Rockford Fosgate RP9316 - Manual (Page 5)

2
The Harmonics graph illustrates the advantage of using the Aeroport over
a conventional tube. The human ear can sense .1% distortion. A standard
tube can reach that amount with only 10 watts of input where as the
Aeroport reaches only .05% distortion with 50 Watts of input. The end
result? You can apply more input power with less distortion or use a
smaller diameter Aeroport in place of a standard tube.
If using a computer aided speaker design program such as Term-Pro, port
velocities of up to 15% can be alleviated.
C
A L C U L AT I N G
P
O R T
L
E N G T H
After the enclosure has been designed, the following formula may be
useful when calculating the port length:
Lv =
Lv = port length in inches
Vb = volume of box in cubic feet
Fb = tuning frequency
R = radius of port
–1.463R
8466.4R
2
(Vb)Fb
2
>
Radius
>
Radius
RP9316 RP9314
When cutting the Aeroport center tube, the length should be cut 3"
shorter than calculated. When the end flanges are affixed, each end
extends the tube one and a half inches. If the determined port length is 10"
then the fully assembled Aeroport (center tube with flanges attached)
should measure 11" (the extra 1/2" on each end contributes to harmonics
and not the length of the tube).
10"
Standard Tube Aeroport Tube
7" Cut Length
11" Overall Length
R=1.34 R=2.03