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Discussion Starter · #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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Very good and easy build it looks like. When you say 1836 cubic ft apartment, do you mean that's the entire apartment or just the room you'll use them in? Either way it will be overkill, which I like.
 

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I'm still new at the whole horn design, but with the total width only being 14.5" wide and only 13" for the baffle wouldn't it be a little tight? Plus wouldn't you have a tad bit of lower extension if you made the width maybe an inch or so bigger?
 

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Discussion Starter · #6 ·
I'm still new at the whole horn design, but with the total width only being 14.5" wide and only 13" for the baffle wouldn't it be a little tight?
There are actual build pics in the diyaudio thread linked in the first line of post 1. Looks OK to me.
 

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Hi,
The designs with the LAB12 seem to all go back to the Danley DTS-20. It would seem that one of these would be more than just sufficient. You may want to use the same Ang entry value (for general comparison I would suggest 2.0xPi).
Regards,
 

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Sure.... the Shiva-X2 also works in Bill Fitz design. I've not built and measured any of these large horn designs so I'll punt on giving you advice. My personal opinion is that it is craziness. You don't live in a stadium or need to fill a full sized IMAX. The tradeoffs for size and complexity are not worth it in a small living environment. What you want is enough SPL so that you can playback anything you want at SPL levels that are convincing. The other thing you want is FR smoothness and the best way to achieve that in a room is multiple devices. The idea of putting multiple horn loaded subs in a typical living room is beyond overkill.

Kevin Haskins
Exodus Audio
 

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Discussion Starter · #9 ·
Hi,
The designs with the LAB12 seem to all go back to the Danley DTS-20. It would seem that one of these would be more than just sufficient. You may want to use the same Ang entry value (for general comparison I would suggest 2.0xPi).
Regards,
The DTS20 has been modelled in the big Collaborative TH thread on diyaudio.
I chose quarter space as in most rooms a sub will be at or very close to a wall/floor boundary

My personal opinion is that it is craziness.
Me too, but asking about 4 in an apartment was just my sense of humour.
You don't live in a stadium or need to fill a full sized IMAX. The tradeoffs for size and complexity are not worth it in a small living environment.
Size, definitely, but they actually look very straightforward to build, and the original design even provides a cut sheet; that was one of the things that attracted me to it, and thought it might also for others who might want to have a go at a TH design.
What you want is enough SPL so that you can playback anything you want at SPL levels that are convincing. The other thing you want is FR smoothness and the best way to achieve that in a room is multiple devices. The idea of putting multiple horn loaded subs in a typical living room is beyond overkill.

Kevin Haskins
Exodus Audio
Overkill can be fun, and the suggestion of 4 units, as well as being a bit tongue in cheek for my space, was for more even performance in the space a la Toole, Welti etc. I'd also rather have drivers being well inside their excursion limits even when I have it up louder than usual.

As I said in the first post, I was tinkering around with the simulator and threw the Shiva specs in for giggles, and it worked very well and improved the performance of the design by using a better driver. Danley has created a bit of a stir with the DTS kit at AVS, but it will only be available for a couple more weeks, and I thought others might try one with this design if interested in the concept, they have the space and can use the SPL capabilities of the unit.
 

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The DTS20 has been modelled in the big Collaborative TH thread on diyaudio.
I chose quarter space as in most rooms a sub will be at or very close to a wall/floor boundary

Me too, but asking about 4 in an apartment was just my sense of humour.
Size, definitely, but they actually look very straightforward to build, and the original design even provides a cut sheet; that was one of the things that attracted me to it, and thought it might also for others who might want to have a go at a TH design.
Overkill can be fun, and the suggestion of 4 units, as well as being a bit tongue in cheek for my space, was for more even performance in the space a la Toole, Welti etc. I'd also rather have drivers being well inside their excursion limits even when I have it up louder than usual.

