Tuning round ports?

[djman37 5,000+ posts]

the calc on http://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 10+ year member]

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 5,000+ posts]

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 //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

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

 

[SSS 18734 5,000+ posts]

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 5,000+ posts]

im thinking increase the volume of the box, you can stay around 32, ports should be more managable, what size Q?

 

[AltarCrystal 10+ year member]

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 5,000+ posts]

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 10+ year member]

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 //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

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 //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

 

[Chevyaudio 5,000+ posts]

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 10+ year member]

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...

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 //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

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.

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 10+ year member]

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 10+ year member]

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 10+ year member]

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...

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 10+ year member]

Looks like it'd work great.

 

[jdawg 5,000+ posts]

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