2 12" infinitys and a kenwood amp

18 tweeters??? Are you kidding me?? Um hopefully all those aren't hooked up to the Alpine HU.

I personally like Kenwood amps (9102D and 9052D more though...Don't like the looks of the Excelons)

Well If your looking for more spl the addition of 2 more woofers and another amp is only gonna give you a 3 db increase.

What I would do is build or have a professional build you a new different enclosure...Have you read about the wicked one? Go to www.decware.com

Those infinity's in that box would most likely give you more output than adding two more subs and another amp...Also going the new box route would put a lot less strain on your electrical system.

Plus...you'd save a lotta money by building a new box than buying 2 more subs and another amp.

2 cents worth

 

Sorry man, gotta disagree on the 3 dB increase. In my experience, you double the cone area, thats 3 dB, you double the power, thats 3 dB, and a neat thing called acoustic coupling is good for 1-2 dB, So in reality if its all installed PROPERLY, he would be good for anothe r7 dB or so.

 

Doubling cone area will generally get a 3dB increase, I agree. But doubling power will seldom get a 3dB increase.

Here is what I have found, if a vehicle is maximized in its performance and you measure SPL, then change only power (2 to 3 times), you will only get a couple of tenths of a dB increase. If I remember right (please correct me if I am wrong) the dB scale we use to measure SPL is a logarithmic function with a limit. As The scale gets higher and higher it aproaches that limit. So inorder to double SPL we would need to increase power 5-10 times depending on how high our SPL was to begin with.

I did a research paper on this about 5 years ago because of an old Ford truck. In a competition his system did a 138dB. I remember because this was in an under 250-watt class. He took second in his class and a few days later we replaced his amp with an 800-watt amp. I was amazed to see only an 1/2 dB increase.

Comments welcome, I really want to hear some.

Hey Buick guy, Your car is well insulated. I would highly recommend a custom built ported enclosure with a really large port. I am a huge Kenwood fan, but for loud there are better options. Your choice of speakers is good. But loud is a function of the box.

Dawg that was a whole $1.15 worth, sorry( I've got to quit rambling)

 

Forgive me, i am rusty in my math! You are correct in the fact that the dB scale is a logarithmic scale. What i have found over the years is what I stated above. Its a generality and not 100% accurate, but is usually in the ball park. The Limit you refer to is an unknown, what is known is the parameters of the drivers and the power of the amps, cabin gain, or tranfer functiion if you will, and number of speakers and gain of the enclsure. All of these numbers can be crunched on a scientific calculator, and with these numbers, an amazingly accurate prediction can be made of the final spl of a vehicle. I was almost always within 10-15% of the figures in most all straightforward systems, excluding experimantal and exotic designs! I need to dig around for the old equation for that, it was really quite simple!

Every 3 dB increase requires a doubling of speaker area, or doubling of amplifier power, and by palcing drivers next to each other in close proximity, a "slight" gain can also be realized. The situation you mention in the ol ford truck with the increase in power yeiding minimal gains in output could be due to a few reasons, as i have seen this also. The issue was the dispalcement limited power handling of the drivers in the enclosure, A speaker in a box allowing it to reach a certain spl at a certain frequency at say 100 watts, will not gain any more spl if fed more power, IF its reaching it mechanical limits already aat the 100 watt input. Thats where some complications can arise with more power and no more spl!

I knd of went on a ramble there, sorry, hope that makes sense, been a long night! will try to clarify more later if this is not a good enough post!

Not tryin to be argumantative with ya Ranger, just tryin to speak from my years of experience in the field of mobile audio, But if I am wrong, I will gladly admit it!

 

LOL! sorry man, got tied up with other things !!!!!!


I am going to answer your question, just dont be in too big of a hurry here!


You want to build a box in your vehicle that is properly built obviosly, so, with that said, there a re afew things you need to understand, IF you do not have the tools or skills to properly build an enclosure, i sugggest the services of a GOOD installer. In your car, say with 4 12 inchers I believe is what you wanted, I would do a simple sealed enclosure. All woofers firning in the same direction on the box. I do not know the power output of your amp, nor the specs on your subs, so this is just a guideline for good performance mind you. I would have the box built to allow the woofers to achieve near their maximium excursion at the power you are feeding them. The box could also be ported if you want, but that is another animal all together and I dont know you or what kind of music you listen too or how much you could respect the volume contol and bass knob, so sealed would be best in this situation! The manufactureer of the subs should supply you with the proper info on this. Build the box out of at least 3/4 inch MDF and keep each woofer seperate from the others by internal baffles, this will also greatly strengthen the box.

There are other methods of enclusre design and methods of installing subs to get extreme BOOM, but that is beyond the scope of this forum!

 

Oh ya, electrical system.......All minimum 4 gauge wiring here.........

From the engine block to the battery neg.
from the battery neg. to the chassis
From the alternator output to the pos. batt ( be sure to run this one in a SAFE manner!!!!! dont want any shorts on this one!!!!)
And, DONT WASTE YOUR MONEY ON A CAP! use that money for larger power wire to the amps!

As far as dynamat goes, its good stuff, again, when properly installed, I might invest a few bucks in it to put on your trunk lid and other key areas once you find out where all the resonce is coming from

 

Well just got back from going out tonight...I didn't mean for you to BUY the box from the website. I just meant it

Building it would be a lot cheaper. You said it's a hobby...well box building is a hobby that is in the same field. This horn loaded enclosure is tight and clean and very efficient. And it can get loud and low. Pretty much its a kickass box. I'm working on one for a pair of 10's right now. Just if anyone wants to know lol http://www.rockfordfosgate.com/ez2/ModelInfo/ModelInfo.asp?ItemKey=10060203
Got em for like 40 bucks from a friend who just needed some money.

Well to have a professional build that box for you do you really think it would cost as much or more than another amp and 2 more subs?

And how are the tweeters wired?

 

Dont know what you wanna pay for an alternator, but these are some good ones, albeit, PRICEY!

http://www.americanarmature.com/partcatolog.htm


just do a search for them, you will find them! just be cautious of over exagerated claims, you get what you pay for!

 

Tape measure and basic geometry. Some masking tape will help you divide the trunk into easier shapes. Divide it into rectangles and triangles, figure the size of each and add them together. It will be a good idea to order a little bit extra for any screwups and overlapping areas.