View Full Version : Port Q that will stump the pros *PICS*

02-13-2007, 10:03 PM
Look at the pics to see the problem. Port is 12.5" tall and box is 23.85" tall. Put port in the middle of box cause it looks the best. I have the "dead air space" pics showing that this way makes the box on the inside flush so air can flow better?? The other pics show how there is overhangs above and below the ports. Would this restrict air flow????
Just look at the pics to see wut i mean

red line represents "dead air space" above and below the ports and how it is flush on the inside.
green line represents the air flow of air in the port
Pink rectangle represents the flush sides on the inside.
Another angle
Another angle
top view of dead air space

Now just the plain port without the dead air space fillers...
See how this has odd places for air to get trapped.. Under and above the port
Just a pic showing the front off

So which one is better. The dead air space filler or the port suspended in the middle of the box??

02-13-2007, 10:16 PM
How much port area?

Just make it a common box with a single port.



02-13-2007, 10:25 PM

02-13-2007, 10:25 PM
but which plan is better

02-13-2007, 10:27 PM
why even make a box/vent like that anyway?

02-13-2007, 10:29 PM
why even make a box/vent like that anyway?I was thinking the same thing???:eyebrow:

02-13-2007, 10:30 PM
ngsm13's plan

02-13-2007, 10:32 PM
Oh didn't stump the pros either...ngsm13 answere right away ;)....the port suspened like that does look pretty cool! Interested to see what the other pros have to say!

02-13-2007, 10:35 PM
cause it looks sick and its something different
Wut about my main question: Will these different plans affect air flow. (i guess its too hard of a question for u guys cause youve never seen something like that before.:naughty: )

02-13-2007, 10:40 PM
i'm sorry- but what is the question?

02-13-2007, 10:45 PM
look at the first 5 pics. The ports have "dead air space" (The red line) It is a seperate chamber just to make the inside walls of the box flush. Compared to the other plan which has the port floating in the middle of the box. Would the floating port affect air flow??

See this is a hard question

W8 a minute
02-13-2007, 10:50 PM
It's the "pressure" in the box that moves the air back and forth in the port. It's not a constant air stream or flow. I don't think what you call dead airspace will have much affect on anything. But, IMHO I don't consider myself a pro either.

02-13-2007, 10:56 PM
right im just using the "dead air space" as an example of what i am doing.

So my question is will the dead air space filler be better than the suspended port???

02-13-2007, 10:58 PM
im not no pro but if you have the right cuft of vol. in ur box, and tune port right then you wont have " dead air space" i mean i understand your plans but like everyone else said why would you do that??

02-13-2007, 11:00 PM
cause it looks sick and its something different
Wut about my main question: Will these different plans affect air flow. (i guess its too hard of a question for u guys cause youve never seen something like that before.:naughty: )


And how do you One thousand and fifty square inches of port?


02-13-2007, 11:02 PM
Just like your screenname entails...your as crazy, and dumb as mickey rooney...

02-13-2007, 11:04 PM
both enclosure will work the same exact way, the last enclosure you posted will have a lower tuning freq because of the increase Vb. why dont you just build the port to go the full hight of the enclosure?

02-13-2007, 11:11 PM
To answer your question, yes it will change the airflow. The real question is how much and if it would be worth it to have to make the box that much larger to account for the 'spacers' and my guess would say prolly not. But only testing will tell you for sure. But one thing proven over and over is that you will usually be louder in a common chambered box with one large port.

02-13-2007, 11:33 PM
so that means put the spacers in the box. Why i said it will look cool is cause in about 10 mins i will be completly done with the plans and you can see why i put the ports in the middle

02-13-2007, 11:37 PM
If your about looks then build it and be happy with the sound and dont worry bout extra space.....if you want sound build a full lenth port.....

02-13-2007, 11:38 PM
IME, it wouldn't be a noticeable difference with the dead air spacers or not. someone mentioned it earlier, build it the wat that gives the proper airspace/tuning, and run with it. i wouldn;t go through the trouble of blocking in the "dead space" . a mic might tell the difference, but i seriously doubt you will.

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee :peace:

02-13-2007, 11:47 PM
i don't see it making any difference-

PV Audio
02-14-2007, 12:29 AM
Looking sick and being functional usually don't go hand in hand. Go with what jizmface said and just make it a full height single port.

W8 a minute
02-14-2007, 01:09 AM
IMHO single ports offset to one side with 2 subs looks like buttcrack. I understand that sharing one chamber "couples" the subs output to some degree but I'm not willing to sacrifice the look of the finished product for that small amount of gain. Every time I see a vehicle like that it looks like someone threw some old prosound/DJ equipment in their trunk and called it a day. Again, just my opinion and it probably doesn't mean jack to anyone else. LOL

02-14-2007, 01:31 AM
W8 a minute.....
Its 1 PORT for each sub. There is a piece of 3/4" birch wood(using birch ply) seperating both ports.

