Enclosure walls construction for 3012LF Neo

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I have another question or two now... What happens if you are using a mid and tweeter which do not really need any rear cabinet, volume at all. This would allow a person to make a flat baffle extending above the woofer cabinet, for the mid and tweeter to mount on. Ala, no cabinet for the mids and highs.
Yet NOT a dipole at all. Both mid and tweeter have sealed rears.
You mean they are in very small cabinets?
 
frugal-phile™
Joined 2001
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-generally you want to keep the baffle as small as possible while also keeping diffraction as low as possible.

In essence you want nice rounded "edges" - particularly with respect to horizontal baffle edges.

How high in frequency are these intended to go… even if you stretch these up to the limits of their axial response ( alot less if you ar epaying attention to polar response), you’d need a 4” or so round over for any significant effect.

dave
 
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[/url]NaO_Note by Cullen Graham, on Flickr[/IMG]Here is something KIND OF what I'm referring to. Try and imagine everything from the white line down, being the woofer cabinet. And everything in the white being the single mid, and tweeter in my application. But with the mid and tweeter being sealed in the rear.

What does a baffle like that do ?
 
Adding a bit of info here ... I have been on the phone or email for two days now. Unless I am buying a pallet, getting ANY sheets of 18mm BB being shipped in, will cost me a fortune. I would be over $600 in plywood alone. NOPE. The drivers in this build total $500. ALL I have available is 5'x5' sheets of the 11mm available at $60 per sheet. Just no.

As far as standard construction, I always make the baffle thicker, and route out for air flow. Use wood glue and TONS of clamps, etc. Constructing the enclosure properly. Bracing it properly, etc, was not really my concern. It was material choices I have available, and possible alternate construction techniques (laminating, concrete lining, etc) , which I was kind of asking about.

My ONLY questions stem from having not built an enclosure this large, since the mid 90s. And having never built an enclosure for THIS exact type of driver before.

Hi Flaxxer, sorry to hear your problems obtaining BB.
I found the same trouble until I visited cabinet supply warehouses in person, .......which exist anywhere folks are having cabinets made, which is almost everywhere;)
I'm thinking that anywhere pricing in the US, picked up, at a cabinet supply house is ... 5x5 15mm under $40, 18mm under $50...and those are pretty high prices I think...

All you have to do is say you're building speakers....warehouse salesmen are inevitably bored, but wishful wanna build something dudes !!! I've been given a tour of the warehouse so many times it rocks !
 
This is what I was trying to ask about !

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[/url]Untitledaa by Cullen Graham, on Flickr[/IMG]

Because my midrange drivers only need .03 cu ft, and my tweeters are sealed cup backed, I can technically do a design like the above.... with the baffle sticking up above the bass enclosure. Are there advantages or disadvantages to doing this, when NOT going dipole ?

Or I can just build a traditional mid cab above and fill the HUGE void behind the driver backs with sand.
 
I have been making a laaaaaaaaht of sawdust. I'm about ready to close the enclosure up, and need to know this … John Busch, you out there ? LOL

This is a heavily braced, ported enclosure of 3 sq ft., for 300hz to 36hz. Should I line 3 walls with the 2.5" denim batts, or leave them bare?


Build thread coming soon!
 
Flaxxer.... Sorry that I have not been monitoring this thread... too much on my plate lately.... As a general rule, on ported enclosures intended for Hi-Fi applications, I keep internal stuffing (volume) to a minimum.... An inch or so thick on the wall directly behind the woofer, (bottom 2/3rds of the rear wall), same thing on the baffle face above the woofer in front of the rear port opening, the enclosure bottom and most of one side. What I am trying to do is minimize internal mid range reflections produced by the rear of the woofer cone and keep them from radiating out the rear port. Part of that strategy is getting the port as far away from the woofer as possible, and of course, having the port exit the rear of the enclosure. And, with the lining only being about an inch thick, it takes up a minimum amount of internal volume. If possible, you don't want any parallel surfaces inside the box naked... However, too much fill can restrict air movement in and out of the port as well as change the box tuning frequency. So as usual it's and engineering balance...
 
Thank you, John. Same thing I always do for ported enclosures. I knew you had enough time with this woofer, to have already figured out what it likes, and doesn't like.

Thank you again for your original recommendation on the Kappalite. I'm building a closure to do it justice! I will link the build thread here, later today.
 
Just a mention of my preferred format for enclosure panels. In the last decade I have built nearly 20 pairs of speakers, and because I place a high priority on non-resonant enclosures, my enclosures have increasingly concentrated on extensive bracing, constrained layer damping, cast resin baffles etc. I have not used BB since it is hard to find where I am at any reasonable cost. I have discovered two facts that serve me well. My main enclosure material is mdf, which is widely available. I have found that glueing two 12mm sheets with pva results in a much stiffer panel than a single 25mm panel of the same dimensions. I invite others to glue up a test panel and compare with an identical size 25mm panel. Hang them by a corner and hit them like a gong. The resulting note is very informative. Stiffer makes a higher tone. When you drill into the glued panel, you can feel the drill bit struggling through the interface. The skin of mdf is stiffer than the core, so the glued panel has a stiffer central core. Secondly, in the past I have laminated 5mm hardboard (masonite or similar) to the back panel of mdf, principally because it provides a nice surface for painting, usually satin black, when the sides and front may be veneered or have a superior cosmetic coating. To my surprise, the back panel results in the best sounding, well damped surface of the entire box. This has lead to my preferred format of, glued 12 mm mdf, laminated with 5mm hardboard. The bonus is that the hardboard is a nice smooth surface to paint. The downside is the extra time and labour in the glueing and trimming. A tip is to use a standard pva for the laminating since it spreads more easily. The expensive brands are designed to be less runny which is a nuisance for large coverage.
My preferred jointing technique is rebates which allows the box to be assembled "dry" to check the fit. When glued up the enclosures have a lovely "pock" instead of "bonk". The interior walls are damped with sound deadening material.
 

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I thank everyone for their input. I have already designed and built my bass bins. I will be posting a build thread later today. My only question above, was about lining three of the walls. Just didn't want anyone to think I was still looking at construction techniques.
 
frugal-phile™
Joined 2001
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… glueing two 12mm sheets with pva results in a much stiffer panel than a single 25mm panel of the same dimensions...

One of the guys i learned a lot from went further, laminating 7 think layers of MDF into a panel (something like 20mm) for a much stiffer panel — one could call it mdf based plywood. Having a 10-ton press helped a lot in that process.

dave
 
A couple of months ago, I wrote that I could not easily afford Baltic Birch plywood locally, I went ahead and accepted the extra build time in order to use it. My side walls are 1" thick. My front, back, top and bottom panels are 1.5" thick. Braced across all directions. It will be stiff enough I think. I only need two more sheets of it to finish. Another $80 in lumber.

Having played around the garage, and testing a bit, leads me to believe the very best way for stiffness, without comprise is an enclosure within a larger sand filled enclosure. NOTHING escapes the walls, if the sand is 3/4" thick. The next best for me is void free birch lined all walls internally with 1/4" Hardi concrete board glued in tightly, with all seams filled with rock hard putty. This is just non flex dead. But you can still hear music playing through the walls just slightly. Both of these are VERY labor intensive !!! I would not even build the Hardi ones again, unless it was for my own reference level drivers in a build, or someone was paying me to do so.
 
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