Adding a subwoofer to a car audio system is the best bang for the buck regarding audio performance upgrades. You can instantly hear the difference, and it dramatically improves the realism and enjoyment of your system. Let’s look at how to pick a car audio subwoofer for your vehicle.

Factory Audio System Limitations

Before we get into how to choose a car audio subwoofer system for your vehicle, let’s examine why a subwoofer is such a great upgrade. In a nutshell, factory audio systems are designed around a budget – both monetary and weight-related. When automakers start looking at car audio products, price is often their primary concern. Automakers also work hard to reduce vehicle weight as much as possible, thereby reducing fuel consumption and, subsequently, environment emissions from the vehicle. This means that the performance of even these so-called “premium” factory audio systems is mediocre at best, and typically can be quantified as disappointing.

A factory audio systems that does happen to include a subwoofer is often limited in the amount of power available for the sub. The subs themselves are typically small, and the speaker cones can’t move very far to produce sound. Finally, the enclosures are often extremely compact, further limiting low-frequency sound reproduction. These limitations combine to produce bass that, if it seems to exist at all, won’t play very loud, doesn’t play very deep, and lacks clarity and definition.

Retail To The Rescue!

A specialist car audio retailer can work with you to design a subwoofer system that can offer an octave or two more low-frequency output. With the availability of subwoofers designed specifically to fit into small enclosure volumes, these subwoofers can be hidden inside storage compartments, inside your spare tire or in the footwell of almost any vehicle. Gone are the days when all your storage space has to be sacrificed for great sub-bass.

Before we delve into how to pick a sub, don’t let the stereotype of “booming bass” sway you from adding a subwoofer. Just as every home theater system includes a subwoofer to accurately reproduce low frequencies, the addition of a subwoofer to your vehicle will add accuracy and realism. Subwoofers make your music sound bigger and more lifelike by letting you hear and feel frequencies as low as 20 Hz. A sub also takes the load off the smaller door and dash speakers that aren’t capable of making accurate or deep bass.

Starting The Process

Before you head out to your local car audio specialist to inquire about a subwoofer system, there are a few things you should do. Accurately quantify your goals for the subwoofer – are you looking to “warm up” the system, are you trying to rattle your fillings loose or something in between? It’s important that you know what you want. A properly designed system with adequate speaker cone area and power will sound dramatically better than an undersized system pushed to its limits.

As with any purchase, have a rough idea of your budget ahead of time. Consider that there will be some installation cost and additional expenses for wiring for the amplifier and vehicle integration.

Finally, have a look at your vehicle and consider how much space you want to dedicate to the subwoofer system. As mentioned, it doesn’t need to be much these days, but every subwoofer needs a proper-size, properly built enclosure.

Auditioning Car Audio Subwoofers

Listening to a subwoofer in a vehicle is highly useful. The small space inside the vehicle boosts low frequencies more than a larger listening room. Once you have established a reference for how a specific subwoofer in a specific enclosure sounds in the vehicle, then you can listen to different options in the showroom for changes compared to that reference.

As with any listening session, you will want to use music you are familiar with, preferably something you have listened to dozens, if not hundreds, of times. In the case of a subwoofer, the performance of the speakers that are playing with it can affect the perception of its quality, so choose something similar to what you will be using. You will want to focus on three aspects of the subwoofers performance: frequency response, how loud it will play and how accurate it is.

Regarding frequency response, you will want to listen to how loud different frequencies are. Some subwoofers produce a lot of energy in the 50–70 Hz range, some between 30 and 50 Hz, and some play well below 20 Hz. You need a find a balance that accurately reproduces your music and meets your performance goals. High-quality subwoofers can be very musical, accurately defining subtle nuances between each different frequency. A pipe organ, piano, harp, bass guitar, contrabassoon and even a tuba all play into the range of a common car audio subwoofer. In fact, some male voices extend down to 65 Hz or lower. The best subwoofers offer smooth and extended frequency response while remaining tight and dynamic.

Quantifying how loud a subwoofer will play has a great deal to do with what type of enclosure it is installed in, and how much power you have to drive it. The limiting factor on output is cone area and how far the speaker cone can move – we call this excursion. Without accurate measurement equipment, all you can do is decide if the combination of the subwoofer, amplifier and enclosure you have chosen meets your needs.

