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Test Ports and Boxes

This page provides details on the test ports and test boxes used in the flared ports turbulence tests.
The WinISD project files for the alignments are provided at the end of the page

Test Ports

For round one of the testing , seven test ports were built

Table of round one port sizes

 

The ports are made from PVC pipe, with a 270mm flange at each end. One or more smaller supporting rings are utilised, depending on the construction of the actual flare. The MDF pieces were glued together with PVA glue, and the PVC pipe was glued into the MDF with epoxy resin. The mounting end of the flare has a bolt pattern the same as a 10 inch driver, and is stepped so that the flare lines up with the inside face of the box.

Round one ports
Round one ports

The ports have a stepped mounting flange so that they line up flush with the inside face of the box, as shown in this picture.

Inside view of flush mounting
Inside view of flush mounting

 

For round two of the testing, another eight ports were built.

Table of round two port sizes

 

The same construction method was employed for the round two ports, except that a larger 360mm mounting flange was required

The eight 86mm ports
The eight 86mm ports - flare radii of 0 10 25 35 50 63 & 71mm

 

The remaining round two ports
The remaining round two ports 100/13 100/52 100/64 152/13 152/25 & 100/75

 

Test Boxes

Several different test boxes were built to test the range of flared ports

To achieve a high enough velocity to test the larger ports, the size of the test box was increased as the port size increased, but there were several conflicting principles:

The solution was to use several different sized boxes.
Round one tests used a 50litre box and had a pair of 10inch drivers driven by the Jaycar 350w amplifier. Into the 7ohm load presented by the two drivers in series, it delivers up to 240w.
The test port is mounted externally and is forward firing, whilst the drivers are located on each side.
Foam gaskets were used under the drivers and the port. The port was mounted with eight roofing screws, which, along with a cordless drill, made changeover time much easier.

 

Round one test box
Round one test box sitting on top of "Blast Furnace" sub, utilising its amplifier

 

Round two tests used a 100litre box which started life as the very first subwoofer I built. Four 10 inch drivers mount to the sides and a 255mm opening for the port is at the front. An identical opening at the top allows fitting of a plain plate, a 50 litre add-on box, or a 30 litre reducing cylinder. Both openings have foam gaskets and eight studs - this proved much more durable than the roofing screws used with the round one tests

100 litre test box with 30 litre cylinder
100 litre test box with 30 litre cylinder fitted, reducing volume to 70 litres

 

Test box with add-on box
Test box with add-on box to give 160 litres

WinISD Project Files

50 litre box - small 86mm ports
70 litre box - large 86mm ports
100 litre box - 103mm ports
160 litre box - 152mm ports

 

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