Milbert Amplifiers

The Most Musical Amplifiers. Made in USA since 1986.

Earl Zausmer's BMW 540

Updated April 2022

May 2022 -- "CarMiza Introduction" by Mike Michne

April 2022 -- "One red car" -- Earl Zausmer interview by SQology

It's rare to win over 90% of all car audio competitions entered in a 5-year period ("best of show", "best in class", "best sound") and even more rare to be featured not only in all of the major car audio magazines but also to appear in Time, on MTV and CNBC, and in more than 211 newspapers in the US as well as 27 magazines worldwide, yet that's only part of the acclaim and attention awarded to Earl Zausmer's BMW 540i which undoubtedly ranks as one of the most widely publicized car audio systems ever.

" In every industry there are people who dominate their field, who strive to overcome the competition. NASCAR has Jeff Gordon, basketball has the Bulls, and IASCA has Earl Zausmer... " --Autosound & Security magazine

Below are some articles detailing Earl's legendary car audio system, which sports two gold-plated Milbert BaM-235 vacuum tube amplifiers among other unique audio goodies.

Feb 2005 update: Five years ago Earl exited car audio and sold his famous car after moving to Arizona. The car's story since is as colorful as its various owners, which included a gold- and platinum-record awarded musician, vintage audiophile and member of the "Golden Boldens," who fortuitously intervened, and for whom we will always be thankful for, to save the car from oblivion. In February, 2005 we purchased the car from a nice Christian family in Oregon for use as a demo and reference system.


  • Two Milbert BaM-235 vacuum tube amplifiers ($5k)
  • Sony XES-Z50 system (~$8k)
  • B&W Nautilus 801D + Silver Signature speaker system (~$13k)
  • Straight Wire Maestro interconnect and speaker wires (~$7k)
  • 2-layer Dynamat on all resonant surfaces (~$3k)
  • Racing Dynamics wheels ($4k)
  • Dinan suspension and performance chip ($3k)
  • Zapco transistorized subwoofer amps ($3k)
  • Two Optima deep-cycle yellow-top sealed batteries
  • Street Wires power wiring & fuses
  • Features:

  • Milbert Tube amplification
  • LASER positioning; Time alignment
  • Head-up mirror-mounted display
  • Trunk shock-mounted changer
  • Custom enclosures & mounts
  • 15" subwoofers, all speakers mounted up front
  • 400 lbs. of sound deadening
  • Remote & control stalk
  • Vented battery compartment
  • Gold & Zebra wood; halogen lighting

  • Dual gold-plated Milbert BaM-235 tube amps on tweeters and midranges for the smoothest, sweetest, most natural sound reproduction you've ever heard in a car.
  • $13k B&W 801D & silver signature series high-end home speaker system with 6 speakers total, all up-front, including 15" woofers mounted in kick panels. No rear fill or center channel necessary or wanted.
  • Audacious speaker "pods" that mount 7" midrange and 1" tweeters facing you at torso level, not bouncing into windshield glass or tucked away.
  • Time alignment from Sony XES-Z50 system, and of course the top quality of the XES-Z50 system itself.
  • Red laser that shines on driver's right earlobe (in rearview mirror) when head in proper position -- XES system allows accurate time alignment, if desired, to within 1/4 inch.
  • "Heads-up" rear-view mirror mounted XES display.
  • StraightWire Maestro interconnect wire and Street Wires power wiring.
  • Zebra wood amp rack in the trunk.
  • 400+ pounds of Dynamat on nearly every surface, damping vibrations and lending a quietness and solidity to the car even while flying down the highway.