A Word On Car Audio Subwoofer Enclosures

There are four common ways of installing a subwoofer in a vehicle. If you have a trunk, you can have your installer create a baffle that separates the trunk from the interior of the vehicle, and install the subwoofer in that baffle. That is known as an infinite baffle installation. You need a subwoofer that was designed specifically for that kind of application.

More common is a sealed enclosure, known formally as an acoustic suspension enclosure. These are forgiving regarding their volume requirements and can offer very smooth frequency response when combined with the output gain that most vehicles offer.

Perhaps the “most fun” of all subwoofer enclosures is the ported design, known as a bass reflex enclosure. In these, which are larger than a sealed enclosure, there is a vent of a specific area and length that uses the back-wave (sound coming off the back of the subwoofer cone) to help reinforce the output. You get more bass output for the same size subwoofer.

Finally, the most complex of enclosures commonly used is the bandpass design. In these, the enclosure acts to filter out high-frequency information. These enclosures sound the best when you have great-quality midbass drivers in the system.

An entire article could be dedicated to the benefits of one enclosure design over another, but your car audio retailer can help steer you toward the correct one for your application.

If you are thinking of upgrading your car audio system and you do not already have a subwoofer, drop in at your local car audio specialist right away! There are enclosures not much larger than a shoe box that can make a dramatic difference in the way your system sounds. If you want something more significant, that is easily arranged. Take along your favorite music and have a listen. Adding a subwoofer not only makes a huge improvement, but can be a lot of fun!

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.

One of the most critical components in a high-quality vehicle entertainment system is your car audio amplifier. While the concept of increasing the power of an audio signal is simple, it can be somewhat complex to execute elegantly the process. Amplifier design is as much as science as it is an art form. In this article, we will look at everything you need to know to buy the right amplifier for your system.

How We Measure Car Audio Amplifiers

For more than 100 years, people have been using amplifiers to take a small audio signal and increase its power so it can move a speaker. We measure an amplifier’s capacity to do work in watts. Before the industry had a reference set of guidelines for measuring amplifier power, we would see outrageous claims from otherwise minuscule products. The Consumer Technology Association (formerly the Consumer Electronics Association) has worked with industry experts and manufacturers to produce a set of standards to allow the power produced by different brands, makes and models of amplifiers to be comparable. This standard is currently known as CEA-2006A. When you see the associated logo on a product, you can be confident that the power specifications are real and directly comparable.

Features Help Increase Performance

Modern car audio amplifiers are equipped with many different features. These can include crossovers, bass boost circuits, remote level controls and equalization. Crossovers allow your installer to limit the range of frequencies that the amp will reproduce. In the case of a subwoofer amplifier, we can send the entire audio spectrum to the amp. With a low-pass crossover set, only those frequencies below the crossover point will be amplified and sent to the speaker. A high-pass crossover does the opposite, sending only high-frequency information from the input to the output of the amp.

Limiting which frequencies pass through the amplifier allows the speakers to operate within the frequency range for which they were designed. You wouldn’t want bass information to be sent to your tweeters, nor would you want midrange and high-frequency information to be sent to your subwoofer. Almost every car audio amplifier includes crossovers.

Infrasonic or subsonic filters and bass boost controls are additional tuning options that can be used to help maximize the performance of a dedicated subwoofer amplifier. A remote level control – something also found on most subwoofer amplifiers is a volume control for the amp that can be mounted in the front of the vehicle. This control gives you the option of fine-tuning the amount of bass right at your fingertips.

Auditioning a Car Audio Amplifier

Quantifying the performance of a car audio amplifier can be very difficult. The speakers connected to the amplifier are an infinitely bigger contributing factor to how a system sounds. To properly audition an amp, you need to compare it to another using the same set of speakers. A display board in a car audio specialty retailer is a great way to do this. You will want to ensure that the volume level of all amplifiers is the same for the comparison to be valid.

How can the design of an amplifier affect the way it sounds? There are always exceptions, but for the most part, whether the amp is a Class AB or Class D design can have an effect on the high-frequency performance. Class AB amps are often more detailed in the highest of frequencies. Switch back and forth between amplifiers on a display and listen to the ring of a crash or ride cymbal, or that of a triangle. You want to hear clarity and detail.

