My first Ported box *pix*

[diminishedpower 10+ year member]

Yea i know what port noise is and i have none, i have the corners all perfectly rounded inside and theres not a single sharp edge in the whole thing. Edges even have filler and then smoothed, it seriously has no port noise.

 

[skadude016 5,000+ posts]

it sounds awesome. No port noise from drivers seat very minimal and only at high excursion at port. You can feel it moving lots of air. And i don't car if people say the port design doesn't work because the sub is behaving exactly as it should in a box about 3.5 cu/ft at 32ish hertz, might be 35 because of the design. If i had a camcorder id video it but I don't.

thought you said there was no port noise?

 

[diminishedpower 10+ year member]

Yea but that was right after i posted up my first pix, now when i went through and repainted the port i sanded down the area that was causeing the noise, and do you just sit around and beat off to finding so small technicality??

 

[BiaBia 10+ year member]

So you sanded down the area that was causing the port noise? Man I need to learn from you

 

[skadude016 5,000+ posts]

Yea but that was right after i posted up my first pix, now when i went through and repainted the port i sanded down the area that was causeing the noise, and do you just sit around and beat off to finding so small technicality??

nope... just curious why you feel you gotta stick up for the desginer //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[diminishedpower 10+ year member]

So you sanded down the area that was causing the port noise? Man I need to learn from you

Im guessing your being sarcastic and most port noise is from going up against sharp edges, or to small port. My port is big enough so i found the trouble spots and sanded. But whatever i got on here to ask about quality of build im sick of arguing about the design when you guys are bashing without hearing

 

[BrianChia 10+ year member]

nope... just curious why you feel you gotta stick up for the desginer //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Because the designer knows what he's doing.

Seriously, a port with two 90 degree bends is not going to have more turbulence than a zig zag port with 2 180 degree turns, or some I've seen with 5 or more 180 degree sharp turns. There is no way that anyone can say an "orthodox" port has more linear air flow/compression if the air has to make so many sharp 180 degree turns, which are inherently harder than 90 degree turns. If you stop and think about this, it makes perfect sense. There is nothing linear about anything other than a straight tubular port. I fail to see what the big deal is with this is, other than that most people have never thought that you could bend ports lenthwise not just widthwise.

Although to really improve the design I would add a curved deflector (or at least 45 degree) at the corners of both ports to keep area consistent throughout both bends.

To help clarify things, here is a picture of the box which I modified. The yellow X's represent intersections which when connected give an approximation of the average length "as seen" by the box/driver. The blue line is the flow of air. The red pieces represent recommeded deflectors which not only channel the air but help maintain consistent port area throughout the bends. The air does not really travel in sharp 90 degree turns (which cause turbulence) but flows best over smooth turns (like a PVC pipe elbow). The only consideration is that a lengthwise bend (as opposed to a widthwise bend) causes a greater increase in port area over the turn which makes the deflector more important.

 

[rpfuror 10+ year member]

^^^

Although to really improve the design I would add a curved deflector (or at least 45 degree) at the corners of both ports to keep area consistent throughout both bends.

Although I didn't want to get into it, that is exactly the "theory" that I designed the box around. But, I didn’t really see the need to place angles as shown.

BrianChia so elegantly explained, via a drawing, how I calculated the length of the port also.

I'm really not the type to debate on a forum, which is why I don't see the need to go back and forth about a design that the builder is happy enough with to defend.

diminishedpower,

Now... As to your original question... the build looks great, ALOT better then the first couple that I put together. Please PM me if you need anything.

Let the banter persist.

 

[mazdakid 5,000+ posts]

i dont get how it works. part of the port length is only .75" long on the top, isnt it?

 

[rpfuror 10+ year member]

It would be measured as half the distance internally from top to bottom plus the 3/4"

 

[PV Audio 5,000+ posts]

Because the designer knows what he's doing.
Seriously, a port with two 90 degree bends is not going to have more turbulence than a zig zag port with 2 180 degree turns, or some I've seen with 5 or more 180 degree sharp turns. There is no way that anyone can say an "orthodox" port has more linear air flow/compression if the air has to make so many sharp 180 degree turns, which are inherently harder than 90 degree turns. If you stop and think about this, it makes perfect sense. There is nothing linear about anything other than a straight tubular port. I fail to see what the big deal is with this is, other than that most people have never thought that you could bend ports lenthwise not just widthwise.

Although to really improve the design I would add a curved deflector (or at least 45 degree) at the corners of both ports to keep area consistent throughout both bends.

