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AltarCrystal
06-19-2007, 11:50 PM
Alright, I've finally got my box all planned out...EXCEPT for the ports.

Due to the boxes shape (5-sided...having some fun with this one :naughty:) I'm using ruond ports.

I've never done round ports before.

So, I found a port calculator, and it said if I use tubes 3" in diamater, it needs to be 8.39" long to tune the box to 30hz. Would this be good for an Fi Q in a box that's 2 cubes?

Now, do I attach the port so it starts at the hole for the tube, not sticking in the box, and goes out 8.39"? I assume so, or do I have part of that in the box? What if I want 2 tubes? Would PVC with custom made flares be good enough for this? It should I buy aeroports?

patrick1202
06-19-2007, 11:57 PM
lmao no you go inside the box not outside of the box and if you got two then the tuning would be off you probably have to divide the length by two not sure if you can do that

patrick1202
06-19-2007, 11:57 PM
have you ever seen a box with 8 inch pvc pipes sticking out of it im not sayin it wouldn't work but i dont think so

AltarCrystal
06-20-2007, 12:18 AM
have you ever seen a box with 8 inch pvc pipes sticking out of it im not sayin it wouldn't work but i dont think so

Well, yeah, I have. Thus, the question.

But alright, cool, thanks.

jaco
06-20-2007, 12:21 AM
have you ever seen a box with 8 inch pvc pipes sticking out of it im not sayin it wouldn't work but i dont think so

my box has 4-4" ports sticking out of it.
what you act like you've never seen that before

patrick1202
06-20-2007, 02:18 AM
no i've seen it before just not much around here and somethin like you app not like a box 8 in port sticking out that would probably cause difficultys unless in a suv or somethin no i could see of your box was to small in a certain demension for you to tune it correctly couldn't you change the tuning by just adding piping??

mazdakid
06-20-2007, 07:10 AM
you should have atleast 2 4" ports for that sub and box. a single 3" one isnt going to sound nice

bdawson72
06-20-2007, 07:25 AM
have you ever seen a box with 8 inch pvc pipes sticking out of it im not sayin it wouldn't work but i dont think so
Aren't you just the smart one

AltarCrystal
06-20-2007, 11:59 AM
you should have atleast 2 4" ports for that sub and box. a single 3" one isnt going to sound nice

Hm, alright. Now, the calculators I found that calculate more than one round port, but when I calculate 2-4" ports to tune a 2 cube box to 30hz, it says the vent length needs to be 34.7". Is that per each tube? Or total, making each tube 17.35"? Also, since that's actually deeper than my box, would I leave lsome room from the back of the box for one end of the tubes, and have ends of it sticking out from the box a few inches?

Sorry for all the questions, like I said, I've never worked with round ports before.

jdawg
06-20-2007, 12:13 PM
is the internal volume of the box 2 cubes minus the displacement of the woofer?

AltarCrystal
06-20-2007, 04:23 PM
is the internal volume of the box 2 cubes minus the displacement of the woofer?

It's 2 cubes AFTER the displacement of the woofer. I havn't built it yet, so I can easily change it by makign it wider or less wide.

mazdakid
06-20-2007, 04:25 PM
you can have the port inside the box or outside the box, doesnt really matter. just dont put it too close to the back wall. when you get the port length its for each port, not both together

AltarCrystal
06-20-2007, 05:32 PM
you can have the port inside the box or outside the box, doesnt really matter. just dont put it too close to the back wall. when you get the port length its for each port, not both together

Man, so to 34.7" long tubes that are 4" in diamater? That's kinda...big.

Am I doing something wrong here? I mean, two 34" tubes? That's about as long as the trunk itself.

mazdakid
06-20-2007, 05:39 PM
dont tune it to 30hz and they wont have to be so long, or make a slot port

SSS 18734
06-20-2007, 05:40 PM
Don't forget to account for the airspace of the port inside your box when building it. They can take up quite a bit.

two 34" ports is too much. You can save space my using a single 4" port and raising the tuning to, say... 35hz. That should make the port at least manageable. You might have some port noise at high SPL levels, but for daily driving, and even moderately loud music, you should be alright. I'd say that beats having two 3 foot ports sticking out of the box.

djman37
06-20-2007, 05:47 PM
the calc on www.psp-inc.com gives lengths for EACH port. The two factors that affect port length are box size and tuning. Bigger box=shorter port, higher tuning=shorter port.
Adding ports, whether inside or outside the box, increases port AREA, but also increases port length.

