If anyone had told me 10 years ago, when I started my first serious competition installation in the 4-Runner, that I'd still be working on refining and improving the audio system installation in the new millenium, I'd have said they were nuts. Well, current evidence proves that I'd have been wrong, and that I may actually be the one who's nuts! Not too many vehicles have been in the competition scene as long as the 4-Runner -- I can only think of a handful. Most people want to start on a new project every few years, and many times, I can't say that I blame them. I've considered that option several times, and, in fact, in 1998, Richard and I had plans to rebuild the Grand National and compete as co-competitors (man, that would have been fun!). But for a couple of unfortunate reasons, we were unable to get that project going. Still having the drive to compete at that point, I opted to take the 4-Runner back into complete rebuild mode once again.

Looking back on everything, sticking with the same vehicle for so long has given me a couple of advantages over starting a new vehicle from scratch. First, I haven't needed to worry about getting the basics established -- things like sound deadening, alarm, and basic system wiring, interior modifications to fit the system, etc., take a lot of time. Second, a great deal of knowledge had already been obtained while learning and mapping out the acoustical properties and characteristics of the 4-Runner. Having these things in pocket was a hefty advantage, and during the system changes over the past two years, great advantage was taken of this knowledge. The result is a dramatic improvement in the sound quality of the system. Starting a new vehicle would surely have taken another year to accumulate the same level of knowledge about it.

Anyway, the 4-Runner is (very fortunately!!!) still with me, and will be for a while longer. It's far better in all respects than anything it has ever been in the past. But the coolest part is that I know the potential for improvement in the current system. All the things needed for further SQ improvements are there, it's just going to take a little more time to extract the next couple of levels of performance.

For those that are familiar with the past articles on the 4-Runner, there are only a few things that remain the same between then and now. We'll briefly touch on these items as we go, but it may help to review the previous articles if you want some background on the system development.

I knew the new system would take a lot of time to complete, but I hadn't planned on it taking two and a half years to do. People at every show ask me how much time has gone into the current system. At this point, I really don't know what it would take to build it from start to finish. I know what it took to build various parts of it, but the total time invested in the complete project is damn near impossible for me to estimate, so I won't even try.

In July 1998, I began formulating a plan of attack for the system upgrades. There were several driving forces behind the changes. First, the absolute top priority was to take the system's sound quality to the highest possible plane. I had learned a great deal about how to improve the sound quality of the system at that time, but couldn't do it with the then current system. So an entirely new system design was created to take it to the next level and beyond. It has always been my opinion that SQ is the most important consideration, and that all installation ideas are held against the sound quality standard. If they might in any way detract from the SQ of the system, they are immediately dropped from consideration. It's my opinion that cool installation features have no place in the 4-Runner if they're going to detract from the potential SQ of the system. If, on the other hand, they fit and don't interfere with the sound, they may be used.

Secondly, the overall system installation quality had to be dramatically stepped up. The system in 1998 was good, but I knew that continuing to be competitive in the Expert Division would require significant improvements. Hence, a great deal of time was invested in craftsmanship, attention to detail, cosmetic integration, creative applications, etc.

Thirdly, I wanted the system to be very easy to service, gaining access to any component quickly, just in case... Every component, every panel, every part of the system can be easily accessed in minimal time. I had grown tired of system designs that take several hours to remove a panel or replace a component. No more. This system is seriously easy to work on and everything is easy to get to.

I had also recently taken a position with Stillwater Designs. It was only appropriate, and very desirable, to get the system changed over to Kicker products.

System Power Supply
The foundation for the system is relatively simple and bulletproof. A Streetwires 135-amp alternator is used for charging purposes, and 1/0 power cable is used to transfer power between it, the batteries, and the rear of the vehicle. The battery system consists of two Streetwires 810 batteries mounted in a parallel configuration under the hood. No isolation relays are used between them, eliminating the potential for one battery to be discharged more than the other, and also providing maximum potential to the system at all times.

The battery mounting system is super solid. It consists of a machined aluminum tray that the batteries sit in, with a machined aluminum clamping structure bolted to it, holding them in place. The truck can just about be picked up with the battery mounting system. The batteries aren't going anywhere!

The main system fuse utilizes the Streetwires fuse holder components on the battery, ensuring the fuse is mounted as close as possible to the battery positive post.

