can a slot port be too narrow?

[danthevanman]

Good evening everyone,
Im currently building a new box for to take 1 of my Ground Zero GZPA15SPL in my new car.
The box is 5 cubic foot with the sub and port face measures internally 33.5 x 18 inches.

I've worked on on box pro that to tune to 33 ish with a port size 31 x 1.5 x 22 inches long. Would this be too narrow?

Or would i be safer making the port on the 18 inch side so that the port measures 18 x 3 x 25 long??

[Rob Himself]

1.5" inches is a bit on the skinny side, esp for a 5cu box... 2.0 should be okay if not.
Check the vent velocity graph, and see if it's gonna whistle. (If not, screen shot + stick it up on here)

[danthevanman]

The red line is 1.5 inch port
The purple line is the 18 x 3 port
and the yellow line is the 1.5 port opened up to 2 inches but when i change the port length to tune to 33ish the figure comes up in red what does this mean??

[FDR]

Green is go, red is "no Go"!

[Mart@BassJunkies]

Originally Posted by FDR

Green is go, red is "no Go"!

wheres the green?

[Rob Himself]

Basically, you see where the line all goes a bit grey-y above 32m/s ? That's bad.
You need the entire curve to be under that line.

[FDR]

Originally Posted by Mart@BassJunkies

wheres the green?

MY Bad!! Let us say the figure was coming up in black when all the parameters were acceptable.[ or whatever color ].

When the figure comes up in red it means one of the parameters is unacceptable,[ port length, port diameter, vent mach, etc..,]

[Mr Bump]

Originally Posted by FDR

MY Bad!! Let us say the figure was coming up in black when all the parameters were acceptable.[ or whatever color ].

When the figure comes up in red it means one of the parameters is unacceptable,[ port length, port diameter, vent mach, etc..,]

That means it doesnt calculate with the other figures entered.

Not that the design is good or bad.

[Beb]

I'd increase the port area, make the width about 2.5" and adjust the length as necessary

[firestarter]

I think there was a rule of thumb of not over a ratio of 5 or 6 to 1 for a ports narrowness.

Although a port over 5 to 1 will start getting losses with todays higher xmax drivers.

[Andy@React]

i have a "thin and wide" port (look in my avatar!), it works fine - i wouldnt go much thinner/wider than it is at the moment though!

on my fiesta "angry robot head" box, which was very thin, i split it into 3 seperate ports, and didnt have any problems really - vent velocity was fairly high, but not enough to make noise with the boot closed (bass covered the noise!)

[danthevanman]

Hi Andy, What size is the port in your avatar and what size was the port in your fiesta?

Thanks everyone for all the info so far,

Dan