We’re back with the second of four articles discussing the listening experience of truly high-end car audio systems. In our first article, we discussed the importance of accurate frequency response. This second article will discuss the soundstage, provide a definition for it and explain why it’s crucial to recreating a recording accurately.

What Is a Car Audio Soundstage?

We need to define what a soundstage is before we get into describing the intricacies of how to evaluate one. Essentially, we’re talking about where the sound comes from in a vehicle. In a poorly executed system, the music might appear to come from each speaker. This is likely because of a lack of level adjustment, improper signal delay settings in a signal processor or a difference in frequency response between one side of the vehicle and the other. Most basic car audio systems with a radio and one or two pair of speakers deliver sound that seems to come from the speaker closest to the listening position.

As a system’s quality improves, the attention to detail in configuring and calibrating the equipment should also improve. Proper calibration will yield the best performance possible from even the most modest audio products.

We’ll be clear in saying that finding a mobile electronics retailer that is experienced and proficient in designing, integrating, configuring and calibrating an audio system so that it delivers what we’re describing is no easy feat. Some retailers still think digital signal processors are magic black boxes filled with voodoo. If accuracy, realism and detail are the goals of your car audio system, you’ll have to visit many retailers and audition their demo vehicles to find one that can deliver the performance you want. Don’t trust statements. Listen to their work and judge for yourself.

Soundstage Options

Before describing what to listen for in the perfect audio system, we should clarify that listening preferences play a significant role in system design and calibration. The standard for the ideal audio system is to recreate what seems like a live performance in front of the listener. This applies to both home and car audio systems. Many car audio enthusiasts prefer to be immersed in the center of a listening experience. This would replicate a listener’s experience at a dance club or when wearing headphones. The music is all around them, and while there are well-defined left and right channels, it fills the listening space. There is no right or wrong in terms of a client’s preference.

Many car audio retailers fail to qualify their clients’ expectations in this regard. Do you want the music to sound like it’s coming from the front of the vehicle or from all around you? Harman International includes an option in some factory-installed sound systems that allows the listener to switch from an “in audience” to an “on stage” experience. While the concepts are similar, we’ll refer to that in-audience experience for this discussion.

Music Source

In an audio system that is designed, integrated, configured and calibrated perfectly, all the music should seem to come from a well-defined location in front of the seating position. In most cases, this can be described as the windshield, as though it had speakers built into it. Some genuinely magnificent systems can create a soundstage that extends beyond the physical limits of the vehicle. We’ve heard cars that present sounds that extend beyond the left and right speaker positions and others that made it sound like Neil Young was standing in front of headlights.

What’s key is that the sound source is coherent. If your music comes from the dash or windshield, all the music should come from that location. The midbass shouldn’t seem to come from the steering wheel or the footwells. The bass shouldn’t come from the back of the vehicle. Specific frequencies shouldn’t move up or down. Think of it like having a set of high-end, full-range speakers in front of the vehicle, positioned so the left speaker is aligned with the left A-pillar and the right speaker is aligned with the right A-pillar.

Delivering Amazing Audio Performance

The key to achieving the goal of delivering an accurate sound source starts with the system design. If all of the speakers are behind the listener, it will be impossible for the system to sound as though the music is coming from in front of them. This overly dramatic statement gets at the core of proper system design.

Next, the speaker selection must deliver smooth dispersion through the listening environment. Let’s say you have a set of 6.5-inch component woofers mounted in the doors and a set of 0.75-inch tweeters on the dash. In this case, the system will be sensitive to the listener’s location because the woofers must play to frequencies well beyond where it becomes directional. This is why higher-end speaker manufacturers offer large-diaphragm tweeters that can play to lower frequencies.

Managing directivity is only the first part of the component selection process. The second involves choosing products with features that minimize distortion. As we demonstrated in our series about speaker performance, some drivers add significant second- and third-harmonic distortion. If the door speakers are playing up to 2 kHz, the harmonics could extend to 6 kHz, resulting in the soundstage being pulled down to the footwell.

The same concern goes for subwoofers. Imagine a crossover frequency of 75 hertz. This means the second-order harmonic is 150 hertz, and the third is 225. If you choose a subwoofer without a low-distortion design, you might have issues creating a stable and coherent soundstage. Few car audio companies focus on linearity and distortion in their subwoofer products. Do your research and choose wisely.

