Rufus

iTrader: (17)

I haven't checked volume yet, but I'd say I'm anywhere from 3.5 to 4 cubic feet. I'm running 2 Diamond Audio TDX 104's, powered by a JL 500/1. Diamond states that 1 cubic foot apiece is adequate for these subs, but I've heard a few in inclosures and they definitely like more airspace. So even at the most I'm looking at 2 cubic feet per sub, not including displacement for ports or drivers. Here's the issue. You can look at the sub box, and it's easy enough to see how it mounts in the car. The bottom of every photo is the back of the box (closest to bumper). Diamond calls for 4" ports at 22.5" long tuned at 35hz for a 1 cubic foot enclosure. If I actually run some ports the length of 22.5, the only way in a round port I'd do it is to run it on the bottom of the enclosure, opening up at the front of the box (just behind the back seat.) I wouldn't run them to the back of the box, as the fiberglass is about 2" from the spot where jack used to be. Technically there is approx .5 square foot of space back where the jack is now between the wall of the trunk and the back of the enclosure, however once the box is mounted, that area is almost sealed. It would almost port the enlclosure into a sealed area. Make sense? They might load well, but it wouldn't really be ported. So the thought I'm having is square ported or slot ports. I don't want to fire the ports upward. I could fire 2 ports on each side of the woofer closest to the cabin. The port would open on the sides (3"x 12.25), go inside the box about 7.25" and go down another 7". These are only AVAILABLE measurements and are not what I intend to use, however I have the same available space on either side, so essentially I could use 2 identical ports of this nature. I will also have a trim piece going over the entire enclosure (opening on top for the subs). The trim piece wouln't let much of the port noise into the cabin, however this would help load the subs too. I had intented to port the rear deck somehow too. Let me know your porting thoughts.

Rufus

iTrader: (17)

pic 2

Rufus

iTrader: (17)

Pic 3

WhiteRabbit

I would suggest not porting the rear deck, I have yet to hear one sucessful story of doing it, and about half a dozen or eight unsucessful ones.

doesnt seem worth it.

as to the ports, you can totally bend it, so the opening can be whereever you want it (same baffle as the speakers)

I used elementals boxpicture as the prime example, but they are revamping the site, check out the picture for reccommended box for the TDX< If i remember the M6 or the TDX reccommended box dimensions from diamond showed a folded port.

Rufus

iTrader: (17)

From what I've heard, now that I've doubled recommended box volume, I can maintain the 4" ports size but drop port length to half to stay at a 35hz tuned enclosure.

WhiteRabbit

oh, definitly download winISD or grab a calculator and get on JL's port tutorial and confirm that!

you are totally right, a smaller port to keep the same tuning frequency at the same port area nad larger box volume, but beware! it may not be a linear relationship between length and volume!

Rufus

iTrader: (17)

It was an eye opener to see on the JL website that port volume is NOT a function of frequency, but a function of cross-sectional area and length. White if I gave you box volume, with the specs I already have (T/S Parameters, recommended ports, etc,) could you could plug them in for me? Here's the thing; I've spent way too much time making this enclosure to screw it up with ports. I really want two ports on each side up front. I understand that I can create a square port of equal length as long as area is equivalent but as you can see I dont have 22" to work with. I need a larger port size that goes inside the box and drops down. I decided to take a break from college afte MAT120 so to me, this formula looks as inviting as a fat chick. Here's a pic of my idea with the port style I'd like. My original post has my available area for ports. If not let me know a better way to calculate this thing. My car is an 03, I've had it just over one year now and my quarter panels and rear deck have been off the car since the month I bought it. I'm half slow and half WAY TOO **** about everything sounding perfect. I gone through 10W6's, Cervin Vegas, PPI Pros, and I'm hoping these subs are finally the SQ/SPL I'm looking for. Thanks

WhiteRabbit

I would worry about porting forward with teh subwofoers facing up. its got the potential to screw up the response just based on positioning, tuning be dammed!

