Midbass J horn

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I want to build a mid bass J horn to cover the kick drum area from eighty to maybe 500 hz. i will cross over to midrange probably around 150-200hz. That way I can put my two subs in optimal places in the room for below that, and whatever can handle the midrange and treble above.

I want it to be full size for its bandwidth.

I want to fudge compression drivers out of a pair Hi Vi B4N four inch aluminum cone woofers:

http://www.partsexpress.com/pe/pshowdetl.cfm?&Partnumber=297-429&CFID=6421164&CFTOKEN=17170838

That cone almost looks like a compression driver itself. Efficiency is absent but i figure with horn loading it will improve. I also like the idea of a four inch driver producing bass if it can, it should be quick. How should I figure out what size to make the throat and the front and rear chambers.

Many thanks and advice is welcome.
 
I like the basic idea, but Magnetar is right - the HiVi's are pretty much useless for this application. No efficiency, and no motor strength. I looked at using 4 of the B3N's in a Unity prototype, and even 4 of them horn loaded only get into the low 90's, and bandwidth was disappointing (according to sims, never built it).
 
Somewhere there is a site with a clever project by a Swedish guy called matheus (sp??), to accomodate that horns really only behave like ideal horns when the WL inside the horn is several times shorter than the horn length, and allow this where floorpsace is limited, by a 90 degree midbass J horn (using IIRC a 15" JBL driver) - with a good "how I did it section"

It sounded like a very good way to get sufficient length for good performance down to about 80 Hz, "using height rather than length".

Does anyone have the link?

thanks
 
I have decided to horn load an eminence beta ten down to sixty hz. i will probably cross them over to subwoofer at eighty hz.

Proof they exist
 

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like to know how that works out.

karlson 12 (~3.3CF) or khyboe 15 (~4.3CF) with 5-8% efficient woofer would have a fair amount of kick in a small footprint. getting pretty graphs might take mucking with baffle & upper board angles. Khyboe in form of acoustic control's 115BK makes fair graph - its port might be blocked down in the middle for better tone.

do karlson make sense for anything?
 
I spent eight hours in the woodshop today!

I got both scoops attached, built the mouths and compression chambers, and attached 1/4" oak ply to the outside surfaces. I flush routed that bit. It was fun to see the horns take shape out of the plywood.

Tomorrow I hope to finish the compression chambers and build the mouths. I will then be ready to party on friday!

They are 6' 3" tall.
 

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The flare is hyperbolic/exponential with a T of .6
I used hornresp to design and I trust the program. Not because I know that it will be wonderful but that I trust it more than myself. The plate is not removable unfortunately; you didn't have a suggestion but keep it to yourself before you knew that suggesting it would mean starting over did you? : )

I may be able to finish these tomorrow if I can get off of work. Wish me luck, I can not wait to listen to pictures at an exhibition by mussorgsky.

Would you explain to me a bit more about the theory of karlson loading?
 
re:Karlson - they're usually coupled-cavity - but there might be something else happening in the way the energy is dumped. I'd like to try a taller k12 and keep overall bulk to less than 4 cubic feet - don't know effects that would have on response and input Z. Your midbass horn should be smooth - hope it has lots of impact when summed - bet you're excited !

ps - here's another J but shortened to bandpass horn - Paul Klipsch's little ba#stard LB-76 for K33E - look at page 2

LB-76
http://www.google.com/patents?vid=USPAT4237340&id=tBE4AAAAEBAJ&dq=4237340

here's a comment on old Karlson twelve loaded with PYM1298 and topped with 806/811 - bet its punchy for a very small package (I've hit >200W into 1298 in k12 on drum beats )

http://db.audioasylum.com/cgi/m.mpl?forum=bottlehead&n=113616
 
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