  Auto Sound & Security magazine, February, 1999

  Time Digital magazine, November 3, 1997

  BMW Roundel magazine, February, 1996

  Car Audio & Electronics magazine, February 1995

  Autosound & Security magazine, December 1994

  Newsweek, 1997  
  Auto Sound & Security, 1998  
  Car Sound  
  Car Stereo Review  
  Vibe Magazine

The Boomin' System

Most car stereos are designed to give what Earl Zausmer, 45, calls "that real fluffy, big-ass sound." The system on his 1994 red BMW 540, meanwhile, creates what's best described as music-ripping-a-hole-through-the-space-time-continuum sound. "My system gives goosebumps to women," says the father of two daughters.

The $46,000 480-watt wonder, which has won an International Auto Sound Challenge Association award, was assembled using off-the-rack technology available in most high-end stereo stores. (Half of the cost went for hardware, the other for custom installation, which took eight months to complete.) Zausmer's boomin' system sports $200-a-foot Straight Wire Maestro speaker cable, two front-mounted B&W 801 13-inch woofers, two rear-mounted B&W ambience speakers, 150-watt Zapco subwoofer amps, Sony preamp and crossovers, and twin 30-watt Milbert BaM-230 vacuum tube powered amps. Each amp power either 801 midrange or tweeters, which rise, phoenix-like, from the fash when turned on.

Dual Sony ES 10-CD changers hold everything Master P's ever made, while the entire car is rigged with a compound that deadens vibrations. Turn the volume up to max, and sound pressure levels inside will peak at 130 dB (a Boeing 707 DC-8 at takeoff reaches 140.)

So why is this trucking company owner selling his ride? Simple. So he can start on another one, an Audi A6 to be exact. "If you buy the stereo," says Zausmer, "you get the car for free!"

--Harry Allen

  Various newspaper articles

Text from Philadelphia and Detroit area newspapers.
Republished in about 220 newspapers:

Building the perfect car stereo system for an audiophile
Sunday, November 26, 1995
By Al Haas, Knight-Ridder Newspapers

When Earl Zausmer turnedon the $30,000 stereo system in his BMW 540i, four speakers rose from cavities in the dashboard, and a vibrant red laser beam came to rest on the right side of my face.

"Ideally, it should hit you right in the ear," Zausmer noted.

The purpose of the laser, he explained, is to make sure the sound is being delivered directly to the listener. Conventional stereo systems might bounce the sound off dozens of distorting surfaces inside the car before laying it on the doorstep of your tympanic membrane. But with the help of the laser, Zausmer's puts it right on the aural money.

That ability to put the music in the right place is part of the reason Zausmer's sound system is easily the best this layman has ever heard. It also figures in the way the system has been received by the experts.

Zausmer's system recently achieved the highest overall point total in sound quality at the International Auto Sound Competition Association (IASCA) finals in Dallas.

"For us audiophiles, the IASCA finals are the Olympics," observed a beaming Zausmer.

Zausmer, the head of a trucking company based in Havertown, Pa., is a boyish 42. He has been an audiophile since he was a truly boyish 15.

According to Zausmer, audiophiles don't just love music, they require it.

"Audiophiles are people who need music to calm their nerves. That's the way we are."

For most of his audiophiliac past, Zausmer's hobby has been building home sound systems. But in recent years, his avocation has taken an automotive turn. That makes perfect sense, since he spends so much time driving around the Northeast, calling on customers.

His interest in building an automotive system led him to the competitions, and an active role in the auto audio community.

The auto-sound community is a growing avocational subculture, according to Bill Burton, technical director at Car Audio and Electronics, which has a circulation of 100,000 and counting. The hobby is popular in this country, and big in Europe, Japan and Canada.

Like so many of his fellow travelers, Zausmer enjoys the social as well as the competitive aspects of the judged shows he enters. After the day's competition, for example, he and fellow competitors go out and have some fun.

"We don't go to bars and stuff like that, and our wives know that. We'll go out to dinner together and talk about stereo systems."

In the case of Zausmer's system, that requires a good deal of fat chewing.

The installation (audiophiles call it "the install") of Zausmer's system required about $30,000 and about 1,800 hours of professional help.

"We ripped apart most of the car," Zausmer recalls.

