My Dual Tang Band 8x12 Tapped Horn Project - Page 6 - Home Theater Forum and Systems - HomeTheaterShack.com
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post #51 of 99 Old 02-18-10, 10:34 AM
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Oliver
 
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Re: My Dual Tang Band 8x12 Tapped Horn Project

Hi Jeremy,

Sorry to hear that. Hope you'll get it fixed.

Regards,
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post #52 of 99 Old 02-18-10, 11:01 AM Thread Starter
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Re: My Dual Tang Band 8x12 Tapped Horn Project

I got it fixed - that's why I'm broke

Fortunately, I was able to do the work myself with some help from a couple nice guys with a heated shop.

A cheap SPL meter arrived off the boat from Hong Kong last week, so I had some fun this morning measuring my 11Hz tuned IXL 18.2.2 for eventual comparison to the horn. With my Pioneer VSX-919 set to -17dB, which is the hottest I usually run it, I popped in War of the Worlds, went straight for the "something's coming up through the street" scene, and flipped over to the DTS track.

Meter said I was getting 112dB peaks at the couch, my RMX-1850HD showed me the blinking red light on channel one a couple times, and I said to myself, "That's it? That's all the room gain I'm getting in here?" Matches the Unibox sim pretty well though.

I think I do need the tapped horn or another three of these 11Hz IXL designs if I want effortless reference level playback in this place. Since the RMX was clipping, I can only conclude the woofer was getting all 600W of safe power before the bottoming out point. If I could give it more, I'd just go ahead and bridge the QSC.

Edit - the IXL's Unibox sim for those interested:



Predicted diaphragm displacement is 25mm at worst with 600W... I'm letting it exceed Xmax just a bit.

Last edited by Oklahoma Wolf; 02-18-10 at 11:18 AM.
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post #53 of 99 Old 02-18-10, 11:03 PM
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Oliver
 
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Re: My Dual Tang Band 8x12 Tapped Horn Project

Hi Jeremy,

That's some serious output for the vented IXL Unibox.

I'll attach two Hornresp Input screens, one for an IXL-18.2.2 tapped horn, and one for a dual (push-pull) W8Q-1071D tapped horn. I simulated both with small throat chambers. The response of the Tang Band is amazingly flat, and both models show good impulse response.

Just some more food for thought :-).

Regards,
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post #54 of 99 Old 02-18-10, 11:30 PM Thread Starter
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Re: My Dual Tang Band 8x12 Tapped Horn Project

Yeah, I've been thinking about one based on the IXL. Problem there is box size - it likes a huge one and this horn already needs 3 sheets of plywood. Not sure I want to buy the wood for the IXL, let alone try a design I've only done once or twice with a $300 woofer. I've been working on Hornresp sims with Hifonics car audio woofers lately - most of them model pretty well.

The W8Q-1071F is indeed a pretty good TH woofer. Unless I'm mistaken, your L12 is too short though - the woofer won't fit. I figured mine was the best compromise of performance vs. ease of assembly... we'll have to see when the time comes to get it built.
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post #55 of 99 Old 02-19-10, 01:06 AM
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Oliver
 
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Re: My Dual Tang Band 8x12 Tapped Horn Project

Hi Jeremy,

It would make a lot of sense to build some of the monster boxes from OSB, especially for testing. The cost of baltic birch plywood is just too high. And for looks one can always laminate some thin plywood (or other material like formica) to the outside of the box. One set of enclosures I build from 1/2" particle board, and laminated the outside with 1/4" Alder plywood; they looked and sounded just fine. It's also an easy way to hide screws used for braces, blend in access covers, etc..

As to the L12 distance: the reason for the small throat chamber is to provide coupling from the woofers to the horn throat. There is no actual L12, and for this reason I'm using the minimum distance that Hornresp allows. This method seems to work. The other method is to reduce S1 to minium with a L12 of approximately one woofer diameter, and the S2 area at the midpoint between the woofers (obviously no chamber). Reducing S1 to minimum, or using a small throat coupling chamber, seems to help with the impulse response in Hornresp. JLH posted an interesting example of a taped horn with throat chamber in the diyAudio Collaborative Tapped horn project around Post #2362 (I cannot post the link).