Car Audio System Calibration

You will need a digital signal processor if you want a car audio system with a well-defined soundstage. A few source units from Sony include enough processing to handle proper configuration. Alternatively, you can choose an amplifier with a built-in DSP or a stand-alone DSP that will work with your existing amplifiers.

Three features in the DSP require proper calibration to align the output of all the speakers in the vehicle. Of course, this only works if all the speakers have dedicated amplifier channels assigned to dedicated channels on the processor. If you have a component set on a single channel with a passive crossover, the ability to fine-tune the system will be diminished. Ideally, the tweeters and the woofers need dedicated processing and amplification channels.

The technician calibrating the system needs to set delays, output levels and equalization properly for each channel. The delays and levels compensate for the different distances to each speaker in the vehicle. The equalization compensates for resonances and cancellations in the vehicle because of reflections off various surfaces. In this context, equalization isn’t intended to improve frequency response, though proper settings simultaneously handle staging and system tonality considerations.

Table for One, Sir?

We skipped over another consideration when creating a soundstage: Do you want the system optimized for the driver or for everyone in the vehicle? The latter is often referred to as a two-seat tune.

If you listen to an audio system configured for a single seat, the location and size of the soundstage, as perceived from the front passenger seat, often suffer. The resulting sensation can vary from being slightly compressed to sounding like all the music comes from the far-right speaker location. Creating a two-seat calibration is time-consuming and often doesn’t sound as coherent as a single-seat tune. However, if you always have someone in the vehicle with you and they care about how the music sounds, it’s worth requesting.

This request might involve using or adding a center-channel speaker. If the signal processor has dedicated center-channel processing, this can work well. However, be sure to ask whether the center-channel signal contains any information found in the left and right channels. If it does, the effect usually narrows the soundstage significantly. Very few processors have full up-mixing capabilities for a center-channel output.

Soundstage Problems – Bass in the Back

Here are a few common problems with the soundstage in car audio systems. The most prevalent issue is not getting the bass to mix with the front-stage speakers. Your system might have a good soundstage for midbass through high-frequency information, but the deeper bass seems to come from the trunk or cargo area.

This issue can sometimes be solved by better calibrating the crossovers and delays between the midbass drivers and the subwoofer. Sometimes, though, this is a distortion issue with the subwoofer(s); the only solution is to upgrade them.

Soundstage Height Issues

Another common problem is that different frequency ranges come from different heights. If the vehicle has a two-way speaker system and the tweeters can’t play low enough, the midrange and midbass sounds seem to come from the lower part of the dash, while the higher frequencies come from the windshield.

Improving this with a steep filter and a lower crossover frequency on a tweeter might be possible. However, the proper solution is a much larger tweeter, or better yet, switch to a three-way system that uses a midrange up high on the dash or in the A-pillars.

Compressed-Width Soundstage

You might also experience a soundstage that’s much narrower than the vehicle width or where one side doesn’t extend as far to the opposite side. This can make the stage seem unrealistic in relation to the vehicle boundaries. It’s akin to the band congregating on the left (or right) side of the stage but never spreading back out.

The solution to this issue could be complicated. It might be level or delay-related. It can also be a speaker placement issue, which makes it harder to resolve without revisiting the installation.

Drooping Soundstage

Though it’s less common now that kick-panel speaker locations are less popular, another possible soundstage issue is a rainbow or drooping stage. In this case, the center image might be in the middle of the windshield under the rearview mirror. However, the left and right extremes might drop into the kick-panel area. The solution is similar to the fix for frequency separation.

No Sense of Depth

This last issue is a mix between a soundstage issue and an imaging problem. Imaging refers to the placement accuracy and size of instruments on the soundstage. Does the singer’s voice sound like it’s the size of a pizza pan, or is it more like a tennis ball? Are all the instruments placed in accurate and precise locations on the soundstage? The issue we’ll discuss is a soundstage with no sense of depth. You might see why this is a staging and imaging issue.

Not all recordings contain a sense of depth or layering. If you listen to a purely electronic recording, you will likely hear a wall of sound unless they’ve done some fancy tricks with phase adjustments. If the recording is of a band, choir or orchestra, and stereo microphones are used to pick up the space in the hall, a good car audio system should be able to recreate this sensation. If your system doesn’t present any sense of depth, it’s usually an issue with the channels not being calibrated equally.