As I said in the first post, I was tinkering around with the simulator and threw the Shiva specs in for giggles, and it worked very well and improved the performance of the design by using a better driver. Danley has created a bit of a stir with the DTS kit at AVS, but it will only be available for a couple more weeks, and I thought others might try one with this design if interested in the concept, they have the space and can use the SPL capabilities of the unit.
If you have observed the forums for any length of time things go in and out of fashion on a regular basis. ;-)

I'd be willing to offer a contest for the best horn design based upon a Shiva-X2 though. Winner gets a free driver. How is that for incentive?

I'd have to set out some guidelines.... maybe people can have some input here. I'd say we limit enclosure size and shape to fit within some pre-determined footprint and that the bandwidth has to at least be usable to 15hz in-room. From your model I think you would be pretty close with that design.

What do you think of that idea?

Kevin Haskins
Exodus Audio
 

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Discussion Starter · #11 ·
If you have observed the forums for any length of time things go in and out of fashion on a regular basis. ;-)
Interesting you should mention that as there is a thread at AVS asking about the same thing; see my comments in post #6.

I'd be willing to offer a contest for the best horn design based upon a Shiva-X2 though. Winner gets a free driver. How is that for incentive?

I'd have to set out some guidelines.... maybe people can have some input here. I'd say we limit enclosure size and shape to fit within some pre-determined footprint and that the bandwidth has to at least be usable to 15hz in-room.
Sounds good, and maybe some fun to design.
From your model I think you would be pretty close with that design.
In room, especially a basement room, I'm pretty sure it would do it. But as it's not my design, should it win, the driver should go to the guys who did the hard work. Or auctioned for charity.

What do you think of that idea?

Kevin Haskins
Exodus Audio
I'll see what I can come up with that improves upon what I've posted so far.
Post the footprint specs, and I'll get to work. However, would height be an issue? A tall single fold TH similar in design to Erik's 15" version, though it takes a lot of volume actually doesn't intrude as much as some by not taking much floor space. In a dedicated, custom designed theatre room several designs like this could even be disguised as support columns and placed at anti-nodes.
(back RH corner)
 

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If you have observed the forums for any length of time things go in and out of fashion on a regular basis. ;-)

I'd be willing to offer a contest for the best horn design based upon a Shiva-X2 though. Winner gets a free driver. How is that for incentive?

I'd have to set out some guidelines.... maybe people can have some input here. I'd say we limit enclosure size and shape to fit within some pre-determined footprint and that the bandwidth has to at least be usable to 15hz in-room. From your model I think you would be pretty close with that design.

What do you think of that idea?

Kevin Haskins
Exodus Audio
I likes. to bad I never designed a horn load sub before.
 

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Sounds like an interesting challenge. I may just play with the Shiva tonight.

aduljr. I've never designed one either, but there is always a first time.

Kevin. I have two questions for you.

1. When I look at the fr graph I see a sub that will do maybe 18Hz in room, but I have no real experience to draw on. To me, the drop off below 20Hz is too steep to get much extension. What am I not seeing?

2. The top end looks to be limited on this design. You get a 5db dip at 70Hz and a huge spike at 80Hz. Even with cabinet loss attenuating peaks and dips, I see issues at 80Hz and above. Does this design need to be crossed at somewhere around 50Hz?

One final comment on horns vs other designs. There seems to be a major cost benefit to a horn loaded design: 1/2 the cost or less for the driver, 1/2 the cost for the amp, greatly reduced electrical usage.

I would love to build a sub around the MX 18 or 21, but I just don't have the $1000+ (CDN) to do so. $400-500 to reach 15Hz (vs the 20Hz of my current sub) seems like a manageable price. The trade-off is a silly amount of space, but given the interior design of my HT - early mancave - it would fit right in. :dumbcrazy:
 

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Sounds like an interesting challenge. I may just play with the Shiva tonight.

aduljr. I've never designed one either, but there is always a first time.

Kevin. I have two questions for you.

