The Biggest Subwoofer Ever Made

[wildfire99]

I haven't seen this reposted anywhere, so here goes:

http://www.ohgizmo.com/2006/03/06/the-biggest-subwoofer-ever-made/

Liquefied innards anyone? Just stand next to Richard Clark and David Navone’s little creation when it’s on full steam: a 60inch subwoofer. Here’s some quick specs.

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.

[David Meek]

;x( ;x( ;x(

[Chris D]

Sweet... however, don't I remember a thread here in the Guide a while ago about a dude that actually built a sub-floor CAVERN that worked as a subwoofer? That would be bigger than this one.

[Alloroc]

Sweet... however, don't I remember a thread here in the Guide a while ago about a dude that actually built a sub-floor CAVERN that worked as a subwoofer? That would be bigger than this one.

You remember well. An inspirational piece of custom hifi, it was(said in my best yoda accent)!

Here's the link again.

http://www.royaldevice.com/custom.htm

[snowball]

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.

:E
car audio ???

[peterS]

:E
car audio ???

spl comps.... 188 dB would breeak a few world records :E

[LikeCoiledSteel]

I think they stole the idea from Back to the Future.
Steel

[george_k]

There's impressive and then there's ridiculous, at 188dB you'd go deaf even if you were standing 250ft away from it.

[ThomasW]

This was news in 1997......

What they don't tell you is that it ran for a few minutes then self destructed after destroying the sides of the van it was housed in.

It's life span was actually a bit of an embarressment for the builders since it fell apart so quickly. The frame and support structure for the driver was significantly underengineered and underbuilt for the drivers's actual output capabilites..

[Hdale85]

actually they mentioned that in the article somwhere i remember reading it this morning lol

[Chris D]

Wow, a sub so powerful it tore the car apart? Sheesh...

I wonder how that underfloor cavern-sub is faring today. creating cracks in the house foundation?

[Hdale85]

it said "the walls were flexing in and out inches" lol that would be a site to see

[NormC]

This was news in 1997......

What they don't tell you is that it ran for a few minutes then self destructed after destroying the sides of the van it was housed in.

It's life span was actually a bit of an embarressment for the builders since it fell apart so quickly. The frame and support structure for the driver was significantly underengineered and underbuilt for the drivers's actual output capabilites..

And now for the real story:

http://www.carsound.com/UBB/ultimatebb.php?ubb=get_topic;f=1;t=023699

[ThomasW]

And now for the real story:

Thanks for the link.... :T

I apologize Norm if my memory of 9 yr old car audio trivia isn't up to your standards. My intent certainly wasn't to mislead anyone.

For an old man trying to recall something I read about almost a decade ago I wasn't too far off.... :B

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
mblsound@aol.com

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The "bread truck" as it has come to be known, was actually an old welding truck. The truck was the responsibility of Tim maynor and his crew. We built the woofer in Burlington, NC, while Tim's guys were building the truck in Georgia.

They whole project didn't get started until very late in the season that year. The woofer was designed and built entirely in only 6 weeks. The truck didn't show up in Burlington to install the woofer until the day before it had to leave for the Finals.

Time crunch...

Like I said before, I don't think Tim and his guys really grasped the extreme level of energy and force that had to be contained to make this woofer do what it was designed to do. The truck was structurally fine for SPL levels below 170 dB, which was the benchmark at the time. The structural design needed to contain the pressures relative to SPL levels in the mid to upper 180 dB range simply wasn't there. And after the Finals, the rules were changed to outlaw it, so it didn't make any sense to do any further work on the truck.

RC did install it in an old Ryder panel truck so it could be used for demos, but it isn't structurally up to the job of containing the maximum capability of the sub either.

It was originally designed to work with the measurement compartment being the "enclosure" and the back side being loosely enclosed. It was also designed to create SPL levels in the upper 180 dB range using a "sealed" or "infinite baffle" type of setup. It doesn't matter what frequency it is reproducing, the SPL will be essentially the same anywhere in the measurement cabin. It is not a one note only design, like most SPL competition systems today. Also, at these very high sound pressure levels, the air becomes very non-linear in it's behavior and response in the vent, and they are not as effective at incresing SPL as they are at slightly lower levels. Besides, I don't even want to think what it would take to build a vented or bandpass enclosure for this speaker...

BTW, for SQSteve, Dr Eugene Patronis from Georgia Tech was heavily involved in the project, doing much of the mathematical calculation and design work for the woofer. He was laughing about it the whole time, but not because he thought it was a dumb idea. He thought it was the one of the greatest, and most fun projects he had been involved in. I can still see him chuckling every time he saw it. Look him up... He's a relatively smart acoustics professor...

Maybe think of it as an interesting acoustical engineering project, not as a sound quality issue. It is strictly concerned with achieving a very specific acoustic goal. The approach is much like that when designing a top fuel dragster... Go as fast as you can, with out regard to driving it on the street, or even trying to make a turn... Pretty simple comcept...

[ January 17, 2006, 11:38 AM: Message edited by: Mark Eldridge ]

--------------------
Mark Eldridge
Mobile Soundstage Engineering
mblsound@aol.com

[NormC]

My apologies if it appeared I was challenging you. That was not my intention. Just pointing out the recent thread on carsound.