ill be glad to wor out port dimensions with you, I think It would be much better to do so live rather than on the forum, you can AIM me anytime whiterabbitttttt, im usually in the CAF chatroom too, but not lately, as ive been busy with a research project.

if you dont have IM or never see me in CAF, we can try it here, ill need VAS, FS, and QTS, along with your desired tuning frequency and/or port dimension limitations, and we can work something out.

ludlam can do the same, as can custom2k1

LudlamTheory

my aim is dubitalie

happy to help

Rufus

iTrader: (17)

You guys are awesome
VAS 17.5
FS 35
QTS 0.53
I'd like to tune to (and Diamond recommends the same) 35Hz

If I fire out the sides onto the wheel wells , like the illustration shows, I'm limited to the ports being a 3"x 12.25 opening, go inside the box 7.25" and go down another 7". The illustration on my last posted pic shows 2 of the required demensions. Substrate would be .5" MDF so we'd need to subtract that for usable airspace. The port COULD actually go down more than 7" into the box, but as it is, the port remains approx. 4 inches from the bottom of the enclosure.

I'll post volume of the enclosure tonight. Here are more pics too 1. Installed in car 2. Area for ports 3. Without baffle

Thanks again you guys.

Rufus

iTrader: (17)

ports

Rufus

iTrader: (17)

no baffle

WhiteRabbit

firing out the sides may actually work.

Christopher Evert did the same inhis civic, except instead of having hte ports fire straight out then bend down, like your drawing, he had the ports partly external to the box, with the 90 degree bend outside the actual box, so the ports fired up, along with the woofers. worked very very well for him.

with a vas of 17.5 liters, qts of .53, and fs of 35 Hz in 1.75 ported (single subwoofer) with a single port 12.25x3 inches, you would have 37.5 inches of port area, needing a length of 42 inches to achieve a tune of 35 Hz. this seems pretty unrerasonable!

with 1.75 to work with, id figure about 16 square inches of port area, giving you 17 inches port length to achieve a 35 Hz tune.

good luck!

LudlamTheory

you sure thats 1.75 cubes per woofer?

seems slightly bigger

WhiteRabbit

rounding. if its like 15.8 ill say 16, and stuff like that. Ususally I will round up, to get a lower tune as opposed to rounding down, I think these guys would be happier with a tuning erring on the low side rather than the high.

Rufus

iTrader: (17)

Here we go guys. After filling it with peanuts, I was left enough room for the 6x12x12 box and a little more. The box was filled with 3.5 cubic feet of packing peanuts. Add on the box in the photo and the spare room: We have 4 cubic feet and a little change. I have added a shot of the ts parameters too, but what you can't see is driver displacement, which comes in at .1 cubic foot per speaker. Metrically it's 2.98L. Let me know what you guys think. My email is dallis_hughes@hotmail.com if it's any easier, but now that you guys are willing to help I'll call long distance to China to get it solved. I appreciate it.

Rufus

iTrader: (17)

Theile/Small

Rufus

iTrader: (17)

I also have 5.5" between the side of the box and the wheelwell, so the ports can stick out of the box. At that point we have two choices: I can build new trim and let the ports fire at the dynamat. As opposed to putting my trunk liner back (which I had intended) and they would fire onto that firm fabric. Or option 2, I COULD cut port holes in the lid and let it fire up but here are my concerns. Will affect loading? Will it be a better sound than the original design? (where the ports firing sideways would be covered by the trim lid when its set over the enclosure). If I put any type of mesh baffle over the ports to protect anything from falling into the box will it affect sound. Not only that but the ports would stick up higher than the trim piece and look tacky. Geesh. Am I **** enough to run this thing down the lanes?

WhiteRabbit

good that its on the big side, thatll reduce your needed port length!

17.5 inches long for 20 square inches of port area, thats 2 cubes plus some change per chamber.

