Wolfhorn SDX Design Finished - Page 2

Interesting idea, but the problem there is that any horn with a 16Hz corner that can put out that kind of SPL is going to wind up being rather deep, even at 90" tall. The one I already built is 74" long, and still ended up being 42" deep.

The double SDX one should end up being a lot more friendly to this kind of thing in terms of width, but I don't know if it'll get you the output you want unless I start increasing the horn flare and the size along with it. It might do it as is in room, but I don't know what the room is like. And this will still end up being deep.

It's a challenge, for sure.

After giving things a lot of thought, I decided that I just can't do it... the 483L version is just not what I want from this project. I feel it's just pushing things too far toward small size. In fact, there's some temptation to let it get even a little bigger than this revision.

So, here's revision 3. Basically, all I did was take version 1 and tweak it for a parabolic flare until I was happy. The throat and mouth are both smaller, but the design is at 521 liters and probably going to stay there unless someone spots a bug I missed.

Below is the half space SPL graph at 300 watts. This takes the woofers just a hair over Xmax at about 19.3mm at 21Hz according to the sim, but that won't be a problem. The TB horn's woofers in reality take more effort to hit Xmax than Hornresp said they would. The SDX's won't even be stressed at this level.



The 300W quarter space graph shows this thing already playing above the 120dB level above 16Hz. This shouldn't be hard to achieve in room. Especially my room, where the TB horn is already hitting 120dB peaks at listening position. This one will be much more capable than that horn.

 

whsdxr3.txt 0.4130859375k . file

Oh, it's getting built... I just don't quite know when yet. A lot depends on money and weather. I hope to have the woofers by January... after that it'll be down to how fast mother nature can get the temperature over 10 degrees Celsius and the snow melted.

Got a preliminary fold done this evening - it turned out to be too short so I'll have to work on that before I share the drawing.

Sketchup wasn't nice to me at first, but I prevailed. The result was a double fold sort of like the last one I built, only with the horn mouth in a different place. The final size of the design had I accepted the result would have been about 33" x 79" x 13.5" - a bit more low profile than my existing horn. But there is a significant length error that raises the corner to 18Hz, so the final product will turn out to be longer than 79." I can go to 84" in my room, and after that I have to find another folding scheme. Will report back when I have time to work on this some more and get the horn to the proper length when folded.

Edit - why not share anyway:



This is the basic shape I got out of it. The mouth is still boarded over, but it's at the bottom left corner. Woofers go on either side of that faint black line on that second horizontal panel down from the top.

Heh - that does ring a bell. I actually have a completely different fold I want to try as well before I try to redo this one. It may result in the box being not quite so long and a bit wider. With my luck, it'll probably make things too complicated and still turn out too long.

Edit - refolded my first attempt to correct length errors. Box is now 84" x 36" x 13.5." Hornresp says the corner is 17Hz due to path length still coming up 19cm short. That's... acceptable. I'll give it another attempt though to try and correct some step errors.

Got my alternate fold idea done - here's the result:



As currently modeled, it is 7' long and 44" wide. There is a big length error in this one too - it's almost a meter too long. As a result it moves the corner down to 14.5Hz at a significant SPL reduction. On this one I folded it into a seven foot package just to see if the plan would work... accuracy could come later I thought.

Honestly, I think I like this idea better than my original folding plan. All I have to do is get that extra meter off the length.

Edit - had a better idea. This brings the corner even lower to 14Hz. Will probably use this idea and just fix the length to get back to 16Hz.



You can see where I used the measuring tape to be sure the first woofer would mount properly.

Yikes... that one may be over my head a bit

This evening's effort may have produced the final folding diagram. I'm not unhappy with this. 78" x 43" x 13.5." Corner appears to be right at 15Hz. Horn turned out a little long again, but not nearly as bad. Attached is the Hornresp sim for the following fold diagram. Not sure it's entirely accurate, but it should be close.



300 watts in, excursion at about 21mm, half space:



Edit - hold the phone, I am unhappy with the phase response. I might tweak that baffle for driver one yet and forget about mounting it magnet down.

 

whsdxr3c.txt 0.408203125k . file

The OCD in me just couldn't leave things alone. After thinking about it for a while, I just had to not only fix up the phase mess on the last revision, but eliminate all path length errors as well.

As a result - this is it. This is what's getting built. Revision 4 of the folding diagram shows a path length error of a whopping three centimeters. That's just over an inch that this one is short by. That does not need to be ironed out unless your name is Adrian Monk.

The final box will be 75" x 43" x 13.5." Length and width will be an inch longer than the TB horn, while the depth will be 4" less. This should pretty well fit the space I have ready for it. Dimensions will be smaller with 15mm wood, but I don't plan on using it. If desired, I'll cook up another fold diagram with 15mm.

Once I get closer to building day, I'll start up a build thread and share the fold diagram with dimensions added for anyone wishing to try this one too. Meantime, I have the final Hornresp simulation file attached - this is more or less what the box as drawn will actually do. I think I got pretty close to my original plan.



SPL, half space, 300W:

 

whsdxr3d.txt 0.4072265625k . file

Thanks - I can't wait to build it

I checked my first folding idea, being the taller and narrower one - it still comes in at 7" too wide. Still, there's nothing wrong with a good IB - that's what I'd be doing if I weren't living in a basement.

I just go by the FR. The compression ratio is important, though... that's why I went with the SDX woofers instead of the TC Epic 10. They both model equally well, but the TC wants a higher (but not unreasonably so) compression ratio.

Well, that and the fact that I can get the SDX's easier and cheaper.

Same thing I look for in the ladies - good looking curves

Really, what I like to see is a mostly even slope inside the intended bandwidth with maybe a small hump in the middle. That first harmonic spike (about 62Hz in my latest SPL screenshot) I usually mentally suppress a little bit to coincide a little better with reality. I also like to see a smooth set of ever decreasing dips and peaks above the bandwidth (I call it the boing-boing-boing effect - I know, I'm a loon)... this is how I know when I'm starting to get close to something that will look decent in the impulse response and phase screens.

I would say about 85% of my Hornresp modeling is done first making the FR graph look good in full, half, and quarter space; 10% checking the schematic for size; and then 5% checking the other factors to see if I got something halfway decent.

Go ahead - ask me how I came up with "vomit factor," or how capable a tapped horn is of making the listener lose his lunch after some bad pizza

My Tang Band horn gets a rating of 4/10 on that scale. I'm hoping for a solid 6 or 7 from this one... not that I plan on eating bad pizza again.