Port And Driver Orientation?


2007-01-17 1:17 am
Hi I'm building a ported box 200cm wide, 53.5cm deep and 58.5cm high out of 2.5cm mdf with 2x16cm ports and an RLP18" sub. Does anyone have any thoughts on the best orientation for the ports and sub? Eg. front firing sub with ports on either the same side or opposing sides or the sub and ports on either side of the box similar to a sonotube but laying down?
I remember seeing in 'high performance loudspeakers' that changing the port position in a bandpass sub changed the port modes up high,although it was LPfiltered,the peaks were rather substantial. They didnt go into detail.

It doesnt matter hugely.But if you point it away from you,and perhaps form an acoustic low pass filter with the floor with downfiring then you can get some difference.

The major differences people hear are due to room modes and change of source position.

Seen http://www.subwoofer-builder.com/ ?


2006-10-20 6:00 pm
I'm sorry but I guess I missed the dimensions...

What is the diameter of the vents? Make them as big as you can.

The old lore was that you should not see any part of the driver as you peer through the vent. I think this means that it should be as far away as possible from the driver.
...the best orientation for the ports and sub...

Maybe not the best but maybe close to.
My simulation places the driver and port maximizing FR smoothness from lowest frequency counted near the ends of the box.
IMO, This driver should have port stuffing due to the high Qts.


1 (1)


  • rlp18in-ported-626l.gif
    68.5 KB · Views: 109


2007-01-17 1:17 am
Dimensions are 23" high, 21"deep and 78"wide with 2x 6" ports.
From the soundsplinter website, box dimensions are;
Optimal Home:
7.0 cu ft net volume sealed
12.8 cu ft net volume vented, Fb = 18 Hz
18 cu ft net volume vented, Fb = 14 Hz
Infinite Baffle
Sub is dual 2ohm 18"