All 31 system fuses are readily accessible in three panels in the rear area of the vehicle with the majority of system components. This may seem like overkill on the fusing issue, but in reality, only two of the fuses are spares for future upgrades and/or additions. There are a lot of different, very unique components in the system now, and I don't want it going up in flames because something isn't properly fused.

The Signal from the Source
The same Alpine 7909 still resides in the dash. It has been there for six years, and I haven't found anything that can replace it yet. It's performance specs and ease of modification are unmatched by any other source unit available. In addition to the modifications several years ago, it's now even more stripped down and modified. All switches and buttons have been removed from the face board. In their place next to the track and time display now resides a digital vacuum fluorescent volume indicator, custom made by Dakota Digital. A quick release bracket system securely holds the 7909 in place behind the new dash assembly. If needed, the unit can be removed from behind the dash in less than two minutes. The track and volume displays are visible through the blacked-out dash panel when the system is on, and the CD is loaded through a slot in the same panel.

The head unit controls are duplicated on the modified Grant steering wheel also. Blue back-lit buttons operate an IR system that controls all the head unit functions. The system control buttons are on the right side of the wheel. On the left side of the wheel are buttons for the turn signals, headlights, driving lights, and horn. There are no stalk-mounted controls behind the wheel. The steering wheel itself is mounted with a quick release mechanism, allowing it to be removed in about one second (seriously!). The whole point of the quick release system is to allow the dash to be removed quickly also, but we'll cover that in a little while.

The signal from the 7909 immediately enters a Navone Engineering N-1000 balanced signal system, which balances and steps up the signal voltage before sending it to the rest of the system. The signal then hits the same Rane setup that's been there for a number of years. The two ME-30 EQs and the AC-23 crossover are mounted on a quick release single piece faceplate. This allows them to be removed in only a few seconds, then be remote located using the umbilical cable system to the front seat area for critical system tuning, or outside the truck via the external connector panel if needed. The internal workings of the Ranes have undergone extensive modification, including lowering the sub/mid crossover frequency to 35 Hz, removal of the subsonic filters, moving the signal delay from the sub channels to the high frequency channels where they could do some good, and adding head unit control switches in place of the power switches.

Beyond the Rane setup, the signal path becomes much more complex. Over the past several years, Richard has given me a number of ideas and a great deal of help in improving various aspects of the system's SQ. The results have been the integration of several new custom circuits that are used in various stages of the signal path. They are all implemented into the Mobile Soundstage Engineering XP-1 processor unit.

The XP-1 allows for control of the system linearity. It compensates for the differences in how the human hearing system perceives frequency-dependent loudness differently at varying playback levels.

The XP-1 also controls very low-level noise. It attenuates the high frequencies when signal levels are very low, so the judges can't hear any "hiss" on the "noise judging" tracks during competition, and the apparent system signal-to-noise level is increased.

The XP-1 enhances the dynamic reproduction of the music also, addressing the attack and decay properties and the overall dynamic impact.

Lastly, it controls the ambient properties of the system. It uses separate circuits to control the ambient properties of the front stage and the overall room effect. The front stage is enhanced to expand the apparent boundaries of the soundstage. An accurate ambient room effect is created by removing the "sound of the vehicle" with specially designed acoustical treatments (which will be discussed later), then allowing the XP-1, in combination with a carefully designed ambient speaker system, to recreates a psycho-acoustic room effect, simulating an appropriately sized listening space.

The XP-1 is one of the real keys to the great improvements in SQ within the system over the past couple of years. There's nothing involved in it that someone else couldn't eventually figure out, given enough time researching the acoustical properties within a vehicle, learning what does and does not work to control that environment, and creating their own signal processors to do the same things. However, at this point, there's just too much time and energy invested in this advanced area of the system's development to give the advantage away for free. So to keep things fun, interesting, and to keep everyone guessing as to exactly what the XP-1 actually does, the controls are labeled appropriately. If you can guess the real meaning behind the XP-1 control labels, you may have an insight as to how it actually does what it does.

Other new components in the signal path include a couple of critical gain control pieces, the Audio Control Matrix and the Audio Control MVC. The two Matrix pieces are very high quality "line drivers" that are incorporated to increase the signal level by about 10dB prior to entering the amps. They are excellent quality components that add no unwanted noise while improving the overall dynamic capability of the system.

