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Discussion Starter #1 (Edited)
I think I've done enough fiddling and tweaking of this design that I'm ready to get some external opinions on it now. I'm nowhere near the building point yet (wish I could afford it), but I thought it would be good to get any bugs I missed squashed in advance. Also, since I'm primarily doing this for people who would otherwise be interested in building my Tang Band horn if only it weren't the size of a house, I'm wondering if I got the size down enough for those folks.

Goals for this design:

  • tapped horn
  • must do Dolby reference in half space to 15Hz
  • must do the above with less than 300 watts
  • must be way smaller than Wolfhorn II - plywood costs money
  • drivers must be affordable for a poor Canadian like me
  • total project cost must stay around $500 minus the amp
I think I've gotten the best compromise out of this design now, but I'd like some second opinions. If modeling is any indication, and my experience in putting one together is any indication, this thing should be a beast. It should be able to hit reference at 15Hz with less than 150W at 8 ohms. Corner loading should get it into the mid 120dB's without problems. Driver displacement in the passband with the full 360W output of one channel of my QSC amp is only 20mm - should be safe for these woofers (CSS SDX 10").

Now, don't quote me on this because I'm still learning... with these woofers, there is a strong possibility this will still have a fair bit of output below 15Hz. 15 should be easy - Wolfhorn II has a lower corner in room than modeled. I'm counting on that again with this design. 13-14 may be possible at reference, but the drivers may be getting into trouble by 13 and I have no idea where the THD will start causing problems yet.

Finally, I have another revision of this design because I wasn't happy with the 1W/1M sensitivity. It adds 2dB from about 17-40Hz or so. However, this one is bigger at 570L due to more horn flare and rolls off faster. I'm leaning for the 517L version I'm posting here, because it meets all my goals already, but if there is any interest I'll toss up the other one for comparison. And let's face it - 517 liters internally is still a pretty big design, even if it is 135 liters smaller than Wolfhorn II.

I can get this design down even smaller with even more output if I raise the corner a bit, but to be honest I have no interest in raising the corner. This was supposed to do everything the TB horn does (and then some) in a smaller package. Can't do that if it only plays to 18Hz


Anyhow, if this thing sounds good to you guys, I'll go ahead and start trying to fold it. If not, there's a good six months of time before I can get something built with which to make improvements.

Hornresp record attached - screenshots to follow in my next post.

Edit - now that this project is done, I'm now adding the plans to this post. The original simulation which was in this post is now invalid, so I'm replacing it with the final product's simulation.



There are some alternate drivers that should work based on published TS parameters. Note that these have not been measured or verified by yours truly. Try these drivers at your own risk. Some work better than others. In order of most to least compatible based on motor strength and general suitability:


  • TC Sounds Epic 10
  • Sundown E-10 D2
  • SEAS XM001-04
  • Dayton TIT280C-4

  • Fi X10
  • Funkin Audio SL-250

  • HiVi SP10
  • ACI SV10

Recommended highpass using a MiniDSP is 14Hz at 48dB/octave.

SDX 3L.zip 221k .zip file



sdxr3lr2.txt 0.408203125k . file
 

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Quote:
Originally Posted by Oklahoma Wolf /forum/post/19161491


Anyhow, if this thing sounds good to you guys, I'll go ahead and start trying to fold it.

Looks very good, about the same as the TH SPUD sims. I'd love to see a fold plan for it.
 

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Discussion Starter #4
Thanks



I plan to fold it much the same way as the TB horn just to make it easier on myself. This will result in some dead space in the box, but not too much.


Some other goals I forgot to list - I also wanted more bandwidth (I think I managed that one), and the hope is to get the final design down to around 14" wide or less. The plan is to use the same 18mm shop birch I used for the TB horn with no bracing at all except for the throat. If I keep the depth down, that should work out.
 

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Sounds good and I'll watch with interest.


If it turns out as big as the previous one and I decide to build it (a 14" width is attractive) I think I'd have to sneak them into the apartment at night. The looks alone might frighten the neighbours.
 

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Ooooooooooh shiny! Looks like a nice improvement over v1. Good to see you back in action, OW--it's been quiet and boring around here without some good design action!


