Quick Question about reverse baffle rings and minimal space in front of the enclosure

[knils 10+ year member]

Thanks man, check these out, my quick shitty sketch-ups of what I was talking about. The first one has them rear firing, the magenta are the rings, imagine they are circular lol. And does yours look anything like the second pic? Is it essentially the same box rotated 90°?

I guess you're right, idk why I was so set on rear-firing, but I've seen countless upfiring setups in other z's and I just wanted to be different but I guess there is just no room. I would have liked to create another fiberglass box set in and under the strut bar glassing it right to the sheet metal floor just ported this time, but one I don't have the time or the resources at the moment, and two I have so many worries about doing that with a ported setup in regards to how it would sound with all of those complex shapes and figuring the tuning. I just wanna jam a sure fire all wood in there and slam it, as I was never happy with how my sealed fb sounded.

 

[bubbagumper6 5,000+ posts]

This is what mine looks like...plus some paint, lol

 

[knils 10+ year member]

alright thanks man, any reason in particular why you set it up like that or will my full length slot work fine? Are there any rules or tips I should know about port placement/shaping in upfiring boxes like this?

 

[nateberrier 10+ year member]

I think you need to quit worrying about facing it back. So long as its not facing forward you should be fine. I have faced subs up and back in hatches and they both get loud as balls. I use aero ports and dont really have to worry about space so i couldnt tell you which one is louder but i can tell you that i hit 135 sealed with a sealed up mb quart 15. thats just a low end sq sub too. thats facing up btw. if you dont have the clearance on the back hatch i wouldnt try to squeeze it cause its prolly gonna sound like ***. that is unless you enjoy watching your trunk rattle.

 

[bubbagumper6 5,000+ posts]

alright thanks man, any reason in particular why you set it up like that or will my full length slot work fine? Are there any rules or tips I should know about port placement/shaping in upfiring boxes like this?

I did it like that because the side of the box that is against the seats is slanted (to use as much of my hatch as possible...18's need a lot of airspace, lol). So it's actually a wedge not a rectangle. Putting the port against a slanted side would have been hard as balls, but since your box is rectangular it will be fine.

 

[knils 10+ year member]

Yeah with thumpers advice and I was already leaning that way and you confirmed it for me. So does anyone have any advice in regards to the port question I asked in my previous post? Any tips or tricks or does my 2nd drawing above look pretty good? Thanks for the help guys, I have them in a sealed fiberglass now and it just doesn't bump like I need.

 

[bubbagumper6 5,000+ posts]

Your second drawing looks fine, provided they have the right airspace/port area/tuning it should be good.

 

[knils 10+ year member]

I did it like that because the side of the box that is against the seats is slanted (to use as much of my hatch as possible...18's need a lot of airspace, lol). So it's actually a wedge not a rectangle. Putting the port against a slanted side would have been hard as balls, but since your box is rectangular it will be fine.

Thanks man, didn't see this before.

 

[EvilSquirrel 10+ year member]

if you haven't already seen this

RE Enclosure Calculator

just change depth with height to make it a port up box.

 

[knils 10+ year member]

Yeah thanks man, I personally think that calc sucks because you still have to take into consideration driver displacement so the tuning doesn't mean shit and some other figures are off in the process. It's much easier to just figure it out yourself picking two out of three interior dimensions, choose your tuning and calculate your port length on your own or use winISD. Then using a couple of simple equations factoring in port disp., net volume as well as driver disp. you can calculate your 3rd dimension (usually length for me) as per the sticky. Then you can use the calc if you still want just to check your math by shortening the length to lessen the airspace to account for your driver displacement and see if the tuning then matches accordingly. Stupid IMHO RE should have an option to factor this in... it makes no sense sitting there punching in arbitrary values until you get what you want and even then it isn't correct and you still have more work to do. I could just be super picky but I can't help it I have an advanced mathematics degree lol it's in my nature.

 

[bubbagumper6 5,000+ posts]

Yeah thanks man, I personally think that calc sucks because you still have to take into consideration driver displacement so the tuning doesn't mean shit and some other figures are off in the process. It's much easier to just figure it out yourself picking two out of three interior dimensions, choose your tuning and calculate your port length on your own or use winISD. Then using a couple of simple equations factoring in port disp., net volume as well as driver disp. you can calculate your 3rd dimension (usually length for me) as per the sticky. Then you can use the calc if you still want just to check your math by shortening the length to lessen the airspace to account for your driver displacement and see if the tuning then matches accordingly. Stupid IMHO RE should have an option to factor this in... it makes no sense sitting there punching in arbitrary values until you get what you want and even then it isn't correct and you still have more work to do. I could just be super picky but I can't help it I have an advanced mathematics degree lol it's in my nature.

Your fairly knowledgeable about enclosure design for a noob, I'm impressed. It is possible to calculate port length without having one of your dimensions as a variable it just takes longer. You calculate what your length should be with your given (static) gross volume, then see what the actual tuning is after the port's displacement. It's going to be off from what you originally wanted, but you just keep tweaking to get to that sweet spot port length, lol. Takes longer but you get to use 100% of your usable trunk volume.

 

[knils 10+ year member]

Thanks man I appreciate all your help, I know I have a low post count I mainly just shop around here but I've been kickin' around here for 6 years I've picked up a thing or two //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif This is just my first ported venture I've built many sealed boxes including some pretty complex fiberglass enclosures, it's just about that time sealed isn't quite enough for me anymore... Can't wait to see how this turns out, if I'm not happy I don't know what I will do, probably trade up for a single 15 and just wang the shit out of it, 9515 or a 15 XXX mehbeeee //content.invisioncic.com/y282845/emoticons/yumyum.gif.0556df42231b304b9c995aefd13928a8.gif

Edit:: Also I'm aware, I wasn't referring to needing the dimensions to calculate the length, the equation just calls for the area and the tuning, I was just referencing the entire process of designing the enclosure, sorry if that was unclear. My particular design happened to have the full length port for simplicity.