Car audio amplifier designs have changed a great deal over the last few decades. Modern amplifiers have more features along with improved efficiency, and they offer consumers better value than their predecessors. This article will examine the key components in the construction of mobile audio amplifiers, their evolution and their benefits.

Amplifier Design Balances Power and Efficiency

When an engineer sets out to design an amplifier, he has to specify the value, size and tolerance of hundreds of different components. The most crucial of these in terms of the amplifier’s performance are the operational amplifiers (op-amps), the transistors or integrated circuits used in the driver stage and the transistors or MOSFETS used in the output stage.

Transistor Cases

Many early audio amplifier designs used TO-3-case transistors. These large cases were primarily a heatsink for the small circuit inside. Fine leads connected the pins on the bottom to the board and to the terminals. TO-3 case devices were introduced by Motorola around 1955 as an upgrade over vacuum tubes. While the metal can offers a good amount of thermal capacity, the size makes amplifiers unnecessarily large.

TO-220 and TO-265 plastic case transistors and MOSFETS allowed designers to dramatically reduce the size of amplifiers. These cases were much easier to attach to a heatsink, and the reduction in connection length between the terminals, along with advancements in component construction, allowed for improved efficiency and faster switching speeds.

Modern surface-mount transistors and MOSFETS can pass amazing amounts of current with blindingly fast switching speeds. The increase in switching speed has improved the quality of Class-D audio circuits to where they rival many A/B designs. Equally, lower internal resistance values allow these devices to shrink in overall size, making amplifier designs more compact.

Product Assembly

A significant part of the cost of building an amplifier is in the time it takes to place components on the circuit board. Through-hole devices like capacitors, inductors, TO-220/TO-265 case transistors, MOSFETS and resistors need to be placed by hand. This is a slow and costly process.

More modern designs use surface-mount capacitors, op-amps, MOSFETS, resistors and diodes that can be placed by machine then passed through a soldering machine. Not only is the assembly process faster and less costly, but the parts themselves are also typically less expensive and reduce the bill of materials (BOM) cost of the amp. In short, you get much better value for your dollar.

Some large components, such as power supply capacitors, high-power resistors and large-value inductors, still need to be placed by hand. The sheer size of these components prohibits them from being located automatically.

Modern Amplifier Designs Delivery Better Performance

If you’re shopping for a new amplifier for your car or truck, drop by your local specialty mobile enhancement retailer today and check out the latest designs that deliver impressive sound quality and performance. Newer amplifiers offer increased accuracy and efficiency – a combination that helps make your music sound better than ever.

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.

There’s a strange car audio myth that claims you can’t mix different brands of source units, speakers, amplifiers, subwoofers and signal processors in the same audio system. While it might be fun for a distributor, sales representative or employee at a car audio retailer to do a one-brand build, chances are you’ll want to pick and choose from the different brands at the store you are dealing with to get the most bang for your buck.

Source Units

Whether you choose Sony, Kenwood, Pioneer or Alpine for your source doesn’t matter in passing audio to a digital signal processor or an amplifier. Almost all source units provide a low-voltage audio output called a pre-amp signal. Some models have pre-amp outputs rated for 1.8 to 2.0 volts, while others have high-voltage outputs capable of 5 volts. The different voltage does affect how loudly your system can play but may reduce background noise in the system by allowing your installer to turn down the sensitivity control on your amplifier.

When shopping for a source unit for your car audio system, you will want to balance features and specifications with an easy-to-use interface. If you can’t walk up to a radio on display at the local car stereo shop and figure out how to use it, the interface is likely either too complex or not thought out well enough. Trying a radio and connecting it to your smartphone is a crucial part of the purchase process.

Digital Signal Processor

If you plan to have a DSP in your car, something that’s crucial to recreating an authentic listening experience, there are three options for feeding a signal into the processor. All processors will accept analog pre-amp signals from any source unit on the market. Some processors include digital audio inputs that use a TOSLINK fiber-optic connector or an RCA jack. If the factory radio in your car or truck can’t be upgraded easily, several interfaces are available that provide analog and digital outputs. Some processors have Bluetooth audio receivers built in or available as an option. You can stream music from your smartphone directly to the DSP and bypass a source unit altogether.

The type of processor you choose is tied directly to the design of your car’s audio system. If you are running a set of components and a subwoofer, then six channels are more than enough. If you want to upgrade an elaborate factory-installed audio system that includes an upmixer, then you might need as many as 18 or 20 channels of processing.