At the opposite end of the spectrum, the impact and definition of lower frequency information can show off differences in the design of an amplifier’s power supply and the way the amp behaves when amplifying a complex signal. What you want to listen for is the perceived “speed” of the car audio amplifier. When a drummer hits the rim of a tom with his stick or the skin of the bass drum with the pedal, you want be startled. It should be very tight and controlled. The sound should be clear and natural.

One thing you don’t want to hear is warmth. While this goes against what many people perceive as good, warmth can be a sign of even-order harmonic distortion. The best amplifiers don’t change the sound; they just make the signal louder.

What’s Right For You?

When it comes to choosing an amplifier for your mobile entertainment system, the right amp for you is the one that fulfills your system requirements. A four-channel amplifier has always been a great starting point for system upgrades. They can be used to run four speakers and a subwoofer. If a dedicated subwoofer amp is added later on, that four-channel amp can do an even better job of powering those same four speakers. A lot of specialists like to use a four-channel amp to power a set of midrange tweeters and some form of electronic crossover to split up the audio signal between the two.

Amplifiers are available with one to eight channels at power levels from 35 watts per channel to almost 20,000 watts. Always make sure you have enough power for your system. If saving for another few weeks will let you purchase a more powerful amp instead of one that is “just enough,” it is well worth waiting.

The Latest And Greatest

In the past few years, many companies have introduced car audio amplifiers that include powerful DSP processors. These signal processors provide your installer with more control over system crossovers and add time-alignment and advanced equalization options. In the hands of an expert installer, this can add amazing accuracy and realism to a system. When tuned properly, they are the icing on the cake!

A Word About Installation

While car audio amplifiers seem like one of the easiest components to install in a vehicle, the challenge of sourcing a proper audio signal for that amp from a factory radio and dealing with varying current delivery challenges found in today’s automobiles can make proper installation difficult. Having an experienced technician at a car audio shop install and configure your amp is highly recommended. In many cases, manufacturers offer an extended warranty when their products are installed by an authorized dealer.

Visit your local car audio specialist retailer and bring along your favorite music. Listen to as many different amplifiers as you can, then choose the one that meets your system needs, your performance goals and your budget.

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.

For decades, there has been discussion after discussion about which of the different subwoofer enclosures are “the best” and why. Let’s take a look at why we need a subwoofer enclosure at all, and how the three popular styles – sealed, vented and bandpass – differ in their design and performance.

Back-Wave Management

If you were to hook any speaker up to an amplifier, hold it in your hand and play music into it, you would find that you don’t hear any bass. That is because the sound coming from the front of the speaker cancels out the sound coming from the back. We need a way to keep the sound coming from the back of the speaker cone from interfering with the sound coming from the front. If you were to cut a hole in the middle of a large, flat piece of wood and mount the speaker in it, you would hear a lot more bass. In fact, until the half-wavelength of the bass frequencies becomes longer than the dimensions of the piece of wood, you will get really good, solid bass. If we put a speaker in an airtight enclosure, none of the sound coming from the back interferes with the sound coming from the front.

Power Handling

The ability of a speaker to use the power produced by an amplifier is limited by two criteria – how far the speaker cone can move and how much heat the voice coil of the speaker can handle. Thermal power-handling limitations are based primarily on the design of a speaker – the size of the voice coil, how airflow is managed around the voice coil and the proximity of the stationary components of the motor assembly to the voice coil are the key contributing factors. The excursion-limited constraints are also part of the speaker’s design – how long the voice coil winding is, how tall the top plate is and how much suspension travel is available are the key factors.

Excursion

When it comes to reproducing bass, a speaker has to move four times as far each time the input frequency is halved. For example, a speaker moving 0.125 inches at 100 Hz has to move 0.5 inches to reproduce the same output level at 50 Hz and 2 inches at 20 Hz. You can see that, for the lowest of frequencies, cone excursion limitations are significant – very few speakers can move 2 inches without significant distortion.

