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Discussion Starter #1
I'm getting an 18" Resonant Engineering SX (not released yet, starts production thursday) and powering it with a HiFonics Brutus1500D, 1500 watts RMS @ 1 ohm.

I'm trying to decide how I will do my box, the best way I can think of is a wedge type inclosure fitted into the sides that kind jut out near the seats, with the port firing towards the rear of the car and the sub pounding up against the glass. What do ya'll think I should do?
 

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do you plan on keeping your spare??...for show or function??and what else do you have in your setup? relocated batt, a cap or two, front and rear ch amp? distro blocks?? from what i have heard and seen though subs facing up dont seem to pound as well as they could or atleast sound like it anyway.. you going with fiberglass or plexi MDF??too many variables right now to suggest a good set up..
 

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Discussion Starter #3
MDF, one 1 Farad Cap, getting new bat soon, and getting alternator checked. Keeping spare tire.

front channel amp, real small

from what i've heard, subs facing up and pounding against the glass of the hatch is BEST. No experiencee with that fact though.
 

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I think the subs firing off the back glass is the best IMO. I have 2 15" Memphis HPO's and they hit pretty sporty. I've had them in different way's in the car and they hit the hardest firing off the glass.
 

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I think the subs firing off the back glass is the best IMO.
The glass creates a sonic resonance, and can cause distortion when the two sound waves intersect each other. One thing to remember about sound waves, they are NON DIRECTIONAL. You can face your subs and which way you want, but the sound originates from the sub and radiates outwards. Moving the box around only affects the reflection of the sound waves. So, its not weather they are facing up, or facing forward, its what they are facing towards that makes the difference.

I'm getting an 18" Resonant Engineering SX (not released yet, starts production thursday) and powering it with a HiFonics Brutus1500D, 1500 watts RMS @ 1 ohm.
How do you plan on running a single sub at 1ohm? What's the speakers ohm rating? DVC/SVC? How much airspace does it require? Building a box for an 18" sub means the face has to be 2 pieces of 3/4" MDF, face to face and glued together -- otherwise the weight of the speaker will crack the box. Remember that the Cougar only has about 4cufu of airspace in the entire trunk (including using the sides, and spare-tire well.)

Btw, there is a reason that competetors generally use 12" subs. When you go with a larger sub, the power required to produce the same sound with a smaller sub is increased exponentially. Here's an example, using numbers pulled outta my ass:

10" creates 100dB @ 100watts
12" creates 100dB @ 150watts
15" creates 100dB @ 250watts

Now, as you can see, the bigger the speaker, the more power required to drive it to the same performance of a smaller speaker. (More voicecoil to move around.) Now, you can get MORE sound out of a larger speaker, yes, but it requires double the power. I have proven this over and over again in competitions with some of my outlandish setups.

For example, my 24 8" Subs w/ 25 watts each was MUCH louder than my 16 12"s. (Each had 192" of cone-diameter.)

E1
 

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Discussion Starter #8
DVC 2 Ohm....parallel...1 ohm.....

I could use two 3/4" pieces...or just 1" thick...shouldn't crack the box.... There are 12s heavier than some 18s. But at the same time this IS a heavy 18.

The sub needs as much space as possible, which will probably be the entire trunk. I wouldn't mind fiberglassing the entire truunk, gotta talk to my dad first. And yes I know that bass is non-directional. But what it is hitting off of does matter and most people say that the glass of a hatch is best. If I can get 4.5 cubes after displacement I would be fine, and I think I can do that.

And I'm not to sure about those numbers you through out....they don't hold much water at all. More power doesn't really mean higher SPL....
 

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i think your best bet is to hide you spare battery in one of the wheel wells..and your front stage amp in the other..and then i would face the sub at the rear seats..remove your rear deck and build a new one as part of the box...possibly do this portion out of fiberglass and have some really sweet directional ports aimed into the passenger compartment..they would almost look like rear fill speakers i am sure the ports are going to have to be atleast 4"'s unless of course you are going vented and then i would do like a hood scoop type vent out the top of the box into the passenger compartment...build a recess into the back top portion of your box (hatch area) that will hoold your amp and cap...possibly glass over it and shine her up with the body colour..or vinyl it out to match interior detailing..
 

