FaitalPRO 15HP1060 vs 3015LF for tapped horn?

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#241
By far the most precise build I've ever done! Going together like it was cnc'd

I am smitten like a kitten 🙂

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Curious light leaks in the second one courtesy of gravity + my phone + concrete
 
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#243
Great progress there. Your cuts are indeed precise and am glad it is all coming together so well. Neat that you are giving us blow by blow updates on the progress. Thanks for sharing.
Looking forward to first sound. If bracing with dowels I think spacing should be no more than 6 inches in between dowels. Do you have enough access room to reach your arm in and tighten screws around driver flanges when mounting and unmounting? Keep that in mind as you populate dowel braces near the mouth.
 
#244
This is how far I got tonight, so far it is just screws holding it together. I still have to pilot the piece just above the drivers "F" on my sheet, the driver mount holes, and the right side face which will be the last. Then it's on to taking it all apart and bracing everything, then finally gluing and painting... And then of course turning it on!

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I plan to pilot the driver mount holes so I can get in there with a short phillips head. Wish I still had some T nuts leftover from my last project! Oh well.

For bracing the visible parts where the drivers mount, I was going to cut an angled piece to go in between- kind of how my perspective model views have been looking. Then for everything else inside it will be dowels.

I'm going to assemble the inner folds separately so they stay perfectly at the proper angles which will hopefully make the inner connections to the right face as close as possible. The wood is fairly straight, but I'm not taking any chances... Not after the obsessive precision I've been demanding of myself for the rest of it.

Whew okay, 4:45am. Time to sleep! Good thing all of my roommates have been at a house party. I've been banging, drilling, and trimming edges with the band saw all night!
 
#245
Jennygirl said:
And thanks again for the double threat double check. I feel like a kid in a classroom with dual professors 🙂 Not in a bad way though, because this is work I am proud of and I'm honored that you want to verify it for me!
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As for my part, I was just curious to see how accurate your folding method was, and that's all that was checked. To check the accuracy of the final design I would have had to demand all the bracing details because bracing will change things.

To explain a bit about my contempt for inaccuracy in simulation and folding - I've seen and talked to way too many people that regard simulation as being barely better than a wild guess, saying that simulation isn't accurate and shouldn't be trusted. This almost always comes from people that either don't know how to simulate at all or were wildly inaccurate in their attempts, either not using the simulators correctly and accurately or not accurately building what they simulated. This is also the type of person that is likely to author the types of posts you have read claiming that accuracy isn't important because sometimes inaccurate results and errors can turn out better than expected. That's very much like saying if you don't know the exact directions where you need to go don't worry about it, you might end up somewhere even better. That may be true but it's unlikely and irrelevant. The truth is that simulation is a great tool and while there are some deviations from real life (because simulators are a relatively simple tool) they can provide shockingly accurate results when used correctly. So I apologize if all the talk about accuracy became boring, that's just my prerogative.

As for the bracing, there's no such thing as too much until/unless it eats up too much internal volume. The nice thing about stick or dowel bracing is that it doesn't need to be as precise as solid bracing does (whatever length you cut it, it will fit somewhere in the horn path whereas plywood bracing needs to be very precise to fit where it HAS to go) and it doesn't eat up too much internal volume. I don't have a CNC and I'm not good at long angled cuts; I also don't like bracing taking up too much internal volume so I am a fan of stick bracing.

Your dowels are very large circumference so depending on how closely you space them they might use up as much internal volume as solid 1/2 inch plywood bracing, in which case the solid bracing method would have been more effective.
 
#247
Reading this I think I am going to pick up some slightly thinner dowels, if they are indeed to be spaced 6" apart. The 35mm stuff I have would definitely eat up a considerable amount of internal volume.

What diameter do you all recommend? 1"?

Thanks again for all the hard work in checking my design accuracy. Guy, even though you did seem skeptic I still appreciated it.. It drove me a little harder trying to nail it, otherwise I might not have spent so much time zooming in and lining up the panels in Cinema4D.

The first CAD models I did (pre v1) are now hilarious to me. They would have been about 20-30% off, I think (if not considerably more). I was just eyeing the expansion to make sure it was always getting bigger. Your comments caused a paradigm shift in my brain, and I quickly became much more aware of the importance of accuracy to the sim. No need to apologize, because you deserve a huge thank you.

It's off to the hardware store for me, then back to the shop. I hope to have this sucker done tonight or tomorrow.

Thanks again guys for the knowledge and direction. I have learned a ton from you the past week and that makes me incredibly happy 🙂
 
#248
Jennygirl said:
Reading this I think I am going to pick up some slightly thinner dowels, if they are indeed to be spaced 6" apart. The 35mm stuff I have would definitely eat up a considerable amount of internal volume.

What diameter do you all recommend? 1"?
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Jennygirl,

Like Sine123, I'd also recommend plywood rather than dowels. A dowel is relying on a very small surface area for glue contact, when you put a couple horsepower into the cabinet the surface ply can tear loose.

