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Cool, what do you think the lowest decent frequency you would pick up with that horn. As you know I enquired about horns a while ago. Really struggled folding the things. I can use sketchup but found it confusing when trying to fold it. Could you make this horn wider and less deeper?

120db is more than my Q's model in their 15 cu ft boxes in my 17hz tune and I am modelled with 1000 watts input power.

Also I presume horns are just as critical with positioning like ported/sealed subs. Is this correct?
 

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Discussion Starter #22
Well... that's not quite as easy to answer as you might expect. The room depends a lot on how low it will reach with any kind of useful output. A sealed airtight room might get good SPL down to 11-12Hz on this thing. But if it's open to the rest of the house like mine, anything below the low corner is gravy.

I'm a highpass nazi with the one I have now. It will do reference to 14Hz and has significant output down as low as 13, but I try not to let it play that stuff. I have it set to drop like a rock below 15Hz. The trouble is, the lower you go below the corner, the more the horn will amplify second order distortion. At a certain point, all you'll hear is distortion and nothing of the fundamental. For example, the Tang Band horn will play 10Hz. Just not at audible levels. And when you start turning it up, suddenly it attacks you with high levels of 20Hz.

And that's actually how I know Hornresp overpredicts excursion. For a long time, my Reckhorn B-2 was boosting at 14Hz due to some weird interaction between the EQ and highpass filters. Effectively, I had no highpass at 10Hz at all... it was more like 6Hz. I actually had it running at reference levels during Tron Legacy when it was set that way. Massive distortion, but no clattering voice coils.

Once I got the Reckhorn set straight thanks to REW, all I get now is intimidating levels of clean LFE on that same movie. Can't wait to try that flick with the new one.

That said, I will soon have two 16Hz tapped horns in here. 13Hz at reference shouldn't be a problem with them both working. I just can't go any lower than that because the TB horn is going to be out of its depth trying to keep up with the new guy.

Yep - placement is still important.
 

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I think 13-14hz in the real world is low enough for pretty much most movies and music especially if its clean down to that frequency. Any pics off this thing standing proud to get an idea on size.
 

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Discussion Starter #24
I'll do better than that - here's a video I did of the TB horn for showing off purposes. Screen size is 102" diagonally.

Shows the horn pegging the SPL meter by the mouth. It was hitting 122dB peaks at listening position. This is back when the B-2 was boosting 14Hz, as well... haven't done a video of it since.


Makes me want to rub my hands and cackle with evil glee when I think that the SDX horn should get louder than this while being thinner at the same time :D

13-14 is at the point where you need to start moving away from horns if you're really serious about those frequencies at high levels. This design will only do that for some few people fortunate enough to have rooms good enough to allow it. Like I said - anything you get below the low corner should be considered gravy.
 

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Impressive indeed and that's not even the dual 10 either. The trouble with trying to achieve sub 13hz at loud levels is sealed and lots off them. That as you know cost big bucks and considering the amount off money you need to spend to get clean distortion free sub 10hz bass its not worth it in my opinion as its far cheaper to get 15hz and up which is where most stuff is in the low frequency range if that.

Really looking forward to the SDX TH results.
 

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Discussion Starter #26
Yep. Not that you can't do 10Hz with a horn, it just becomes impractical enough to not be worth it. Driver choices get scarce, and box sizes go way up. My IXL 18.2.2 for example models great in a 1300L 10Hz TH design. Will I ever build it? Not a chance. In fact, I might be selling that driver soon. I just don't use it anymore.

The thing about the Tang Band horn is, I stumbled into doing a better design in reality than I realized. The challenge with the new guy is to do those same things on purpose this time. Thankfully, Hornresp has improved by leaps and bounds since then, and I've learned a lot.

Only thing I can't get around on the new one is that it's a longer design due to the kludge block in the throat to make the tap position come out right. But there's really no way around that without coming up with some exotic fold I wouldn't be able to put together (I'm honestly about as much of a woodworking master as Tim "The Toolman" Taylor). I figure keeping it easy for me to build is more important than really optimizing the space in the cabinet. As long as it still fits into three sheets of ply, I'm happy.
 