When we put a speaker in an enclosure, the combination of the enclosure and the speaker create a high-pass filter. We are effectively decreasing the low-frequency output of the speaker. Why would we want to do this? The benefit of an enclosure is that we can control the motion of the speaker cone. Looking at a simple acoustic suspension (also known as a sealed) enclosure will be the simplest illustration of this explanation.

Compliance

Each and every speaker – from the biggest of subwoofers to the smallest of tweeters – has a springiness to the cone. We call this the compliance. We measure compliance by comparing it to a volume of air with the equivalent springiness. We call this characteristic of the speaker Vas. In general terms, a speaker with a very small Vas specification has a tight suspension, and a speaker with a large Vas has a softer suspension. There is a lot more to it than that, but for the discussion of enclosure features and benefits, that’s all we need to get into for now.

When we put a speaker in an enclosure, we stiffen the suspension. When you push in on the speaker cone, you are pushing against the speaker’s suspension (which wants to center the cone) and you are trying to pressurize the air in the enclosure. When the cone tries to move outward from rest, you are putting the air in the into a vacuum state – it wants to pull the cone back to its resting position. We do sacrifice low-frequency output, but we gain significant power handling and control over the motion of the speaker cone. For the latter, the combination of the air in the enclosure and the speaker suspension helps to stop the speaker cone from moving once an electrical signal starts it in motion.

Think of it like a shock absorber on a vehicle. You can see that having an enclosure is critical.

Acoustic Suspension Subwoofer Enclosures

The simplest of enclosures is called an acoustic suspension or sealed enclosure. In these enclosures, we are putting the speaker into an airtight box. When we put a speaker in an enclosure, the system resonates at a specific frequency that – we call this Fc. Below that frequency, the output is reduced at a rate of -12 dB per octave. If the system has a resonant frequency of 50 Hz, the output will be 12 dB quieter at 25 Hz.

Acoustic suspension enclosures are amongst the smallest of the different enclosures we will discuss. They are also the easiest to construct, and most forgiving regarding calculation error. If you combine the roll-off of the enclosure and speaker system with the increase in efficiency you get from the relatively small air volume of the vehicle interior (often called transfer function or cabin gain), you can get a very flat in-car response with good infrasonic output. Bass from an acoustic suspension enclosure is very tight and controlled, thanks to excellent transient response.

There is a down side. If you are looking for loud bass, then you need a driver that has a lot of excursion capability, and you need a reasonable amount of power to move the speaker cone back and forth to get the level of output you want. There is another drawback that isn’t talked about as much, and that is distortion. As a speaker increases in excursion, the amount of distortion it creates increases. Likewise, distortion increases near the resonant frequency of the speaker. So, what can you do?

Bass Reflex Subwoofer Enclosures

A bass reflex (also known as ported or vented) enclosure uses a vent to increase low-frequency output by making use of the speakers back-wave energy. The vent, often a round tube or sometimes a rectangular slot, has an area and a length. The specific area and length of the vent and their relationship to the total volume of the enclosure cause the column of air in the vent to resonate at a specific frequency when excited by the speaker. We typically tune bass reflex enclosures quite low to emphasize the bottom octave or so of the audible frequency range. They can be tuned higher to increase efficiency for high-SPL applications. There is always a sacrifice, though – when we tune the enclosure higher, we sacrifice low-frequency performance.

Bass reflex enclosures are typically larger than sealed enclosures. There is no hard-and-fast rule to associate with the size relationship, but 25–50% large is common. The trade-off for that extra volume is two-fold – more efficiency in the tuning frequency and more power handling, at some frequencies.

When the subwoofer used in a bass-reflex subwoofer enclosure produces frequencies around the resonant frequency of the vent/enclosure combination, the driver excursion is reduced to almost nothing and all the “work” is done by the vent. Put more succinctly, around the tuning frequency, most of the music is being produced by the vent. The benefit to this is that power-handling problems caused by cone excursion limitations are dramatically increased. Since the cone is barely moving, very high sound pressure levels can be achieved. Around the tuning frequency, power handling is limited by the thermal capabilities of the subwoofer.

As we mentioned earlier, one factor that contributes to loudspeaker distortion is cone excursion. With a bass reflex enclosure, the driver moves significantly less than with an acoustic suspension enclosure design. As long as the vent itself has enough area and a smooth transition at both openings, the distortion produced by a properly designed bass reflex enclosure can be impressively small.