The MVCs are the system's volume control. They are VCA type attenuators, controlled by the big volume knob. They're located in the signal chain just before it enters the amplifiers, allowing the signal level to be at maximum throughout every component in the signal path.

The gain structure of the system has been carefully thought out, and all components are optimally matched so that the overall system signal-to-noise ratio and the system's maximum output capabilities are maximized. The 4-Runner system definitely does not suffer from the typical SQ competition system inability to reproduce the music at realistic listening levels and/or very compressed sound at moderate to high levels. This system will rip your head off if you're not careful! It plays very loud, is incredibly dynamic, and very accurate.

Amplifiers
When initially redesigning the amplifier system for the system, several requirements had to be met. The amps had to be very easy to access and simple to replace if needed. The design had to be totally unique and show off the quality of amps as a whole as well as the Kicker amplifier circuit boards. I wanted them to be liquid cooled, as in previous system designs. And, they had to provide a great deal of available power to reproduce the music accurately, and for SPL testing purposes.

With these things in mind, the amp design was created over a 4-month period. The heat sinks for the amps were custom machined by RK Machine in Ripley, OK. The top plate is 1/2-inch aluminum, and the rails under the power supply and output devices are 3/4-inch aluminum. The rails are rifle drilled through their length, with the ends plugged. Quick disconnect no-leak female fittings were installed in the amp rails and mating male fittings are located in the amp racks. When the amps are installed, the liquid coolant is pumped through the heat sink rails. When an amp is removed, the fittings shut off flow, and no liquid is lost.

The electronic connections are a quick type release also. Custom connectors are used to transfer all electrical signals including power, speaker, signal, and computer inputs through a single multi-pin assembly. The combination of these electrical and liquid fittings allows for a very rapid removal and replacement ability. Simply by loosening two socket head cap screws under the handles, an amp can be removed in about 30 seconds, and replaced just as fast.

The amp circuit boards are modified Kicker pieces. Three ZR1000 amps are used to power the three subs, and two ZX460 amps are used to power the mid-bass, horn, tweeter, center channel, and ambient speaker sets.

The amp racks are located around the rear side windows. They are constructed of fiberglass, and have a lot of my friends' blood sweat and tears cast in them. Making them work properly with the quick release electrical and liquid coolant requirement, taking up minimal space, and providing amplifier visibility both from inside and through the outside window was a difficult task at best. The heat sinks are visible inside the interior, and cosmetically blend with the rest of the interior theme, using paint, polished aluminum, and multi-color graphics. From outside the truck, the amp circuit boards are visible through the rear side windows whenever the neon lights are turned on, and not visible when the neon is off. The window glass incorporates an LCD film that is opaque when at rest, and turns clear to allow viewing when the correct voltage is applied.

The liquid cooling system consists of a pump, tank, and heat exchanger mounted behind the right rear bumper area. It is computer controlled by the LP-1 Logistical Processor, pumping coolant through the system as needed to control the amp temperatures.

Logistical Control
System logistical functions are controlled by the LP-1. Doug Winker was instrumental in its development. The LP-1 is a relatively simple unit, but that's by design. It turns on instantly, not requiring a full operating system to boot up, and performs several tasks. First, it monitors system parameters like voltage, the five amplifier temperatures, the SQ sub temperature, liquid coolant temperature at the amp inputs and outputs, and coolant pump pressure. It displays these things on the LP-1 display to the left of the Rane setup. It controls the liquid cooling system, varying the pump speed to control the amp temperatures. It also controls the turn on/off sequencing of the system components, and determines what components are turned on depending on what mode the system is in. There are four modes available: SQ, TEF, SPL, and RTA. The SQ mode is self explanatory. TEF mode allows an input signal to be fed into the system from the TEF-20 analyzer through the external connector panel for system testing purposes. SPL mode turns on only the three ZR1000 amps and configures their inputs to connect to the externally mounted SPL head unit. RTA mode (one which I hope I can get rid of soon) turns on only the left channel and engages an Audio Control EQT in place of the Rane ME-30 for RTA competition purposes. The control panel also has switches for actuation of the aperiodic membrain, neon, manual pump control, etc.

