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60" Subwoofer

Poster: Moto (see all of this user's photos)
Views: 724
Rating: (None)
Date: Fri Feb 24, 2006
Filesize: 32kb
Dimensions: 450 x 338
Keywords: 60" Subwoofer
Description: This is the world's biggest subwoofer to ever be put into a car. On the left is Richard Clark and on the right is David Navone, the creators of this beast. How powerful is it? Here's what Mark Eldridge had to say about it.

The 60-inch subwoofer absolutely has the capability to produce SPL levels well above 180 dB. It is simple math and the laws of physics.

Actually, before designing it, we looked at a comparison between a large number of conventional subwoofers, or a single giant one. After we did the math, the obvious choice was the one giant woofer. It's output displacement is comparable to 160+ ten inch woofers. It can move a lot of air!

The original idea for the giant subwoofer came about in 1994 when Doug Winker, Chris Lewis, and myself were investigating how to create the highest SPL levels, just for fun. The giant sub was the best performance option, but we didn't have the capability or finances to build it at the time. Anyway, that year was when Chris and Doug installed the dual compression drivers with the horn mouth right below the mic location against the windshield. Unfortunately, the horn system was "disqualified" by the head SPL judge because the rules said the competitor could not have any windows cracked open, and Chris' windshield was cracked. I guess it didn't make any difference that the rule was intended to ensure all the windows were rolled up, and there were no openings to the outside that could affect the SPL reading.

Anyway, the 60-inch sub came about in 1997 while I was working with RC and Dave in North Carolina. Tim Maynor wanted to build a new SPL vehicle, and wanted Autosound 2000's help. We looked at the different possibilities for woofer configurations, and with Dr. Eugene Patronis' help (from Georgia Tech), we designed and built the giant subwoofer in about a six week period.

Unfortunately, Tim and his crew didn't realize just how much acoustical power the sub could generate, and didn't build the vehicle to contain it appropriately. Even at less than 1/2 output, the doors were blown off the tracks, and the entire vehicle ballooned in and out several inches. The woofer was installed in the "bread truck" anyway, and it went to Finals not fully tested.

At the Finals in 1997, Alma protested the use of the computer used to control the energy fed to the subwoofer by the power supply, so RC had to try to do it by simply touching two cables together with no feedback, and hope that the energy level was correct when it was set off. As it turned out, it wasn't at the right level, and the speaker's motor simply drove the cone assembly too hard and too fast, and snapped part of the main conecting tube in half. But, it did do 162+ dB with a single positive stroke of the cone before it broke!

The woofer was updated with several modifications after that incident so that it won't have problems with breaking again.

A couple of facts about it...

The cone moves 6 inches peak to peak under full-tilt output.

The actual cone diameter is 54 inches, with the 3 inch wide surround on the outside of that. The radiating surface area is 2,290 square inches. That yields a one way displacement of 6,871 cubic inches. That is equivalent to the displacement of 161 ten inch woofers that move 1.5 inches peak to peak.

The motor is capable of producing 6,000+ pounds of linear force, which is necessary when considering the very large surface area and displacement volume required to produce high SPL levels.

The woofer was designed with the capability to produce SPL levels of 188 dB, which are entirely possible, given an appropriately built vehicle. It is simply a matter of displacement and containment.

It hasn't seen the light of the car audio industry since 1998 for several reasons. First is money... It isn't cheap to haul it around, and unless it would produce some significant return on investment... You get the idea. Basically, it would be a very high price to pay for some entertainment value and bragging rights.

Also, it would not be legal in competition by current rules because it isn't a typical production, commercially available product.

It is still one of my goals to bring it back out, and let it rip a huge SPL number. Maybe someday, it will prove what it can really do. But for now, only a few people have truly experienced its capabilities. It is outrageously loud, and can make you a sick to your stomach when it plays those very low frequencies.

For those that don't believe it can do what it can do, that's your choice. But, I can tell you that it was designed with strict attention paid to solid engineering principles and practices. Believe it or not, given the right vehicle design, structurally built to withstand the acoustical power of the giant woofer, it could easily produce SPL numbers in the high 180's.

It is one of the coolest things ever created in car audio. It's just too bad no major manufacturers recognize what it could do for their marketing efforts, with a little creative effort.

Oh well... Someday...

Mark Eldridge
Mobile Soundstage Engineering

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