The process included taking off the front fenders and welding a set of 13-inch woofer, or bass, speakers in the steel structure behind each of the kick panels.

"The woofers are welded to the car. That's why you feel the bass notes through your feet. ... In effect, you're inside the speaker cabinet."

Fenders, doors, floors and roof were covered with 370 piounds of a special sound-deadening insulation made of asphalt and butyl.

Next, motorized little elevators were fabricated to lift $5,000 worth of high and midrange speakers from their "silos" on each side of the dash. The high-range speakers (tweeters) are B&W Silver Signatures, so named because their metal componentry is solid silver.

"When you work with silver, you get better sound," Zausmer said.

The speakers get their motivation from three amplifiers. One is a conventional Zapco solid-state unit that powers the woofers. The other two are Milbert vacuum tube units used to actuate the tweeters and midrange speakers.

Vacuum tubes are long obsolete, of course, having been replaced decades ago by transistorized, or solid-state, technology. But they persist in the world of exotic audio electronics, Zausmer says, because they "make a gentler, less harsh sound" than solid-state devices.

The speakers and amps work in tandem with two 10 CD players, one in the trunk, the other under the front seat. The whole system is tied together by a Sony ES control unit.

Since the sound-quality competitions also take installation quality into consideration, Zausmer lavished a lot of attention on detail. Housings and connections were handsomely machined from brass and aluminum. Everything possible was done to make the installation neat, safe, and pleasing.

Zausmer says original ideas, like welding the speakers to the car's front structure, added points to his score at the Dallas finals. So did his extensive efforts to make the installation as discreet as possible.

What also helped Zausmer was his considerable gift for tuning stereo systems. Tuning is the key to winning. It doesn't matter how good yours components are if you can't get them to work together properly.

Says Burton, whose magazine recently featured Zausmer's system: "Earl has a wonderful understanding of how to get what he wants."

Apparently so, because the results are pretty stunning. When he plays music for you in his car, he make it seem as though you are listening in an intimate room -- or a cathedral. And the sound is so natural, pure and precise. I could hear the trumpet player's fingers hitting the valves during one selection.

And the music is so wonderfully focused. It was as if the singers and musicians in the various recordings he played had carved out their own distinct turf on the dashboard.

Unlike some of his fellow competitors, Zausmer doesn't treat his champion like a show car. He doesn't trailer it to the shows and keep it locked up in the garage when he's isn't competing.

"If I have this great system, why shouldn't I listen to it?" he asks.

"I really enjoy listening to it when I'm on the road. And sometimes, when I'm at home, I'll go out in the garage, get in the car, sit back, open a book, and listen to music."


(c) 1995 Knight-Ridder Newspapers. Distributed by Knight-Ridder/Tribune Information Services.

Earl's red BMW540i   Version #2

It's rare to win over 90% of all car audio competitions entered in a 5-year period and even more rare to be featured not only in all of the major car audio magazines but also to appear in Time, on MTV and CNBC, and in more than 211 newspapers in the US as well as 27 magazines worldwide. Yet that is precisely what Earl Zausmer's 1994 BMW 540i and more than $20,000 of car audio/electronics hardware, as well as over 2,000 hours of installation work has accomplished. Some affectionately named Earl the "King of IASCA."

This 1994 BMW 540i rides on 17" Racing Dynamics wheels and Dinan suspension. According to the dyno, the Dinan chip boosts performance to 325hp and 318ft-lbs torque at the wheels.

This car earned its reputation with features such as hinged fenders which fold open. Not just for show, they make it easier to access the front-mounted 15" subs.

In the trunk, both Milbert BaM-235 vacuum tube amps are mounted for a unique look. One amp per channel (120W total on mids and highs). Both Zapco Z600 amps (driving the woofers) and the Sony XES CD changer are suspended from the rear deck by rods.