Panel Work
The construction of the rear area started by first locating the amps and building the amp racks in place. They are made of MDF and fiberglass and can be easily removed if access is needed behind them. The processor racks were then laid out and constructed of fiberglass also. Once all the components were located and in place, trim panel construction was commenced.

There are only three panels that cover the entire rear compartment area of the truck from top to bottom. One panel on each left and right side around the amp racks, and a single "ski slope" panel that covers everything in between from the ceiling to the tailgate. They were created by first building frame works around the edges of the panels and the equipment mounting racks, then stretching cloth over the frames and soaking it in resin. The cloth was then reinforced with fiberglass from behind. On the surface, the three panels were molded as if they were a single panel, creating a smooth contour transition between them. They are each covered with a single piece of Select Products HF vinyl, and dyed to match the rest of the interior. There are only two vinyl seams in the compartment, one along each side of the center panel adjacent to the side panels. The panels are strong enough to support just about any weight applied to them. There are also no visible fasteners holding the panels in place, yet all three can be completely removed in 15 minutes.

The Front Stage and Beyond
When I first decided to rebuild the front stage system, it was supposed to be a simple two to three month project. I hadn't planned on completely rebuilding every part of the front half of the passenger compartment. After pulling the old dash out and spending several days looking at what room was available, and what could be fit without major structural modification, it was finally decided that everything against the firewall had to go. This was going to be a no holds barred front stage system design with no compromises. Period! So began an 8 month marathon process of mapping out the system design, of major structural reworking of the vehicle firewall, floor board, and behind the dash components, of creating an entirely new front stage speaker system, and the fabrication of the new dash assembly. In the end, it turned out better than I had imagined, but I don't ever want to spend as many hours in the shop over such a short period as I did during that 8-month timeframe. :)

Let's Talk Acoustics...
The one area where more time was spent than any other was in mapping out the acoustical properties of the vehicle and learning to control them. Accurately controlling the acoustical environment within a vehicle is perhaps the most important, yet least pursued and/or understood area of car audio. The biggest improvements in most systems can come from properly addressing certain acoustical issues. We all know about speaker placement, but many times, no attention is paid to reflections, absorption, nodal response, etc. These things are almost as important as speaker placement. Once the signal leaves the electrical realm in the speaker's voice coil and enters the mechanical world in the moving diaphragm and then into the listening space, it's at the mercy of the acoustical properties of the listening space. No amount of signal processing can ever correct or compensate for improper speaker placement or a poorly designed acoustical environment.

There are two areas dealing with acoustics that I was concerned with in the 4-Runner: the front stage design, and the environment surrounding the listeners.

The front stage design consists of several different components, with the most critical being the horn design. Having spent several years learning about horns and using them in car audio, I knew that the horn design in the system in 1998 wasn't going to take the system's SQ to the highest level. After many, many hours of research, testing, and in several discussions with Richard, the current design was finally developed. It's based on a planar symmetric diffraction design, with a number of modifications to optimize performance in this specific application. The horns critically control the dispersion pattern of the 300 Hz to 7 kHz frequency range. One of the biggest advantages of this design is that the dispersion pattern is controlled to the point that early reflections from the windshield, side windows, and dash are either eliminated completely, or are directed towards an area where they are absorbed. No image and/or stage degrading early reflections are allowed to proceed directly to the listeners' ears. The angle of the horn throat axis, the physical dimensions and flare characteristics of the horn itself, the ability to control potential reflections off the windshield, and the dash design all play critical roles here. As before, the windshield and dash are integral parts of the design. Rather than fight them as enemies of good sound, they are used as allies (so to speak) and actually contribute to the cause.

The horns are about 20% larger than the previous design, the throat length being two feet. Additionally, Richard loaned me a set of his large format Altec compression drivers to use in the system. The combination of the much larger drivers and the larger horn design required a substantial amount of structural reconstruction work to accommodate them behind the dash. The entire foot well / wheel well area was cut out to make room for them. 14-gauge steel was welded and riveted back in place around the compression driver and creating an optimal enclosure and placement of the mid-bass drivers. Located in the wheel well area above the front tire is an aluminum access panel, providing the ability to replace a compression driver diaphragm quickly if needed. Heavy steel brackets are used to mount the compression drivers, as they weigh over 30 pounds apiece.

