Shiva Tapped Horn - Page 3 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #21 of 166 Old 01-27-10, 10:34 AM Thread Starter
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Re: Shiva Tapped Horn

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Ricci wrote: View Post
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.
Incorrect. As I stated in MY sims everything is referred to 1/4 space. The first image for the LAB12 is someone else's generation, but I did change the space loading for the graphs I did.
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Ricci wrote: View Post
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.
I already stated why I chose that; most subs in enclosures in rooms will be acoustically near a floor/wall boundary. If you want, run them yourself in 1/2 space. I doesn't change the FR very much, just drops it 6dB.

I fully understand that apart from a concrete bomb shelter that walls are not rigid, and some losses will exist. However, build a pair of these, one with a LAB and one with a Shiva, and place them in the same position in the same room, and you will get proportionally similar results.
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Ricci wrote: View Post
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.
So, as stated, drop 6dB to get 1/2 space.

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Ricci wrote: View Post
A9X,

Why use an inducter if the simulated differences with it are so small? Looks almost negligible in your sim?
The presence or not of the inductor makes a large difference in FR. In the first graphs I simply added the Le value, but forgot to include the DCR of the coil itself. It was the effect of the DCR alone (ie everything else on the data input page was the same except for Rg) that I was demonstrating in the last curve.

I had no intention of redoing all the graphs because of this small difference because photobucket was a huge PITA that day and crashing when I was trying to upload images.
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post #22 of 166 Old 01-27-10, 10:37 AM Thread Starter
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Re: Shiva Tapped Horn

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lsiberian wrote: View Post
This is borderline crazy, but fun to watch. Horns are typically used in pro-audio for large rooms.
It is no crazier than a lot of IB systems out there. If either my apartment, or my house (cathedral ceilings, rammed earth floor) supported an IB, I'd go that way myself.
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post #23 of 166 Old 01-27-10, 01:38 PM
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Re: Shiva Tapped Horn

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A9X wrote: View Post
Incorrect. As I stated in MY sims everything is referred to 1/4 space. The first image for the LAB12 is someone else's generation, but I did change the space loading for the graphs I did. I already stated why I chose that; most subs in enclosures in rooms will be acoustically near a floor/wall boundary. If you want, run them yourself in 1/2 space. I doesn't change the FR very much, just drops it 6dB.
I was merely stating the above because some forum members are not aware of the 6db positive effect that it will have on the graphs and that they would not be apples vs apples between these and something like winisd or Unibox's default. There has been a lot of action regarding horns lately and a lot of people see the huge output #'s on the HR SPL graphs compared to these other programs that they are used to seeing and get really excited without realizing that there is an extra 6db or even 12db added on top of all of the extra output the horn is already going to be giving. That's all I was saying and the reasoning behind it.


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A9X wrote: View Post
I fully understand that apart from a concrete bomb shelter that walls are not rigid, and some losses will exist. However, build a pair of these, one with a LAB and one with a Shiva, and place them in the same position in the same room, and you will get proportionally similar results.
So, as stated, drop 6dB to get 1/2 space..
Agreed. I was not questioning the base simulations or the fact that the Shiva should have significantly greater max headroom available over the Lab12.


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A9X wrote: View Post
The presence or not of the inductor makes a large difference in FR. In the first graphs I simply added the Le value, but forgot to include the DCR of the coil itself. It was the effect of the DCR alone (ie everything else on the data input page was the same except for Rg) that I was demonstrating in the last curve.

I had no intention of redoing all the graphs because of this small difference because photobucket was a huge PITA that day and crashing when I was trying to upload images.
Ahhhh.... I missed the part about only the DCR. I thought you meant that was a before and after with the inductor and I was surprised at how little of an effect it was.
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post #24 of 166 Old 01-27-10, 02:22 PM
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Re: Shiva Tapped Horn

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It is just a simulation and I don't know how accurate HR models the actual results.
I have only seen two comparisons of simulations to ground plane measurements and I was surprised at how close they were in both cases, including the ripples at the top end.

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Sure... there are situations that are right for any tool.
I guess thats what I was trying to say. In my case, I have already investigated my room and have a corner that has the space and also gives the best response in my accoustically ugly room.