Experience Your Music Like Never Before

If your car audio system doesn’t have a solid soundstage, drop by a local specialty mobile electronics retailer today. Start by auditioning their demo vehicles to see whether they can create an experience you will enjoy. Bring along your favorite music and listen to a half-dozen tracks. Pay close attention to where the music is coming from. Everything should seem to come from the windshield. The bass, vocals, guitars, drums – all should be coherent and realistic. If the vehicle doesn’t deliver, don’t fret. Find another shop and audition their work. Even once you’ve found what you think is the perfect solution, it’s often a good idea to listen to as many vehicles as possible to get a reference for tonal balance, soundstage, imaging and dynamics. Imaging will be the next topic in this series. Stay tuned!

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

In the 1980s, most car stereo shops had charts in the install bays that showed what size power wire should be used with different amplifiers. Some charts were based on current and cable length, while others suggested amplifier power ratings and lengths. In all cases, an essential piece of information was missing. Today, we’ll sort that out. Let’s consider why we need large power wires, what factors affect the current draw, and how to select the wiring that’s the right size for your car’s audio amplifier.

Low-Voltage Electrical Systems

Most cars, trucks, boats and motorcycles operate on a 12-volt electrical system. The battery should rest between 12.2 and 12.6 volts when the vehicle isn’t running. Depending on the application, we might see 13.4 to 14.6 volts when the alternator charges the battery. These voltages might be slightly higher if your vehicle uses an AGM battery.

Power is the product of voltage times current. So, if a load like an amplifier or light needs 100 watts from the 12-volt electrical system, it will draw 8.3 amps of current. If we want 1,200 watts, we need 100 amps of current. This is Ohm’s law at its most basic.

Now, if we had the 120 volts we find in our homes and offices, the current draw for 100 watts would only be 830 milliamps. A load of 1,200 watts would only draw 10 amps. The amplifier might have a 240-volt supply if this was a concert or sizeable public-address application. If so, it would only draw 415 milliamps of current at 100 watts and 5 amps at 1,200 watts.

Here’s the problem with large amounts of current flowing in electrical conductors. The formula to calculate power is Current squared times Resistance. If we have a conductor with 10 amps of current flowing and 0.005 ohm of resistance, a voltage drop of 50 millivolts will be present across the wire, and 0.5 watt of energy will be wasted as heat. If that current draw increased to 20 amps, the heat wasted in the wire jumps to 2 watts. At 50 amps, 12.5 watts of energy is wasted in the wire; at 100 amps, there is 50 watts. This is the equivalent resistance to 12 feet of all-copper, full-AWG spec 6 AWG wire. Think about how hot a 50-watt incandescent lightbulb gets after being on for only a few minutes.

Cable resistance is why electric utility companies transmit power across the country at levels like 345,000 volts. You can transmit massive amounts of power this way without incurring significant losses from cable resistance.

Amplifier Efficiency Is Crucial

The second item to remember is that no electrical or electronic device is 100% efficient. This means you put more power into the device than you get out. Car audio amplifiers vary dramatically in their efficiency. We’ve seen subwoofer amplifiers offering more than 92% efficiency and others less than 58%. The amplifier’s efficiency plays a massive role in determining how much power it will consume.

Let’s say, for example, the above amplifiers are both rated to produce 1,000 watts of power. The 92% efficient amp would draw about 87 amps of current from a 12.5-volt electrical system. The inefficient amp would draw a comparatively mind-boggling 138 amps to produce the same power. Statements about power cable requirements based on amplifier power ratings need to be scrutinized.

Music and Test Tones

It stands to reason that we want to size the wire in our car audio system for a worst-case scenario. We don’t want to waste energy when we max out the power production capabilities of the amplifiers. However, average power consumption is much lower. We’ve analyzed a good amount of modern music, and the average power level is around 7.5 dB below the peaks. This means that if we average the power requirements of our amplifiers over the length of a song, they produce less than 20% of their maximum power when set so the peaks reach clipping.

Turn the volume down one notch, and the current requirements will likely drop by half. It stands to reason that we could, theoretically, undersize the power wire significantly and not run into much trouble. We’ve seen dozens, if not hundreds, of large amplifiers installed with woefully undersized power wiring. Is this a “best practice”? Most assuredly not. However, it happens frequently, and most of these installations don’t run into issues. Is there a downside? Yes, the amplifier will likely never make its maximum power rating, so you’re limiting the performance of your audio system.