The grille over the horns is removable, again for easy access. It is a two piece aluminum frame with perforated 68% open area steel grille material, and grille cloth covering the top. Over 50 hours were spent in machining the grille and fitting it to the top of the dash contour so that it doesn't interfere with the sonic performance of the horns.

Above and Below Horns
Located in the A-pillars just above the dash behind the upholstered covers are two of the new prototype Kicker high-end tweeters, one on each side. They cover the frequency range above 7 kHz flawlessly. These drivers are incredibly smooth and detailed, the best I've ever heard.

The mid-bass set up was the next area to be addressed. The path length difference between the left and right drivers is critical. They are mounted in the enclosures created as part of the steel reconstruction of the foot/wheel well area, allowing them to be mounted further forward than the stock floorboard would allow. They are aperiodically damped. The enclosure baffle is made of 3/4 inch MDF fiberglassed directly to the enclosure as part of the vehicle structure. Additionally, the mid-bass drivers are clamped between a custom-machined aluminum ring and the baffle, using foam rubber isolation rings between them and the driver. This system completely isolates the driver from the mounting structure, creating a very non-resonant mounting system.

The grilles over the mids are machined aluminum and steel pieces that pressure fit into the front mounting ring. These grilles, like all the others are finished on both front and back sides and are easily removable for quick access to the drivers.

The 8-inch drivers are custom, one-off Kicker pieces. They were designed specifically to work in this aperiodically damped system over the specific frequency range of 35 to 300Hz. Their transient response is exceptional and they handle more than enough power to reproduce the music at the high dynamic levels needed to keep up with the high frequency system.

The Dash
Along with the actual drivers used to reproduce the music, the dash assembly is a very important part of the acoustically controlled front stage system. Many people look at it and say "what a cool, futuristic looking hot rod style dash." Well, it may have ended up that way, but it was not designed just to look cool. It serves a very real acoustical purpose. There was no preconceived idea of what the final product would look like. The only driving force behind the design was to ensure it provided the best possible acoustical coupling effect for the mid-bass, horn, and high frequency drivers.

The top of the dash must provide the correct acoustical loading effect for the horns in order to control their dispersion pattern. In this design, the angle of the dash top is critical. Several days of testing with the TEF-20 and listening were needed simply to determine the best shape, size, and angle for it. Once that was accomplished, it was on to the underside.

The underside of the dash had to be as clean and open as possible to minimize and control potential mid-bass problems. This is another area that is currently under addressed in many systems. The underside of most dashes as well as the center consoles that go along with them cause acoustical problems in many vehicles. The design of the new dash effectively eliminates these problems. The center console is very low profile, and the dash itself tucks up tightly above the mids. From the listening position, it is a straight shot from the ear to the mid-bass driver. There are no reflective surfaces under the dash (save for the very small steering column cover) that can cause the typical 150-300 Hz problems found in many systems.

Once the acoustical design work had been done, the task of integrating it all together was at hand. This is where the cosmetic design work began. The driving idea for the dash look was to make it as simple, clean, and solid as possible so that no part of the dash might provide a potential visual distraction for the judges. The idea being that the judges can get in, see only the head unit display and a clean looking dash, but nothing else, then close their eyes and listen to the music. To this end, the ends of the dash were contoured into the armrests on the door panels, giving it a wrap around look. Also, a Dakota Digital engine instrument display system was installed behind the blacked out panel across the dash. When the key is off, there's nothing to see. When on, they show clearly through the panel.

Also behind the dash is a very compact air conditioner unit from Old Air Products in Fort Worth, TX. It is essential to have an operational A/C system when it competes at shows in Texas and Oklahoma in mid summer. The new unit fits nicely below the center channel enclosure and still allowed for the desired low profile dash contour. It replaces the entire factory blower/heater/cooler assembly taking up about 1/3 of the same space. The system was also converted to an R-134a type. The aluminum A/C vents on the center console are also from Old Air.

Some of the other tricks behind the dash are reconstructed cross braces, wiring harness relocation, steering column modifications, and relocation of all dash mounted controls. There are no switches on the new dash. The critical functions like turn signals, headlights, horn, etc., are located on the steering wheel itself. The other switches are located in the center console.