AX9. I have read the BassHorn thread several times over and it looks really interesting. That design may be a little big for my space.
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post #25 of 166 Old 01-27-10, 04:07 PM
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Re: Shiva Tapped Horn

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Kevin Haskins wrote: View Post
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?

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This was interesting but it just got really fun.
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post #26 of 166 Old 01-27-10, 04:25 PM
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Re: Shiva Tapped Horn

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A9X wrote: View Post
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)
awesome idea - since space is such an issue (for you people <snicker> ), I like the idea of taking things to the top to decrease the footprint... columns in nodes, genius

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Ricci wrote: View Post
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.
Ricci has to design too, cuz he's invaluable here... but I'd like to exclude him from winning, it's just not fair. How about the free driver goes to runner up?

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Ricci wrote: View Post
Why use an inducter if the simulated differences with it are so small? Looks almost negligible in your sim?
what is the inductor for? What does it do?
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post #27 of 166 Old 01-27-10, 04:36 PM
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Re: Shiva Tapped Horn

Well... lets set some guidelines. In general I think 15Hz would be a good tradeoff. I've seen people asking for 10Hz but they obviously don't understand the enclosure size they are asking for. Smaller is better and I'd rather see a design that people can actually build rather than something that has to be built into the structure of the house. Something that is visually unobtrusive is a bonus and economy of use of materials is a consideration. It should also be something that can easily be built and copied. If you need CNC cut parts then that seriously cuts down on how many people would be interested.

I know HR is accurate for simple horns. I don't have any experience in comparing the simulation to a measured result on these more complex folded horns so any design would have to be built and measured.

I'd propose this. Anyone who can model something in HR and comes up with a plan will be eligible for the contest. I'll either approve or turn down any plan submitted. A submitted plan has to have the model, a quick proposed drawing (napkin is ok) and if I give it the thumbs up. The person submitting the plan has to be ready to build and measure the finished design in a reasonable amount of time (lets say 2-4 weeks). I'll happily supply a Shiva-X2 for $115 shipped anywhere in the continental USA for anyone submitting a plan.

For the person who I declare winner, I'll credit their credit card for the $115 and they receive the driver free of charge. For others who participate but don't win, they still get to keep the Shiva-X2 for $115 for their efforts.

Does that sound fair?

Kevin Haskins
Exodus Audio
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post #28 of 166 Old 01-27-10, 07:01 PM
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Re: Shiva Tapped Horn

Quote:
Kevin Haskins wrote: View Post
Well... lets set some guidelines. In general I think 15Hz would be a good tradeoff. I've seen people asking for 10Hz but they obviously don't understand the enclosure size they are asking for. Smaller is better and I'd rather see a design that people can actually build rather than something that has to be built into the structure of the house. Something that is visually unobtrusive is a bonus and economy of use of materials is a consideration. It should also be something that can easily be built and copied. If you need CNC cut parts then that seriously cuts down on how many people would be interested.

I know HR is accurate for simple horns. I don't have any experience in comparing the simulation to a measured result on these more complex folded horns so any design would have to be built and measured.

I'd propose this. Anyone who can model something in HR and comes up with a plan will be eligible for the contest. I'll either approve or turn down any plan submitted. A submitted plan has to have the model, a quick proposed drawing (napkin is ok) and if I give it the thumbs up. The person submitting the plan has to be ready to build and measure the finished design in a reasonable amount of time (lets say 2-4 weeks). I'll happily supply a Shiva-X2 for $115 shipped anywhere in the continental USA for anyone submitting a plan.

For the person who I declare winner, I'll credit their credit card for the $115 and they receive the driver free of charge. For others who participate but don't win, they still get to keep the Shiva-X2 for $115 for their efforts.

Does that sound fair?

Kevin Haskins
Exodus Audio
Who is this Kevin guy and who is Exodus Audio?
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post #29 of 166 Old 01-27-10, 08:19 PM
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Re: Shiva Tapped Horn

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Ryan Anderson wrote: View Post
Who is this Kevin guy and who is Exodus Audio?
Just some jerk.
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post #30 of 166 Old 01-28-10, 12:59 PM
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Re: Shiva Tapped Horn

Keep it under 300L? That's a little over 10 cubic foot.
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