel. Sealing these openings will dramatically improve lower midrange and bass performance from the audio system. This increase in output means your technician can reduce the power sent to the speaker so it will last longer. Likewise, a reduction in how hard a woofer has to work will reduce distortion and improve clarity.

Floor and Firewall Deadening

Modern vehicles are designed using computers to deliver a balance of strength and weight to make the vehicle drive well. Most automakers work hard to save every ounce so that fuel economy is optimized. You’d be surprised how much noise from the engine and transmission comes into the vehicle through the firewall and floor. Of course, the answer is to have these surfaces treated with high-quality deadening material. The process does require some significant work to remove the center console, seats and carpet, but it’s well worth the investment.

Pickup Truck Noise Control

The back wall of a pickup truck is another surface that can transmit a lot of sound energy into a vehicle. Though it’s blocked from wind noise, it still transmits drivetrain, exhaust and tire noise. Treating the back wall is a great way to improve the comfort of these vehicles.

Sound Deaden Your Vehicle’s Roof

Easily the biggest and probably the flattest panel in a vehicle is the roof. Whether you have a short-cab pickup or an SUV with 40 square feet of metal, wind noise will transfer into the vehicle through this flat surface. Having the roof liner removed can take some time, but the effort is worth the expense to improve your vehicle’s background noise level. With microphones for Bluetooth hands-free systems typically installed up high in the car, cutting down on noise will dramatically enhance an outgoing phone call’s clarity.

Trunk and Cargo Area Sound Control

If you have a car with a trunk, especially if you are having subwoofers installed there, controlling panel vibration and rattles will make a huge improvement to the performance of your audio system. Likewise, road noise and sound energy from the exhaust system will be reduced by treating the floor, fenders and hatch or trunk lid.

Picking the Right Deadening Material

As you can see, different areas of the vehicle need to be upgraded for different reasons and with different results. What remains constant, no matter where your technician is working, is the need to use high-quality materials. On surfaces that are vertical or where the deadening will be installed upside-down, proper surface preparation is paramount, and using a product with excellent adhesion qualities is a must. Avoid deadening that is bitumen- or asphalt-based as they can soften and come loose in high-heat conditions.

You’ll want to choose a shop and technician with the experience and training to remove the interior components of your vehicle in a way that prevents any potential damage and ensures that the vehicle can be reassembled properly once the work is complete. The last thing you want is to have clips or brackets that are loose, resulting in more noise added to the interior as you drive.

Having sound deadening installed in your car or truck is one of the best upgrades you can make to the vehicle’s comfort and your audio system’s clarity. Reducing background noise will make the subtleties of your music easier to discern. Likewise, if you have a hands-free Bluetooth system, the outgoing audio quality will be clearer. Drop by your local specialty mobile enhancement retailer today to inquire about having sound deadening installed in your car or truck.

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 significant car audio system upgrade takes four items: a budget, great gear, expert installation and proper configuration. If you’ve read any number of the articles here on BestCarAudio.com, you’ll know we hold the importance of quality equipment, proper installation and expert calibration in the highest regard. Deciding how to distribute your budget should include that crucial final step that brings everything together. This article will look at what it takes to achieve an awe-inspiring listening experience in your vehicle.

Establish Your Car Audio Budget

We know that everyone has different budget constraints and equally diverse expectations for upgrading their car audio system. Some are willing to spend thousands of dollars to achieve the most accurate, realistic listening experience in their vehicle. Conversely, many want the most bang for their buck and seek out the biggest upgrade possible from a small investment. Neither approach is wrong, and your local specialty mobile enhancement retailer can typically work with either end of the spectrum.

The key to getting the best value is to be clear about your expectations and how much you want to spend. If you want your car audio system to sound as though you’re sitting at the mixing console at Abbey Road Studios in London, England, but have a budget of $1,500, you’re going to be disappointed. Yes, the shop can make your system sound much better, but that last bit of sparkle, detail and transparency will likely be missing.

Be open and upfront with your budget. The product specialist designing your sound system can work backward from your budget to help you get the best value for your investment.

Avoid Used Car Audio Equipment

A friendly word of warning, if we may: It’s tempting to start shopping around for deals on previously enjoyed equipment to achieve a higher goal than your budget would allow. Most of the time, these efforts turn out fine, but surprisingly often, they end up being frustrating. It’s nearly impossible to know if a set of speakers has been abused and the voice coils are on the brink of unwinding. You can’t tell if an amplifier has been exposed to vibrations because of improper installation, and a component is on the verge of breaking loose. For a head unit, CD mechanisms have a finite life span; for the better units on the market, finding replacement parts is difficult.

If the shop you’re working with will accept third-party products, there will likely be an additional charge to test them before they are installed. In most cases, the installation warranty doesn’t apply to removing and reinstalling those components should they fail or have issues.

Choosing the Right Car Audio Upgrades

Just as asking “What’s the best car audio system?” is a relative question, finding the best products for your system is difficult if you aren’t experienced in auditioning audio equipment, even for those that often have a surprisingly low benchmark for what sounds genuinely accurate. Accuracy is the key word here. Any brand that describes its gear as having a “sound” or “style” has missed the boat in terms of understanding what audio equipment should do.