The dash is constructed almost entirely of fiberglass. It is a single piece, extending all the way across the vehicle and from the top of the dash to the floorboard. A mold was created with the basic shape of the center section, then the ends were custom molded in place inside the vehicle. Steel brackets are used to hold it in place. The dash is very solid, being a minimum of 1/4 inch thick, and is mounted securely enough that the truck can be rocked vigorously by pushing and pulling on it.

One of the coolest features of the dash however is how quickly it can be removed. Even though there are no visible mounting fasteners, a single person can, after taking a second to remove the steering wheel, remove all mounting screws and carefully pull it out in under 10 minutes. With two people, it takes less than 5 minutes. If there's a problem behind the dash, I want to be able to get to it now!

The center console was molded as part of the dash to continue the smooth contour all the way to the back seat area. The A/C vents, shifters, volume knob, and switch panel are integral parts of it. The shifters were machined to match the cosmetic look of the volume knob, and are single piece shaft and knob pieces.

The switch panel behind the volume knob has a sliding aluminum panel that covers it when access is not needed. Inside the panel are control switches for the LP-1, parking brake actuator, A/C controls, door locks, and the windows.

The Rest of the Front Compartment
Additional work up front includes massive amounts of sound damping material added to the doors, roof, floor, etc. Dynamat Original and Super were used to control vibration in the doors, roof, and in the rear of the vehicle. Cascade Audio Engineering VB-1 and VB-2 were used in the mid-bass enclosure and foot well area, and behind the dash. Additionally, Deflex pads from CAE are installed behind the mid-bass and the center channel drivers to attenuate and control unwanted resonances and distortion products inside the enclosures. The floor areas under the listeners feet was treated with 1.5 inches of rubberized plastic. This material is mixed like two-part epoxy, then poured into the floor area. It effectively eliminates any resonant problems that would otherwise attract the listeners' attention to the floor due to vibration under their feet. Eliminating this vibration was a big step forward in fine tuning the psycho-acoustic front stage at eye level illusion.

Through out the rest of the interior up front are layers and layers of absorptive material. The custom designed door panels and seat covers were reupholstered by Southeast Auto Trim in Tulsa, OK. The new upholstery aids not only in the acoustical control area, but also cosmetically adds to the interior appearance.

The headliner above the listeners is made of several layers of Dynaliner covered with headliner material. It provides a great deal of absorptive capability, eliminating reflections from above the listeners.

Behind the Listeners
Acoustically, the area behind the listeners, especially in a very small listening space like a vehicle, is extremely important when trying to create the illusion of being in a large listening space. All the factory reflective and absorptive parts in all vehicles to the side of and behind the front seats wreak havoc on attempts to trick the listeners into the illusion that they are in a space larger than the vehicle itself.

The original configuration in the 4-Runner interior, with hard plastic and glass next to the listeners' ears, a very resonant fiberglass roof, and lots of reflective and absorptive materials all the way to the back of the interior, was a very acoustically hostile animal. To tame it was going to require the same attention to optimal acoustical treatments as the front stage area did.

With the front stage system in place and operational, the TEF-20 really became the tool of choice for mapping out the acoustical properties of the "room." The TEF allows the user to send a signal through the system, then using a properly placed microphone, measures the acoustical response. It can measure the arrival time of the primary sound as well as the reflected energy, the frequency and phase response, noise criteria, distortion, etc., etc., etc. It is one very powerful tool.

Anyway, several hundred hours were sunk into testing, designing acoustical treatments, testing again, redesigning, and so on until the final version of the acoustical treatment layout was optimized. The same headliner is used as in the previous article. It is 2 inches thick made of fiberglass reinforced ribbed wood construction. Several layers of Dynamat Super were added on the top side, and a layer of Dynaliner and headliner material cover the underside of it. It tremendously increased the stiffness, as well as the non-resonant and absorptive properties of the roof.

From the back edge of the doors all the way around the back of the rear seat area at ear level are custom proprietary acoustical panels. They are designed not to directly reflect nor absorb any sound energy that impacts them, but control the energy in such a way as to aid in the psycho-acoustic illusion of being in a larger listening space. If you stick your head in this area and listen to the ambient sounds, it's rather different than what you'd expect, and somewhat disconcerting because the visual cues are different than what the aural cues would tell you about the space.