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Played around with Hornresp the other night and I couldn't get a single driver version to work below about 22Hz. I also couldn't find any way to improve your design, so I can confidently say "nice work" for whatever my opinion is worth.

One question--how did you chose that 13.2" width. I'm guessing it was just a convenient number, or is there something more to it? If not, do you see any reason I couldn't up that number to about 15" which would allow me to cut that 42" dimension down to about 37.5" and keep the same area?

Thanks again for the inspiration, and the starting point from which I've found a lot to read.
 

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Discussion Starter #28
A single driver version requires roughly half the horn but keeping the same horn length. I can think of ways to improve it, but they either require upping the folding difficulty or more wood. As long as the current version proves as good in reality as it simulates, I'll be happy with it.

Width is chosen to be the narrowest it can get and still easily mount the drivers using 3/4 plywood. I think I left about a half inch wiggle room. This also allows much less bracing, because I'm using thicker wood with narrower spans.
 

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Discussion Starter #29
Say, is it just me or are there three big sheets of wood and two big tubes of PL next to my old tapped horn?



Once again, I went with C2 grade shop birch from Windsor. 11 ply, as good as it ever was. You couldn't beat the price with a bat even before they put it on sale for the month of May. $30 a sheet means all my wood cost me $95.

So far, I'm in this project about $320 for drivers, $95 for wood, $12 for screws, and $20 for two gigantic tubes of PL Premium. I get $447 when I do the math.

Of course, I did have to drop $60 into the gas tank to go get the wood from Medicine Hat...
 

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I was hoping you'd go first...now I'm drooling, waiting for your progress. As little comfort as it offers, I can tell you that I paid about twice as much for a 5x5 sheet of baltic birch. These things are a money drain no matter how you look at it, but so far, it's been quite worth it. Even if the filthy rich could buy something 2% better, they'd never really own it.
Please post your progress.:clap:
 

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Discussion Starter #31
This stuff ain't baltic birch quality, but it's pretty much the best quality imported cheap stuff I can find around here. The veneer will still peel if you let it, which is why I leave all the screws in after building, even after PL.

Home Depot's shop birch can't touch this stuff. 5 ply < 11 ply.
 

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OK...maybe a stupid question (I'm quite the building novice)...why would one want remove the screws? Finished look?
 

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Discussion Starter #34 (Edited)
And now the fun part - giving away the plans :D



Sketchup zip file attached. It's 2D, but all internal panels are 300mm deep. Not hard to remember. I was too lazy to make this one 3D.
 

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Discussion Starter #35 (Edited)
3K has some errors in the corners, it turns out. No horn gain on the two 180 degree bends. Spent the morning working on it, and I now have a version 3L. Box length gets slightly shorter, horn gets slightly taller.

Not bothering with the Hornresp sim on this one. It's almost identical to 3K with a slightly higher corner. In comparisons with the Tang Band horn, however, the slightly higher corner and corresponding 3" shorter horn length is probably an issue with my quick and dirty Sketchup measuring. I won't lengthen this one any more out of concerns I'll run out of wood.

As is, 3L still fits on 3 sheets of stock. Still need the extension piece on that one internal panel. But there's horn gain in the corners again. Probably not the most mathematically accurate, but this is literally all I am willing to do on this. Y'all can pick 3K or 3L as you wish. I'm building 3L. Hoping to start cutting wood later this week as I find time.

 

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Would you be willing to add top/bottom measurements for those two turns, corresponding to the 233mm and the 137mm ones in the 3k plan? I think it would simplify tracing out board placement onto the side walls.
 

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It looks like you're using a 1.8mH series inductor. The graphs on hornresp look subtly better with the inductor in place-slightly flatter spl curve and about 1mm less peak excursion-but I'm not sure if there is another reason. Is this why? Also, how do you actually hook up the inductor?
 
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