Plywood provides more glue surface area, and using pocket screws also provides a mechanical connection. Subject to the power and off road abuse your sub will be enduring, do it right the first time, trying to fix broken plys and rolling dowels is almost impossible.

Art
 
#250
Xrk971 said you have extra space to play with so you can probably use plywood bracing if you want. Just run the sim again with the cross sectional areas at the S markers reduced to reflect the amount of bracing and see what it does. If you have the extra wood, can comfortably cut angled braces accurately and the sim says it's ok, it's probably a good idea.

EDIT - xrk said the same thing while I was typing.
 
#251
I'm going to do it with plywood for sure, but I don't think I'm going to do the 6" max unbraced width you guys are recommending.. Not quite that much. I'll probably do 3 or 4 lateral sections or every 12" or 9". The internal panels are beefy... 3/4". Every 6" with ply bracing seems drastic to me, my stadiumhorns basically have none and seem solid as heck (they are built out of the same material) with no panel flex that I could notice
 
#253
Jennygirl said:
I'm going to do it with plywood for sure, but I don't think I'm going to do the 6" max unbraced width you guys are recommending.. Not quite that much. I'll probably do 3 or 4 lateral sections or every 12" or 9". The internal panels are beefy... 3/4". Every 6" with ply bracing seems drastic to me, my stadiumhorns basically have none and seem solid as heck (they are built out of the same material) with no panel flex that I could notice
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The 1060 is a massive beast in comparison to the 3015lf. 2 1060 will cause a lot more panel flex. I dont know if you reviewed my thread with the 1030 loaded horns, but even braced as pictured in the cad picture, I wish I had braced a bit more (mouth flex when pushing near xmax).
 
#254
Hi jennygirl,

Your are making great progress, and fast. There are tons of discussions on bracing THs here is one w/ pictures you might find interesting:

http://www.diyaudio.com/forums/subwoofers/190635-th-18-flat-35hz-xoc1s-design-11.html

here is another example:

http://www.diyaudio.com/forums/subwoofers/190635-th-18-flat-35hz-xoc1s-design-16.html

As long as you cut holes into the braces they will not affect the cross-sectional values materially. Often thinner plywood is used for the braces, e.g.: 1/2" for otherwise 3/4" boxes. One rule of thumb is to not let any unsupported span go beyond 14". When using dowels it is good practice to attach small pieces of scrap, e.g.: 2"x2" to the ends of the dowels to provide larger glue joint areas. Use cleats (3/4"x3/4") in corners you are not sure about, it makes a big difference in strength.

Regards,
 
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#255
sine143 said:
The 1060 is a massive beast in comparison to the 3015lf. 2 1060 will cause a lot more panel flex. I dont know if you reviewed my thread with the 1030 loaded horns, but even braced as pictured in the cad picture, I wish I had braced a bit more (mouth flex when pushing near xmax).
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Do you have a link to the post? I'm in the shop beasting this thing out! 🙂

Which part of the horn mouth? I'm assuming the panel adjacent to the driver, or up where the tap is?

tb46 said:
Hi jennygirl,

Your are making great progress, and fast. There are tons of discussions on bracing THs here is one w/ pictures you might find interesting:

http://www.diyaudio.com/forums/subwoofers/190635-th-18-flat-35hz-xoc1s-design-11.html

here is another example:

http://www.diyaudio.com/forums/subwoofers/190635-th-18-flat-35hz-xoc1s-design-16.html

As long as you cut holes into the braces they will not affect the cross-sectional values materially. Often thinner plywood is used for the braces, e.g.: 1/2" for otherwise 3/4" boxes. One rule of thumb is to not let any unsupported span go beyond 14". When using dowels it is good practice to attach small pieces of scrap, e.g.: 2"x2" to the ends of the dowels to provide larger glue joint areas. Use cleats (3/4"x3/4") in corners you are not sure about, it makes a big difference in strength.

Regards,
Click to expand...

Thanks tb! Whew that makes a lot more sense, 14" sounds a lot more reasonable. I'm going to stick with 2 braces spaced at 3rds for a 12" max unbraced width.

As far as the cleats, should I stick to square or do an angled cleat? I have also seen many THs use a 45deg piece spaced a few inches out from a deep corner, as if to smooth out the horn path (almost as if its following an outer offset of the advanced centerline). Looks like it adds a bit of strength as well as the smoother path profile. I wasn't planning on doing this, but if it doesn't affect internal volume and has some sort of benefit I might as well do it
 
#258
Yes, you can brace right over the driver on the inside of the compression section as you have shown in your sketch (very Wacom-like lines and a nice touch to give some hand artistry to your nice cad drawings). I have seen it done and it should not affect things too much as long as you are not using thick ply. The mouth is where I think more bracing is better. Put cleats near mouth joint for transport strength in case you ever drop it.
 
#259
Thanks. Is 3/4" what you would consider too thick? I'm just thinking it will be easier to screw into and get a stronger hold. I do have the 1/2", too

Edit: nvm. I'm just going to stop asking questions and use the 1/2 😀
 
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