After the acoustical treatments had control of the environment and had removed the "vehicle sound," an ambient speaker system was designed to work with the XP-1 to create a true room effect. Several speakers were carefully located in the back seat area to work with the acoustical treatments in reproducing a proper ambient sound field around the listeners.

How About the Subs
With the acoustical treatments being up at ear level, they were now placed on top of what used to be the placement of the sub woofers. So, the subs had to be moved. It was decided for several reasons to place them in the "back seat" below the panels. This allowed for use of parts of the existing enclosure, and allowed for a "wall" to be sealed off between the back seat and cargo areas. This improved the nodal response problems that had existed when the entire cabin was open from the firewall to the rear window. It also helped increase the SPL numbers generated because the measurement space air volume is reduced. This is one of the very few things that had benefits for both SQ and SPL.

Three Kicker S15L7 Solo-Baric subs are used in the system. These are not stock L7s by any means. The suspension has been specially designed to work in this application, and they work exceedingly well.

As you can see in the photos, a panel can be raised or lowered in front of the subs. This panel serves two purposes. Note that the speaker side of the panel only has an opening in front of the center sub. The outer two subs are blocked with solid aluminum when the panel is up. The amps connected to them are also shut off when the panel is up. This is the configuration for SQ. Only the center sub is used for sound quality listening. The panel itself is actually an aperiodic membrain for the center sub. (Imagine that, I did another aperiodic sub woofer system! :)) It also provides absorption in front of the outer two subs when up. As before, there is a vent in the bottom of the enclosure that opens to the outside above the rear axle during SQ mode. This system design yields an overall Qtc around 0.45, giving a very desirable over damped response, allowing the system to reproduce the sub bass very accurately with no undesirable hangover or ringing.

Additional control of the sub is obtained by using a sub woofer servo-controller, designed by Jeri McCord, on of the Stillwater Designs engineers. The sub is a dual voice coil design. In SQ mode, the ZR1000 drives the speaker with one of the coils, and the other coil provides the necessary feedback for the servo to control the sub. The servo compares the signal fed into the amp to the feedback signal from the speaker itself, then instantly sends a corrective signal to the amp if necessary to make the speaker's out match the amps input. A positive, closed loop feedback system is the only way to really control a subwoofer system!

When the system is placed in SPL mode, the membrain panel lowers exposing all three subs. The vent to the outside closes and seals, and the amps on the outer subs fire up. This creates a sealed box, three sub system with a little over 4500 watts on it. At this point, the system hasn't been fully maxxed out on SPL yet, but even with all the acoustical treatments and absorptive material in the cabin, it is knocking on the 150 dB door.

The sub enclosure itself is made from 3/4 inch MDF, cross-braced internally in all directions, and reinforced with several layers of heavy fiberglass mat. (Thanks Dave!) The internal volume is 6.6 cubic feet in a common chamber for all three. The mounting baffle is solid aluminum and is solidly bolted to the enclosure. It is drilled and threaded for mounting the subs. The hand fabricated aperiodic panel is also constructed of aluminum. It is comprised of a frame sandwiched between the front and back panels that hold the fiberglass membrain material in place. The hinges connecting the AP panel to the baffle are hand fabricated also. Two electric actuators are used to raise and lower the AP panel for SQ or SPL modes as desired.

Many people have noticed the dramatic improvements in the quality of the sub-bass in the system this year. The combination of the much better enclosure design and construction, location of the sub, newly designed speaker, tons of power, and the servo make for an awesome sub system.

Connecting from the Outside
Behind the driver's door behind a removable cover is a panel containing connections for various parts of the audio system. A 37-pin connector allows the Rane processors to be used outside the truck if needed. A switch console to control the internal system head unit can be plugged in also. The external SPL head unit is also connected through this panel during SPL testing. And for acoustical testing purposes, the TEF-20 and a microphone can be plugged into the system, preventing the need to run cables through the door jamb.

Now for the Fun Stuff!
All right! We're finally through the audio system stuff, and it's time to talk about the really fun stuff, the external mechanicals, the paint, and the motor.