What Determines Acceptable Wire Size?

The answer to the question, “What wire size is right for my amplifier?” requires that we pick an acceptable amount of waste or loss. Specifically, how much voltage drop is acceptable across the length of the power wire? The ANSI/CTA-2031 standard for car audio power wiring suggests we select power wire based on a maximum voltage drop of 0.25 volt. Given that the resistance of all-copper, full AWG-spec wire has precise nominal and maximum resistance requirements, we can create a table that provides the maximum allowable current in varying lengths of commonly available wires.

The chart above outlines the maximum allowable current for a given wire size (on the vertical scale) and length (on the horizontal scale). For example, if we have 16 feet of 4 AWG wire, we want to keep the maximum current draw to 58.3 amps. Putting that number back into our amplifier efficiency means we can run an efficient 670-watt amplifier or a 423-watt low-efficiency amplifier without exceeding 0.25 volt of drop across the wire.

One common mistake is to think of the values in this chart as a target. They are a worst-case scenario. For example, if you need to provide 60 amps of current to an amplifier, then 16 feet of 4 AWG wire seems about right. What about the ground wire? It only needs to be 2 feet. Would we want 2 feet of 14 AWG wire? Most definitely not. The goal is to have as little resistance as possible in the power wire to and from the amplifier. Use the same wire for all power connections.

Wasted Energy in Wiring

Now, this isn’t the end of the discussion. We always want to know what happens at those extreme limits, right? The chart says we can draw 2,412 amps of current through 2 feet of 4/0 (0000) wire. That sounds like fun! Or does it?

We need to calculate how much power is wasted in the wire. Two thousand four hundred amps is a lot of current. Here’s a second chart that outlines how much power is wasted (as heat) per foot of the conductor.

The chart above shows how much heat is generated if we draw the maximum possible current to provide a 0.25-volt drop through conductors of different lengths. So, our 4/0 cable with 2,412 amps flowing through it will produce 301.6 watts of heat per foot. I don’t need to tell you that the jacket on the wire will melt off quickly. Our calculations show that a bare 4/0 wire heats at a rate of 121 degrees Celsius per minute when producing 301.6 watts. Most wiring is rated for only 105 degrees C. I’m sure you see the problem. Even if we’re way off on our calculations, managing or, more accurately, preventing heat in conductors is crucial in making sure that the wiring in a car’s audio system functions reliably.

Big Wire Is Expensive

While the math checks out, using 16 feet of 2/0 cable for a good ~1,200-watt amp is expensive, right? What if we allow for 0.5 volt of drop across our power wire? Yes, the maximum power out of the amplifier will decrease, and the wire will get hotter. However, it won’t hit our wallets quite as hard. Is the trade-off worth it?

Here are the same charts again with 0.5 volt allowed as the drop.

With the higher allowable voltage drop, the maximum current for a given wire size and length increases significantly. Our 4 AWG wire is supposedly acceptable for 116.5 amps of current or a really efficient 1,000-watt amplifier. The 2/0 cable can supposedly handle 186 amps of current. It would be a good choice for a similarly powerful low-efficiency amplifier.

Wire Size Reality Check

While charts and spreadsheet calculations are interesting, the reality is that there are practical thermal limits that can’t be exceeded. How exciting would 4,800 amps of current through a 4/0 conductor be in creating a fireworks show? The answer is fascinating.

The maximum current a conductor can handle continuously has a lot to do with the environment in which it is used. Under the hood of your car or truck, where it’s likely very hot, the hot wire will heat up even more as current flows through it. This has the effect of increasing resistance. More resistance for a given amount of current means even more voltage drop and more heat being generated.

To put constant current demands into perspective, electric arc furnaces like those used to create steel often use 40,000 to 60,000 amps of current. The conductors that pass this current are sized in the thousands of square millimeters. A 0 AWG cable is 53.5 square millimeters. The furnace cables are usually encased in liquid cooling systems to maintain the conductor temperature. Yes, liquid-cooled conductors.

What Wire Size Does My Car Audio Amplifier Need?

