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dbhittin
09-12-2003, 02:04 PM
Dual-Chamber ported systems are systems that have the following physical characteristics:
The system consists of two separate volumes, connected together by a port.
Each volume is vented to the outside by a port.
All ports are typically of the same size and length.
One volume, typically the larger one, contains the driver.
The primary advantage of the dual-chamber system over a simple ported system using the same driver is a further reduction in driver excursion, caused by the addition of a second port resonance within the passband of the system. This reduction in excursion results in increased power handling within the system's passband, making this type of system particularly suitable for use for drivers with low Xmax. However, because of the additional chamber and venting requirements, this system is considerably more difficult to design and build when compared to a simple vented system.

Design Notes:

To design a dual-chamber system, first start by selecting a standard ported alignment for the driver in question. Then, select two ports of equivalent length and diameter to tune the system to the required frequency. Split the required volume for the alignment into two, placing one port in the smaller chamber (1/3 total volume), and the other port and driver in the larger chamber (2/3 total volume). Finally, join the two chambers together with a port that's the same size and length as the ports used to vent the chambers to the outside.

Example:

Driver's Parameters:
Dia = 12 in.
Vas = 2.41 cu.ft.
Qts = 0.42
Fs = 30 Hz

Parameters for simple maximally-flat ported system:
Vb = 2.75 cu.ft.
Fb = 28.8 Hz.

As this is a 12 in. driver, we select two 3 in. ports to vent the enclosure, which results in the following required port parameters:

Number of ports: 2
Port Diameter: 3 in.
Port Length: 14.5 in. per port

Now, we split the enclosure into two parts:
V1 = Vb*2/3
V1 = 2.75*2/3
V1 = 1.83 cu.ft.

V2 = Vb*1/3
V2 = 2.75*1/3
V2 = 0.92 cu.ft.


Therefore, the box needs to be built with the following specifications:

First section, 1.83 cu.ft. net volume, containing the driver and one 3 in. port, 14.5 in. in length (this tunes V1 to 24.9 Hz)
Second section, 0.92 cu.ft. net volume, containing one 3 in. port, 14.5 in. in length (this tunes V2 to 35.2 Hz)
Both sections connected together by a 3 in. port, 14.5 in. in length.

ws140
09-12-2003, 02:21 PM
What is the response you get? Like a ported with a higher peak or what?

dbhittin
09-12-2003, 02:34 PM
When i made this box for my shocker 15", the lows where insane! But when i played rock music, couldn't really hear too much bass. But i think i made mine to big.

B&R Innovation2
09-23-2003, 05:14 PM
I want to make an enclosure like this. I have a few 8 W3v2's laying around. I'd like to tune it between 28-34hz

DO you think it makes sence to do this with 8's?

I heard that dual 6.5" audiobahn setup that was just blowing peoples minds...I want to do something similar with these 8's

bumpin_blazer
09-23-2003, 05:23 PM
I want to make an enclosure like this. I have a few 8 W3v2's laying around. I'd like to tune it between 28-34hz

DO you think it makes sence to do this with 8's?

I heard that dual 6.5" audiobahn setup that was just blowing peoples minds...I want to do something similar with these 8's

problem with that thought is the dual 6.5"s were not in a ABC box. it was a dif. type of horn box i believe not totally sure though. that design is much more complex and harder to reproduce.

adam