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hulkss
09-15-2003, 11:11 PM
Hello,

This post follows my first post on the analysis of the Lab Subwoofer:
http://www.prosoundweb.com/community/read.php?board=3&id=150938

You can learn about the Lab Subwoofer Project here:
http://www.prosoundweb.com/community/forum.php?board=3
Thanks to Tom Danley for sharing his expertise.

Here will I describe some modifications to the Lab Subwoofer cabinet. My initial goal was to simulate the measured response of a Lab Subwoofer. Now that I can model it, I am going to make some minor but significant changes. I will be using the same analysis method as described before as it produces results close to measured data.

I want to use the Lab Sub in smaller spaces taking advantage of wall or corner positioning to get by with only two cabinets. I would like the frequency response to reach 200 Hz to work with the top box I am designing for it.

Here is a comparison of the original cabinet and what I am calling the HCR Cabinet. Short for High Compression Ratio:

Original:
Throat area 80 in^2
Throat Chamber 20600cc
Compression Ratio 2:1
Back Chamber* 17 liters
Horn length 110 in
Mouth Area 898 in^2
Overall(inches) 45x45x22.5

HCR:
Throat area 51 in^2
Throat Chamber 7800cc
Compression Ratio 3.1:1
Back Chamber* 23 liters
Horn length 117 in
Mouth Area 780 in^2
Overall(inches) 45x45x22.5
*driver volume subtracted

The big changes are reduced front chamber volume, reduced throat area, and increased back chamber volume.

Input files:
http://home.mn.rr.com/blitzweb/index.html/Lab%20Sub/OriginalInputCorner.jpg
http://home.mn.rr.com/blitzweb/index.html/Lab%20Sub/HCRInputCorner.jpg

SPL Response Comparison:
http://home.mn.rr.com/blitzweb/index.html/Lab%20Sub/ComparisonResponse.jpg

I think this accomplishes what I was trying to do.

Here are some CAD illustrations of the HCR cabinet:
http://home.mn.rr.com/blitzweb/index.html/Lab%20Sub/ModuleTopRemoved.jpg
http://home.mn.rr.com/blitzweb/index.html/Lab%20Sub/ThroatAssem.jpg
http://home.mn.rr.com/blitzweb/index.html/Lab%20Sub/ThroatFiller.jpg
http://home.mn.rr.com/blitzweb/index.html/Lab%20Sub/HornPath.jpg
http://home.mn.rr.com/blitzweb/index.html/Lab%20Sub/SidesHidden.jpg
http://home.mn.rr.com/blitzweb/index.html/Lab%20Sub/Complete.jpg

I did not want to continue the throat flair into the first bend (it would be a pain to build) so I gave up some mouth area moving the first bend to the front. In actual use, the baffle area created increases the effective horn mouth area. I tried to fill all the excess volume in the throat as you can see. There is plenty between the driver cones.

How I plan to assemble it:
http://www.kregtool.com/pocket_hole_applications.asp

The wood I plan to use:
http://www.statesind.com/prod/ind_2a2.html

Any suggestions would be appreciated. I have not made any sawdust yet.

Brad

boputnam
09-01-2004, 09:46 AM
Doods...

Looks like this guy got 'em built. Very nice job. There's hoards of Links and drawings, etc. Great effort, Brad!

http://www.geocities.com/hulkss/index.html