High-end amplifiers should amplify the audio signal. There shouldn’t be “warmth,” and they shouldn’t sound “smooth.” The signal that goes in should be increased to drive a speaker. Speaking of speakers, they have a similar task. They should transform an audio signal into sound with the addition of as little distortion as possible. Speaker systems should be designed so that the frequency response and dispersion characteristics of each driver compliment those operating in adjacent bands. You don’t want a 6.5-inch woofer and a ¾-inch tweeter working together. The woofer becomes too directional before the tweeter starts playing.

Expert Installation Is Crucial

Installing car audio equipment properly requires a few essential skills. First, the technician needs a thorough understanding of the laws of physics, including AC and DC theory and acoustics. They also need excellent problem-solving skills, excellent mechanical skills to construct adapters and mounting panels, and a certain amount of artistic flair to make it all look as though it belongs in the vehicle. Finding someone who excels at all of these criteria is difficult. Often, you’ll need to visit more than one shop to find the right match before you let someone start modifying your expensive vehicle.

Proper component installation doesn’t need to be fancy; it needs to be reliable. An amplifier will sound the same bolted to a piece of extruded ABS or a welded steel bracket as it would to edge-lit plexiglass or carbon fiber. Don’t fall prey to fancy designs while missing out on the opportunity to use higher quality equipment. Sadly, we see this all the time.

Proper System Calibration Is the Most Important Step

If you are expecting to hear Diana Krall’s voice as though she were really in the car with you, then your car audio upgrade is going to need a properly calibrated digital signal processor. No matter how great your installation is, how fancy a source unit you’ve purchased or how impressive your speakers are, your audio system won’t sound right without proper equalization and level setting. The bare minimum here is that each channel in the vehicle is equalized to remove the effects of resonances and cancellations in the vehicle. You will also need to decide if signal delays should be used to optimize the soundstage for a single seat (the driver’s seat) or both front seats. The latter may require some changes to the system design, so this decision is crucial to the design stage.

Your technician will need a calibrated microphone to properly tune the audio system. He or she will also need to have a thorough process to complete the task. Setting up a DSP properly isn’t an art, and it doesn’t take unnatural talent. It’s a scientific process. With that said, it does take practice to execute efficiently. Knowing what characteristics of the response need to be addressed and what needs to be ignored or dealt with by changes in crossover points takes proper experimentation. There’s no guessing or voodoo involved.

Before you commit to having a sound system installed and calibrated, you will want to audition several systems that the installer has completed. Hopefully, and expectedly, the shop will have a demo vehicle or two that you can audition. If not, ask if they can put you in touch with a previous client.

The cost of the calibration process is an important part of the overall car audio budget. Don’t be shocked for there to be at least one to two hours’ worth of labor dedicated to the process. For a four-way system or one designed for two-seat imaging, three hours isn’t at all unreasonable.

How Do I Know if the Calibration Is Correct?

We hear horror stories about signal processors being installed but not configured properly all the time. Here are a few things you can listen for while auditioning the demo system before you commit to letting a shop work on your vehicle.

The audio system should produce a stable center image. This means the voice of a performer that would be center-stage should be reproduced in the center of your windshield. The voice shouldn’t move left or right as the pitch changes. If the system is calibrated extremely well, the image should be small, about the size of a softball. Sounds on either side of the center image should be equally focused. If there is a guitar, backup singers or a saxophone, they should be placed accurately, and the source of the sound should be easily discernable.

Some music enthusiasts prefer to have the music wrapped around them with an equal amount coming from the back as the front. In this case, you will want the center image to be focused on you, the driver. There should still be a realistic balance of left and right instrument placement on either side of that position. If you like this style of listening (which is akin to a great seat of headphones), be sure to let the product specialist know before the system design begins.

The overall tonal balance of the system should sound natural. No part of any performer’s voice should stand out. This applies to both treble and bass. Sibilance, or having too much emphasis on S sounds, could be a tuning issue or a distortion issue with your speakers. If it’s the latter, only better quality speakers will resolve the problem.

Deciding how much bass is right is tricky. We know bass is a lot of fun, so it’s not unheard of to have much more than would make a drum kit or upright bass sound realistic. This is another criterion that needs to be determined before the system design process begins.

It’s Your Job To Get the Most from Your Car Audio Budget

Unlike buying a set of speakers for your home audio system or a soundbar for your television, a car audio system needs to be designed for the speaker locations and size options in your vehicle, installed securely, safely and reliably, then calibrated for the environment so that it sounds excellent. It’s your job to define a budget, then seek out a specialty mobile enhancement retailer that can complete this car audio upgrade task professionally.

Lead-in Image: The interior of this stunning Roadster Shop-built 1970 Chevy Camaro, known as Road Rage, was built by Avant Garde Design in Palm City, Florida. It should come as no surprise that a 3D rendering of the interior was completed before a single square inch of leather was cut. Thanks to Roadster Shop for the photograph.

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.