BsEMS

well.. you shouldnt get anothe sp4. b/c on a stock alt (unless you add a HUGE battery bank back there) you wont be able to power 2 sp4 sufficiently.

Before you do any changes.. ie new box, wall, adding a sub, changing amps.. UPGRADE YOUR ELECTRICAL. THeres no way your getting the spec'd rms out of that amp if you havent done all of the following. 1. BIG 3 wiring upgrade. 2. Added at least 1 extra battery. 3. Installed an high output alternator. And then Id say get yourself a 3500 watt amp. AQ, SAZ, or M3B. You will experience serious gains and it will sound like you have a new system all over again. :cheers:

Ohh ok, I have an sp4..and my design is on the forum.. its a basic slot port.. I keep it simple, clean, and LOUD!

You should have already invested in a fire extinguisher if you have any type of high(er) powered audio installation. Shit happens.

Me personally, I only used two charts to design my box. Rear port velocity, to show what the speed of air would be exiting the port at each frequency, and the graph that displays the output bandwidth. The others I didnt find usefull, or I just didnt understand quite well enough. With those two you can play with your tuning and see how it effects the output bandwidth of the design, and how much stronger/weaker the port velocity is at your desired range of frequency.

Nice design! From the 1st box designs.. i dont get the"4th port wall" area.. what the point of having that little box'd out area? THen i see its changed in your 2nd dwg.. .but as far as the 45degree corner slabs.... ive read that they actually hurt spl numbers when put in corners that have nothing to do with helping the port flow.

I got it to work. Must have been the jobs' computer internet limitations.

I guess a single page pulled from a book with a couple pictures is a lot to read these days.If you clicked on the link you would see a page refrenced lol LOL. man when I clicked the link it took me straight to the cover page. And yes..there was two pictures on it! B-)

I'd love to sit and read all of that. But cant right now. What chapter or page references what we're discussing?

Minor change- I will tune a bit higher @ 32-33 hz. Doing this should gain overall output and lose very little low end.

 How is this so? I assume kerfing the inner port wall (opening) would kind of act in a expanding wave type deal. But if only at the edge..how would an inch or so distance of port opening kerf be more effective than kerfing the entire inner wall(s) of the port? My goal with kerfing is to create a more efficient path for air to travel, increasing port air velocity and lessening resistance from the traditional 90degree L-Port design. I am not an engineer in fluid mechanics but I would think it would be more beneficial to decrease turbulence at the mouth of the port. Any bends throughout the port length are typically cut at a forty five degree angle to reduce turbulence. Which is standard practice for many speaker enclosure designers. What is most important is that your port is properly designed for your enclosure. Is there legitimate turbulence at the mouth though? I dont know. I assumed since it is coming from a confined space into an open space that turbulence(resistance to flow?) would be minimal at the mouth. But yes, I did try to calculate port volume as accurately as possible for my setup.

I seriously considered dowel rods.. but only b/c i see a lot of builds with them. But if I take into account the largest "empty" space of my box w/o bracing is going to be around 33 x 12 inches of area. Theres no way that small space will need extra support, especially if the sub isnt going to be mounted on top the box.

I've already built a mock-up. And the only adjustment I made was having total height at 16.75 instead of 17. And it fit like a muthfreakin glove. 40" wide fits just perfect into the trunk opening. I bought some cheap 3/4 cello foam from Home Depot, got a straight edge + a retractible blade. And cut, taped it to perfection. It turned out to be a solid representation of my enclsure... all dimensions falling within 1/16 to 2/16 tolerance (due to the density of the foam board and the cleanliness of the cuts)

How is this so? I assume kerfing the inner port wall (opening) would kind of act in a expanding wave type deal. But if only at the edge..how would an inch or so distance of port opening kerf be more effective than kerfing the entire inner wall(s) of the port? My goal with kerfing is to create a more efficient path for air to travel, increasing port air velocity and lessening resistance from the traditional 90degree L-Port design.

wait a minute.. ( i just caught up on the thread). You DONT want to unscrew the sub and LOOK at the spider and or tinsel lead / cone connection point? you must not really be worried about it. The woofer showed you signs of malfunction..but you ignored them and didnt evaluate the problem other than writing emails to FI. Now it has worsened to a point where there is a safety issue within your vehicle...and you STILL dont want to unscrew it and see what is happening? I really hope you car stays safe, but If i were you, I wouldnt put my health, my cars health, my sound systems health, in jeapordy soley because im too lazy to remove the sub and re check wiring.