ProSoundWeb Community

Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => SR Forum Archives => LAB Subwoofer FUD Forum Archive => Topic started by: A.J. Cooper on July 05, 2006, 07:54:19 pm

Title: Automotive LAB based horn. ACTUALLY BUILT!
Post by: A.J. Cooper on July 05, 2006, 07:54:19 pm
Hey Everyone!


I forgot to update my alias to reflect my real name so my previous post got deleted.  Some of you may recognize my name as one of the first to build the LAB horn back over four years ago.  In the interim I've devoted my time to earning my BS in electrical engineering and gotten significantly into circuit design and layout.  That first LAB horn I built is now for sale on the LAB Marketplace as I prepare for graduate school.

During my last semester of senior year I got this bug to build a horn subwoofer for my car.  It's a 1999 Subaru Outback and the strange roof contour seemed like an ideal place for an extended horn.  The actual volume for the horn was dictated by the size of the rear area behind the back seats.  A first version was drawn up utilizing the maximum volume for everything which meant losing the space for the spare tire.  Having a spare tire floating around your car takes up a lot of space.

All the flares were simulated using HornResp which is an excellent program but it's accuracy is going to be questionable in such a strange environment.  Since it's kind of loading into two corners, the passengers are essentially within the horn.  Now I have heard before that the pressure modes would cause awful sound without the doors open or something strange but I beg to differ.  The first version has been one of the best sounding automotive subwoofers I have ever heard.  It had a 38L rear volume which caused the driver to unload at too low of an input level so I decided to build a second version after graduation.

Version 2 of the subwoofer was built with a 15L rear volume which causes a little bit of a "boomy" sound to the bass.  That was tuned out with two 12db/octave filters.  One is centered at 80Hz and one around 100Hz.  I really like my subwoofer to only cover the low bass range so that it is harder to localize.  In the next week sometime, I plan on improving the rear volume to 25L while still ensuring that the spare tire sits comfortably below the sub.

I have built a small page with the CAD models and simulations as well as construction and final pictures on sounddomain.
 Soon I will add some new pictures of the final box so that it makes a bit more sense.  I hope with the pictures available you can figure out how it was built and give me some feedback.

I would really like to hear what you guys think and any suggestions you all have.  If anyone else has attempted something like this, please let me know.  Thanks for all the inspiration and advice and I look forward to hearing from you all again about this crazy project!


A.J. Cooper
Title: Re: Automotive LAB based horn. ACTUALLY BUILT!
Post by: Nick Ozanich on July 05, 2006, 08:07:33 pm
I bet that sounds killer! Looks Nice and seems very fuctional too! I imagine that in the car the horn effect is not utilized that much. Instead, its a super controlled sealed woofer. I bet you flattened the bass responce and gained some low end over just having a sealed 12" in your trunk. Outside the car is possibly a different story, it would be great fun to test different window settings and "tune" your horncar, I mean carhorn, I mean labcar..... Of course airleaks and passangers would change things a bit also.  Just my guess, I am doing a sub addition in an Acura RSX in a bit for a friend. Hmmmmmmmmm. Are you gonna sell that car with the sub? I need a hatchback! Very Happy  Nick
Title: Re: Automotive LAB based horn. ACTUALLY BUILT!
Post by: Nick Ozanich on July 05, 2006, 08:17:00 pm
Forgot to ask if the rear panel of the hatch door was reinforced with a baffle, That seems like a ton of energy firing into the door! ALso I would love to see a comparison of just a sealed box plotted on the same computer programs, just to see what the computer says the horn added. Again, super nice design, enclosure, fit ect. Bravo! Nick