What wire size you need depends on how your audio system will be used, the music you play, and the efficiency of the amplifiers. Rock or heavy metal music is more likely to have dynamic bass information, while rap or EDM is much more likely to have lengthy low-frequency notes. The energy the subwoofer amp requires will differ significantly for these two applications.

If you want to get the most power from your amplifiers, targeting a maximum voltage drop across the longest length of wire of 0.25 volt is a good reference point. If you aren’t as concerned about power as the installation cost, then the 0.5-volt drop chart is an acceptable concession.

Remember that the charts above are based on full AWG-sized, all-copper conductors. If your installer intends to use tinned copper, you might need a one size larger wire. If the wire is undersized or constructed of copper-clad aluminum, it’s anyone’s guess how much current it can handle. Work with a specialty mobile electronics retailer to choose high-performance amplifiers and appropriately sized power wires to ensure that your car stereo sounds great and performs reliably.

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.

High-quality speakers and proper installation are crucial when upgrading your car’s audio system. The ease with which your installer can reliably integrate tweeters into your vehicle will determine a portion of the labor cost. Will the technician need to fabricate a mounting bracket? Will they need to create a little pod? Is there even enough hardware provided to ensure a reliable and safe installation? Let’s look at some tweeter installation hardware solutions.

Why Are Tweeters Important for Great Sound Quality?

Before discussing tweeter installation, we should review the importance of having dedicated tweeters in a car audio system. By definition, tweeters are relatively small speakers designed to play the highest audible frequencies. They vary from 0.5 to over 1.25 inches in size. The larger tweeters can typically play lower frequencies, making them ideal for two-way front speaker systems. However, a large diaphragm might have some resonance at extremely high frequencies.

Tweeters are made from a variety of materials. Textile domes like silk, metal domes like aluminum, titanium and beryllium and plastic materials like polyetherimide are among the most popular. While the metal versus textile performance discussions will go on forever, what’s more important is that the tweeter diaphragm doesn’t have resonance issues. Most companies add a damping material to the diaphragm to prevent this. The damping applies to both textile and metal designs.

Most tweeters in the car audio market use a dome-shaped diaphragm. However, some use a ring-radiator design, like the tweeters in the Rockford Fosgate T4652-S set. The concept of the ring tweeter is to eliminate the chance of resonance in the center of the dome. While it’s unwise to make blanket statements about one design over others, we were very impressed with the clarity of the T4 ring radiator tweeter.

Flush-Mount Tweeter Installation Options

There are four common options for tweeter installation. First, we have flush-mounting. In this type of installation, the tweeter and a grill are mounted in a panel, and the result is basically flush. This means the tweeter may only protrude a few millimeters or 0.25 inch. This type of installation requires that the panel be modified to accept the tweeter, which means a hole between 1 and 1.5 inches must be created.

The most basic reliable tweeter mounting method uses a U-shaped spring-steel bracket that bolts to the back of the tweeter assembly. The bracket must be spring steel to retain tension and hold the tweeter securely.

Some companies have created more complex installation solutions for flush-mount applications. For example, KICKER’s QS-Series speakers include a nut that threads onto the back of the tweeter to keep it pressed tightly against the mounting surface. The legs of the nut can be trimmed to work with mounting surfaces of different thicknesses.

Rockford Fosgate’s Dual Discrete Clamp mounting solution is one of the most elaborate mounting options we’ve seen. The DDC comprises two cast aluminum brackets sandwiched on either side of a mounting surface to hold the tweeter in place. Once the two clamps are secure, the tweeter locks into place, and a trim piece finishes the installation.

Surface Mounting Options

The second type of installation is to mount the tweeters on the surface of a dash or door panel. This is less invasive as there doesn’t need to be a huge hole cut. That said, holes for wiring or hardware might be required depending on the location. Many tweeters include surface-mounting solutions that position the tweeter parallel to the mounting or at an angle. Angled mounting solutions are helpful when mounting a tweeter off-axis to the listening position. Ideally, a tweeter should be within 15 to 20 degrees of being on-axis with the listener. Alternatively, the tweeter can point at the windshield, dispersing high-frequency information into the listening area.

Tweeter Pods

Another option for installing tweeters is to use pods included with the system. These pods are typically bullet-shaped and mount through a single hole. The design should have a way to conceal the wiring for a neat appearance. You will want to ensure that the pods can be directed at the listening position for maximum performance.

