Problems with Cabinet design

[WilZirkle]

So I still haven't decided the speaker I am building next Swope or Kahnspire however I do know the shape I want to build the cabinet. Now don't get too excited here I will keep the baffle width and final volume within the designers specs when I pick the speaker. Just look at the general shape. I'm worried I will have issues with reflections or something else I have no idea about. Anyone have some help on what I need to watch out for?



Thanks everyone,

Wil

[WilZirkle]

I may set the face back so that it is flush with the face of the curve, if not then I would round over the edges.

[AdelaaR]

B&W does sort of this kind of shape, but then cone-shaped all the way round and in seperate enclosures, with their "nautilus" speakers.
If you add dampening to the sides there shouldn't be reflections, should there?

[JonMarsh]

This should work quite nicely, as good lining on the side wall will provide a smooth damping of the rear wave with no discrete frequency of reflection such as a fixed back panel gives. Recess or round over the front baffle to control diffraction, keep the same baffle width and overall volume, and you should be in great shape! :B

[WilZirkle]

Adelaa,

Over on parts express someone pointed out that they look like the Cirrus from Vapor http://www.vaporsound.com/#Cirrus

[joeybutts]

uhmmm watch out for BUILDING IT. :E

Should be a beaut. Hope it comes to fruition!

[yzracer14]

You should be fine. Wonderful shape. I look forward to seeing this.

[WilZirkle]

Thanks everyone, I hope I can build it, I think it will be a real challenge but exciting.

I need to finish my sub first. Probably should finish the tritrix MT that I started for the rears too.

Wil

[---k---]

JonMarsh has spoken, so I'm not sure what else I can add.

Really, other than complexity of construction, I don't see significant issues.

Appearance wise, I think these would look fantastic in a small tower. I'm not sure how they would look 54" tall. They aslo look like the shape would add a lot of size to the Khans. Just guessing, but even if you stretch the depth a little, you'll probably loose like 1/3 of the total volume. So increase your height even more. Import a human into your sketchup and maybe some furniture to see how it looks in room. That might make your decision on what design to build easier.

I can't believe I'm trying to talk someone out of the awesomeness of the Khan's. :doh:

[yzracer14]

... Just guessing, but even if you stretch the depth a little, you'll probably loose like 1/3 of the total volume. So increase your height even more...

Great point. You'd be suprised how much volume you actually gain from the bulge. The goal of my build was to make a moderately aggressive curve that didn't ressemble more of a taper, and that would allow me to keep the same height that I would have used if the box was rectangular. The volume gained by the bulge replaced the volume lost by the tapering towards the rear of the box perfectly. Granted, this one has a back-side inward curve so there will be volume loss from that area, but I think 2"-3" added to the total height will get you very close.

This is the stage that always intrigues me the most; tweaking all the variations of the original idea to get as close as possible to what you want.

[---k---]

And this is the point I step aside to your artistic judgement. I took my inspiration from this Chicago landmark:



and NOT this other Chicago landmark:



You're certainly free to do whatever you like. CJD probably would side with you.

[Paul W]

Looks great! What material(s)?

[WilZirkle]

Paul,

probably bendy ply. 3 layers of 1/4"

[WilZirkle]

I messed with what the Kahnspire would actually look like. I worked at it till my area in a cross section was within a fraction of the original Kahnspire and then used the same height.


I think its sexy.

[yzracer14]

:T Now thats what I'm talking about!!!

[joeybutts]

Yowzers. pass me a rag to wipe up this drool. Better make this happen WZ!

[CADman_ks]

Paul,

probably bendy ply. 3 layers of 1/4"

I like the look!!

What is the minimum radius that bendy ply will bend? The radiuses in your drawing look to be about 3" or so I'm guessing at the tightest spot. That sounds pretty tight to me, but I've never worked with bendy ply...

[Hank]

Now you've got it! That's what I call a rounded over edge. I was going to offer to loan you my 1 14" radius roundover bit, but you've THE roundover!

[WilZirkle]

CADman, That's a good question and I don't know the answer. I can also get it in 1/8" thickness but the cost per sheet is the same. I will do some research but if worse comes to worse I will order a 1/4" first and see what it can do. Thanks

Joey, no dripping on the wood and thanks

yzracer, thanks

[WilZirkle]

CADman, worst off appears to be some brands of 1/4 with a min radius of ~4". I believe I'm better than that in the model so I should be OK!

[CADman_ks]

CADman, worst off appears to be some brands of 1/4 with a min radius of ~4". I believe I'm better than that in the model so I should be OK!

That's good to know!

I did some quick looking on the internet, and I couldn't find the minimum quickly, but my search wasn't exhaustive. Did see a lot of picture of it bending, and like you said, it appears from the images, just gauging by scale that it's probably in that 4" range as a minimum...

[cjd]

I think you're going to want to bend and bond the sides on a form, trim it, and then add baffle. Overshoot your target "edge" by a fair bit and through-bolt with an iron angle on each side, on the baffle edge at least, though I'd recommend both sides. This will help keep the ply from becoming wavy along these edges and give you leverage. You'll need a form on both sides of the ply I think., but that will let you clamp across easily. I suspect you'll find at least some springback.