The Sony XES-Z50 head unit display was mounted into the mirror to keep it near eye level. This customization of the stock mirror required Bondo forming and lots of sanding. The smarts for the wireless remote, joystick and tuner all reside in the glovebox. All other DSP brains are in the main 10 disc changer in the trunk.

Two 15" B&W 801D woofers, each driven by a Zapco Z600, were mounted up-front (yes, 15"). In this location, as opposed to the rear where subs are usually mounted, the listener can literally feel the sound and air right in the face, and the resulting immediacy and coherence of the sound is breathtaking.

Passenger side view. Digital time alignment in the Sony XES and a red laser ear positioning guide ensure that frequencies are coherent and bass is taut, allowing rock music to kick listeners tightly in the chest at higher volumes.

One design goal was to ensure as much sound as possible hit the listener before bouncing off other interior surfaces. This was accomplished by placing speaker pods in a top-of-dash position. Previously motorized to rise up out of the dash, these pods now sit stationary. Each pod holds a B&W Nautilus 801D 6" FST Kevlar midrange and Silver Signature tweeter. The speaker pods were inspired by the B&W Nautilus seashell design, and in this picture they are ready to be fiberglassed.

The halogen lights, antenna, and Sony XES-Z50 fuse use the rear deck fuse block, which was placed under the rear stock speaker grill. Larger fusing is near the batteries, near the capacitors and behind the amps in the trunk. Thick, stranded Street Wires power cabling is used throughout.

The customized rear seat can easily be removed, revealing carpet and fiberglass work and batteries. Dynamat layers cover the metal chassis underneath. Everything is independently fused, capped and powered by thicker-than-necessary cables.

Close-up view of the Optima batteries powering the Milbert amps and other trunk-mounted electronics. These sealed batteries are fitted with gold-plated buss bars as well as custom caps that vent any gases to the outside, per IASCA regulations.

Dynamat was applied generously throughout the car to maximize sound deadening. There are no rattles, buzzes, or reverberations.

Layers of Dynamat in the trunk lid. All other body panels are multiply coated. The trunk, hood and four doors feel heavy and close with a solid thud.

System wiring diagram. Each Milbert tube amp needs 5 amperes ... about the same as one headlight. The other electronics consume about 5 amperes, for a total system idle power consumption of 15 amperes.

  Version #1, from Earl's original site, courtesy Earl Zausmer and Jason Abott 

  The following content is from Earl's 1999 site, which was  

Earl had two systems in his famous red BMW 540i.

Version #2, with Milbert tube amps and also noted for its earlobe/head-position laser guide and Sony XES-Z50 system with rearview mirror mounted display (suggested by his daughter Julie), includes B&W 801D 15" woofers mounted in the front floorboards and non-moving dash speaker "pods" that hold the unique FST 6" midrange and Signature Silver tweeter (from the B&W Nautilus Prestige). Pictures and details from Version #2 are shown above.

Version #1 had Milbert tube amps plus a Sony ES system with B&W Signature 800 speakers with up-front/in-fender/side-mounted 13" woofers and motorized dash speakers (4" midrange + bullet tweeter) that raised up and twirled out of the dash when the system was powered on. The pictures and details below refer mostly to Version #1.

The car sports Racing Dynamics rims with P700 17-inch tires, Dinan engine chip (325HP), shocks and rear suspension.

325HP + 315ft-lbs. Torque // Top Speed I have Had The Car To so far is 153 MPH, and it was still going. Not bad for a family sedan. I learned a bit about high speed driving from my old boss in Germany on the Autobahn, numerous times.

Over $50,000 of labor and equipment. Milbert Amplifiers vacuum tube amps along with exotic B&W 801 Nautilus speakers, Straightwire interconnects, Streetwire power wiring, ZAPCO, and Sony XES. Two 15" subs in the front fender/floor and custom molded pods for the tweeters and mids. Remote controls and display for system. An everyday driving car with sound from heaven.

