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Shiva Tapped Horn

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shiva tapped
52K views 165 replies 26 participants last post by  Lucky7! 
#1 · (Edited)
Last year the design below was posted on diyaudio for a tapped horn with a LAB12 driver in this thread.



With the Danley DTS10 being a bit of a craze at AVS at the moment, but not available forever, I was looking at this design again and wondering whether it would be worth building. The aspect that puts me off most is the size, but I have no WAF issues and a quad of new LAB12's still in boxes.
The DTS10 uses a driver 'similar' to the LAB12 (actually 2 of them).

The limiting factor for the most TH designs is excursion at some frequencies. This is definitely the case for this one and the LAB12, so I wondered how the Shiva might work. So after nearly a minute's hard work plugging the driver parameters into Hornresp and making Le 10mH, I came up with the following (note, all are quarter space in my images);

Shiva TH input screen:



2.83V FR comparison at 2.83V: Black = Shiva, Grey = LAB12



Displacement Limited SPL Comparison: Black = Shiva (52V), Grey = LAB12 (24V)



Shiva Cone Displacement at 52V:



LAB12 Cone Displacement at 24V:



This ERSE Inductor is the one I had in mind for the Shiva.

I also just realised I forgot to add the DCR of the above coil into the earlier calcs (Rg=0), so I redid the Shiva 2.83V with and without.
Not enough difference to worry about for me.
Edit: Black is with inductor R, grey without.



Note: 52V into 3.8R is about 700W, and 24V into 4.26R is 135W.


Do you think 4 of these, either driver, would be too much for a 52 cubic metre (1836 cubic ft for countries still stuck in the 19th century) apartment?

Thought this might give some Shiva owners, or potential owners, another option to play with.
 
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#57 ·
Thanks for trying to make me feel better publius. I just don't have a clue what I'm doing yet and there are a whole lot more variables to play with here than other sub designs. I'm still struggling to see the relationships between various parameters. Its still fun though.


After mocking up the one in the OP with cardboard and tape, I don't think I'll be using them myself, they're just too big.
That will be the case for most people. I have a lot of lattitude and still, most of what I have seen that reaches low is larger than I am willing to accomodate.
 
#58 · (Edited)
Yay - the pictures are here!!!

Figured I'd throw my hat in the ring. :D

While it is not a perfect driver for use in a tapped horn, the Shiva X2 is no slouch.



Cabinet is about 400 liters net, impulse response looks fairly well damped, phase is pretty good.

2.83V 2pi SPL


Impulse


Phase


SPL is limited by xmax to around 115 @ 500 W, 2pi, so it should do reference levels in room. I'd suggest a highpass near 14 Hz if you listen loud. There is no such thing as a perfect corner is my house (best I can get is 1pi), so add 5 dB - you'll probably get near 120 @ 1m in room, probably 110-115 at your couch before running out of xmax. I am not sure what the mechanical limit is, so I stopped here.

500 W Excursion


Experience building and measuring several tapped horns tells me that the sharp spike at 56 Hz will either be greatly attenuated or not present at all in the real world. I have also learned that poly batting placed appropriately will significantly attenuate the 10 dB step in response above 70 Hz, but the best placement is arrived at through trial and measurements.

With appropriately placed batting, and a proper crossover frequency and slope, this should have a usable bandwidth of 15 to 100 Hz.

I'm working on a folding pattern, I have several in mind. My Sketchup abilities are pretty light compared to some of these guys.

Here is my general idea for a fold:


Folded like this, the cabinet will be approximately 4.5' high, 2.5' wide, and 1.5' deep.

I have the tools to construct this and measure the results reasonably accurately.
 
#60 ·
For under 300L, a front loaded horn is better at 20hz than at 15Hz:



2Pi, 2.83V in, Offset Driver front loaded horn using lilmike's specs from the above hornresp window...the 15Hz horn gives up output to get the extension in such a small enclosure size....

Although hornresp gives a sub-300L figure for these horns, I always add ~25% to that for wood volume before I begin folding.

Kevin, if there is a chance you'd be interested in me folding up either of these two, let me know. A tapped horn may be able to dig better to 15Hz, and that's why lilmike is here...I am not as good at tapped design as I am with front-loaded designs...


JSS
 
#61 ·
Kevin, if there is a chance you'd be interested in me folding up either of these two, let me know. A tapped horn may be able to dig better to 15Hz, and that's why lilmike is here...I am not as good at tapped design as I am with front-loaded designs...


JSS
How about a 'fold along with me' session for those of us that have never done this? :devil:

I have 0 design expertise, but I'm pretty good with DIY and have played enough with REW to be able to measure reasonably well. I also have the perfect 1pi space: a concrete construction apartment and the perfect corner to put one of these. 300-400 liters will leave me enough room for proper corner loading.

I would love to be able to fold up one of these. Now that I have some models to aim for, I will keep plugging away to see how you get from where I am starting to where you guys are, but I don't know if I can do that in a reasonable amount of time.