1. When I look at the fr graph I see a sub that will do maybe 18Hz in room, but I have no real experience to draw on. To me, the drop off below 20Hz is too steep to get much extension. What am I not seeing?
It is just speculation on my part. You won't know how low it will go in-room unless you specify placement and actually measure it with the boundaries, corners etc...

2. The top end looks to be limited on this design. You get a 5db dip at 70Hz and a huge spike at 80Hz. Even with cabinet loss attenuating peaks and dips, I see issues at 80Hz and above. Does this design need to be crossed at somewhere around 50Hz?
Once again I don't know. It is just a simulation and I don't know how accurate HR models the actual results. You might be able to acoustically damp some of those ripples or they may be swamped by the room issues. The bottom line is you would need to build and measure.
One final comment on horns vs other designs. There seems to be a major cost benefit to a horn loaded design: 1/2 the cost or less for the driver, 1/2 the cost for the amp, greatly reduced electrical usage.

I would love to build a sub around the MX 18 or 21, but I just don't have the $1000+ (CDN) to do so. $400-500 to reach 15Hz (vs the 20Hz of my current sub) seems like a manageable price. The trade-off is a silly amount of space, but given the interior design of my HT - early mancave - it would fit right in. :dumbcrazy:
Sure... there are situations that are right for any tool. That is the nature of the beast and every solution isn't going to be right for every person/build. It depends on what your build skills are, where your size constraints are and what you feel comfortable building. This goes for any sub, horn or otherwise but the larger you build it and the more dependent its output is upon room boundaries, the less flexibility you will have in maximizing the listening position FR. That is just the nature of the beast so you have to think through the complete solution.

Kevin Haskins
Exodus Audio
 

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This sounds like a cool contest Kevin. Set out some guidelines for the enclosure size externally and maybe a desired bandwidth?

I would like to note that from what I've seen so far the resonances in these horns are overstated because the enclosure is assumed to be unobtainium strength and completely rigid with no losses. They are still there, but the magnitude is decreased from that shown. How much is the question.
 

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Discussion Starter · #16 ·
1. When I look at the fr graph I see a sub that will do maybe 18Hz in room, but I have no real experience to draw on. To me, the drop off below 20Hz is too steep to get much extension. What am I not seeing?
It's about 30dB/oct, same as most PR subs.

2. The top end looks to be limited on this design. You get a 5db dip at 70Hz and a huge spike at 80Hz. Even with cabinet loss attenuating peaks and dips, I see issues at 80Hz and above. Does this design need to be crossed at somewhere around 50Hz?
It's a narrow band design. The peaks never seem to come out anywhere near what the sims say when others have built and measured their TH, especially double fold designs like these. I'd probably cross at 50-60, but I usually wouldn't cross a sub higher than that anyway.

I would love to build a sub around the MX 18 or 21, but I just don't have the $1000+ (CDN) to do so. $400-500 to reach 15Hz (vs the 20Hz of my current sub) seems like a manageable price. The trade-off is a silly amount of space, but given the interior design of my HT - early mancave - it would fit right in. :dumbcrazy:
It would be huge, but because the depth need not be much more than the driver, a false wall behind a screen could house a pair of large designs.

Here's a thread with a deeper tuned unit to give some ideas.
Cinema Basshorn

Danley also sells some larger units;
TH221
 

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Ill follow this thread with great interest :)
 

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One thing to note above is that those 2 sims are using different simulated spaces or at least appear to be. One is quarter space (Shiva) and the other is 1/8th space (LAB12), so they aren't directly comparable. Both of those (1/8th and 1/4 space)are overly optomistic IMHO too. If you were to compare to WinISD or Unibox, or any number of other simulation programs the default is 1/2 space or 2.0 x pi in HR. This chops either 6db or 12db off of the graphs shown above respsectively in order to compare to the usual graphs that you see of sealed and ported subs.

A9X,

Why use an inducter if the simulated differences with it are so small? Looks almost negligible in your sim?:scratch:
 
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