Missing from the explanations is the importance of time alignment (via the Sony head unit), the taughtness of the bass and overall impact (due to having all B&W speakers up front), the overall quality of the speakers and wiring (B&W 801 Nautilus & Straight Wire Maestro), and the smooth purity and natural sound of the midranges and tweeters (Milbert tube amps).

This car and the stereo system was featured in Time Magazine, CNBC, MTV, 14 TV stations throughout the US, 211 newspapers around the US and 27 other magazines worldwide.

This was the first competition car:

  • to have fold open fenders
  • to use the B&W 801 and Silver Signature speaker system in a car
  • in the world to have the B & W 801 Nautilus System installed in a car
  • to use the all digital Sony XES system
  • with laser-alignment for the driver's head sweet-spot positioning
  • to compete with the Milbert vacuum-tube amplifiers
  • to have speakers that rise out of the dash
  • to have a motorized tweeter that spins to face listeners
  • to have mid and tweeters directly on axis within 2 degrees of drivers ears
  • to have such extensive machining work throughout the entire car
  • to have a microwave speaker protection system
  • to have a machined tube venting system for Optima battery
  • to use Straightwire Maestro speaker cables
  • to mold the ES stalk into the steering column for easy operation
  • to change the color of the fluorescent display
  • to have a write-up in BMW Roundel magazine in 15 years
  • to have a custom equipment rack made of African Zebra Wood
  • to be in Time Digital magazine (4,250,000 circulation)
  • to appear on CNBC television

  Battery Mounts & Machining

I wanted this part of the car to shine for extra points. Due to the large power draw of the system, two batteries were needed. Instead of just using a cable between the batteries, Henry got a brainstorm and the work started. The end result was great. What to do about venting the battery? Another Henry brainstorm. Why not make caps to fit over the battery vents and pipe it to the outside. The final touch was to gold plate all of the battery for a highlighted and different look.

Photo Descriptions
  • Start with a solid brass bar and get it true.
  • Round the edges and thread the end posts so they grip the battery.
  • Cut the expansion slot with a side cutter.
  • Aluminum wire, guide brackets were machined to fit cable and battery stubs.
  • For the battery vents, square metal was first drilled with vent holes.
  • Then turned on the lathe inside and out.
  • Screws then had their centers drilled out so gas can flow.
  • Final caps are shown.
  • Who could miss the gold plating?
  Capacitors & Rear Power

Again, if you have some space let's highlight it and do something special. Henry came up with a strong plan for making these parts. Machining new capacitor bars and rods out of solid brass and making a wire loom bracket for the fuse block. I always get a bunch of points for this.

Photo Descriptions
  • A solid piece of brass was first marked off for shape.
  • This was followed with some machine work and smoothing of the edges.
  • A brass rod was then put on the lathe and sized with a end notch.
  • Another special shaped positive power connector was then made.
  • It then bolted together as one unit as planned.
  • Looms for the cables were then added to the fuse block.
  • When all was done, it was clear coated for safety reasons. You can touch most of the brass and nothing conducts to the touch. This prevented us from having to make a Plexiglas cover, which would have ruined the look.


After competing for five years, you get to see that 99.9% of the cars have stretch carpeting because it is easy to install. After a while, most of the trunks look the same, with the same fuzz. On one occasion, I saw a new Rolls Royce trunk, and this changed my thought pattern. It look finished, with all edges neatly stitched: a nice clean look. That is when the decision was made to go with hard-backed carpet. Keep in mind this is very hard to work with. If you can completely do a trunk in stretch carpet in 6 hours, this will take three to four times longer and a lot of muscle. When you see the car in person, you tell me if the effort was worth the time. Most everyone comments on the clean look.