The good news with this approach is that it allows you to adjust for "didn't quite hit it exactly perfect" on the shape when you add the baffle, etc. You probably won't want to go with attaching the baffle the way you have it drawn up here either, though you could if you're into joinery that takes patience and custom fitting.

[WilZirkle]

Hank, I have to get a big round over bit for my sub still. I forget what Neo Dan uses for the easy button its like 1.5 or 1.25

Chris, I wondering about the springback, I watched a few videos awhile back and when they pulled stuff out of the form the shape stayed. As far as using a form I have't decided if I will make a full form and use it as a press or a half form and use a vacuum bag.
I will probably cut the back of the baffle on an angle that is close enough and use a large amount of gap filling glue.

Wil

[cjd]

I'd just straight-cut the baffle and biscuit it, but that's me. If you're a glutton for punishment, you could do hidden dovetails on the inside. That gives you good control over alignment every direction that matters. Make the baffle very slightly proud by design, soften the edges...

If you can go with the vacuum, that'll help a TON. That'd be on a full form not a skeleton, right? I'd just go halvsies that way, and there may not be springback with this approach. It usually happens if you work really close to minimum radius of the bending ply and don't do all the layers at once.

I'm probably going to be building a vacuum setup soon. Venturi setup - I have a pretty big air tank from when I raced (and thus did lots of maintenance on) my car, so I can probably do some pretty big bags too. Speaker-sized... Well, small-speakers, only 4 or so feet tall. The bigger ones, maybe not.

[WilZirkle]

Yeah full form for just bottom when forming instead of full form top and bottom as a press.

I haven't done any vacuum forming before but it seems straight forward. I have a gast vacuum pump that I used to use on my lathe to clean up the foot of a bowl. It draws a nice vacuum.

[WilZirkle]

orders have been placed!!!

Now I need to get back to building that sub woofer.

[WilZirkle]

The Kahncenter with the same treatment



I will build a stand for it that will hold it level (still working on the image). Right now i am thinking of having it directly over the tv to give it the infinite baffle required by the Kahncenter.

Ryan, I ordered all the parts using your write up, I hope I did the right thing and ordered two 7 and one 6 instead of the two 6 and one 7 that is in you BOM.

Wil

[WilZirkle]

I keep thinking it looks like a giant fish.

The design on the regular Kahn keeps me thinking of the calipers I used to use when turning.

Wil

[---k---]

Ryan, I ordered all the parts using your write up, I hope I did the right thing and ordered two 7 and one 6 instead of the two 6 and one 7 that is in you BOM.

Wil

Ha! That is funny. I can't believe I made that mistake. See, that is why I'm not in charge. I'm glad you caught it and got it right.

[WilZirkle]

Two of this four of that, I'm sure I messed up that order somewhere. Of course now that I teased you I will be real quiet when I find out my own.

Got the perfect lays from Madisound yesterday, that little box was so heavy I couldn't believe it. Everything else from Parts Express should be coming today. It will be awhile before I need the parts. I can't wait to see the dayton RS 6, 7, and 8 in the flesh, they look so nice in everyone's pictures.

Wil

[joeybutts]

I can't wait to see the dayton RS 6, 7, and 8 in the flesh, they look so nice in everyone's pictures.

Wil

They are that nice. No funny business with them now....

[WilZirkle]

LOL but they are so sexy, and until they are hooked up they can't complain...

[WilZirkle]

So long long ago...

I'm coming back around to this and finding I lost my sketchup for the Center. I don't know how upset about that I really am. I've started poking around with some of the new plugins, they have some great tools for bezier curves and joint pull push, that I didn't use the last time. I was able to create a mock up over lunch that would have taken me at least a day before. The point of this being that I think I want to tweak my curves a little from where I was before anyway.

In the previous incarnation the curves belonging to the Center and Mains were not the same. I had stuck to the exact height and width from Ryan's original designs while keeping the baffle and overall volume the same. Now I am thinking I would like to keep the curve universal between the two. Doing this will cause the depth of both to be the same.

So keeping the baffle width (height on center) the same as Ryan's design, I will need to pickup some width on the center to keep the volume as designed.

Ryan I know you stated that the depth could be lessened on the Center but by how much? What is the minimum volume and how will it affect the speaker? Will increasing the baffle length from 23.5" to say 29" on the center cause any problems? I know that the length is typically ok to mess with but my change seems like a lot.

Just my ramblings right now, but wanted to clear my head.

Wil

[joeybutts]

Will I replied to your email but it didn't go glad to see that this is going to be back in action!!


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[WilZirkle]

Thanks Joey, I'm glad to be back to it. Thanks for the tip about my email address too, you made me realize that my account on here was using an old one, so I updated it.

[WilZirkle]

I guess I should mention, this thread will be concluded in my new thread:

https://www.htguide.com/forum/showthread.php?41422-Curvy-Kahns-my-ambitious-Kahnspire-and-Kahncenter-build

I hope to post some design pictures this weekend as well as start on the ribs for my bending form.

[Finleyville]

If you're a glutton for punishment, you could do hidden dovetails on the inside.

One of the biggest understatements I have heard all year! Thanks cjd for the chuckle.

I am not saying it cannot be done. It definitely can. But that sounded so far above my skill level that I had to comment. Of course, sometimes adhering two pieces of wood with Velcro sometimes can be challenging for me! lol