Car Audio Amplifiers

Just as with processors, almost every amplifier is designed with analog audio inputs that work with the pre-amp signal from a source unit or processor. Some amplifiers include additional components or circuitry that allows them to be used with the speaker outputs of a factory-installed audio system.

Amplifiers increase the voltage of the signal coming from the source unit, and the relatively low impedance of the speakers in your car or truck results in reasonable amounts of power being produced.

Speakers and Subwoofers Take Some Attention

Where source units, processors and amplifiers don’t care what feeds them, the speakers you choose need to be of the correct impedance for the amplifier you are using. Most car audio speakers have a nominally 4-ohm design, but some subwoofers offer impedances as low as 1 ohm. Mixing and matching brands doesn’t matter, but choosing the proper impedance does. The product specialist you are working with can help ensure that you get the right combination.

Expert Technicians Make It All Work

No matter what brands you choose, you’ll need someone who can integrate everything into your vehicle so that it will function properly and reliably. Unlike home audio systems, it’s not just a matter of plugging everything in. The colors of factory wiring need to be matched to the connections on a new radio or speaker. Likewise, the products you’ve chosen need to be mounted securely, and the cables that run between components need to be routed safely. Selecting a professional installer is often more difficult than choosing the audio components for your system. With that said, it’s worth researching to find the best company to upgrade the audio system in your vehicle.

Too Long; Didn’t Read

The bottom line is that few companies excel in all areas of car audio components. Some offer excellent amplifiers and signal processors, some make great source units, and others have amazing speakers. Mixing the best products across several brands can result in an audio system that sounds amazing and offers the features you want. Start your shopping at the specialty mobile enhancement retailers near you to find out what options are available to upgrade the stereo in your car or truck today!

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 long ago, we saw a post where someone asked whether they needed to dedicate a channel of their digital signal processor to equalize the subwoofer in their car audio system. As usual, several amateurs chimed in with their opinions, but nobody presented any facts supporting a yes or no answer. As professionals, when we’re challenged with a question to which many variables can affect the answer, the best bet is to set up an experiment. Let’s find out if your sub needs equalization to sound great.

What Happens When You Install a Subwoofer in Your Car?

Since we already have the data from one of the Test Drive Reviews the BestCarAudio.com team is working on, let’s look at the Rockford Fosgate P500-12P subwoofer system and analyze its performance in and out of the vehicle.

The graph below shows a frequency response sweep of this impressively compact 12-inch enclosure with the sub sitting in the middle of a parking lot.

Given the roughly 1-cubic-foot volume of the enclosure, it’s no surprise that the response looks like it has energy focused around 70 Hz. Most would say that this system won’t deliver good low-frequency performance in a vehicle. They’d be wrong.

The graph below shows what happens to the subwoofer when placed against the back seat of a 2019 Hyundai Santa Fe midsize sport utility vehicle.

There’s 9 dB of boost at 80 Hz and a mind-boggling 19 dB of boost down at 45 Hz. If you think that’s amazing, there’s more than 26 dB more output at 30 Hz. What looked like it might be boomy or peaky on paper now offers amazing extension down to below 30 Hz. It’s clear that the engineers at Rockford Fosgate considered the transfer function that happens when you put a small subwoofer in the relatively small confines of a car or truck.

Let’s Talk About Subwoofer System Equalization

We’re going to brew up a second example using a different amplifier and subwoofer. We dug out an old 12-inch Elemental Designs e12a.22 sub and connected it to one channel of the ARC Audio ARC1000.4 that the BestCarAudio.com team reviewed in early 2021. This amplifier has the IPS8.8 digital signal processor installed, and as such, we have 37 bands of fully parametric equalization available to fine-tune the subwoofer’s response. Let’s start with a baseline measurement of the subwoofer system with all the EQ bands flat.

As is clearly visible, the 60 Hz dip evident in the measurement of the Rockford Fosgate subwoofer remains, and there are smaller dips at 26 and 37 Hz. Left alone, there’s more than 20 dB of variation between 43 and 63 Hz. That’s not what we’d call a smooth response in any sense of the term. It’s time to fire up the parametric EQ and do some tweaking.

After about 20 minutes of cutting and boosting on the subwoofer channel, we’d tamed the resonance at 43 and boosted the dips at 26, 37 and 63 Hz. With another 10 minutes, we could have the range between 36 and 37 even flatter and added some boost at 70 Hz, but we are within a 3 dB window from 21 Hz to 65 Hz, which is close enough for this example.