Precision ports are good, but I hear real AEROPORTS are due out again in a day or so.

AltarCrystal
06-20-2007, 05:56 PM
Don't forget to account for the airspace of the port inside your box when building it. They can take up quite a bit.

two 34" ports is too much. You can save space my using a single 4" port and raising the tuning to, say... 35hz. That should make the port at least manageable. You might have some port noise at high SPL levels, but for daily driving, and even moderately loud music, you should be alright. I'd say that beats having two 3 foot ports sticking out of the box.

True, but isn't 35hz kinda high for a 12" Fi Q? They suggest 29-33hz, would 35 be a drastact change from 30?

Though a single 4" tube would only have to be 15.89". If I leave what...3" from the back (Isn't that what most people suggest?) of the box, that'll be about 9" inside the box, and only 6" would be sticking out, which to me, is a lot more reasonable than 3'.

donpisto
06-20-2007, 06:02 PM
have you ever seen a box with 8 inch pvc pipes sticking out of it im not sayin it wouldn't work but i dont think so

Home depot and lowes didnt have 8" pvc pipes :(

I'm stuck with only two 6" pipes, oh wellz

SSS 18734
06-20-2007, 06:03 PM
True, but isn't 35hz kinda high for a 12" Fi Q? They suggest 29-33hz, would 35 be a drastact change from 30?

I guess that depends on how picky you are with your music listening. More than likely, you won't notice anything except for overall increased output. Why don't you try increasing the box size by 1/4 square foot and raising the tuning to 33? Don't forget to account for port displacement as well.


Though a single 4" tube would only have to be 15.89". If I leave what...3" from the back (Isn't that what most people suggest?) of the box, that'll be about 9" inside the box, and only 6" would be sticking out, which to me, is a lot more reasonable than 3'. Ports sticking out of your box are ugly... it just looks tacky. Make sure your ports are at least 4" away from the back wall if you do choose to go that route.

jdawg
06-20-2007, 06:07 PM
im thinking increase the volume of the box, you can stay around 32, ports should be more managable, what size Q?

AltarCrystal
06-20-2007, 06:08 PM
Another question, what if I put an elbow or two, so I can have the longer pipe, but it isn't sticking stright out. Or better yet, keep the pipe inside the box.

SSS 18734
06-20-2007, 06:11 PM
Another question, what if I put an elbow or two, so I can have the longer pipe, but it isn't sticking stright out. Or better yet, keep the pipe inside the box.

You could probably do that but I'd imagine it would be more trouble than its worth... although you are making an odd box...

AltarCrystal
06-20-2007, 06:27 PM
You could probably do that but I'd imagine it would be more trouble than its worth... although you are making an odd box...

Yeah, the whole box is more trouble than it worth probably :laugh:

The reason for the shape is due to two reasons. One, the back of my trunk is sloped (Since the seats fold down). Two, my parents insist (and I can see where they're coming from with this one, because I'll be driving 1.5-2 hours 4 days a week for the next 4 years) that I shape it like this so I can still get my spare out (cut the board over it so it will sort of hinge up, going with the angle of the bottom of the box). I'll see if I can get some quick sketches made in MS paint or somethign of the side (all I have done so far) so you can see what I'm talking about.

So, it's gonna be tough, but meh, I have nothing to do for the next 2 months, it'll keep me busy :laugh:

Chevyaudio
06-20-2007, 06:36 PM
also if you do 2 ports...and the calculator says the tube should be 8" make sure BOTH tubes are 8" NOT each 4" long.

AltarCrystal
06-20-2007, 09:27 PM
Alright, here's the basic shape of the box, and how it will look in the trunk so you can see what I was talking about...

http://img523.imageshack.us/img523/7407/boxshapeintrunkbz6.jpg

The box is the 5-sided shape, not EXACTLY how it's shaped, but close enough. The yellow line is where the board will be cut to "hing" the carpet so I can still get my spare out.

Now, for the tuning.

I want to say before I say anymore, I have no clue if this will work at all or not, so I'm sorry if it's retarded :laugh:

For 2 ports, 4" in diamater, they have to be 34.7" long to tune the box to 30hz, or 30.15 to tune it to 32hz.

Here's my idea. First, a drawing.

http://img341.imageshack.us/img341/2419/boxtuningii6.jpg

To explaine that mess, the black circles are the holes on the outside of the box. If all goes well, they'll be flush with the box. If not, atleast smooth.