Or, to put it another way, I don't have all the toys, but I really, really wanna play too! :bigsmile:
 
#65 ·
For giggles, and to encourage others at the beginning of the learning curve, here is my first kick at the can, tapped horn:




The first try is grey. The first is just over 400 liters with a large mouth (1500 cm^2) the second increases s1 slightly but has a significantly smaller mouth (980 cm^2). That takes it down to 337 liters.

I don't think its going to reach 15Hz so I need to increase path length I guess.
 
#66 ·
A version with a 20Hz corner would make sense too. There are some people that insist on LF corners and others wanting the extra output that a 20Hz corner would bring.

I'm not limiting you guys in any way for the contest. You can choose your box size, corner and bandwidth with complete freedom. Also it matters not what type of horn you use. The only basis for judging the design is size, bandwidth, and output. Of course the practicality of construction is important too.

The reason for this is two-fold. First... it is fun to get everyone involved. Often people come at problems from different directions so collaboration breeds innovation. Second, I want something people can copy so that I can sell more drivers.

Once we come to a design consensus I'll build and measure one. I just don't have time to build a dozen designs. Also... the Shiva-X2 is probably the best candidate for horns. I know people are asking about the Tempest & Maelstroms but they are the wrong drivers for the application. Trust me... even without running simulation I can tell you that the enclosure sizes would be unrealistic.

Kevin Haskins
Exodus Audio
 
#68 ·
"give us the napkin drawing next. ;-)"

kevin, here is a napkin drawing. again, not a tapped horn, but a formidable one.

i haven't worked out all the measurements/angles/etc., but something like this should replicate the sim more or less.

question: what compression ratio is the max for the shiva driver?

 

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#70 ·
kevin, here is a napkin drawing. again, not a tapped horn, but a formidable one.

question: what compression ratio is the max for the shiva driver?
As I said, it doesn't matter if it is tapped or not. Only the results matter. In terms of the compression ratio the answer is "I don't know". I didn't design it around a horn and it wasn't part of the design constraint. I don't think you are going to see a huge difference among drivers of the same size/format though in terms of what is acceptable for that compression ratio. I'd need to build the horn and destructively test a couple to see where the limits are.

You are only going to see those ratios under full bore/stroke so lets not get excited about 4:1 at this point.

Kevin Haskins
Exodus Audio
 
#73 ·
"As I said, it doesn't matter if it is tapped or not. Only the results matter."

oh...cool. i must have missed that part. i was feeling bad because i thought i might be spamming your thread with unrelated content.

well, in any case, my design is open source; i'd like to see some folks best it.
 
#77 ·
For a front loaded 15Hz horn, I need around 600L to get good output (over 90dB 2.83V, 2pi). The 20Hz horn gets the same output (but less extension) with 1/2 the size....

Or you could do a PA style horn (30Hz tune), same size as 20Hz horn (approx 260L), but with 120+dB on tap at Xmax at 30Hz, 2Pi space...the 20Hz horn is Xmax limited to 112dB at 20Hz in 2pi space, and the 15Hz horn at just over 110dB at 15Hz.....pick where you want to get off the train....

Choices, choices....

Which would you rather I work up (if any)?


JSS
 
#80 · (Edited)
I'll work up the 20Hz front loaded horn, and make it the subject of the folding tutorial I promised everyone at AVS. Should be complete tomorrow. I'm gonna draw up 1/2" ply (12mm) for panels and reflectors, and 1/4" ply for bracing.

Quick fold tells me that this one will be around 12.5 cu ft. first folding gave me 33"x33"x20". To get under 10 cuft, you need to start with a 225-230L model...with 1/2" building material.

JSS
 
#81 ·
I'm messing around with hornresp now, but if I'm doing it right I've got a ~15 cubic foot enclosure with a 13 hz lower knee with a single shiva. I've got some tweaking to do on it but it's looking pretty promising as a tapped horn. It would yield about 90 db at the lower knee with 2.83 volts in 1/2 space. We'll see if I can get it worked out. Now getting it folded in a decent way will be another story... I haven't tried to mock up the full horn before. Hoping it will work, but if not I'll try again.

I also tried messing around with a dual shiva tapped horn, but that got way too large. If I get the single driver shiva down I'll mess with the dual driver one to see if I can get it down to a more acceptable size.
 
#85 ·
OK. I've played with the throat section, but not the mouth.

Thanks.


Yeah, showing someone else forces you to think hard about what it is you think you know.
And - the smart kids pull you aside and quietly point out the things you don't quite have a grasp on yet.:D

Seriously - without the people that helped me, that thread would have a fraction of the value it does.

I'm actually still listening to that little sub. Think I have the gains about right now - probably won't bottom the drivers out during big kabooms any more.
 
#88 ·
Here's a decent 1st try: 33"x33"x20". It can be refolded to be a taller box than just square on one side...



The Shiva really gets to flex it's muscles in a bigger box, though. Here are corner loaded, Xmax limited outputs for the horn above, and one more optimized for the Shiva Driver (but 120 liters larger):



The larger horn in grey.

Before I dimension this guy up and draw plans, I have to know if this size and shape would be acceptable....

JSS
 
#89 ·
Here's a decent 1st try: 33"x33"x20". It can be refolded to be a taller box than just square on one side...






The larger horn in grey.

