My Dual Tang Band 8x12 Tapped Horn Project - Page 7 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #61 of 99 Old 04-04-10, 07:36 PM Thread Starter
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Re: My Dual Tang Band 8x12 Tapped Horn Project

Progress was made today after taking all day Saturday to fix a van. As predicted, this thing is a whole lot of a handful to put together. Everything went fine up until the driver baffle went in and I messed up my drill holes for that panel. Now I have holes to plug - will do that with #8 screws and generous doses of PL Premium.

The following pic is where I'm at right now. The PL hasn't gone on yet - need to be sure everything's in place before I get to the glue phase. Tomorrow I hope to get the bracing cut and the driver holes cut so I can do the final assembly by Wednesday.



This thing already looks monstrously huge in person. Need to get it done and into the corner where it belongs ASAP. I'll be putting it on casters. Decided to just use binding posts - they'll be underneath between the front casters. Don't have a bit to drill the hole for the Speakons - need to stop spending money now. I'll do that some other time, like maybe never
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post #62 of 99 Old 04-04-10, 07:52 PM
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Thumbs up Re: My Dual Tang Band 8x12 Tapped Horn Project

Looking good.

Can't wait for the sound tests!

Mark

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post #63 of 99 Old 04-04-10, 08:00 PM Thread Starter
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Re: My Dual Tang Band 8x12 Tapped Horn Project

That makes two of us. It had better sound as big as it is

Note to self - do not forget to add the damping material in the horn corners and especially the mouth before gluing stuff up.

Forgot to mention - no access panel either. The woofers will be right at the mouth - no access panel needed methinks. Will bolt them up using #10 wood screws. I hope I have enough duct seal to seal them off, or I'll have to run into town and face the temptation of the all you can eat Chinese food I should be avoiding.
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post #64 of 99 Old 04-04-10, 09:58 PM Thread Starter
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Re: My Dual Tang Band 8x12 Tapped Horn Project

Couldn't help myself - got the bit between my teeth and ran:



Found a better way to secure panels while I fixed up the main screw holes for each panel - I pocket screwed them down at an angle from the inside first. That way, they stayed put while I lifted the box up vertically to secure the panels properly. Worked great.

Now I can stop for the evening - my back is killing me

Have to remeasure for the bracing - ended up correcting a step issue on a fold.
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post #65 of 99 Old 04-05-10, 04:32 PM Thread Starter
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Re: My Dual Tang Band 8x12 Tapped Horn Project

Just a small update today - decided to rest up and get it all done tomorrow if I can.

Got the driver holes cut. Gave myself a moment of panic when I realized my folding diagram didn't match the latest changes - I had moved the woofers further in to lessen the compression ratio at the expense of impulse response. However, I realized today this would have also amounted to less bracing in the mouth segment as well as difficulty in getting the woofers bolted in.

So, I changed it back. Compression ratio in Hornresp is given as 3.25:1. I'm hoping that won't be a problem, but we'll see. Moving the woofers further in only drops it to 3.11:1, so I'm not really affecting it much. Besides, the woofers are firing through 18mm thick plywood - I'm betting this is not going to be an issue at all. So I picked up the jigsaw and made the original plan permanent:



The holes came out almost perfect - you can bottom or top mount the woofers in those holes - naturally they'll be bottom mounted. Used the plastic protector that came over the woofers as a template for the cuts.

Tomorrow, bracing gets cut and will at least get started on final assembly.
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post #66 of 99 Old 04-06-10, 10:45 AM
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Re: My Dual Tang Band 8x12 Tapped Horn Project

What's the external size and the HR calculated internal volume on this dude?
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post #67 of 99 Old 04-06-10, 02:19 PM Thread Starter
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Re: My Dual Tang Band 8x12 Tapped Horn Project

Hornresp says 649.1 liters or 22.9 cubic feet. Final enclosure size is 1876 x 1062 x 428mm, which is 852 liters or 30 cubic feet. That's external dimensions though.

It's like a coffin built for two people... seriously. Even with some of the internal baffles in place I had room to lie down in the thing, except for it not being long enough.

Just about to go get some bracing cut, and then I can start playing with the PL.
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post #68 of 99 Old 04-06-10, 10:49 PM Thread Starter
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Re: My Dual Tang Band 8x12 Tapped Horn Project

No pics in today's update.

As promised, the braces are all cut and everything but the top and the braces is PL'd together real good. I learned several things today:
  • PL will get on everything if you let it, and make a big mess. It's like my dog. It's best to build a little fence around the tube and maybe put it on a little leash.
  • One big tube of PL is not enough for a horn this size. Still have lots, but the plunger is way down the tube now. There may not be enough to finish up. So, I'll get some more and grab some extra duct seal as well.
  • 852 liter sub designs hurt when you drop them on your foot. Even if only a few panels are in place in that particular stage of assembly.
  • Despite rumors that PL doesn't smell too much... it does when you use enough to put this kind of a monster horn together.
  • T'was a bad idea to use #6 screws for 3/4" plywood, even with Robertson heads. The good drill kept stripping the heads out, and the cordless wasn't quite powerful enough.
  • It takes an hour and a half to PL a box this size.
  • The drill/screwdriver/PL is always over there when you need it over here.
  • Vacuum cleaners suck... unless you park them too far away and end up yanking the hose out reaching for that far corner of the box. Then they don't suck. Then you get to explore whole new levels of cussing.
  • Why did I have to make my first tapped horn design roughly the size of a Chevy?
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post #69 of 99 Old 04-07-10, 06:14 AM
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Re: My Dual Tang Band 8x12 Tapped Horn Project

Seven cubic feet bigger
Ouch

But I hope you get what you were shooting for. Your putting in a great job.

Mark

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post #70 of 99 Old 04-07-10, 08:09 AM Thread Starter
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Re: My Dual Tang Band 8x12 Tapped Horn Project

Thanks

I thought I had a serious issue with the driver baffle being too far away from the top panel, and there was a pretty large gap there before I started PL'ing, but something must have changed when the glue went on - the gap moved to the bottom where I was able to stuff extra PL into it. So, things are looking good for the top panel going on without leaks.

As it turns out, there is a leak in there I need to plug - showed up when I shined a flashlight along all the joints in the dark. It's from me not paying attention after the thing fell on my foot and not getting enough PL in that joint. It's a small leak - will plug it when I get the bracing on.
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