My Dual Tang Band 8x12 Tapped Horn Project - Page 2 - Home Theater Forum and Systems - HomeTheaterShack.com
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post #11 of 99 Old 01-17-10, 12:39 AM
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Re: My Dual Tang Band 8x12 Tapped Horn Project

I would stay away from any bass horn with over 16:1 compression.
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post #12 of 99 Old 01-17-10, 12:40 AM Thread Starter
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Re: My Dual Tang Band 8x12 Tapped Horn Project

Quote:
soho54 wrote:
I believe we have had a conversation about the parameter numbers used before.
Did we? Can't remember anymore. I think my brain is totally shot now. Of course, that could be a side effect from trying to make sense of Lady in the Water earlier this evening.

In the event the new parameters are more correct than the old ones (I just can't figure out where that 450 cm squared Sd comes from instead of 460), I did some more fiddling in both Hornresp and PSP on the folding diagram. I came up with a way to turn the original design into a 13.5Hz monster by merely adding one more fold to the box with no flare. I don't think it would outperform the LLT that way, but it should match it and it wouldn't be too awfully hard to tack that extra section onto the box. Downside is, the box turns into a seven footer that way, so it'll be longer than me by six inches. But it will still fit the room that way.

Edit - 16:1?

Yeah, I think I'll have to pass on that one.

Last edited by Oklahoma Wolf; 01-17-10 at 01:03 AM.
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post #13 of 99 Old 01-17-10, 12:08 PM
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Re: My Dual Tang Band 8x12 Tapped Horn Project

Quote:
soho54 wrote: View Post
I would stay away from any bass horn with over 16:1 compression.
Wow...Yeah. Just saw that.

BTW thanks Jeremy. Almost 89db with 1w in at 20hz anechoic is actually not bad all. Plus you get up into the 95db area in the normal kick drum range.
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post #14 of 99 Old 01-17-10, 01:57 PM Thread Starter
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Re: My Dual Tang Band 8x12 Tapped Horn Project

You're most welcome

After you hinted at that MTX 15" being good for tapped horns I went ahead and modeled it. What a monster that would be... wish I could afford one of those. The IXL 18 came close, but with the size of that driver plus the compression ratios needed (not to mention the box size) I don't think I want to try it with something I just paid $275 for only last year. I should email Mach 5 and see what he thinks about the idea.

Meantime, I'm going to model the two MCM 55-700's I have collecting dust on a shelf and see if I can do something useful with them at long last.

Edit - so much for that. The 55-700 is lacking just about all essential specs for horn modeling, either online or in my old MCM catalogs. Probably for the best - they don't have a whole lot of cone travel to them.

Last edited by Oklahoma Wolf; 01-17-10 at 02:13 PM.
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post #15 of 99 Old 01-17-10, 05:46 PM
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Re: My Dual Tang Band 8x12 Tapped Horn Project

Hello Jeremy

The design I posted is of course only an example. It is not optimised for your drivers and is a preliminary design I did for other drivers with your Tang Bands plunked in only. Feel free to mess with it and see what you get for results. I only posted it to get you thinking a bit. It is but an example of what can be squeezed out of drivers if you put your head to it.

What you have posted is basically a tapered quarter wavelength resonator. Not a true tapped horn. I have posted below the same drivers in an optimal vented enclosure. I know the response looks ragged but we are talking less then 3 db rise and fall. You would be so happy to get in room response like that!

To get hornresp to help you calculate a parameter double click on the box and a little pop up will guide you through.

I attach the input screen and 1 watt 2 Pi results for a vented version of your box. This is again just for comparison. I did this by getting an optimal box in WinISD and plunking in the numbers into Hornresp to do a fair head to head comparison. It to is quite interesting.

Every time I don't know how to do something in Hornresp I go to the manual. I have learned quite a bit over the years from it. Never hurts to read it.

By the way I'm not trying to say anything you have posted is wrong or bad. Just before you go and commit wood to the project it is good to get as accurate of a result through simulation that you can. I have simulated quite a few horns of various styles and sizes and sometimes they are not anymore efficient than a vented enclosure using the same drivers. I do the vented comparison as a reality check.