Before I dimension this guy up and draw plans, I have to know if this size and shape would be acceptable....

JSS
Stretch it tall so that it can go in a corner and I'd give it the thumbs up. Imagine a corner specific sub that is designed to go left/right corners without taking up a large footprint. It literally gets built into the room and you could drywall over it. Leave an access panel to get to the sub. Keep in mind standard 4x8 material dimensions for cutting panels.

Kevin Haskins
Exodus Audio
 
#91 ·
I think that would be cool. Most of the people I deal with who don't have enclosure requirements for size are building a home theaters including the room. If you are building a room from scratch these large enclosure horns make sense, especially if you unwind them and make them tall rather than fat and wide. If you need <8-10 cubic feet or deep smooth bandwidth a traditional sub makes more sense because they are much easier to design to get the desired bandwidth and keep to a manageable size. They are easier to build and only maybe 2-5% of my customers will build a sub > 10 cubic feet anyway. It is a small minority that are willing to accept that large of an enclosure in the room.

But the people who are building a HT from scratch often have 1-2 ft of space behind a screen or in a false wall. If the design was tall rather than deep/fat it would fit their application. A big rectangular box does not.

Kevin Haskins
Exodus Audio
 
#92 ·
Kevin,

If I keep it 20" wide, I have 1089 square inches to fill for the other 2 dims. that comes out to 24"x45", 28"x39", or whatever 2 numbers that multiplied together hit 1089.

Changing the width from 20" is more work, but can be done...

What kind of dims do you need specifically, so I won't have to be guessing if the box is 'tall enough' compared to the width/depth? I have 21780 cu in worth of volume to make into a box...

Oh, in case people are wondering, the horn as designed above will beat a 17" wide THT loaded with a 12" DVC in hornresp sims, by a non-trivial margin in both extension and max output. The 15" DVC loaded, 24" wide THT beats this one in output, but also requires 18 cu ft in a 36"x36"x24" box....

JSS

PS - Mike, I will definitely not change the width (or anything else) if your TH smokes this design....so I'll wait on you to develop this any further...
 
#93 ·
I gotta get back to the Shiva project. Have some ideas on a nice and easy tall/skinny fold pattern and it looks like I still have to tweak my model some more, my phase is not quite right according to a quick check with AkAbak.

Go ahead and change away....I'm not done tweaking mine yet either.:D Though I doubt I'll get much more efficiency out of it, I'm pretty confident that I can find some more low-frequency extension.

I'm not here so much to "win" but rather to learn all I can and maybe teach a little. If part of that is learning that when given same volume, a Shiva likes a ODH more than a TH, so much the better, ODHs are a TON easier to fold up!

By the way - everyone - be sure and check out the new version of Hornresp.
 
#99 ·
The Anarchy looks really good.
That's almost an understatement - I finally got around to modeling them myself, and... let's just say I already liked them before I saw I could put four into a tapped horn and build a 16Hz monster horn with them.

Now, I'm strongly considering either a full 7.1 channel tapped horn setup with the big Tang Band horn handling the LFE and seven little 30Hz Anarchy horns helping out the main channels, or just re-building the mains with the Anarchys in a back loaded horn config. Or building the tapped horns into the main speakers. Or something else crazy along those lines, like adding my IXL horn plan to the Tang Band horn.

I'll need to borrow a stopwatch so I can time how fast the cops get here though.
 
#97 ·
But, you can build an OD horn w/o patent infringement....but it takes a ton of labor to do so for commercial gain, and not usually feasible.

OK, I'll see what I can do to make the Shiva horn a slimmer model...

BTW - the Maelstrom 18" models well in a big horn....in fact, an HTS user is going to build TWO of them, watch for the build thread soon. Big box, 32"x40"x64". He will be placing them in an attic space, IIRC. Compression Ratio is under 2.5:1 (the hardest thing to lower and keep a decent response).

Here's what hornresp predicts for two of them, corner loaded, 50V into each, just under Xmax at the excursion maximum at 15Hz:



highpass, and you can get into the 140s from 20Hz and up....or until the driver burns up or tears the cone/surround....

JSS
 
#107 ·
OK,

How about 20"x24"x45"? Got it to fit, and response is almost identical to the one graphed above, +/-0.25dB, hornresp sims Xmax limited output at almost 125dB corner loaded (with 25mm excursion), max excursion occurs at 17Hz, so a 20Hz highpass will get you more clean output. I need to clean up the fold before I post a drawing....

Also, room gain will get you more dBs below the 20Hz corner. The THT has a low corner at 25Hz, but room gain makes it almost flat to the high teens. I imagine this horn should do pretty well to 15Hz in a medium sized room (20'x15'x8' or so). But room gain depends a lot on construction and room/house layout, so I can't promise anything other than you should see some improvement below the 20Hz corner than what is simmed, just like any other sub...

JSS
 
#111 ·
Yea... drive on. Room gain is just one of those things we don't control. You estimate that you will get some but at the end of the day people use them in all types of rooms. Most of the action is well above 20Hz so picking a corner that gets you into the mid-teens with some assumed room gain is a perfectly good plan.

Kevin Haskins
Exodus Audio
 
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