# Logic behind the build. Was Alma right?



## Jonny Hotnuts (Mar 15, 2011)

I wanted to start of in saying I have been out of the SPL game for longer then I will mention but was well into the 160's. 

That being said there was a build concept for high SPL that I always personally wondered about until I seen the Alma Gates PPI Bronco (this is what they were doing). 

The build concept was that the drivers were enclosed only by the volume of the cab and nothing more. The backs (or fronts depending on orientation) were open to atmosphere. 

I noticed from my installs utilizing a sealed 'wall' enclosing the speakers were essentially in a bandpass box with the port blocked, the cab being one side and the box being the other. Both the box AND the cab acted like a box and creating positive and negative loads on the cone. 



So in an ultra high SPL system with massive cone area wouldnt it be better to calculate the volume of the cab and place a sealed wall at the volume for what you want to tune the drivers to, and leave the backs open (the cab is the ONLY enclosure) or increase the volume of the box substantially assuming the cab and pressure created also act like a box?

The only drawback I see is that you could not lower your windows/doors and must have a perfectly sealed cab. (unless you are very aware the drivers would be running free air and paid close attention the the volume). 
I ran calcs years ago and thought you could gain 2-3 db. 

Is this a known concept?
Is there any merit to it? 

Just wondering if it would work....just one of those un answered questions I always had. 

~JH


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## Streetbeat Customz (Mar 19, 2011)

You must remember, you would be 6-7 db down now with the new mic's - as far as the cab for an enclosure, look into the latest spl vehicles (Butler, Owens etc)

Usually in a 4th order


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## RunNE1 (Feb 4, 2011)

If I remember correctly, wasn't it illegal to vent outside the vehicle for DB Drags back then. I thought they could only pop the top during non-competitive runs? 
You bring back alot of memories. I saw the changing of the guard. I remember when vehicles started showing up without windshields you could see through or drivers seats, or steering wheels. I did get to see Fakuda's Blazer before it/he retired.


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## Streetbeat Customz (Mar 19, 2011)

RunNE1 said:


> If I remember correctly, wasn't it illegal to vent outside the vehicle for DB Drags back then. I thought they could only pop the top during non-competitive runs?
> You bring back alot of memories. I saw the changing of the guard. I remember when vehicles started showing up without windshields you could see through or drivers seats, or steering wheels. I did get to see Fakuda's Blazer before it/he retired.


You could do alot back then - 

Fill the vehicle with co2 - play wayyyyy over 80hz etc.

Of course the meter was +7db back then aswell.

People like Alma paved the way, but that vehicle is inferior nowadays - technology and ideas are ever changing :laugh:


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## Jonny Hotnuts (Mar 15, 2011)

Holy Christ I havent heard of Mark Fukuda for ages!

16 Punch 15's
8 Power 1000's
(*I think)

I have met to MF on a few occasions. Wonder what the guy is doing these days. 
I just gave a clue to how O/S I am!
LOL

~JH


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## Streetbeat Customz (Mar 19, 2011)

Yup, its been a while lol


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## [email protected] (Nov 7, 2010)

I think some of that idea is based on boyles law..


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## thehatedguy (May 4, 2007)

I don't think it was ever legal to put any gas inside the cabin other than what was in the atmosphere. But then again a lot of people said John Henry did something like that when he had that silent increase on the meter after he burped the van.

Yeah, something like what you are talking about would not be legal today in any SPL competition organization...not even in the Old School Extreme class in dB Drag (no bandpasses or loading walls). Most of the top Extreme cars today are in the 180s using a bandpass arrangement. 

Heck, Street C at this years Finals (this past weekend) had a couple of CRXs in the upper 158s...no wall, no big charging system, no interior mods, and box lower than the window line. One had 2 15s and the other 6 10s. Both of these cars are louder than what Alma was doing in the Bronco back in the day...and she had to play like 250 hertz to do it.

Steve Cook was doing a 170 and change with a stock interior before the van would eat the windshield...I was standing 6 feet away one time that happened.

SPL has changed a lot since the mid-late 90s.


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## Jonny Hotnuts (Mar 15, 2011)

I had experimented with making a 'cabin compressor'. Basically it was a reinforced 4'X3' plywood panel inside a square tunnel (suspended with lanyards with skateboard bearings on each side, surround made from rubber boats). The panel was driven with air rams, used an amplifier to drive the air solenoids. 

Basically it was a 12 square foot sub with a 6" xmax.
It was our plan to use it in conjunction with a pair of real subs. 

Never got it behind a meter. Doubt it would be legal (I remember reading something that all components needed to be made for automotive sound by a legit manufacture...blah, this is also why we used an amp to drive the solenoids but still dont think it would of flew) 

The homemade 'super sub' did work. It would compress the poop out of the cab....but it did make a god awful mechanical noise and constant air releasing when changing directions. 

Good times.....

~JH


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## thehatedguy (May 4, 2007)

Sounds a lot like what Richard Clark and Tim Maynor did in their Bread Truck...60" round diaphram with inner tube surround driven by a servo. It only appeared at one show where Alma beat them. But in all fairness the servo controller was damaged on the trip to the show. That was either 96 or 97 at IASCA/dB Drag Finals in Greenville, SC...I was there watching in the stands.


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## Jonny Hotnuts (Mar 15, 2011)

Similar but mine were based more closely to a secret project conducted by the US Army back in the time of Manuel Noriega. An old family friend who is a now retired Colonel who was in charge of psyops told me about these speakers they were testing to send low Hz waves into buildings to disrupt the occupants. He explained that it was like a "24hr earthquake". 

He knew I was into audio and thought I would like to know about the project and how the drivers were made. I have subsequently looked for info in the net about them and can not find anything anywhere. But this story is true to the best as I can remember. 

Maybe someday I will build another. As bad as it sounded it was quite a spectacle. 

~JH


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## thehatedguy (May 4, 2007)

Just to clarify, that was 6 10s in the CRX that did a 158.9 and backed it up with a 158.7...not 2 15s.


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## Kane (Mar 3, 2009)

I was also in to the usac scene back in the alma gates, fakuda days. I saw Gates go against one of our local sensations John Henry and get sent to the trailer that year in K.C.

I do have a RF t shirt from that year with Alma and Fakudas signatures.... lol


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## thehatedguy (May 4, 2007)

John Henry was no slouch himself. He did have his share of controversy thogh.


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## Kane (Mar 3, 2009)

yes he did.... i cant believe how things have changed, what i did with 8 15's can be done with a 10 or 12 these days


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## English audiophile (Sep 25, 2010)

The last time I saw Mark(which was a few years back) he was working at Rockford, has he left?


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## thehatedguy (May 4, 2007)

He did own a rep firm last I heard...but that was a couple of years a go.


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