Original Equipment Locations

Most modern vehicles have tweeters integrated into the factory audio system. These are often behind small grilles in the A-pillars, the dash, the doors near the release handle, or the sail panels in the front corner. Often, the factory tweeters are quite small in diameter and overall size. As such, it can be tricky to replace them with aftermarket tweeters. Some companies offer tweeter designs specifically engineered to work in original equipment locations, eschewing grilles and other hardware.

The key to a successful installation in these locations is reliability. We’ll be very clear in stating that mounting with hot glue or butyl rubber is unsatisfactory. These materials can quickly melt when the vehicle interior gets hot in the summer, causing the tweeters to fall out of place. If there aren’t options for mechanical fastening solutions, an epoxy adhesive like 3M Scotch-Weld DP8005 designed to work with plastics is an acceptable alternative.

Custom Installations

Of course, a custom installation solution for your tweeters is always an option. You may want them to blend into the A-pillar, dash or door. You may want a technician to create a custom pod that puts the tweeters in a specific location or points them in a particular direction. You may wish for the installation to look unique. So long as the guidelines about tweeter directivity are heeded, you can have the technician construct almost anything.

The Importance of Proper Tweeter Installation

While a tweeter doesn’t seem like a large item, in the unfortunate event of an accident, the last thing you want is to get hit by a tweeter that’s come out of place. Yes, this is a bit extreme. However, true professionals put significant effort into ensuring that their upgrades to our cars and trucks are safe and reliable. Do you want a tweeter to fall into the door or an A-pillar because it was held in place with hot glue? Certainly not. When shopping for car audio speaker upgrades, drop by a local specialty mobile electronics retailer and ask them which component speaker systems they offer. Be sure to inquire about how they integrate the tweeters into client vehicles.

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 while back, we looked at how different subwoofer locations affected system performance in a Hyundai Santa Fe SUV. A client of ours asked if that information was relevant to a sedan. So, let’s take a cool little enclosure and see what happens when we try several different sedan subwoofer locations.

The Test Subject

Our goal in this experiment is to evaluate how the location of a subwoofer in a vehicle affects what we hear. We reached out to Lee Mattason at Burlington Radioactive in Burlington, Ontario. He let us use his 2001 Honda Accord for the test, lent us a subwoofer and provided room in the install bay to do the measurements. We’ve known Lee and his team for over 25 years, and he’s a class act.

We didn’t want the size of the subwoofer to affect the measurements, so the goal was to choose something very compact. Lee had a JL Audio CP108LG-W3v3 8-inch ported MicroSub enclosure in stock. This little monster measures 18.625 inches wide, 11 inches tall and only 5.125 inches deep. The enclosure uses a 8-inch 8W3v3-4 subwoofer. The sub is rated to handle 150 watts of power, and the enclosure’s build quality and finish are exemplary. Honestly, this is a subwoofer solution we’ve been curious about. Will it play low enough for this test? Let’s find out!

The Measurement Configuration

As we’ve seen with other subwoofer enclosure systems designed by manufacturers with extensive experience in the industry, they know how to get the most out of a system by taking advantage of the transfer function of a vehicle. Before doing a complete set of tests, we took a frequency response measurement to ensure that the little woofer was suitable for the application. We set up our Clio Pocket microphone in the front seat and powered the subwoofer with a home audio amplifier. The output level was set to produce a sine sweep referenced to 6.32 volts at 60 hertz. This works out to 10 watts of power into a 4-ohm load. Here’s the first measurement we made with the sub placed in the middle of the trunk.

Um, what? This incredible little subwoofer measures ruler-flat to 10 hertz in the car at an output level of about 100 dB SPL when driven with 10 watts of power. Knowing it can handle 150 watts of power, it can easily produce 110 dB SPL. This is another prime example of expertise in subwoofer enclosure design and an understanding of vehicle acoustics. Sometimes, what looks “right” in a computer simulation might not transfer to in-car performance. There’s no equalization or filtering applied to this. It’s just a signal from the Clio Pocket to a full-range amp. Kudos to JL Audio; this is a little masterpiece!