Regards,
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post #56 of 99 Old 02-19-10, 08:06 AM Thread Starter
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Re: My Dual Tang Band 8x12 Tapped Horn Project

Ah, right - I see it now. Just needed sleep, which is hard to come by around here lately.

Regarding box material, my physical health issues won't let me work with anything that produces a lot of fine dust (allergies and asthma). Plywood is ok, but still gives me problems. I also have to drive two and a half hours to get anything decent for a fair price. More than that though, I'm not sure about compression ratios with the IXL, which is why I want to get a few tapped horns under my belt before I try it.
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post #57 of 99 Old 03-29-10, 07:55 PM Thread Starter
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Re: My Dual Tang Band 8x12 Tapped Horn Project

Shamelessly copied and posted from my AVS thread...

Gasp - something's actually happening!



This is the week, folks - I have wood, I have spare time, I have PL Premium, and I have no semblance of sanity. This thing's getting built. That's a new 98" saw guide next to the wood - cheap, but should work I hope.

Wood shopping went ok. Home Depot was a disappointment as usual - Arauco only up to 5/8" and not very cheap at $45 a sheet. So, I ended up at Windsor Plywood where the best and cheapest they had was, once again, import 11 ply C2 shop birch. $40 a sheet.

After getting these sheets down to the basement, I'm wondering again why I thought I needed to use 3/4" stock. This project is going to be heavy as all get-out.

For those who use the stuff routinely - how long do I have after popping the seal on my PL Premium to put the stuff on before the tube is no good anymore? Worried about the length of time it'll take me to get this together. I just bought one big tube of the stuff - I probably should have gone with multiple smaller ones.
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post #58 of 99 Old 03-29-10, 07:59 PM
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Re: My Dual Tang Band 8x12 Tapped Horn Project

Tape over the tip every time your finished and you will be able to coax it out for around a month. When it gets a bit to hard you can use brute force and a twist drill in a power drill and drill a hole through the plug that eventually forms.

Mark

___________________________________________________________________________ ___________

Mark

Artificial intelligence is no match for natural stupidity.
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post #59 of 99 Old 03-29-10, 09:05 PM Thread Starter
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Re: My Dual Tang Band 8x12 Tapped Horn Project

Okie dokie. If it takes me a month to get this horn together, there's something wrong with me, I figure

Here's a graph for comparison purposes later - my REW measurement of the IXL at the listening position:



No EQ, Reckhorn B-2 SSF set at 10Hz. The horn's going to be firing at the same corner the IXL is in now.
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post #60 of 99 Old 03-31-10, 07:18 PM Thread Starter
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Re: My Dual Tang Band 8x12 Tapped Horn Project

Got all the panels cut today. Started at 1:30pm, done by 5pm. Every part of me aches right now.

Didn't have too much trouble, except when it came time to cut the long panels - the two sides and the driver baffle. That 102" saw guide isn't that great. Led to those panels being as much as 7mm off in places, and dead on in others. Argh. One is glad one bought PL Premium - one is going to need its expansion abilities.

Other than those three panels, the rest are about 1-2mm of being within proper measurements.



This is at the end of cutting sheet #2, and getting ready to start on the hard one. You can see my long saw guide in this pic - it's held on with clamps, which got in the way of the circular saw. Had it not been for the clamps, I feel those three panels would have come out a bit better.



I'm done for the day right here - the only thing missing in the picture is the bracing. Will cut that on test assembly day. I will say the dowels are planned to be part of the bracing... they're only 5/8" thick (best I could do locally), but they will only be doing side to side bracing. Everything else will be either CDX plywood or the leftover C2 shop birch.

I'm still impressed with this wood. Cut through three sheets of the stuff, and still no voids of any consequence.
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