Nothing is free, is it? A factor in deciding to use a bass reflex design is how fast the output decreases below the tuning frequency. Where an acoustic suspension enclosure rolls off at -12 dB per octave, a bass reflex enclosure rolls off at 24 dB per octave. Below the tuning frequency, the vent acts more and more like a hole in the enclosure, offering increasingly less back pressure as frequency decreases. Designing for, and managing, driver excursion is a fundamental part of bass reflex enclosure design.

Bandpass Subwoofer Enclosures

We will quickly touch on bandpass enclosures to wrap up this article. There are several different designs for bandpass enclosures. Some use a sealed enclosure, and some a vented one. Independent of whether the rear chamber is sealed or vented, the output of the subwoofer plays into a vented enclosure. This enclosure acts as a low-pass filter. Why would we want to design a bandpass enclosure?

First and foremost, all of the output of the enclosure is produced by the vent or vents. This allows a creative designer to build an enclosure in the trunk of a vehicle and have the vent opening play through the rear parcel shelf. There have been some amazing bandpass enclosures build in the front storage area of mid- or rear-engine vehicles. The vent allows the bass to enter the interior of the vehicle. Bandpass enclosures can also offer impressive gains in efficiency over acoustic suspension and bass reflex enclosures, but they do so at the sacrifice of bandwidth and enclosure volume.

A bandpass enclosure has two resonant frequencies – one for each of the enclosures. The resultant management of cone excursion can allow a great deal of bass to be produced from limited excursion drivers. While the speaker cone itself does not move a great deal, the amount of work done by the motor assembly is still significant. You are still putting power into the speaker, and work is being done. Because the front chamber of the enclosure acts as a filter, it can also be very difficult to hear when the speaker is distorting.

Regarding the complexity of design, and forgiveness of construction error, bandpass enclosures are the most complicated to execute perfectly. Unlike an acoustic suspension or bass-reflex design, bandpass enclosure designs must be tailored exactly to the speaker they are being used with. Never trust the concept of a “generic” bandpass enclosure.

Lastly, because a bandpass enclosure includes an acoustic low-pass filter, it has to be used with good-quality, appropriately sized midbass drivers. If not, the bass can sound lost or disconnected relative to the rest of the music.

For More Details On Subwoofer Enclosures, Visit Your Local Specialist

As you can see, there are many ways to install a subwoofer – or any speaker, for that matter. Navigating the available space in the vehicle, as well as different speaker sizes and designs, can be tricky. The design and construction of an enclosure can be complex, especially when complex shapes are involved. Visit your local car audio specialist retailer to explore different enclosure options for your vehicle.

This article is written and produced by the team at www.BestCarAudio.com. Reproduction or use of any kind is prohibited without the express written permission of 1sixty8 media.

When it comes to high-current wiring in a vehicle, there are two types of stranded power wire available: solid copper and copper-clad aluminum. This article looks at the differences between each kind of wire, and explain the challenges of ensuring your high-current device gets the power it needs to do the job you want done.

Car Audio Power Wire: Background

In mobile applications, or anywhere that a conductor may be exposed to movement or vibration, it is recommended to use only stranded conductors. Solid conductors (like single-strand house wiring) may offer slightly more conductor area for a given wire diameter, but over time, the solid wire can work-harden, become brittle and eventually break from repeated back-and-forth motion. Imagine using large-gauge solid copper wires in the wire boot in a door jamb or to your trunk or hatch lid. That is a recipe for disaster.

The term OFC (oxygen-free copper) has become abused and is used synonymously with solid or all-copper conductors. In actuality, OFC is a type of solid copper. When molten copper is cast and drawn into a conductor, the process to make an OFC conductor reduces the oxygen content of the wire. If all is done perfectly, the copper-oxygen content is around 42 parts per million (PPM) vs. a conventional copper with content that is roughly six times that amount.

In the mobile electronics industry, there is no way to know if the solid copper conductor you are purchasing is oxygen-free or not unless you can witness the casting process in person. Everyone in the industry uses “OFC” for a piece of wire that is not copper-clad aluminum (CCA).

