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Old 11th September 2002, 02:00 AM   #1
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Question Need help with horn-loaded sub

Ok I have done some thinking and I decided my next project is going to be a subwoofer. The rest of my system is great and my last sub was an extremely great success. It performs better and goes lower then any sub of double to triple what it cost me to build. I love my home theater and I just want lower response and higher SPL! My last sub is great but I am going to be giving it to my brother for a welcome home gift in a few weeks, so I was looking to building something more complex then my good old ported enclosure. I was thinking that maybe I could design a horn loaded sub. A horn loaded sub appeals to me because the have the capability of reproducing bass very well as well as SPL (aka efficiency) levels that will knock you on your ***. I donít want boomy bass; I want rich clean bass that just sings. Enclosure size is not a problem and I would love to achieve SPL levels of say 105-120 db and a frequency response of say 15 or lower - 100hz. I am going to be using this in a high-fidelity environment. I donít know how much power these things need but that is something I need to learn. I know many people have driven their bass with Crown Micro-Tech Series pro amps with good results, would this be a good resource for power? Anyway I would like to design the enclosure and I was wondering where I can get resources on building horn-loaded subs. any comments would be greatly appreciated and any help would be praised.

Thanks,
Slice

Note: I have never built a horn-loaded speaker before...
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Old 11th September 2002, 04:44 AM   #2
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Default Re: Need help with horn-loaded sub

Quote:
Originally posted by slicemaster101
15 or lower - 100hz
Hey Slice,

That is going to be a VERY big horn to go that low. If you can put the mouth in the corner & you cheat it by cutting the horn early (say 70%) you will still need a mouth area of 40 ft^2. So if you have 8 ft ceilings and run the mouth floor to ceiling the mouth will eat up 5 ft on either side of your room. And then you need to fit the horn in behind it.

this thread has a link to Dinsdale's papers which is a good starting place.

Building a rear-loaded PA horn subwoofer

dave
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Old 11th September 2002, 09:17 AM   #3
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IMHO the best horn loaded subs by a long sretch are the new Funktion One subs I heard at PLASA a couple of days ago. They're twin 18" units which is probably a bit excessive for what your doing. But, I do know that their drivers are custom Fane ones so maybe have a look at the Fane standard drivers and see if there's anything which would do the job.

For amps, I would (although I'm a little biased) recommend the C-Audio Pulse amps. They're now badged and sold by Crown (it's a long story) but they're exactly the same amps as the C-Audio ones. Very good amps - I know a lot of people who use them for hifi as well as PA amps.

Presumably you're going to use an active crossover?
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Old 11th September 2002, 05:09 PM   #4
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Default I'm fond of my design....

diy bass horn


I've had a ball building this unit. With a longer neck and a larger mouth, it will go much lower. The bass is "rock solid". The stronger and denser the reinforcement, ie: stone and plaster walls, the more solid the response. I use a digital time delay unit to stall the upper frequencies 10 milliseconds. The results are outstanding!


John Inlow
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Old 11th September 2002, 05:38 PM   #5
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Peter,

I've read the Dinsdale papres and I'm not sure the basshorn will get down to cutoff. With a trax, you can't use the back chamber volume to annul the throat reactance very well as you can with a hypex, or elliptical. I'm basing this not on my direct personal experience, but the comments of Bruce Edgar who has a lot more experience in this area than me.

John's horn would be better, as would 2 or 4 or Jeff Robinson's <a href="http://www.geocities.com/loudspeakerguru/jeff_18_horn.gif">Leasebreakers</a> (don't forget the licence fee for more than 2) or LABhorns. But none of these will get you to 15Hz.

Horns are at least an order of magnitude harder to get right than sealed or ported boxes, even with experience, so my suggestion to slice would be to leave them alone and build some ported boxes with decent quality Pro drivers.
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Old 11th September 2002, 10:26 PM   #6
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Default Sledgehammer Sledgehorns

It just so happens I am also trying to design a folded horn. It is a rear-loaded horn with two JBL 15" 2226 woofers. This isn't for myself, of course. It is for my church, which is currently building a gymnasium-type room with a stage. They do not have a PA so I am recommending a pair of my concept basshorns with a pair of Electrovoice Eliminator 15" 2ways. The Eliminators have good midbass performance on their own, but once you get music bands in there, they will be wanting more bass. In the end, it's the bass that gives the music its extra energy and feeling, and I wanted the unmistakable presence and effortlessness of horns. I am calling my design the Sledgehammer "Sledgehorn". I hope to make all the Sledgehammer PA sub plans available on the Internet very soon.