Upgrade Your Subwoofer System with a DSP Today!

The benefits of equalizing your subwoofer are clearly visible. Whether you are listening to a recording of a pipe organ with someone playing progressively deeper notes or you want to experience a bass drop in your favorite Skrillex track, equalization makes a huge difference. Reproducing different bass frequencies at different volume levels doesn’t accurately represent what was captured in the original recording.

Drop by your local specialty mobile enhancement retailer today to learn about the digital signal processing and equalizer options that are available to fine-tune the output of your car audio system. You’ll be amazed by how much better your car audio system will sound with proper calibration.

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 stumbled across a discussion about the need for large-gauge car audio speaker wire to be connected to a high-power amplifier. The comments on the post were prime examples of how little some audio enthusiasts understand about the signals going to the speakers in their car audio system. So, to help as many people as possible understand the subject, we put together this article to explain why you don’t need 12-AWG wire for your tweeters.

Audio Signals – Amplitude and Frequency

The amount of voltage produced by your amplifier is dependent on the volume setting and the frequency content of the audio signal. Suppose you’re listening to a recording of an electric guitar. In that case, your amplifier will produce significantly less power than it would take to reproduce the lowest notes of a synthesizer or bass, even at the same perceived volume level.

Why do higher frequencies need less power to reproduce? Most of the sounds we hear follow the same approximate shape as pink noise. If you analyze the energy in a pink noise waveform, you’ll see that its amplitude attenuates at a rate of -3 dB per octave or -10 dB per decade as frequency increases.

If you have a typical car audio system, then you may have a subwoofer or two to handle reproducing audio frequencies below 80 Hz, midrange drivers to handle the sounds from 80 to 3,500 Hz and tweeters for those frequencies above 3,500 Hz. The graph below shows the energy fed to the subwoofers, midrange drivers and tweeters using these crossover points.

It’s clear to see that the tweeters are receiving a lot less energy than the midrange drivers in the doors. In fact, it’s about 20 dB less at the highest level. If you had 100 watts going to the door speakers, your tweeters would only need 1 watt of power to keep up. In this example, the average amplitude of the signal going to the mids compared to the tweeters is 13.9 dB louder. So, you need about 4.1 watts for those tweeters if the mids are getting 100 watts. With nearly 5 dB more output required, the subwoofers would need 316 watts, assuming they had the same efficiency as the midrange speakers.

Power in Alternating Current Signals

A commenter in that thread wrote, “Yeah, but it’s AC, not DC,” as if to imply that an AC signal wouldn’t deliver as much current to the speaker. For pure sine waves, this with where the Root Mean Square (RMS) value comes in. An AC sine wave of, say, 10 volts RMS can do the same amount of work as 10 volts DC.

Music isn’t a single constant sinusoidal waveform. It varies in amplitude and frequency. As such, we need to look at an average level. To keep our example simple, let’s use 300 watts, 100 watts and 4 watts for the math involved in calculating how much power is lost due to the resistance of speaker cabling. We’ll also maintain the simplicity of the example by assuming all the speakers in the system have a nominal impedance of 4 ohms.

Current in Car Audio Speaker Wire

For our example, our 300-, 100- and 4-watt power levels translate to 8.66, 5 and 1 amp of current flowing through the respective speakers. Let’s use a piece of 12-AWG speaker wire with a length of 10 feet for our benchmark. If the speaker wire is full AWG spec and is made from pure copper, the 10-foot length will have a total resistance of about 36.3 milliohms. The voltage drop in the wire will be 0.314, 0.181 and 0.026 volts which, if my math is correct, represents a reduction in output of 0.157, 0.091 and 0.018 dB, respectively. In short, these differences aren’t going to be audible at anything other than when the volume is turned up all the way. At even one notch down, those reductions diminish significantly. With the dynamic characteristics of music, it’s safe to assume the average required power is 1/10 of the maximum.

What happens if we run 14- or 18-AWG wire instead of 12-AWG? The chart below shows the reduction in output at the most extreme cases with test tones being played. For your tweeters, it just doesn’t matter. For the mids, at full power, maybe there is a minute loss that might affect the balance of the system. Should you use 18-AWG speaker wire with your subwoofer? Probably not.