Looking at the alternative, we have CCA conductors. In these conductors, the core of the wire is a cylinder of aluminum and around it is a layer of copper. From the side, it looks like copper, but if you cut off a piece and look at the end, you can see the gray aluminum content.

There are further variations. Some companies manufacture all-copper strand wire but coat the outside of each strand with a thin layer of tin to help prevent corrosion.

Car Audio Power Wire: Size

When it comes to flowing electricity, or, more specifically, flowing electrons, the most important thing to consider is wire size. In the mobile electronics industry, we use the American Wire Gauge (AWG) standard. This sets a specific diameter for a conductor. It’s not a debatable number – the conductor either meets the standard or it doesn’t.

Here is where the games begin. There is a second term used in our industry: gauge. In the steel sheet industry, gauge is an important tool for specifying material thickness. In car audio, it means nothing. If you have been around the industry for any amount of time, you will have seen wires that claim to be 0 gauge but have a conductor area equivalent to a 6 AWG. If a wire is labeled as 4 gauge, then sadly, you have no way of knowing how big it is, other than attempting to measure it.

Cutting a wire and looking at the area also doesn’t always tell the story. Some wires are wound quite loosely. This makes the wire very flexible, but does so because there is space around the strands. You sacrifice effective cross-sectional conductor area for flexibility.

Car Audio Power Wire: Materials

In solid copper stranded wire, we ideally want everything to be pure copper. That said, pure copper is quite expensive, even though the cost of pure copper has come down over the past few years; it currently sits at around $2.00–$2.25 a pound on the commodities market. When a manufacturer wants to purchase wire, there are many options: strand count, how the strands and bundles are woven, how tightly they are woven, and so on. Manufacturers also have a choice in the “kind” of copper they make the conductors with. It could be pure copper, recycled copper or a copper alloy. Again, you have no way of knowing unless you are witness to the process.

Don’t let the variations in copper scare you. A solid copper conductor always outperforms a CCA conductor. The biggest challenge with car audio CCA wiring is that it does not, and will not, specify the ratio of copper to aluminum. There are publically displayed measurements of different CCA wire samples where a smaller-diameter wire outperforms a slightly larger wire because it has less aluminum and more copper. Unless you measure it yourself, you just don’t know.

On its own, pound for pound, aluminum has about 60% more resistance to the flow of electricity. When we talk about CCA wire, there is some copper in there; in most cases, the difference diminishes to 30 to 40%.

Car Audio Power Wire: The Challenge

When you look at car audio wiring, there is no way to know what you are getting with a CCA amp kit or roll of wire. Some manufacturers make CCA wire that functions nearly as well as solid copper. In fact, one company makes an oversized CCA that has less resistance per foot than solid copper. The downside is that the wire doesn’t fit into a lot of connectors or terminal blocks. Overall, unless you want to take the time to measure the properties of the kit you are buying, it is better to stick to solid copper.

From the standpoint of long-term benefits, solid copper wire resists corrosion much better than CCA wiring. In climates where road salt or brine is used in the winter to keep surfaces clear of ice, we have seen instances where unprotected CCA power wires have failed completely in less than two years. Why risk the performance of your audio system, when you can simply choose the solid copper wire?

How do you know if you are getting something good? The Consumer Technology Association (formerly the Consumer Electronics Association) has developed a standard for wiring. It is called CTA-2015 (formerly CEA-2015) specification. It describes the minimum standards for wiring for use in mobile electronics applications. The standards include that the wire must be stranded solid copper, the minimum number of strands for a given AWG wire size, and the area of the wire and its maximum resistance. If you stick to the brands that support the CTA-2015 standard, you should never have any problems.

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.

For decades, car audio enthusiasts have been fiddling around with the gain control on their amplifiers in hopes of “getting more out of them.” Many professional installers have scientific, repeatable processes in place to ensure these controls are set to provide the maximum performance and reliability from your audio system. Let’s look at the most misunderstood, and most often adjusted, control on car audio amplifiers – the gain control.

What Is a Gain Control?

When a manufacturer decides to develop an amplifier, they need to decide how many channels it will have, how much power it will produce, what additional features it will include and what source units it will work with. Because modern source units have maximum preamp output voltages that range from 1.7 to 5 volts, amplifiers have to be adjustable to make their full rated power when driven with these signals.