Mark
Attached Thumbnails
My Dual Tang Band 8x12 Tapped Horn Project-tang-band-8-x-12-oval-input-screen-vented-enclosure.jpg  

My Dual Tang Band 8x12 Tapped Horn Project-tang-band-vented-enclosure-1-watt-input-2-pi-space.jpg  


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post #16 of 99 Old 01-17-10, 06:04 PM Thread Starter
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Re: My Dual Tang Band 8x12 Tapped Horn Project

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mwmkravchenko wrote: View Post
To get hornresp to help you calculate a parameter double click on the box and a little pop up will guide you through.
That's how I got Rms and Cms. Still not sure where your conflicting Sd figure (450 vs. 460) comes from, as I cannot find anything in Hornresp to calculate it. I do know about the manual

Did the cut sheet calculating today - the design needs four 4x8' sheets, along with my existing leftover wood for bracing.
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post #17 of 99 Old 01-17-10, 06:09 PM
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Re: My Dual Tang Band 8x12 Tapped Horn Project

Sd is me being to blind to see the right number!

Calculating into 4 Pi is an interesting concept. Who of us listens 30 feet off the ground outside to a subwoofer 30 feet off the ground?

2 Pi is the most general free field SPL calculation.

Your woofers will sun to almost an 8 Ω load so you can do it as 2.83 volts into 8 ohms and be very close.

Four sheets! Heavy stuff!

I hope you get what you are looking for. I know you will get some deep bass no matter what.

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post #18 of 99 Old 01-17-10, 06:19 PM Thread Starter
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Re: My Dual Tang Band 8x12 Tapped Horn Project

There are three panels that come out just a bit too long, or I could get away with three sheets. Debating doing one of two things - 1/2" thick stuff for the interior folds, or just shortening the horn a bit. Maybe I could get the fourth sheet cut at the store... not sure I can get four full size sheets home in a short wheelbase 2003 Caravan. I suppose I could enlarge the mouth a bit and get the most out of those four sheets too.

The whole aim of this project is to replace the IXL LLT in a package that will hide behind the projector screen and give a little more output at the expense of the subsonic extension my room doesn't allow anyway. The LLT is a 450L design tuned to 11Hz... it's just barely enough at my normal listening levels, but my problem with it is that there's not much headroom. Reference level with it makes me worry about the driver if I should dare to watch a movie mixed too hot.

Last edited by Oklahoma Wolf; 01-17-10 at 06:42 PM.
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post #19 of 99 Old 01-17-10, 06:59 PM
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Re: My Dual Tang Band 8x12 Tapped Horn Project

Ricci, I am also wondering about the free space graph request. I would assume everyone would be happy with ground plain equivalent half space sims.
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post #20 of 99 Old 01-17-10, 07:43 PM Thread Starter
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Re: My Dual Tang Band 8x12 Tapped Horn Project

After debating some more, I think I might try to draw up a revision 6 tomorrow with the mouth size increased to between 1800-2500, the horn the same length, and the placement of the horn tap a little different so as to allow a front firing exit right in the corner of the box. It's showing enough improvement in the SPL sims to consider it.

Even if I don't do it that way, I might still move the tap - found a placement that seems to sim a bit better, and I think my brain is finally remembering enough high school geo-trig to let me fold it that way. May also go down to half inch stock on all four panels and just brace it well. The wallet's worried about four 3/4" thick panels as well, even though Windsor's C2 isn't too expensive.

About the graphing - just wanted to add a reminder that I'm designing this thing for eighth space placement. It will not be used any other way. The plan with the current revision was to park it with the mouth pointing right at the corner from about 15" away... concrete floor, and wood paneled concrete walls. If I point the LLT's woofer at that corner, the Pioneer's MCACC sets the LFE 6dB cooler than when front firing it. But that's the problem... with the screen installed, I can't do that anymore. Now, it's under the screen pointing at the wall, and I've lost some output.

I expect that even though the LLT and Wolfhorn II model pretty similarly in terms of SPL in half space (with a slight edge to the horn), the horn will wipe the floor with the LLT once I get it into the room and hit the magic corner with it.

Hmm... I better get the horn stuff out of my brain for today so I can go watch 24 in a bit
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