What happens at normal listening levels? Say you are commuting to work and the radio is on so you can hear traffic and news with the odd song thrown into the mix. With the typical midrange driver having an efficiency of 86-88 dB at 1W/1M, you are likely to be averaging a lot less than 1 watt of power to the doors. For argument’s sake, let’s say you are. To maintain the same relative output levels, the sub would be getting 3 watts and the tweeters are at 40 milliwatts. Our losses in the speaker wire drop to imperceptible levels of 0.063 dB on the woofers, 0.036 dB on the mids and 0.003 dB on the tweeters. Still worried about speaker wire size?

Let’s Look at More Subwoofer Math

Car audio companies seem to like to design car audio subwoofer amplifiers that produce their maximum power into low impedances. We’ve already looked at the sacrifices in amplifier efficiency and increases in distortion at low impedances in another article.

In short, for the same power delivery to the subwoofers, lower load impedances require more current to flow through a speaker’s voice coil. More current means more energy is wasted in the speaker wire due to its resistance. Let’s cook up another example – 750 watts into 4-, 2- and 1-ohm loads with 12-, 14- and 18-AWG speaker wire. Here are the results:

As you can see, this is yet another good reason to avoid amplifiers that require low load impedances to produce large amounts of power. OK, 750 watts through an 18-AWG conductor that’s 10 feet long is a pretty extreme example, but it punctuates the point pretty clearly.

In reality, you will never deliver full power to all the speakers in your car, save for maybe the subwoofer if you compete in SPL contents. In those cases, where tenths or maybe even hundredths of a decibel matter, having oversized speaker wire and amplifier power cable is impossible. Knock yourself out and have your installer run eight-AWG power cables to the subs! For the rest of us who listen to music at even modestly reasonable power levels, 14-AWG speaker wire is well more than adequate, and your tweeters don’t need anything over 18-AWG. Drop by your local specialty mobile enhancement retailer to find out about the audio upgrades that are available for your car or truck. Spend the money you’ll save on not buying monstrous speaker wire for your tweeters and midrange drivers on better 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.

Car audio sound deadening has been a popular upgrade to improve the comfort of your vehicle and enhance audio system performance since the early ’90s. The original concept of sound deadening was to make cars and trucks quieter and more comfortable by limiting the ability for noise outside the vehicle to get into the cabin. Car audio enthusiasts realized that having their vehicles deadened would dramatically improve the efficiency and performance of their audio upgrades. Today, dozens of companies offer noise control solutions. With that said, they aren’t all created equally. This guide will help you choose the best solution for your vehicle.

How Does Car Audio Sound Deadening Work?

Noise sources such as an exhaust system, the mesh of gears in a transmission or the vibrations of your tires rolling down the road produce sound energy that vibrates the metal panel on the body and chassis of your vehicle. As these panels vibrate back and forth, that sound energy is transferred into the interior of your car or truck. The effect isn’t as significant as having a window rolled down, but this unwanted noise and vibration are clearly audible.

One of the key differences between an entry-level vehicle and something more luxurious is the background noise level in the cabin as you drive. Companies such as Rolls Royce may add more than 200 pounds of noise control materials to their most luxurious vehicles. Along with thicker glass, plusher carpets and even wheels and tires with noise-absorbing technologies, reducing noise in vehicles is big business.

Automotive sound deadening or damping products add mass to metal and plastic panels to reduce the amount they vibrate. Energy from the sound source is converted into microscopic amounts of heat rather than being passed through the panel and into the vehicle interior. High-quality sound deadening products have a second function. Most doors, rear parcel shelves and the rear side panels in coupes have large openings. Some of these exist to allow for the installation of power windows and locks. These large openings do nothing to block sound from entering the cabin. As such, sound deadening products can be used to span these spaces and dramatically reduce noise inside the vehicle.

Sound Deadening Materials

When noise control products originally entered the car audio industry, they were partially petroleum-based and carried a unique and distinct odor. While the damping characteristics were good, long-term adhesion was mediocre, and many consumers complained about the smell. Most of the current high-quality deadening solutions use a butyl base layer with varying thicknesses of aluminum to balance absorption and rigidity characteristics. These are called constrained-layer damping (CLD) solutions.

The characteristics of the material have to be balanced in their design to absorb energy (soft and gooey works well here) while having the rigidity to span openings and reduce noise transfer (firm and dense). Many products branded as car audio solutions come from other markets and fall at the extreme ends of this balance. As such, they don’t provide the best overall solution compared to those engineered specifically for car audio applications. In short, what might offer the most ideal damping when affixed to a flat metal panel might be the worst for bridging open spans in your doors or the rear deck of your car.