One common characteristic I've noticed with low-tuned tapped horns is that 60-70Hz ringing spike...In your experience, is it an issue, or is it just another figment from hornresp's 'unobtanium' modelling? If it's not a big deal/easy to EQ out, it would be easy enough to get the FR flat to 100Hz+, which would make it a lot more desirable for regular DIY'ers.
 

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The spike is the 5th Harmonic. It will really be there. Not quite as pointy, but there.


1st H = (4/1)*Horn Path Length

3rd H = (4/3)*HPL

5th H = (4/5)*HPL...


Then Speed of Sound/H= frequency in Hertz


The lower the cut off, the longer the horn, and the lower the frequency of the harmonics. The less area the horn takes up the greater their amplitude is in relation to the rest of the FR.
 

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Looks good, I'd suggest that you try your model with a parabolic flare though.


Re the harmonics - yes, they are real, and yes, they can be dealt with. I've greatly reduced them through some luck - one of the fold dimensions created a null at exactly the right spot in one of my projects, but active EQ is a lot easier, and can be used to help with room problems too.
 

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Discussion Starter #9

Quote:
Originally Posted by A9X-308 /forum/post/19162133


If it turns out as big as the previous one

It won't be - I don't think my back will stand for another one that big.

Quote:
Originally Posted by Starkiller4299 /forum/post/19162150


One common characteristic I've noticed with low-tuned tapped horns is that 60-70Hz ringing spike...In your experience, is it an issue, or is it just another figment from hornresp's 'unobtanium' modelling?

It will be there, just not as pointy as the others mentioned. I got lucky with the TB horn in that the spike was gone, totally, in the final product. My operating hunch is that either the lack of side to side bracing or the room has created a null at around that frequency. I get a dip there, rather than a spike. I really can't tell it's there by listening to it.


But yeah - I do want this to go from 15-100Hz. It has a real shot, unlike the TB horn.

Quote:
Originally Posted by lilmike /forum/post/19162272


Looks good, I'd suggest that you try your model with a parabolic flare though.

Your ideas intrigue me, and I wish to subscribe to your newsletter



That didn't occur to me to try, but I have lots of time so I probably will give it a stab.


Edit - an early bout of Hornresp fiddling leads me to believe that the parabolic approach would lead me to a fair amount of size reduction. However, I also think this may be above my current skill level in regards to folding and building. Will have to give this some more thought.
 

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Quote:
Originally Posted by Oklahoma Wolf /forum/post/19162511



Your ideas intrigue me, and I wish to subscribe to your newsletter



That didn't occur to me to try, but I have lots of time so I probably will give it a stab.


Edit - an early bout of Hornresp fiddling leads me to believe that the parabolic approach would lead me to a fair amount of size reduction. However, I also think this may be above my current skill level in regards to folding and building. Will have to give this some more thought.

Newsletter? I'm just now getting back to playing on the forums a bit....

Don't hold your breath for anything from me any time soon, summer's not over yet. Still doing a lot more wrenching on my big toys than horn-designing.


I would suggest that you try plotting up a parabolic flare before you get the idea that a parabolic flare is harder to fold....
 

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Discussion Starter #11
Ok... I'm just getting back into playing around with this stuff after being away for a month. Not sure all the gears in my brain are turning the same direction yet.


Edit - ooh, shiny new Hornresp! That explains it, I was getting behind in Hornresps again.


Edit 2 - revision 2 is looking good so far. Will post details when I'm happy with it. Got the size down a bit more.
 

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Discussion Starter #12
After much tweakery and head scratchery, I have revision 2 ready to show. Parabolic numbers and all. This is really pushing the woofers and the design to get as close to my original goals as possible, in as little space as possible.


The result - the design now clocks in at 483 liters. I can't ignore that. Hornresp record attached. I only bothered with one screenshot - SPL with 360W in, half space:




Screenshots get old when you love playing with Hornresp



It will not do reference in half space to 15Hz anymore, but it'll do it to 16Hz. That said, getting this to happen in this size cabinet demands the drivers going past Xmax up further in the passband. 21mm at worst. I think the woofers will be just fine with that, but it's still pushing things a bit.


That said, this thing will still do reference to 15Hz in room, easily. I modeled the same power in quarter space and got 119dB at 15Hz. In my room, over 120dB should be possible due to the effects of the room on the sub. I want to peg that cheap SPL meter at listening position, and I think this is the sub for the job



Of course, Wolfhorn II will be assisting...