After many years of being just a normal looking 4-Runner up to 1998, it was time to give it an all new look. A number of companies stepped up to help out with the project. BF Goodrich 12.50-35X15 Mud Terrain tires were mounted on Colorado Custom 10X15 wheels. To fit the bigger tires, a Trailmaster 4-inch lift kit was installed, along with additional custom lift components added to the rear suspension to compensate for the increased weight. To add a more aggressive look, and to help the judges get into the truck, Smitybilt side nerf bars and a front brush guard were installed with Pilot driving lights adding to the frontal light structure.

Once all these pieces were on, it still needed more. After a couple of failed attempts at vinyl graphics, it was time for some serious paint. I've been relatively successful at creating acoustical, electrical, and mechanical stuff, but when it comes to artistic creativity, I'm at a serious loss. So I knew I didn't stand a chance of designing a cool paint scheme for the truck. After seeing the paint work on Markie Deitrich's car and Cory Himel's van, I had a good idea of who was going to do the paint on the 4-Runner. After the Perry, GA show this year, it was dropped off with Kal Smith in New Orleans for a month. After looking at his photo books of the work he'd done in the past, I was comfortable enough to just leave it with him. The only requirements I gave him were no pink, no purple, and the Kicker Competition Group logo had to be in there. Other than that, I'd just pick it up when it was done. Well, I think it turned out totally awesome! Totally unique, definitely attracts attention, and really gives the truck a totally new image. Exactly what it needed.

While the truck was with Kal, the build up of a new motor was undertaken. The stock 4-banger only had about 90 horsepower in it. And with the big tires and factory gears, it just barely could get on and off a trailer, much less be driven for fun. So, after searching many different companies for Toyota performance parts, I contacted LC Engineering. They were able to really hook up the engine mods. They put together a complete kit for what I wanted to do. A complete engine rebuild ensued, starting with a bored, cleaned, and freshly painted block. Next came a new set of JE pistons for an 8.0 :1 compression ratio, and LC Engineering Pro rods, all balanced with the crank. A new LC Engineering Pro head was installed, including their turbo camshaft. A new LC Engineering Pro clutch now resides between the motor and the transmission. But the real reason all these parts were installed was to handle the LC Engineering turbocharger kit that now sits to the left of the motor. The header is hand fabricated stainless steel, ceramic coated for heat resistance and long life. The turbo itself is a Turbonetics T3/T4 unit with waste gate system. It is capable of producing well over 15 psi of boost, but I keep it down around 10-12 pounds. The drive train hasn't been upgraded yet, and I don't really care to leave a drive shaft lying around in the judging lanes. To keep the entire engine under control, an LC Engineering computer controlled fuel control and ignition system was installed. This piece has the capability to dial in every possible parameter you can imagine that affects engine performance. The total engine package produces around 300 HP. Exact figures aren't known as it hasn't been on a dyno yet. That will happen this winter. :)

The last performance items added were a complete Jacobs electronic ignition system and changing the stock 4.11 differential gears out to 5.29s.

Some have questioned whether or not the truck ever gets driven. It has 140,000 miles on it now, and after doing all the engine work, it would be a shame for it to sit in a garage forever. In fact, I took it off road for the photo shoot for this article. It was fun to actually drive it like it was originally intended when I bought it in 1987, and I'm looking forward to future episodes.

That's About It...
And that's enough! There's so much involved in the audio system and the total vehicle that it's impossible to cover it all in enough detail to fully explain it. This article would be much longer than it already is.

Anyway, the 4-Runner had some great success during the 2000 competition season and will be back for more next season. As long as it can keep advancing and pushing the limits of car audio, it will continue to be on the circuit. There are a number of future upgrades planned for the system, but I just haven't had time to perfect and install them yet. I really think the system will mature into its highest sound quality capabilities next year. It works really well now, but it still has more potential to improve its sonic performance.

And that's what it's all about; improving and advancing the level of sound quality in car audio. No one in the world has yet built the perfect car audio system, the one that truly creates the illusion of being at a live performance. But working towards that goal is the fun part. That's the only reason the 4-Runner system project was started 10 years ago, and it will continue to be the driving force to keep it going.

• Check out Mark's Sidebar, "Oh But For The Help of Others..."

• Check Out CAR SOUND & PERFORMANCE'S Video
of the 4-Runner from the IASCA World Finals

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