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.