When shopping, ask to see a sample of the product. If you hold a piece of deadening horizontally and it falls limp, it’s too soft. Conversely, if it’s stiff like cardboard, it might not conform well or stay adhered the to complex shapes and surfaces in the vehicle.

Many CLD solutions add a third layer of closed-cell foam on top of the aluminum to reduce noise from wire harnesses, trim panels and door release and lock actuator rods while the vehicle moves down the road.

You’ll want to choose a product that’s primarily black where it might be seen through a speaker grille. The last thing you want is a shiny silver or gray finish attracting attention where it’s not required.

Another class of aftermarket noise control product is mass-loaded barriers. These products are typically a sandwich of closed-cell foam over a lead-like alloy sheet. The dense layer in the center acts as a second barrier to noise and offers impressive energy absorption properties. These products are ideal for installation on the floor and trunk or cargo area of vehicles, and they serve as an excellent replacement for carpet pads.

Adhesive Properties of Sound Deadening

Aside from balancing noise control properties, it’s important to pick a sound deadening solution with excellent adhesion properties. The last thing you want is for the damping material to release from the inside metal on a car door and get stuck against the window.

The deadening needs to stay in place in extreme cold temperatures below -40° C or F to scorching conditions well above 140° F/60° C. If the material breaks down and falls off of vertical surfaces, the mess can be extremely expensive to clean up, and upholstery or interior components such as carpet, door panels or roof liners may need to be replaced.

Safety Considerations

Anytime you’re adding something to your vehicle, safety should always be a priority. Automotive engineers agonize over what would happen in a worst-case scenario to ensure that the occupants remain safe. In the event of a catastrophic accident or serious malfunction, that last thing you want is for something that’s been added to your vehicle to burn quickly. The Federal Motor Vehicle Safety Standard Number 302 is a test designed specifically to evaluate the flammability of automotive materials. Flame propagation from an ignition point must not exceed 102 mm per minute. Ideally, the material will self-extinguish. Likewise, the Underwriters Laboratory UL 94 flammability test for plastics requires that plastics stop burning within three seconds, with an afterglow of less than 30 seconds. The UL 94 standard would apply to foam products in the context of this discussion.

Installation Options for Maximum Noise Reduction

It would be great if sound deadening could be applied to every square inch of a vehicle during the manufacturing process. For hot rod and restoration projects, the installation of more than 100 square feet of sound deadening is commonplace before the wiring and interior are installed. For daily driver applications, many components will need to be removed from your car or truck to achieve the same results. Here are a few suggestions that offer excellent noise control improvement:

• Car doors are large, flat surfaces that allow significant amounts of noise into the vehicle. Having the rear of the outer door skin treated can offer significant benefits. Covering the inner door skin not only helps to reduce vehicle, road and wind noise from entering the vehicle, it can dramatically improve the performance of the speakers installed in the vehicle. In fact, if the inner door panel has access holes in it, having it treated with sound deadening will improve audio quality for less money than a speaker upgrade.

• Floors and cargo areas are another source of significant noise transfer. If you’re going to have the floors done, be sure the installation extends up the front firewall as far as possible to help reduce the transfer of sound from the engine and transmission. Having the wheel wells treated can dramatically reduce noise, especially when it’s raining. The sound of water spraying against a metal wheel well is surprisingly loud.

• The roof and trunk lid are even larger than your doors and can transfer a surprising amount of sound into the vehicle interior. If you’re going to have these surfaces deadened, make absolutely sure the product you’ve chosen has excellent adhesion and thermal properties. You don’t want any peeling issues here.

Benefits of Automotive Sound Deadening

Aside from making your vehicle quieter while you drive, the reduced background noise improves outgoing call quality when using a hands-free Bluetooth system. Likewise, voice recognition technologies such as Android Auto and Apple CarPlay work better when the vehicle is quieter.

In terms of audio system performance, sealing openings in a car door can increase the bass and midbass performance of a speaker by more than 10 dB. That’s like having an amplifier that’s 10 times as powerful! Having the trunk or cargo area of your car treated can help with the performance of a high-power subwoofer system by reducing the energy lost to vibrating panels. Deadening solutions that include foam reduce the buzzing noise of wire harnesses or the sound of interior trim panels rubbing against the metal car components they are attached to.

Upgrading your vehicle with car audio sound deadening is an amazing investment. If you’re interested in improving the comfort of your vehicle, drop by your local specialty mobile enhancement retailer and ask them about adding sound deadening to your car, truck or SUV.