Cars as Mobile Sound Stages – Wall Street Journal

Posted: Tuesday, May 10, 2016
Mark Eldridge, 53, owner of Mobile Soundstage Engineering from Bixby, Okla., has built car audio systems that have won competitions for years. This is his latest creation—thousands of dollars of electronics built into a 2002 Nascar Sprint Cup Dodge.

Mr. Eldridge estimates he has put some $200,000 to $250,000 into this car, including initial purchase, all mechanical and audio components, and his time. ‘When I go the car in 2002,’ he says, ‘it was just a beat-up shell.’ The paint scheme was courtesy of Carefree Paint & Body, in Tulsa.

A peak inside the car. The interior, from the dashboard to the center console, had to be built from scratch. Mr. Eldridge kept the car on a scale while working on it, to make sure the weight distribution was close to 50/50 from front to back and side to side.

This dbx signal processor tunes the sound. What kind of music does Mr. Eldridge listen to? ‘If it’s good music, recorded well, I’ll listen to it,’ he says. ‘I prefer blues rock, a little country, some jazz and classical—all of it.’ His favorite of all time: Stevie Ray Vaughan.

The center console features this big knob front and center. It controls volume, song choice, power on/off. ‘Everything you need to control the audio system while driving,’ says Mr. Eldridge, ‘you can do from this one knob.

Eight JL audio amps provide power (two are spares). That’s enough to provide 3,900 watts to the speakers. Your average factory-installed car stereo system will provide from 300 to 400 watts, Mr. Eldridge estimates. So 3,900? That’ll do the job.

A view of the car from behind. The license plate stands for U.S. freedom. ‘I served in the Air Force,’ says Mr. Eldridge. ‘We do a lot to support military veterans. That’s a huge part of what we do.’

In the trunk, Mr. Eldridge built a completely separate entertainment system for parties and such. This includes an Xbox 360, another audio system, and a video screen.

‘I have always loved music,’ says Mr. Eldridge. ‘When I got my first car, the first thing I did was rip out the AM radio and start installing my own audio. You got motor vehicles and you got music—what else is there?’

Mr. Eldridge installed a 360-cubic inch Mopar V8 engine. ‘It’s no trophy car,’ he says. ‘I’ll take the car onto a track and drive the snot out of it at 150 mph.’

This photo shows some detail of the dashboard that Mr. Eldridge built into this vehicle. The car was raced in Nascar’s Sprint Cup in 2002, handled by driver Casey Atwood.

Mark Eldridge, 53, owner of Mobile Soundstage Engineering from Bixby, Okla., on his world champion car audio, as told to A.J. Baime.

I’ve been building car-audio systems and competing since the early 1990s. Numerous organizations sanction competitions, like the Mobile Electronics Competition Association (MECA) and the International Auto Sound Challenge Association (IASCA). I compete in sound quality—the best sound wins, according to professional judges. Some others compete in volume—the loudest car wins. But that’s not for me.

Being a little OCD, I tend to take things to the extreme. I can count some 80 world and national competitions that vehicles I’ve built have won.

My current project started out as a Nascar Sprint Cup Dodge Charger used in the 2002 season. I bought it in 2004, and I’ve put about 3,500 hours into it. The car was perfect for building audio, because as a racing car, it had no passenger seat, no dashboard or center console, none of the stuff the factory usually puts in, that you have to build around when installing audio. I could build the audio first, place all components in the optimal position, then build all the other stuff around that.

Mark Eldridge with trophies he has won competing in car audio competitions. His current ride is ‘one-of-a-kind,’ he says. ‘Nobody has ever built anything like it.’

I spent 800 to 1,000 hours just making the car street legal. It needed functional doors, headlights, taillights, turn signals, the works. The audio starts with an Alpine source unit, that plays any kind of music source. A dbx signal processor behind the front seat is for equalization, for tuning sound. I have a 12-inch subwoofer built into each kick panel (near where your feet go), and 14-speakers behind the dashboard. Eight JL amplifiers supply 3,900 watts of power. (I’m not using all of that. I look at volume like money in the bank. If you need it, it’s there.) And, there’s an Xbox, stereo, and a TV built into the trunk, a completely separate entertainment system. Including all the mechanical audio and video equipment, paint, the initial purchase, and the biggest investment, my time, I’ve probably put some $200K to $250K into the car.

It’s everything I ever wanted in a car. I can listen to music and close my eyes (not while driving!), and the listening space feels so much larger than the car. I can envision the musicians—drummer in back, vocals up front, guitars spaced around. Then, I’ll take the car onto a track and drive the snot out of it at 150 mph.

It’s one-of-a-kind. Nobody has ever built anything like it.

Contact A.J. Baime at


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