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Old 2nd April 2008, 06:53 AM   #1
jpvt68 is offline jpvt68  Australia
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Default Port And Driver Orientation?

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?
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Old 4th April 2008, 07:46 AM   #2
pkm is offline pkm  New Zealand
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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/ ?
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Old 4th April 2008, 12:29 PM   #3
CarlosT is offline CarlosT  United States
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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.
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Old 4th April 2008, 12:55 PM   #4
AndrewT is offline AndrewT  Scotland
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Hi,
keep the driver pointing sideways, unless it is designed to be used pointing vertically.

BTW,
500litres is a big box for a single 18inch driver.
What Qbox and Vas are you using in your alignment design?
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Old 4th April 2008, 03:30 PM   #5
bjorno is offline bjorno  Sweden
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Quote:
...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.

b

1 (1)
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Old 6th April 2008, 10:24 PM   #6
jpvt68 is offline jpvt68  Australia
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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"
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Old 7th April 2008, 06:59 AM   #7
AndrewT is offline AndrewT  Scotland
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Hi,
this driver is outwith the normal Q range for use in a vented box.
I suggest you look at sealed box or maybe open baffle.
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Old 7th April 2008, 10:30 PM   #8
bjorno is offline bjorno  Sweden
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Quote:
…Dimensions are 23" high, 21"deep and 78"wide with 2x 6" ports… Sub is dual 2ohm 18"…
Ok, if 1 inch wood thickness, no fillings in the port due to another driver: 1(1)

b

1(1)
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