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Discussion Starter #1
Greetings, fellow bass nuts. Some of you may remember me from this thread, which chronicles the progress of my very first tapped horn project. Even before I was finished with that one, I always intended to go back and do it all over again; improving on the design as I better learned from my experience with that first project what made for a good tapped horn.

After several months of work, with a lot of help from many other people, this thread is the result. I was going to wait on this until I actually got started the building phase, but I think I'll post this early now that the drivers have been ordered.

My original goals were to replicate the Tang Band horn mentioned above in a smaller package with greater output and greater bandwidth. This here design isn't the best I can do for these woofers, but folding a more complex design into a package I can build is something that I'm still working on. So, I tried to keep this as simple as possible.

Here's what I wanted from this design:

  • 16-100Hz at 115dB in half space, 120dB+ in room at LP
  • less than 550L before materials
  • shallow, to enable better use as a riser
Other than that, I didn't really have too many other limits on it. The result of all my work is that I have a 533L design here before materials that will do 113dB in half space at 16Hz with 300W before reaching Xmax. Based on experience with my last TH project, it will have no trouble at all sustaining 120 at LP, because that horn already hits 120 at LP. It will also likely handle 600W+ before the woofers get into any kind of excursion trouble, so I'm going to push it at 2 ohms off one channel of my RMX-1850HD. It may or may not be highpassed... we'll see. It has the kind of headroom my old horn can only dream about, so I may not need to.

A drawing of the final Sketchup file is below, and my Hornresp file is attached. As drawn, it's 79x42x13.2." Big, but very shallow. I could fit four of these, two in front of two, behind my screen if I needed to. Building won't start until the snow goes away... I can't do any woodworking outside until it does, and there's no room inside.

Materials needed will include three sheets of 3/4" plywood. The four sheets needed for the last one was really too much. The throat will be braced, but other than that I won't be doing much extra bracing due to the shallow depth. I'll be picking up several 1" dowels, however... if I feel like the horn's gonna need the extra bracing, I'll use them. PL Premium will again be used - two large tubes will do. The open space in front of the throat and above the mouth will house a Speakon, and two of the horn's folds will get a thin lining of polyfill much in the same vein as the last horn I built.

I'll post a diagram with the actual plans for construction and/or the Sketchup file once I start building. I'm reluctant to let anyone try my unproven design before I know what it's like in the flesh.

Hornresp screenshots with 350W in, half space, excursion peaking at a safe 20mm above the corner:







 

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Hi there,

I just flipped through your other thread and am very interested in the possibility off doing a horn myself. I have pretty much zero knowledge on horns as I have only built sealed and ported subs. I would be interested in finding out what I would need to build in order to beat my current 2 15 cu ft ported Q18 subs. My winisd plot for my 17.5hz tune (which is the one out off the 3 I have on my subs) shows 117db at 20hz and 120db at 30hz for one sub. Now I haven't really properly tested them fully but I have space in each corner for about 36" wide by 22" deep by however high. I am guessing I wouldn't be able to use my Q18's as the box would either be massive or the driver specs just wouldn't allow for a good horn.

I see that you were comparing to the mach audio driver and you favoured the horn over it. There seems to be alot more and more with regards to horns that is making me think there must be a good reason why so many people are building them.

I would appreciate your advice if you wouldn't mind.

cheers and looking forward to your build.

cheers

Graham
 

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Discussion Starter #3
Start here, with Soho's most excellent spreadsheet and a copy of Hornresp: http://www.hometheatershack.com/forums/diy-subwoofers-general-discussion/36538-eazy-horn-spreadsheet-dum-everyone.html?highlight=spreadsheet

These days, I start all my designs with that spreadsheet. It saves me a lot of time. My hunt for good TH drivers usually starts with finding ones that have an Fs about 1.6 times higher than the corner frequency I want, as well as a nice low Vas to keep the box size down. From there I plug them into the spreadsheet and then Hornresp and see which ones come out best. I then usually do a fair bit of tweaking from the output of the spreadsheet to get all the little things just right.

If you're looking for a 17Hz corner, I can tell you right now the SDX10 is almost perfect. It actually likes being at 17Hz better than 16Hz. I haven't looked at the Q18 to see how it does in a horn.

I like tapped horns because they're more efficient and they sound better than direct radiators when done right. 350W into my Tang Band TH gives me about 10dB more output across the board than my Mach 5 IXL 18.2.2 LLT with 600W. It doesn't play as low, and is much larger, but that's ok. Horns aren't for everyone, but I'm definitely hooked.
 

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Thanks for that I will have a look at that. I did download hornsrep and tried reading the help section and pretty much got confused from the off. There are some off the driver parameters that I don't seem to have that are required in hornsrep.

Sounds like its time to read.

cheers

Graham
 

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Discussion Starter #5
Hornresp will calculate many needed parameters... double click each field to see.

The program does have a steep learning curve, that's for sure.
 

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Discussion Starter #6
Drivers have arrived. First impressions... I picked the right tools for the job. These things are seriously beefy... much more so than the Tang Band woofers I used last time. Diaphragms are nice and strong - the compression ratio of the horn should be no problem at all for them. At any rate, they're in one piece and the DMM says the coils are just fine. I'm good to go when the warm weather gets here. I'll break them in sometime between now and then when I get a chance.

Here's a picture of them on top of the Tang Band horn:



And one posed inside the TB horn to give some idea how the SDX compares to the W8Q-1071F:

 

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I'm very interested in your build progress, if you're still working on it. Man, 'though, will that be a big cabinet. I've been measuring around my room to see where I could put one, but I don't have anywhere to hide it away. Maybe instead of a couch...
 