Photo Descriptions
  • The spare-tire well gets carpeted.
  • Next a board was trimmed to size and a cutout for the spare tire was made.
  • A metal support ring was then made to hold the spare tire cover board.
  • The entire assembly was then carpeted.
  • I bought new factory trunk side panels for recovering.
  • First thing that needed to be done was to strip the rubber backing off of carpet.
  • A major job in itself. The rear, seat armrest board was then covered with a tube made to cover edges.
  • The side panel was done in two pieces due to certain curves on the panel.
  • All edges were taped so the glue would dry with a tight fit.
  • Notice finished side panels with their clean look?
  • The bottom panel of trunk was then stitched around the entire edge.
  • Carpet was cut for the struts and edges turned first and glued.
  • Carpet was then wrapped and all edges filled in.
  • The same was done for the trunk hinges.
  • Rear sill panel for the lights were carpeted for a factory look.

The idea was to get a very strong front stage of which the subs were considered part of. So the placement of the subs ahead of the listener was the natural choice.

It is sometimes hard to locate bass, but when the subs are right in front of you, their location is easily found. Many people have listened and always comment on the very accurate and strong bass line. Keep in mind that since the subs are up front, the sound hits less surfaces and bounces and changes directions fewer times before hitting the listener. These subs have a resonant frequency of 17 Hz running full free air. The subs will port through this cutout.

Photo Descriptions
  • First the fender was removed and the original brackets that held them in place were modified for easy removal of outer fender at judging time.
  • The car body was opened up and trimmed to the same shape as the sub ring opening.
  • Then the Bridgeport Milling machine did all cuts within 5/1000 of an inch tolerance.
  • Due to the hardness and thickness of the steel, three passes were made, each one deeper.
  • Once the ring was positioned into place and clamped down the welding could start.
  • The front and back of the ring, got welded all around for added support to the car.
  • Holes were then tapped and threaded for the woofer box mounting.

  Rear Deck

The rear deck fuse block was added for the halogen lights, antenna and Sony XES fuse. This was all done under the rear speaker grill. The grill now covers the fuse block and is easily removable for display.

Photo Descriptions
  • A wood box was first made and then all cable holes got drilled.
  • The box was then carpeted with factory stock.
  • A top carpet trim piece was then stitched for a finished look.

  Deflex Absorption









Without Dynamat sound deadening material in this car, I could never get the real sound that it is capable of producing. One to eight layers of different Dynamat was used in all different places throughout the car. Lots of Dynamat pictured, and throughout many of the other car construction pages. You should get the idea this is a very solid car with no extra vibrations.

  Fenders & Subwoofer Mounting

To be a top-scoring car you need to be different with your ideas. This is the first IASCA car to compete with fenders that fold open. They are totally waterproof and just before most shows, I just dust the inside down for a clean look. This idea has taken many judges by surprise. Changing a woofer is also made easier.

My record for opening up the fender from scratch is 37 seconds. Due to the closeness of the sub to the back of the fender, a lot of reflected bass was hitting the sub and producing a slightly boomy sound. To fix this, four soft DEFLEX panels were glued to the inside of the fender. Any sound or energy that hits these pads dies right there. After putting them in, there was a noticeable improvement in the sub response and sound.

Photo Descriptions
  • An adjustable stainless-steel cable holder was made and drilled into the car body.
  • This allows me to set how much I want the fender to open for display.
  • Having the fender stay in this position allows me to keep the presentation moving without having to worry about where to put the fender.
  • Glue was applied and the DEFLEX pads to hold them firmly in place.
  • Two panels were then applied per fender.



  AU Spells GOLD

  Head Unit & Stalk

To keep this system easy to use, I had the main system controller mounted on the steering column. I never need to remove my hands or fingers off of the steering wheel to do any system function. It also looks factory, because it is mounted at the same angles as factory turn signals and wiper stalk.

Photo Descriptions
  • The stalk was bolted into place, and all angles got adjusted.
  • Bondo was then applied and it was sanded smooth.
  • The entire unit was then painted.

  Mirror & Display

This car did have the display in the factory radio position, but this time I felt brave. I always had to take my eye off the road to see the display. So this time it was put at eye level. The mirror got reformed. All system functions are in the mirror now, like the remote receiver.