Im not that dumb to make one port.....

This is why i am putting them in the center of the box...This is wut im gonna build. Just finished the details of the box. I think it looks pritty cool.:eek:

A flared port w/ two 3/4" birch boards on the front

02-14-2007, 01:48 AM
i think powernaudio hit it on the head. it will just be easier to build the one without the spacers...dead air...or whatever you call it. as long as the volume is the same in both plans, and the port area and length, then they will sound the same.

still how did you get 1050 for the sq"????? they don't look 42" tall...

02-14-2007, 11:55 AM
There's no "dead air" unless you have it significantly blocked off from the rest of the air in the enclosure. Unless your port is too small area wise there shouldn't be a ton of air "flowing" through the port. It is a transfer of pressure not a conduit for the transfer of air. With a setup that has no port noise the air velocity in the port is usually low enough that air at the inner port opening does not have the time during a half cycle to make it to the outer port opening. Thus he port output is nothing more than a pressure wave traveling down the port. The air volume in the box determines the pressure required to get the port pressurized and the air above and below the port in your design is just as much a contributor to the volume/tuning and any other air in the enclosure.

02-14-2007, 06:00 PM
go with the plan that doesn't have bracing under the port which causes your "dead air space" or air space not being used...get a little bit more volume...it should make your tuning go up slightly though....if i am not mistaken...

02-14-2007, 06:23 PM
ok i guess ill go with the regular port and no spacer above and below the port.

Some people asked how i got the #'s for the port area.
Well if i am right(i think i am) you take your port w=3" H=12.5" D=28"
So 3 X 12.5 X 28= 1050"

02-14-2007, 06:37 PM
Here are a couple answers.

You statement above is incorrect.. you just calculate the H x W, which gives you 37.5 sq/in.

I agree with what PV Audio said (can't believe I'm saying that ;))

To look cool you’re going to sacrifice something. In this case you are going to add unnecessary turbulence into the design.

You also stated “Im not that dumb to make one port.....”, there is absolutely nothing wrong with making one port for the entire box as long as the design is good.

PV Audio
02-14-2007, 06:38 PM
That's the volume of the port bud, the port area is only 37.5 sq in.

02-14-2007, 06:50 PM
alright ill try to redo the box and post some pics of it later tonight.

Keep the sugestions coming

02-14-2007, 09:51 PM
ok so ill say.... it kinda was dumb to have the port in the middle of the box. Oh well. Here is the new box. Port is same height (12.5") and length (28"), the box dimensions have changed for the port to be straight instead of curved. The subs have more room on either side of them also. I think it looks better than the old one.
A question on the 45's in the back of the port.... My 45's are 1/4" out from the corner on each side. Should i go bigger 45's or will that affect sound movement.

So wut do ya think. Is it better. Is it a better design than the original.
Anything i should do differently.
(box volume w/ out port for one side is 4.01cu ft.. I wanted a 3 cu ft per sub. Im gonna use the exttra volume for bracing on the sides. Dont need to worry about the front because im using 2 3/4" birch ply back to back. Should be strong enough.)

02-14-2007, 10:05 PM
looks good.
now about the 45* angles deflector on the inside of the port. for them to be effective in the form your using them the flat face of the deflector facing the inside of the port needs to have the ports width in distance from the corner of the baffle that is helping deflect the wave or smaller. so 3" would work fine or a bit smaller, but the 1/4" corner deflector that you have is really just a waist of time and a hazard while cutting it.
also you can use a single baffle in between the ports instead of two, two will work perfectly but you can cut labor down and the size of the enclosure by a hair by just using one.

02-14-2007, 10:51 PM
never thought about cutting the 3/4" piece....:blackeye:

I guess put in 3 inch ones instead... But wont that affect the sound flow out of the ports.

02-14-2007, 11:03 PM
But wont that affect the sound flow out of the ports.

it will affect the flow trough the port, it will maintain the proper 3" of port width along the full length of the port, from the outside opening of the port to the inside opening of the port.

02-15-2007, 12:53 AM
i understand.

Is there anything else wrong with this box.. sugestions...

02-15-2007, 01:44 AM
so i just made the thingy at the corner of my port 3" wide. I used a arch pattern with 3" maintained throughout will this work. This is better than just having a strait line there correct?? easier for sound waves to go out...

02-15-2007, 03:39 AM
i have use the curve like that in a port before and it worked well. also round the inner end of the port wall to match.

i used 4" pvc ripped lengthwise in 1/4's and countersunk short screws for mounting.

02-15-2007, 04:59 AM
Just make it a common box with a single port.



thats what id recommend as well.

02-15-2007, 08:44 PM
so you mean round the edges like this??

02-16-2007, 02:38 AM