Measurement Consistency

The graph above shows the subwoofer enclosure frequency response from 10 hertz to 1 kilohertz. We noted that the information below 20 hertz varied significantly during our measurement process. There is a machine shop next door to Burlington Radioactive. Whatever equipment they were using affected this infrasonic range. Sometimes the response was flat; sometimes it had a 10 dB peak at 13 hertz. We know the latter isn’t possible based on our measurement configuration and process. As such, we will leave that data out of the subsequent measurements.

Sedan Subwoofer Location Testing Round 1: The Middle

We started the testing with the enclosure in several locations through the middle of the trunk and facing different directions. The graph above, and as shown in light green in the chart below, shows the subwoofer in the middle of the trunk, standing up on its long side with the subwoofer facing rearward. The medium green trace has the subwoofer facing toward the front of the vehicle. Finally, the dark green trace has the subwoofer lying down on its back, with the driver pointed upward toward the trunk lid.

This graph will serve as a giveaway for what we’ll measure as we continue the testing. The direction doesn’t matter significantly in terms of deep bass, from about 45 hertz and down. The output levels are within a few decibels of each other. What does change is the upper bass performance around the crossover frequency. We’ll leave it at that until the summary at the end.

Round 2: To the Back!

The next three tests will have the little subwoofer enclosure placed at the very rear of the vehicle by the taillights and trunk latch. Once again, we repeated the testing with the subwoofer facing forward toward the front of the vehicle, facing upward toward the trunk lid and facing rearward toward the taillights.

The results mimic what we saw with the enclosure in the middle of the trunk. From about 45 hertz and up, the output is consistent. In this test, the upper bass output changes significantly.

Round 3: Back of Trunk

The next test has the enclosure at the back of the trunk, right up against the rear seats. It’s a long and painful story, but we lost a measurement here, so there are only two. We saw the graph of the subwoofer facing forward in this location, and it wasn’t much different than these two. I know it’s frustrating. It is for us as well. The car isn’t available to repeat the test, or we’d be on it in a flash. Sorry.

These measurements have the light orange line with the sub against the seat back and the driver facing rearward. The darker line shows the sub’s output, with it lying on its back and facing upward.

The conclusion is that there isn’t much difference in output from the various measurements at this location, though up is better than backward. If we recall the measurement with the driver facing forward, it was better in mid-bass output than either. Down low, it was the same.

Round 4: Hide in the Corner

The last location we’ll measure is the right corner of the trunk. We stood the enclosure up on its long side. There are measurements with the driver facing inward toward the vehicle’s center and outward towards the fender. We also flipped the enclosure over so the vent would be facing forward toward the front of the car and at the taillights.

Once again, the direction changes didn’t affect this location’s upper or lower bass output. The last measurement, with the woofer facing the fender and the port directed towards the rear, would be the “best.” However, there is just a few dB SPL variance across all the measurements.

Conclusions on Sedan Subwoofer Locations

In terms of deep bass, below 40 hertz, it doesn’t matter where the enclosure is located. The graph below shows maybe 2 dB SPL of variance across all the tests.

What does change, as we indicated earlier, is mid-bass performance. When installers experiment with different locations, the process likely won’t significantly affect how much bass you hear. The difference is in the mid-bass. The best location is in the corner of the trunk, with the subwoofer pointed outward to the fender and the vent pointed rearward. In contrast, the worst location was with the subwoofer lying flat on the floor at the back of the trunk, with the woofer pointing upward. At 90 hertz, there is more than 20 dB SPL less output. The lack of midbass is typically perceived as the presence of more deep bass. These measurements show otherwise.

If you compete in SPL competitions, this data might not be transferable to that application. At high excursion levels, the vent in an enclosure can be affected by its proximity to nearby surfaces. Moving an enclosure forward or rearward by an inch can yield measurable changes. You’re looking for a peak in the response, not flatness or extension. Different rules altogether.

Yes, different vehicles might present slightly different results. However, our editor-in-chief did this test 21 years ago for another publication and found the same results. Given the variance, we’d ignore that green trace.

When upgrading your car audio system with a subwoofer, the corner of the trunk is an excellent choice. This location keeps the subwoofer out of the way when carrying cargo. It also allows access to the spare tire or a battery that might be stored under the floor. Of course, if you want to run a pair of 12-inch subwoofers, then the back of the trunk will be about the only option. Drop by a local specialty mobile electronics retailer today and ask about adding a subwoofer to your car stereo system. It’s easily one of the best upgrades you can make.

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.