Earl's original BMW (the white one) had the Sony head unit display mounted in the dashboard. That was cool, but it was his daughter Julie's idea (and insistence) to move the display up onto the rear view mirror in the red BMW.

Photo Descriptions
  • The factory mirror and the Sony XES head unit get joined into one piece.
  • Bondo forming and sanding was then followed by more sanding.
  • The control cable exits the rear with a grommet. Paint was then applied.

  Motorized Speaker Pods

  Rear Seat

I have been in some other competition cars, and when someone would sit in the rear seat the seat back or bottom would sink in sometimes. This was due to woofers behind the seat with all support for the cushions removed. Since I use this car every day, a good rear seat with the correct support was needed. Secondly, why not use the area under the seat to gain more points? So I made it a display area and fully finished.

Photo Descriptions

  • Rear seat, bottom cover was removed to expose the foam.
  • 1/8 inch, thick metal was heated and bent into shape. This could support hundreds of pounds.
  • It was then attached to the seat body and formed into a different shape due to the two larger then stock batteries.
  • For the under seat and battery cover plate, tin foil was laid down to the needed shape.
  • Seven layers of fiberglass were then applied.
  • After it was dry, Bondo was used to smooth out this piece.
  • An opening was left to highlight the running of speakers cables.
  • Easy removal was a must in the design.
  • And the finished look.

  Speaker Pods


If you want the most impact from a system, be sure the sound hits your face before it hits any inside surfaces of the car. Putting the speaker pods in top of dash position assures this. No flat surfaces, but all hand contoured and sanded. The design follows in the footsteps of the B&W Nautilus Sea Shell design. The pods are free air and vent to under the dash, where Deflex panels are waiting to disperse any leftover sound. In person they I look elegant and like a piece of art.

Photo Descriptions

  • We first made some molding foam, and then cut it down in size.
  • Inch by inch Jim shaved and formed to the new shape, while trying it in place.
  • When the form got close, the long process of filling, shaping and continuous sanding goes on.
  • The front of the pods got put on a sanding belt for a flat speaker mounting surface.
  • Two pods on the table ready to be fiberglassed.



The new B&W Nautilus system uses a newly designed 15" hollow magnet woofer. To keep the sound as close as the original designer wanted, I kept the 15 inch. A tough fit but after some listening, well worth it. Anyway when is the last time you saw a regular sedan with 2 15" subs in that location? Size matters!!

Photo Descriptions

  • All wires in passenger area get tied down.
  • The front plate gets shaped and put into place with sub and side panel.
  • The speaker ports into the fender.
  • Halogen lights are then installed for color accenting during presentations, and fiberglassing begins.
  • Deflex panels were glued into place. Having Deflex in the sub enclosure is VERY important to the end sound quality. VERY highly recommended.
  • Carpet was glued down for the front grill area and trimmed.
  • Catch the size of that magnet.
  • Finished shots of passenger and driver side subs after painting.


Photo Descriptions
  • The top rear lid was not level so we had to build a new level one so all equipment would lay flat.
  • We started with a metal panel and trimmed it into place.
  • Holes for wires and grommets got drilled.
  • The space left on the front edge got Bondo filled and sanded.
  • Next we made trunk lid arm trim covers and then fit them into place. Carpet was then applied.


I was tired of all the trunks done in stretch gray carpet, so I said "Why not an exotic wood with a strong grain?" I picked Zebra Wood from South Africa. This wood once cut is soaked in elephant manure for three months to darken up the grain. (When you sand this wood, it smells very bad).

Both amplifiers are mounted on German chromed Steel Spikes. This gives me a different and distinct look compared to any other car. All amps, players and ES system are suspended from the rear deck by rods. In person, this look is strong.