To help clarify things, here is a picture of the box which I modified. The yellow X's represent intersections which when connected give an approximation of the average length "as seen" by the box/driver. The blue line is the flow of air. The red pieces represent recommeded deflectors which not only channel the air but help maintain consistent port area throughout the bends. The air does not really travel in sharp 90 degree turns (which cause turbulence) but flows best over smooth turns (like a PVC pipe elbow). The only consideration is that a lengthwise bend (as opposed to a widthwise bend) causes a greater increase in port area over the turn which makes the deflector more important.

No, just no. The problem with this port is that it USES compression to function, not that it's a by product. You cannot force air to move up when it's going straight, so it's being forced to go up through the hole once it hits that wall. Would the deflectors help? Yes, definitely. But don't think for a minute that a properly built labyrinth port has more compression that this. Turbulence? Perhaps, which is why you add 45s in the corner to redirect the airflow, but they don't actually require it.

 

[BrianChia 10+ year member]

No the "wall" you describe is no different at all from the back wall of an enclosure with a zig zag port. In a zig zag slot port, airflow will be going straight into a perpendicular wall and then is forced to turn 180 degrees and go the other direction. In this design air hits a perpendicular wall then must turn 90 degrees and go up. Air is forced out through compression no matter how you design the port. The less severe the angles and the fewer the number of bends the better. The air "doesn't care" if it is going horizontal vertical diagonal or whatever. Just because a port bends on three different axes as opposed to two doesn't make it disfunctional.

The deflector pieces are more necessary to maintain consistent port area rather than redirect flow. Air will be leaving through the port through compression no matter how you design it; ideally a straight tubular port will minimize this. The bend causes an increase in port area as it turns the corner so it is necessary to fill in the extra area with a deflector. Edit: not necessary, but optimal.

 

[PV Audio 5,000+ posts]

No the "wall" you describe is no different at all from the back wall of an enclosure with a zig zag port. In a zig zag slot port, airflow will be going straight into a perpendicular wall and then is forced to turn 180 degrees and go the other direction. In this design air hits a perpendicular wall then must turn 90 degrees and go up. Air is forced out through compression no matter how you design the port. The less severe the angles and the fewer the number of bends the better. The air "doesn't care" if it is going horizontal vertical diagonal or whatever. Just because a port bends on three different axes as opposed to two doesn't make it disfunctional.
The deflector pieces are more necessary to maintain consistent port area rather than redirect flow. Air will be leaving through the port through compression no matter how you design it; ideally a straight tubular port will minimize this. The bend causes an increase in port area as it turns the corner so it is necessary to fill in the extra area with a deflector. Edit: not necessary, but optimal.

It isn't the same because in a labryinth port, the direction of the port is the direction of the airflow. It can be restrictive, as I already said, but the airflow is continuous in one direction. Since air is a fluid, let me show you what I mean by talking about fluids. In a labryinth port, if you shoot water down the port, it will flow through the port and will eventually come out the other end in relatively the same stream. In this design, let us assume that the flow is high enough for it to fill the port, but when you flow the water through it, it will collect at that wall area until enough water has collected to force it through the opening. Is a labyrinth port inefficient? Yes, but not on the same level as this, because the air in this design literally meets an obstruction in it's flow, and isn't redirected until air is compressed enough to exit.

 

[shortyg83 10+ year member]

To me I just dont see how this port is really that much different then the normal bend in the the back of a port. The normal L hits the wall and is compressed one way. This only problem Is really its just adding a second bend which is in fact most likely just causing more compressions. Air isn't bound by gravity it doesnt know the difference between up and down and such. I am not arguing for either side Im just looking for an explanation on why you think goin up is differnent then the normal changin in direction by a L bend in a port

 

[BrianChia 10+ year member]

I don't want to argue any more but the water analogy is invalid. Say you turn this box on it's side and flow water through the port with the a front firing alignment. The box is the exact same one which OP built. Then find an equivalent labyrinth slot ported box, also front firing. Now take a garden hose to both ports. Now which one flows better? The OP's box / rpfuror's design now has gravity to it's advantage and will flow better than the labyrinth port. You can't use water as an example because it's 3rd axis of travel is bound by gravity. Air is not significantly affected by gravity which is why we can build upwards firing ports and speakers. As I've said before, this bend is no different than a 90 degree bend in a "labyrinth" port. The second you build a bend into ANY port (labyrinth or otherwise), airflow is NO LONGER in one continuous direction. Once air reaches the end of a straight segment it hits an obstruction and is forced into redirection by compression in both designs. The only practical way to maintain single direction continuous flow is a tubular port with no bends.