As a way to publish this information to everyone that has purchased an INF10 I will put a few things up on this page regarding my efforts with this driver.
I tested 5 drivers for T/S Parameters. I returned one driver because it was faulty but the other four tested OK and the results are;
Fs = 24.44
Qm = 9.71
Qe = .391
Qt = .362
Vas = 120 liters
I ran frequency response data using the close mic method and altho generally satisfied with the results a few questions remained. It was after some discussion with several list members that I decided to do a few more measurements. I did ground plane, regular 1 meter, 4 feet off the ground, and close mic measurements.
Plotted below are the results of the speaker mounted in a 1 cu ft test box. This box is a little small but the purpose of these measurements is to compare the results of this driver in different situations.
The difference between the close mic and the ground plane are quite dramatic. You can clearly see that the lack of any diffraction effect when close mic'd makes a big difference in the output above 200 Hz. If you are going to be using the driver at higher frequencies then be sure to account for the baffle diffraction effects.
It should be noted that the levels of these various plots are arbitrary and Laud averages the data at 0 db. Don't use this data to draw any conclusions about level changes.
This plot compares the close mic measurements in three different sized boxes. In the 2.66 cu ft box(see pictures below), the output is getting real close to flat. This box is stuffed 100% with fiberglass insulation and the inbox Qtc was measured at 0.49. This is the configuration that I am going to use. I have a lot of confidence in the data since I only plan to use it up to 100 Hz. The nice gentle rolloff will be augmented by some room gain and should provide a nice smooth bass extension down into the 20's. It may seem that with a Qtc this low that the frequency response would be falling from somewhere above 200 Hz. That is what all the pictures in the books do. Well this is not a picture, but a real life driver that doesn't behave like the theory suggests. This driver has a large hump in it's response. To tame that hump it needs a larger box and a lot of stuffing! If the theory was always right then we wouldn't need measurements and we wouldn't have so much fun.
I hope this helps somebody.
Here are a few pictures of a sub (two actually)I'm working on using the INF10. It uses 16 inch diameter Sonotube that is 24 inches long. The net volume is 2.66 ft3. The completed speaker sits on 3 1/2 inch tall legs giving it a finished height of 29 inches.
The ends are made from two layers of 5/8 inch MDF. One is 16 inches diameter and a snug fit inside the tube and the other is 16 1/2 inches. These two layers are glued and screwed together (using yellow wood glue), then the assembly is glued to the tube with construction adhesive(subfloor glue). Before trying to glue to the waxed inner wall of the tube, I sanded it with 100 grit sandpaper until it was uniformly dull. So far this has been working fine. There are no rods between the end caps and no screws holding the cap to the side wall. Time will tell if the glue is up to the task. I'm betting on the glue!