13.75 inches long for 16 inches of port area

15.75 inches long for 18 inches of port area

WhiteRabbit

here is chris's civic:

http://www.geocities.com/geolemon/in...tion-civic.jpg

youll need to copy that URL and reopen IE, THEN paste it in and hit enter for geocities to load liek that

Rufus

iTrader: (17)

Is that rating on a per chamber basis? If they share the same airspace, do I need 2 ports of

13.75 inches long for 16 inches of port area
or
15.75 inches long for 18 inches of port area ?


Just checked out the pic too, the angled PVC is an option.

WhiteRabbit

you dont have to do PVC, you can angle a slot port, just liek you ahve designed, just formed the way christopher has his!

yeah, jsut checked winISD< its the samwe if they share airspace.

if they share airspace, its like 4.1 cubes total, two ports, 16 square inches, 13.75 inches long each, etc, same stuff.

dual 4 inch PVC, 10.5 inches long each
dual 6 inch PVC, 25.75 inches long each

or you could do a single port.

4.1 ported to 35 Hz, single port:

24 sq inches of port, 8.75 inches long

36 sq inches of port, 14.25 inches long

6" PVC = 28.27 sq inches of port area, 10.75 inches long

Rufus

iTrader: (17)

So it I chose the second option, I could build a port with a 3"x5.25" with a 7" drop into the box but have the horizontal length be about 9" This would protrude out of the box about 2" but would work. From my understanding it's not actual length but effective length. So I assume if I measure from the back bottom to the outside top edge, I'd have a measurement approx. 15.75 inches

Rufus

iTrader: (17)

How come the larger port area "dual 6 inch PVC" requires more length? The problem is that the side wall where I was going to build Would only fit a 4" tube, which has an even smaller area. If I could use 4" tubing (and figure out the actual area, I could find a way to bend it around to fit in the box. Whats you're opinion on ports styles and how they sound? But yes, it's solved now, and I can figure out fabrication, Thanks a million.

WhiteRabbit

slot ports asre supposed to be less noisy, i have no idea why.

I like slot ports because I can build it into the side of the box and use it as bracing. I can always route out the port to reduce whistling.

PVC is more expensive than MDF

dul 6" pvc requires hte most length because it has the most effective area. as youc an see, the more area we build into teh box, teh longer the port neesd opt be to achieve the same tune

Rufus

iTrader: (17)

Ok it took me a bit but I think I get it. Even though the area of the port would enlarge using a 6" vs a 4", because we are in fact causing MORE displacement with a larger port, we must effectively make up for that extra displacement by making the port longer.

WhiteRabbit

displacement usually refers to volume, not area, but im just nitpicking.

you are totally correct.

Rufus

iTrader: (17)

oops, meant volume. I'd nitpick too. Finished the slot ports with mdf and installing them tonight. The only part I didn't like is that the ports, on the outside of the box, are only 3" from the supports in trunk. I would have liked to have been at least 4" from anything. One last question if possible: I'm putting my alum dome Diamond tweets in my a-pillars and silk domes in the kicks. Is there anything I should pay attention to when installed them other than installation itself. I know that the harsh sound from the alum domes goes well when faced almost at each other in the a-pillars. I also have the entire front window tinted which should help reflection. Should I attempt to aim them both at the very center of the window? Should I install them at ear height? They will prob be at a 2db below the kicks, I just want to do it right the first time.

WhiteRabbit

im not sure what the response is for your tweeters, but try this.

listen to some music with one of your tweeters, aluminum or silk, with teh tweet pointing right at you. then slowly tilt it away, and listen to its performance as it goes off axis, especially at around 30 degrees-ish

whichever tweeter sounds better to you offaxis at approx. 30 degrees, and whichever tweerter sounds better to you (not louder!) directly on axis, put the on axis tweet in the a pillar and the off axis tweet in the kickpanel.

silk or aluminum, the right tweeter will end up in the right spot.

Rufus

iTrader: (17)

Should they be positioned in any specific direction (degree) on the pillar? They're tweets from a Diamond Audio Hex 6.5 Component set. I'm sure I could spot response somewhere.