The Sledgehorn is rear-loaded and the drivers each fire forward into a manifold, so that energy from both sides of the cone is used. Planet10 has a set of PA Basshorns with Celestion 15"s in them and they look top notch. Wht the addition of some carpet, casters, and handles, they look ready to go on tour.

The Dinsdale articles look like they will be very helpful to me as I come up with the final design for the Sledgehorns. I'm opting for a much more reasonable frequency response: 35-200Hz. This is good because it's almost futile to try and pressurize outdoor air below 40Hz, and I have not one, but 2 15"s to work with, and 1200 watts of RMS power, which will be supplied by a Crown CE2000.

I don't know what my church is going to be using these for, but they need to be able to handle anything that they can dish out, because I don't want them to be smoking 18's when they try to play music outside with a conventional box.

Thanks, Planet10, for your help earlier.
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Old 11th September 2002, 10:29 PM   #7
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Default Might Be too Big

Size issues may force me to only run these down to 40 Hz. I don't know yet, because I haven't gotten that far. Designing horns is a lot of fun because they just look so impressive. Keynote Communications, the Music Ministry of Campus Crusade for Christ has been smoking 10-year-old EV 15's at outdoor shows, so maybe they'd be interested in building some sledgehorns to replace them, and then some. As it is looking now, these will have some very fine results.
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Old 11th September 2002, 10:58 PM   #8
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Default Re: Might Be too Big

Quote:
Originally posted by BAM
Size issues may force me to only run these down to 40 Hz.
The horns in the picture i posted were designed using Dinsdale. A pair per side was designed to go to 50 Hz when on the floor (half-space). They are a tractrix, and designed to have maximum mouth area for the box volume -- they aren't very deep. The pics were of the Mk II. I have plans for the MK III (never got built) i could try to dig out.

dave
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Old 12th September 2002, 01:55 AM   #9
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BAM says

<b>I'm opting for a much more reasonable frequency response: 35-200Hz.</b>

Then why bother with such a messy compromise like a rear load? A front horn will give you at least the same bandwidth, better efficiency and the ability to get all the way down to Fc if you use a hypex and tune the rear chamber correctly. You'll also only have a single source for energy, so you don't have the signal being heard from the front of the cone, as well as delayed by the pathlength of the of the "horn" section at the rear. A rear load is a compromise best suited to situations where you need the bandwidth of the front of the cone to get you up to a CD at 800Hz+.

JBL 2226's have an Fhm=258, so it will work in a fronthorn in the range you want providing you design it correctly.
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Old 12th September 2002, 03:51 AM   #10
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I'll admit, my understanding of horns is still very much limited. I wanted to use energy from both sides of the cone in order to get every bit of output I could squeeze out of this. With both woofers arranged vertically, the horn is only going ot be about 20" wide, and the mouth of the manifold to the outside is about 14" high and 18" wide. The mouth, judging from my concept drawings, should only be about 24" tall and 18" wide, for an area of 432 sq. inches. The area of the mouth of the horn is 108 sq. inches, being 6" x 18". The length, by my estimation, looks to be 45" long. As in my concept drawings, the horn looks straight (conic) and only makes one 90 degree turn, but there are provisions to make another 180-degree turn. It really isn't all that big.

I still haven't found an easy set of equations that I can plug the T/S parameters into and find the optimum length and flare angle of the horn, and it's starting to get frustrating, but I know if I don't give up on this, I will have a very good result.

Incidentally, what is the usual cutoff point for PA subwoofers? I don't want to overkill myself on this if it isn't necessary. I want to try and get the output of two dual-18" boxes in one of these if I possibly can, nothing on the order of the LABhorns.

Let me just say, Dang! This is really complicated! Oy.

I've always loved designing designs that were out of the ordinary, but now it looks like I'm in over my head. The drivers are mounted magnet-side out in a manifold for motor cooling.
What makes a rear horn into a messy compromise?
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