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i just thought of something else...you said you wanted to keep your spare tire...so when you build the bottom of the box flat to fit the shape of the trunk area...leave the front of the box 3 or 4 inches from the seta...that will give your sub clearance but also if you put a hinge on the front edge og the box you would be able to put like a handle on the hatch side of your box for easy access to your spare just buy lifting...if your feeling really creative you could put some gas shocks down there that would even lift and hold the box up for you so you can access the spare...and hey while it is up like that you would be able to access any of the wires and front stage amp and other battery...possiblities are endless.
 

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Discussion Starter #12
Not sure what I'm going to do but right now its looking like a custom fiberglass install with the sub and port firing towards the rear of the car.
 

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Originally posted by: EternalOne
I think the subs firing off the back glass is the best IMO.

How do you plan on running a single sub at 1ohm? What's the speakers ohm rating? DVC/SVC? How much airspace does it require? Building a box for an 18" sub means the face has to be 2 pieces of 3/4" MDF, face to face and glued together -- otherwise the weight of the speaker will crack the box. Remember that the Cougar only has about 4cufu of airspace in the entire trunk (including using the sides, and spare-tire well.)


E1


im not trying to bash ya in the least bit...but i used to have an audiobahn 1505 and i built a 5.5 cu/ft box using only mdf in a very simple shaped box and i had at least 3-4 more sq ft that i could have utilized with the use of fiberglass and the spare tire well.

as far as the best place for the sub, it depends on what you're going for....

SPL, you would probably be better off putting the sub as far back in the trunk as you can, and firing it up.
SQ(which i doubt is your aim with an 18)...i would suggest either firing it perpendicular and towards the rear of your car, or at the glass.

EDIT: and cougarballa...just wondering where u get 1" MDF from...ive never seen it at lowes or home depot...just wondering if there is another place to buy it

later
james
 

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you can go to a plywood supply store for cabinet shops, like Diamond Hill Plywoods in Greenville. then you can get many different thicknesses other than what you can find at lowes or home depot.
 

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i dont see how you could physically put an 18" sub in our hatch, have the sub firing back or up at the glass, and still get 4-5 cubic feet in there..just doesnt seem like there is enough room..you definately cannot get it to fire at the glass since the rear deck is only 14 or so inches deep..you could make it fire at the hatch though but firing back would be easier but i dont think you will get the volume you want and still have room to be able to see all you work..ahhhhhh maybe there is more room back there then i think..
 

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Discussion Starter #16
I'm working with Xeks through PMs to get the final design down, but right now it looks like it will have the sub and port firing towards the rear of the car. And the rear deck cover will be removed and the box will be where it was, and down into the hatch. If that makes sense to you. And Xeks says I should be able to get 7 cubes after displacement, so I'm pretty hopeful for that!!
 

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im sure u can get 7 cu/ft, but if your sub is firing towards the rear, then it would probably be almost all the way against the wall...if that is the case, i would suggest firing it up to not only look better, but to prevent any cancellation of sound by the tight quarters u will be leaving for your sub.
 
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firing ports upward and subs backwards is not going to help the two interact with each other in a positive manner :D
If you are going for an all-purpose "bump" system, fire the subs and the ports backwards. This will give you the most rear wave reinforcement.

To explain this, if you have ever went to a db drag competition where the competitors are *really* serious (i.e. one note wonder systems with several kw of power), a lot of people will be running a wall of some type. The theory behind this, assuming the subs are in the middle of the vehicle, facing front... is that if the distance between the sub and the mic is X, then the distance from the sub to the back of the box to the front of the box (out the port) to the mic would be 3X.
The rear wave fires through the box (one distance of X where it is out of phase), bounces off the back (reverses phase), travels forward through the box (another distance of X, this time in phase), and then out the box and to the mic (a final distance of X).

If that doesn't make sense, read it again. All the box is doing is converting that rear "pull" wave from out of phase to in phase so it constructively interferes with the forward "push" wave. By firing your woofers backwards, you elongate the distance that the wave has to travel, making it closer to that "X to 3X" ratio.

Hope that helps. Fire them backwards :D
 
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