Need help with horn-loaded sub

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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 don’t 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 don’t 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...
 
frugal-phile™
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slicemaster101 said:
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.

http://www.diyaudio.com/forums/showthread.php?s=&threadid=5883

dave
 
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?
 
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
 
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.
 
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.
 
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.
 
frugal-phile™
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Re: Might Be too Big

BAM said:
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
 
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.
 
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, :bigeyes: Dang! This is really complicated! :mad: :xeye: 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?
 
frugal-phile™
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BAM said:
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.

Martin King is starting to distribute versions of his model that will do horns.

Incidentally, what is the usual cutoff point for PA subwoofers?

50-70 Hz is common.

dave
 
BAM,

With the numbers you've given, I doubt you'll get a lot below 150Hz or so. Why? Non optimum throat area, mouth far too small, flare probably too short and the wrong flare type (conics have poor bass).

How low do you want it to go, where will the subs be positioned in the room (freespace, corner, wall/corner, floor?) and what sort of SPLs do you want? When I know this I'll step you through the numbers and run some sims. For reference, bottom note on an electric bass is 41Hz. If you plan on having rock played through it, you need this sort of extension.
 
ANY IDEAS FOR THIS?

Well,
I have looked through all the stuff you guys have said and I think I have out done my self. I do have a friend that is a DJ and he wants me to experiment with what I could do. I guess horns do not provide the low bass that I want for my HT so I will just build two new 15 tempest subs in ported enclosure but anyway back to horns I would like to still tinker so I can eventually build a bass horn for my DJ friend, he loves what I have done with my HiFi system and he needs a bass horn or 2 and he wants me to build them but I told him I know nothing about horns and he wouldn’t listen so I am going to learn. Now I know he wants bass that you can not only hear but also feel. I am not sure how low that is but I am sure you pa people know. Could you guys possibly give me some help on this? I have seen the decware Wicked One ? Would a scaled up model be good for PA use? Any way any help would be wonderful. I have good wood working skills so I can follow plans very well. I don’t have to design my own the first time around so do you guys know of any proven designs for this PA type application? Free is good but I would pay for some…. Any way I hope to hear more.

Thanks,
Slice
 
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Joined 2002
Hi Slice,

Here is a site I've posted a couple of times in the past. Look through the site and you'll get to the actual horns, but read toward the bottom of this page first. They speak of what it takes to make a 10Hz horn. It basically goes back to what Dave pointed out at the start of this thread. Go big, or go home;)

Here's the thread:

http://www.royaldevice.com/thoughts.htm

Be sure to look at the installation page.

I remember back in the 70's when the movie "Earthquake" came out (pre-THX) with "Sense-Surround", or something like that. It used 2 - 11ft corner horns sitting in the back of the theater to produce the sub-sonics at high SPLs. I don't know if it was a gimmick, but the center seating sections were roped off because supposedly, people were getting sick from the sub-sonic vibrations.

You got a strong stomach?:drool:
Rodd Yamas***a
 
Sledgehorn design = Public domain

I am going to make it so when I'm done designing the Sledgehorns (yes, I do intend to go all the way on this one), you will be able to build my design. I am thinking of stepping up my mains recommendation to the Carvin 1562 2-way dual 15" loudspeaker or the 1588 3-way dual 15". Originally I had recommended the EV Eliminator 15" 2-way with a single woofer.

The sledgehorns' frequency response will be like this: 45 Hz or Bust and probably up to 160 Hz.

I am downloading Mathcad 8 Explorer and I will get the final results on dimensions for the horns probably this weekend or next week sometime. The only requirement for my design is that it will have to be able to fit through my bedroom door.
 
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roddyama said:
Back in the 70's when the movie "Earthquake" came out (pre-THX) with "Sense-Surround", or something like that. It used 2 - 11ft corner horns sitting in the back of the theater to produce the sub-sonics at high SPLs. I don't know if it was a gimmick, but the center seating sections were roped off because supposedly, people were getting sick from the sub-sonic vibrations.

These went down to 17-18 Hz but got close enuff to the human resonant frequency that some people tended to get quite ill. The middle section could easily have a standing wave node that could be particularily bad.

dave
 
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