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ContourSPL
02-10-2009, 02:56 PM
Anybody with any modeling programs want to help me out here? I've been researching tapped horns (with no success) and transmission lines and I've came up with this. I think it would be more of an expanding transmission line. The "throat" area is equal to the cone area of the speakers and it expands from 8" to 16.5" Maybe I should have a more gradual expansion? I don't know, I've never been able to model TL's and horns. The drivers are Mach 5 Audio SPL 12's and the red line is the line length of ~88 inches which is right around 7 feet for a 1/4 wavelength of 40 hz. Any help would be greatly appreciated.


http://i95.photobucket.com/albums/l125/contourSPL/tappedTL.jpg

Immacomputer
02-10-2009, 10:13 PM
With that expansion, your line 1/4 wave frequency is closer to 43hz instead of 40hz. Your step expansion from 8" to 16.5" isn't really an issue below 80hz so I wouldn't worry about it. The Mach 5 SPLs should work pretty well in an expanding line. What type of vehicle is this going in and how will it be firing?

ContourSPL
02-11-2009, 10:47 AM
It's going in a 98 Jeep Grand Cherokee, facing the rear. I could also configure it to have the throat area half of the total Sd. I figured that would be a good starting point because that's what a lot of people have used with success.

What do you think? Go with a smaller throat area? It gives it a smoother expansion.

Immacomputer
02-11-2009, 12:05 PM
Maybe decrease the throat area and increase the mouth area slightly and you should have a pretty workable design. If you want to make it closer to a 40hz 1/4 wave frequency, you should increase the line length to about 98-100 inches instead of 88.

ContourSPL
02-11-2009, 12:34 PM
Cool. Do you think half of the total Sd is a good starting point for the throat area?

Immacomputer
02-11-2009, 01:02 PM
I would go with something around .4 to .5 times total Sd and then go to 1.2 to 1.5 times total Sd at the mouth. If you do that, a line length of 103" would give a 40hz 1/4 wave frequency and should give extension well into the upper 20hz range and should be pretty loud around 40-50hz.