Photo Descriptions
  • Trunk lid gets covered with Dynamat and then with forming board.
  • BMW factory carpet is then applied and a rubber edge is put on.
  • A plywood form was made before cutting the final Zebra Wood. This wood is too expensive to waste.
  • Once cut, all edges were sanded down.
  • I used 600-grit sandpaper to finish the surface before clear coating.
  • Cable and spike holes were drilled on a press.
  • Grommets were drilled out for all cables.

  Update September 2012

Earl's BMW was among the first to use this technique, at least ten years before Mercedes-Benz' 2005 patent.

Perhaps Earl's car showed Mercedes how to do bass? -- "...the frame utilizes an unconventional body structure that enables the 'front bass' music system design, and indeed the 2012 'SL' models will be the first to feature mercedes's 'front bass' audio system, which provides clearer bass and dynamic range...instead of featuring bass speakers installed in the doors, the system places them in the footwell in front of the driver and front passenger...cavities behind the speakers act as resonating chambers, while the location at the vehicle's front, framed by the floor and underside of the dashboard, funnels and concentrates the sound." designboom

The Absolute Sound Sep 2012:

"...Mercedes-Benz has created a novel technique for greatly improving the sound of car audio. The technology, called FrontBass, moves the woofers from the door panels to the footwells and uses the car's structural beams as enclosures behind the woofers...The primary reason for this unusual placement was the opportunity to load the woofers in the 'longitudinal beams,' two hollow rectangular structural members that run parallel to the ground from the footwell toward the engine compartment. Loading the woofers in relatively large sturdy metal chambers of just over half a cubic foot each instead of the doors confers significant sonic virtues, as you might imagine.

"The SL 550 sounded extraordinary, with wide dynamics, outstanding bass, and a big, open sound that belied the two-seat roadster's small interior volume. Playing tracks from organist Joey DeFrancesco's CD Part III, I heard bass depth and pitch resolution that was unlike any other car audio system I've heard. On many tracks DeFrancesco plays the bass line on the Hammond B3's pedals, and the SL 550 kept up with the very high levels of very low bass. I played this track at unrealistically loud levels to test the system and was surprised by the bass' depth and power, lack of strain, and clarity of pitch. If the audio system can handle this disc at these playback levels, it can handle anything. Kick drum not only had real extension and impact, but the SL 550 system exhibited a transient fidelity that I've not heard before in an OEM car audio system. That is, the kick drum had a steep transient attack and equally sudden decay, infusing the music with a lively and propulsive quality rather than sounding thick and slow.

"Vocals on the Signature Sound disc were particularly impressive, with convincing imaging above the dashboard. Lead vocals and other centrally placed instruments were spatially distinct from the rest of the mix, but fully integrated with it rather than sounding detached or disembodied. It's an interesting phenomenon to hear from a car stereo a centrally placed image as a pinpoint in space (just as we hear it from a high-end home system).

"The midrange and treble were similarly impressive, with a smooth yet detailed tonal balance. The cymbals on the great 88 Basie Street combined delicacy and finesse with detail and resolution. The sense of air around the cymbals was also outstanding. I was particularly impressed by how much the sound changed with the recording quality. The SL 550's system didn't impose a "sameness" to all music, but rather was transparent enough to resolve subtle differences. Overall, the SL 550's audio system was terrific, particularly considering the small cabin. I wish I could have heard the top-of-the-line B&O system.

"The car environment poses some difficult challenges for audio designers. The speaker placement options are limited, there's lots of reflective glass, and the cabin volume is small. On the plus side, however, the designer has several advantages over, say, a designer of freestanding loudspeakers. The car-audio designer knows precisely where the speakers will be positioned, where the boundaries are, and where the listener will sit. The design team behind FrontBass and the SL 550's audio took maximum advantage of these variables to create an exceptional-sounding system."

Milbert Amplifiers, The Most Musical Amplifiers. Made in USA since 1986.
Milbert Amplifiers
The Most Musical Amplifiers
Made in USA since 1986

8051 Citation Drive #C
Gaithersburg, MD 20877 USA
phone 202-558-5502