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Discussion Starter #8
Haven't started yet, but will be soon. Winter was real late leaving town, and because of the unusually heavy snowfall we got there was a high flood risk. Didn't want to start anything and end up having to clear out in a hurry. But it looks like the flood risk is dwindling to almost nothing now.

All I need at the moment is a couple people to pay up what they owe me, and I can go on a wood buying trip.

Big is a relative term. This thing should do mid 120's with ease in room at one meter down to 16Hz or so. My current tapped horn already hits 120 at listening position, and this one will blow it out of the water. Hard to come up with anything direct radiating that would compete with it in any less space for the same $500 or so it takes to build one of these ;)
 

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I agree it's likely worth it. That's why I've been trying to see if I could emulate your design. I think I read somewhere that you can put your sub on the front wall out of sight. I'm thinking I'd have to do some sort of floor platform, but the 42" dimension would have to come down a bit, maybe by straightening out the box to make it longer.

I'll probably have to dust out my cranium and learn enough to design two single SDX10 tapped horns. I've got four of those drivers laying around, slated for sealed, but in looking at your response I was thinking I could do a hybrid tapped horn--longer and thinner-- and integrate a sealed compartment into where one of your folds would be. Sealed seems like it would integrate well where the tapped horn starts to break up.

I just started reading about this last night, so excuse me if I'm speaking nonsense.

I hear you about the weather. I'm waiting to work with my garage open but it was still snowing off and on around here as of last week and now it's just pouring.
 

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Discussion Starter #10 (Edited)
They're a steep learning curve, but I enjoy difficult challenges like this. There are a number of tutorials on Hornresp and Akabak floating around both here and at AVS that can get you started there. Pay special attention to lilmike and Soho54 - these guys really know their stuff.

With regards to mine, you don't necessarily have to have the mouth firing out the end panel. As long as it's at the end of the horn, and the exact same area, you can put it on the bottom panel or either side as well. I'm just end firing it because I'm too lazy to bother with driver access panels.

Single driver tapped horns with these is an option. Two would take more wood than one of mine, but would give you many more placement options. I haven't done a lot of experimenting there. I already have a tapped horn that's bigger than this will be... only have the room for one more ;)

Sealed? Not following there, I'm afraid. Isolating one side of the driver in a sealed box isn't a tapped horn anymore, it's a more traditional front loaded horn.

Edit - can't believe I forgot to post the break-in video:

 

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By the sealed, I meant just integrating a seperate sealed sub into the same overall structure (I wish I could draw it)--it would require a different folding pattern, leaving dead space which would be used for the second driver/sealed compartment. It would probably be more of a pain than just doing a separate box and folding neatly like you have done.
 

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Discussion Starter #12
I would forget about that idea, honestly, if you want to fire the sealed unit right into the room alongside the TH. Integrating two different types of subwoofers isn't that easy to begin with, and it's even trickier with horns. You'd have issues with time alignment and phase, not to mention the fact that a single sealed SDX 10 will not keep up at all with the same thing in a decently designed tapped horn.

With the sealed box firing into the tapped horn somewhere down the line... that would change things drastically. Not sure how it could be made to work and still sound good. I doubt you can even simulate that situation with Hornresp. Definitely not something I'd suggest experimenting with for a beginner.
 

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Great job on the design!! If you dont mind I might just copy your build. :)
 

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Discussion Starter #15
What do you use for between 60-100 Hz? Or, am I missing something?
Truth be told, even though the simulations say my current tapped horn shouldn't sound good up to 100Hz, it does. I think it has around a 6dB dip at 80Hz, which I barely notice. It covers the whole LFE channel... no other subwoofers needed. I now get the punch in the chest during Star Trek 2009's warp scenes I always missed with my 11Hz IXL 18.2.2 build. I love horns.

I should be pushing almost three octaves of usable bandwidth on the SDX design... that's not easy to do in a tapped horn. EQ is recommended for best performance... I suggest the MiniDSP and a copy of REW for that. Cheapest and probably the best way to do it.

Great job on the design!! If you dont mind I might just copy your build. :)
Go right ahead... I was hoping this one would prove interesting enough for at least a couple other people to try it out :)
 

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Very interested now. I've got a miniDSP on the way anyway. Now, if I figure out how to copy yours, I'll have to also figure out what to do with my other pair of SDX10. Shouldn't be too hard as I seem to have an unlimited supply of speaker envy.
 

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Discussion Starter #17
Build two, wire them at 2 ohms, run each off a channel of an EP4000, and see how long it takes the cops to show up :R

Or just keep the extras on hand in case you clank the coils off the backplates by accident. Really though, that won't be too easy. Hornresp does not factor in a few important things into the excursion plots, like suspension compliance getting stiffer as the cone moves in, or the effects of the compression ratio increasing as it does so. It also doesn't figure on the effects of the changes in BL after Xmax. I fully expect to see 130dB at one meter out of this thing in my room, corner loaded, without the drivers even moving much past Xmax. But I'll want to quit before it gets to that level. Hard enough to get up close to the one I have now, when it's pegging my SPL meter at one meter.

I tried to make it as easy as possible to build. I managed my first one ok with no help, though it was a bit tough at times due to 3/4" plywood not exactly being light for the two biggest panels. The biggest challenge really was making sure I gooped enough PL Premium on to insure there were no leaks.

Soon as I get my wood I'll post the Sketchup file and a drawing with dimensions. That should make copying easier ;)
 

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Hope it turns out well! I have a new found interest in horns, so I generally try to follow new horn builds...

I wish that I was more adept at folding and optimizing horn designs. It's much more work than it seems at first glance!
 

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Discussion Starter #20
When I get the measurement gear for that. Not sure when that'll be. I can do some in room stuff with my SPL meter, but it won't be anywhere near accurate.
 
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