The grey lines is the tubing running the the box, white dotted lines is tubing continuing to run BEHIND the sub, and the grey circle is the other end of the tubing in the box. Each tube will go twords the back of the box, either up or down, and then across. Finally, the third bend is probably just an elbow, just to get the opening away from the walls.

They'll be on either side of the sub (as in, above and below). First thing I thought of was these tubes rattling, so I could braces them agaisnt the back wall no problem.

Assuming these fit...is this possible? Or is this completely retarded?

AltarCrystal
06-20-2007, 09:31 PM
Forgot to mention, yes, I'll adjust the box to accomadate for the displacement of the tubing. Basically I'm planning on applying basic science to this one, and just dunking it in water and measuring how much water the tubing displaces.

AltarCrystal
06-21-2007, 12:01 AM
And to make it a third post in a row, should I just do somewhat like I was talking about earlier, except insted of two 34" long of 4" pipe, a single 4" pipe, whilh would be 15.89" long. Probably be sub on the left, port on the right. It'd run back, up or down, and then across the back. Brace it to the back (This would be smartest, right?) and put an elbow and point it in the most open area to get it out from against the walls.

I'm also planning on making custom made flares...no clue how, but it will be done. Luckily my dad is into construction and stuff, as is much of my family, so we'll think of something. Maybe even fiberglass?

We were thinking of getting a reduccer, from like 5" or so to 4" if they even make them, cut off at the end of the transistion, and sand it down.

How much of a difference would 2 ports be over one port? Would this mess with the sound as opposed to just having normal ports?

AltarCrystal
06-21-2007, 02:23 PM
Alright, here's a MUCH better pic of the proposed box. This is if I can somehow do dual 4" ports. If not, the sub will be on the left, port on the right...

http://img523.imageshack.us/img523/6508/renderedprofilede7.jpg

So, what do you think? Would my idea for dual ports on the inside work? Like I said, I can adjust the width a good amount to accomodate for the pipe.

maldecido33
06-21-2007, 02:29 PM
Looks like it'd work great.

jdawg
06-21-2007, 02:34 PM
dunking your ports in water wont work because the ports will fill up with water, just figure out the volume of a cylinder, http://www.the12volt.com/caraudio/boxcalcs.asp

AltarCrystal
06-21-2007, 10:44 PM
dunking your ports in water wont work because the ports will fill up with water, just figure out the volume of a cylinder, http://www.the12volt.com/caraudio/boxcalcs.asp

I thought it was jsut the acual space taken up by materal of the box? I have to accomadate for the actual volume of the pipe? Hm, alright, thanks for the heads up!

Anyone know if running my ports like I mentioned (along the back wall, braced, and have a few elbows in there) will work if I calculate everything correctly? Would 2 4" ports sound much better than one 4" port? One 4" would only have to be like 15.9" long, much more managable (Half the width of my box, about.

Trixter
06-22-2007, 01:09 PM
first off, when finding port displacement, you need to account for the material the port is made of and the air space it takes up. however, if your using 3/4" mdf for your box, then you can subtract 3/4" from the length...this is only for finding it's displacement. since you use the internal volume of the box, the thickness of the wood is already accounted for.

secondly, the port must stay at least the port's width away from the back of the box.

third, why don't you put the ports on top?

fourth, if you use pvc, use the pvc 90deg. elbows (remember to measure down the center for port length). a single 4" port will need to be 15.75" long to tune a 2cu' box to 30hz...this is 2cu' net...after all displacement is accounted for...you may be better off going this route.

AltarCrystal
06-22-2007, 01:16 PM
first off, when finding port displacement, you need to account for the material the port is made of and the air space it takes up. however, if your using 3/4" mdf for your box, then you can subtract 3/4" from the length...this is only for finding it's displacement. since you use the internal volume of the box, the thickness of the wood is already accounted for.

secondly, the port must stay at least the port's width away from the back of the box.

third, why don't you put the ports on top?

fourth, if you use pvc, use the pvc 90deg. elbows (remember to measure down the center for port length). a single 4" port will need to be 15.75" long to tune a 2cu' box to 30hz...this is 2cu' net...after all displacement is accounted for...you may be better off going this route.

Well, the reason I don't want to put the ports up top is because the box 14.5" tall, and my trunk is only about an inch taller than that..

And yeah, I guess I'll just go with a singl 4" port. It's not going to be a drastically noticable difference, will it?

Edit: Here's the design I did a quick sketch of real quick. Everything is to scale. It's actually EXACTLY 2 cubes after ALL displacements (Including the pipe).

http://img517.imageshack.us/img517/8068/renderedprofilesinglerofy8.jpg