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Old 6th April 2014, 03:37 PM   #1
moldo2 is offline moldo2  Denmark
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Question Which horn to use

Hello!

I am in the process of designing a speaker system to be used on a festival camp. Naturally, we want as high SPL and low frequency as possible in a small enclosure. I know that small and loud/deep are contradictory when it comes to hornspeakers, but which design is the better compromise? I am debating wether to build scooper subs, or front loaded horns. I am trying to keep the dimensions of the thing below 0.8x0.8x0.8 meters. My plan is to build two 12'' drivers in the thing, but which horn design would you guys recommend then?
I hope I made myself understandable ;-)
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Old 6th April 2014, 04:09 PM   #2
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You should pick a design that will deliver the response you want and build it using whatever driver it is designed for. The most compact horn loaded sub design you're gonna find will likely be a tapped horn but even then they're probably gonna be bigger than your goal in at least one dimension.
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Old 6th April 2014, 04:28 PM   #3
moldo2 is offline moldo2  Denmark
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The thing is, I already have the drivers. I got them off a pair of old speakers. They are junk, but it's what I have for the budget. I have looked into Hornresp, but naturally I don't have the specs for the 12'' drivers. I don't need good sound quality either, the main goal is loudness. People are probably going to be drunk while listening to them anyway...

Any suggestions?
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Old 6th April 2014, 04:40 PM   #4
JLH is offline JLH  United States
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Without driver specs, there is little anyone can advise. Measure the driver specs and report back.

Measuring Loudspeaker Driver Parameters
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Old 6th April 2014, 07:15 PM   #5
moldo2 is offline moldo2  Denmark
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Alright, thanks, I'll try that!
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Old 6th April 2014, 10:17 PM   #6
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Originally Posted by moldo2 View Post
Alright, thanks, I'll try that!
To get started, can you establish what the free-air resonance of your "junk" drivers are? If you don't understand that sentence, we'll just have to go one step further upstream.

(Gawd, the fabulous tones of the ending of the Scottish Symphony are playing... love that sound).... you want to try known low notes (say, from 45 down to 30) to see where the cone starts floating.

If you can get that, no sensible person would think anything else is essential to proceed.

Don't despair. Not everybody on this forum is a wannabee engineer.

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Last edited by bentoronto; 6th April 2014 at 10:22 PM.
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Old 7th April 2014, 06:26 AM   #7
moldo2 is offline moldo2  Denmark
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I'll try to determine the basic T/S specs of the drivers tomorrow or the day after. My school has some equipment handy.

And thanks ;-)
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Old 7th April 2014, 04:53 PM   #8
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Quote:
Originally Posted by moldo2 View Post
Hello!

I am in the process of designing a speaker system to be used on a festival camp. Naturally, we want as high SPL and low frequency as possible in a small enclosure. I know that small and loud/deep are contradictory when it comes to hornspeakers, but which design is the better compromise? I am debating wether to build scooper subs, or front loaded horns. I am trying to keep the dimensions of the thing below 0.8x0.8x0.8 meters. My plan is to build two 12'' drivers in the thing, but which horn design would you guys recommend then?
I hope I made myself understandable ;-)
There was one guy here in the forum building speakers for his fraternity and we just found the best trade offs between both. He was asking for speakers for both a 15" woofer and a 15" sub and we just linked to an Altec A7-8 type speaker (horn) and a new Dayton Audio driver in substitution of the vintage Altec 416-8A (or 515B for the A7XX system) with great LF extension that you don't need to use subwoofers or nothing like that nonsense of having two giant speakers for the same low (+ lower) frequencies.
ALTEC LANSING A7-8
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File Type: jpg ALTEC LANSING A7-8.JPG (33.8 KB, 129 views)
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Old 7th April 2014, 05:40 PM   #9
DrBoar is offline DrBoar  Sweden
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What do you have beside the 12" drivers? If a fullrange 12" is all you have you have to have a backloaded horn. IF you have midrange/tweeter then a frontloaded horn is an option.
A really good backloaded horn is Matching driver with vintage BLH
With a high Fr low Q driver you get bass down to 35 Hz and it is not that sensitive to the driver paramterers. Being an open horn below the cutoff the driver is really unprotected so a good sharp high pass filter at 40 Hz is important. The horn is used standing upright and then the legs are not needed.

A frontloaded horn usually works up to 200-600 Hz so you need a midrange driver and tweeter above that. A tapped horn gets you deeper bass but it usually can only be used up to 80 -100 Hz so you need a bassdriver above that. Tapped horns also need to be designed around a specific driver.
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Old 23rd April 2014, 04:24 PM   #10
moldo2 is offline moldo2  Denmark
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Okay, so I finally got around to meassuring the T/S parameters after a busy easter. The parameters for the 12'' bass drivers are:
Fs = 46 Hz
Re = 7.8 ohms
Dd = 290 mm
Qms = 5.312
Qes = 2.656
Qts = 1.771
Sd = 660,52 square cm
Mmr = 9.7611 g
Mmd = 61.8154 g
Mms = 71.5765
Vas = 103.6137 L

That's some mouthful for a beginner like myself, but do any of you have suggestions, now that there's a bit more to work with.
And I have midrange 8'' and tweeters beside the 12'' drivers, so I'm interested in getting as much bass from the horn as possible.

Late happy easter btw ;-)
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