Let’s make up an example: Imagine a 100 watt mono amplifier that was designed to produce full power (100 watts) when it receives 2 volts of audio signal. This is a reasonable amount of signal gain, but leaves us open to two significant problems. What if we want to use this amplifier with a source unit that can only produce 1.7 volts? We can’t get the amplifier to full power even with the volume control on our radio turned all the way up. In fact, we only get 72.25 watts out of our amplifier. On the flip side, if we have a source unit that can put out 4 volts of signal, then the amp would attempt to make 400 watts with our fixed gain setting. Since the power supply of the amp was only designed to provide enough voltage to produce 100 watts, the signal would be severely clipped and distorted, and there is a great chance that the amplifier and your speakers might be damaged.

The Solution

For a single amplifier to work with multiple sources, amplifier manufacturers have to make the input signal level adjustable. We call this the gain or sensitivity control. It doesn’t adjust how much power the amplifier will make, but it does adjust how much of the input signal the amp uses to make full power.

There is a secondary reason for adjustability: Not every speaker has the same sensitivity. This means that sometimes you have more power than you need. Let’s say your front speakers produce 90 dB of output from 1 watt of power, but your rear speakers are much larger and produce 93 dB of output from the same 1 watt of power. For them to appear to be of equal loudness at the listening position, we only need half the power to the rear speakers. We turn down the sensitivity of the rear channels of an amplifier to balance these out.

Making Gains (Using Your Gain Control!)

Your installer may use one of many different processes to adjust the gain controls of your amplifier. We want the gain controls to be as low as possible, but still allow you to get full power from the amplifier. Why do we want the gain low? That is, perhaps, the fundamental key to this article.

We want the amplifier to accept an input signal with as much voltage as possible for it to produce full power. Having more voltage on your interconnect cables helps drown out noise. Less amplifier sensitivity (lower gain setting) also helps to reduce noise. When the amplifier gains are set properly, you get full power from your amp without unnecessary hiss or background noise.

There are four common methods for adjusting gain controls: by ear, with a small amplified speaker, with an oscilloscope or with a distortion detection device. Setting by ear with music is very difficult and can lead to inconsistent settings. That being said, if your installer uses a test tone, the “by ear” process can work quite reliably. Using a small amplified speaker is similar to that process – there is a test tone, but the small speaker allows your installer to check the preamp signal from the source unit, and in and out of any signal processors.

Using an oscilloscope to set an amplifier’s gain control is one of the best ways to get an accurate reading. Oscilloscopes work for any frequency, so they are very flexible. Your installer can see exactly when the amp has reached its peak voltage.

Finally, companies like D’Amore Engineering and SMD have developed products designed specifically for mobile electronic installers to check for signal distortion on preamp or speaker signals. All you have to do is plug the device in and turn it up until the red Distortion LED comes on. Bam – done! A word of warning on these devices, though: They are very accurate and can detect distortions other than signal clipping. Many product design problems have been found when attempting to set gains with these.

How Can You Check Your Gains?

If the sensitivity controls on your amplifiers are set properly, you should be able to get your amplifiers to distort a little bit with the source unit at full volume. If you are wondering why a properly set amplifier will distort, that’s a great question. It’s called gain overlap. We want to have a little extra sensitivity in case we are playing a song that is recorded quietly. A great example of this is the well-known “Brothers In Arms” album by Dire Straits. It needs a good 5 extra dB of gain to get rocking. In fact, the original 1985 release from Warner Brothers Records had several songs where the loudest part of the song was below -5 dB. “Why Worry” has a peak level of -13.27 dB. A nightmare for an installer trying to set gains, but, luckily, that’s not a song most people rock out to.

If you can’t turn your volume control past halfway without your amplifiers running out of power (distorting), then it’s time to visit your local mobile electronics specialist. Likewise, if you hear a significant amount of hiss at low volume levels, then you likely need an adjustment.

Properly set gain controls won’t make your system quieter, and turning up the sensitivity doesn’t make your amplifier more power. Gain controls exist to ensure that your system is always working the best it can. Please leave them alone, or ask your installer about how they are set.

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.