 

whsdxr2.txt 0.4130859375k . file
 

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Wolf,


Just wondering, but have you put any thought into doing multiple, smaller 15Hz horns vs a multi-driver single large horn?


Playing with that driver, it is possible....


JSS
 

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Discussion Starter #14
Some, but not much... I already have the one horn taking up a whole lot of space in the room and have only two other corners to put more horns in. One of those corners is unworkable



If I could find a good home for the TB horn that might be something to play around with, but I do kind of like the idea of using both horns, this one and the TB horn, at the same time too. Even if the landlords probably wouldn't find the idea quite so appealing
 

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OW, I think you may have misunderstood max's query--he's suggesting that instead of building a ginormous horn with 2 drivers, why not build two cabs at (roughly) half the size and one driver each? That would help your placement options considerably, perhaps allowing for stacking in one corner.


Although 2 full size monstrosities would be pretty sweet too
.
 

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Discussion Starter #16
Nope, I see what he's getting at - I just haven't spent a lot of time looking in that direction.


Really, the whole plan was to see if I could do the same thing I did before, only smaller and louder. Any extension below 16Hz is gravy, as is any in room SPL over 120dB at listening position. If I can do that in two boxes that uses less wood than one box with two woofers, that would be something I'd have to consider. But I need time to see what I can do with the idea first... the dual SDX design I've been working on for quite a while now. It's been months since I picked those woofers for the next project
 

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Is a low FS, high efficiency, light weight stiff cone to much to ask for. The auto subs model so well but the FS is just way to high.


I would gather most of us are shooting for the DTS-10. Looking at the LAB 12 driver it looks really close to what danley uses in the DTS-10. Since it is made by emminence did they just up the X-max on it and lower the FS a bit?
 

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Discussion Starter #18
I usually shoot for an Fs that's about 1.4x higher than the corner I'm after, give or take a few Hz.


Actually, I'm not really targeting the DTS-10 with this one - I'm still looking for a TH-SPUD that goes a bit lower, and in the process teaches me a few more things about tapped horns. Sealed and ported designs are dull to me now - there's no more mystery in them for me. If it should come close to the DTS-10, that would be sweet. But I'm not counting on it happening.


The DTS-10 woofer is a custom job.
 

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Quote:
Originally Posted by stgdz /forum/post/19165807


Is a low FS, high efficiency, light weight stiff cone to much to ask for. The auto subs model so well but the FS is just way to high.


I would gather most of us are shooting for the DTS-10. Looking at the LAB 12 driver it looks really close to what danley uses in the DTS-10. Since it is made by emminence did they just up the X-max on it and lower the FS a bit?

Folks that know a lot more than I do suggest that there is more to it than this. The motor has been changed considerably, and there is very little on the market that is close.


Some of the automotive subs work well in tapped horn subs. The biggest issue I have with automotive subs in general is that the specs we need for accurate modeling are filtered through the marketing department and may not represent reality. With the prices involved and return policies what they are, I'm not willing to stick my neck out and try them based on the provided specs. Additionally - with larger, high-displacement drivers that have a stiff suspension, measuring the driver's parameters accurately is beyond what my WooferTester II can do, so I have to use alternative methods.


I'm not one of those shooting for the DTS-10, I simply do not have the space to park a pair of something that size in my room. I'd be thrilled if I could achieve performance similar to a TH-50 in a smaller cabinet size. The models suggest that I am close, but proof comes from a measurement, which is still a ways off unfortunately.
 

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Quote:
Originally Posted by lilmike /forum/post/19166458



Some of the automotive subs work well in tapped horn subs. The biggest issue I have with automotive subs in general is that the specs we need for accurate modeling are filtered through the marketing department and may not represent reality.

I've dug around the harman sites for awhile and found this 12" driver
http://manuals.harman.com/INF/CAR/Bo...262W_final.pdf


it modeled really well in my THT 12" driver model compared to the dayton 12" at 10 volts each.



At 96db it's a really really efficient driver and the cone is nice and light, its just got that 25fs and 13mm of Xmax that keeps it from being and excellent driver for a sub 20hz design. At least in my THT model.
 
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