Enclosure walls construction for 3012LF Neo

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I am building a 2.8 cu ft gross, bass cabinet for the 3012LF Neo woofer. It will be slot ported, or I can use a 6" vent. The inner dimensions are 12"x19"x23"
I do not have access to Baltic Birch ply. And could not afford it, with cabinets this large, considering I would have to laminate 1/2" sheets together.

So I can use 3/4" MDF, laminated to 1/4" hard board. Or I can double up the 3/4" MDF for 1.5" thick material. What are your suggestions, for enclosure material for these? Thanks
 
frugal-phile™
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Woofers in particular want stiff boxes… something MDF is not good at.

The plywood we use is manufactured closer to you than us… Murphy Ply in Eugene or Sutherline Oregon. Well braced 18mm should do the job. Murphy Plywood: Hardwood, Softwood & Engineered panels | Murphy Company

If you use 2 tightly coupled smaller woofers push-push you can get away with less since active force cancelation dramatically reduces box loads. The difference is not subtle.

dave
 
frugal-phile™
Joined 2001
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Your braces in that box are running the wrong way. Heavy is actually a detriment, unless it brings extra stiffness to the build.

email Murphy, and see who sells it in your area. Or if they’ll ship you some if it isn’t.

I fully expect, from personal experience, that the box in my 2 x 10” push-push woofers built with 15mm BB (cheap grade) will outperform your box in ¾” MDF + extra layer — even if you concrete it… brute force vrs clever design.

Note: it will be marketed as ¾” in the USA but quality plywood is almost always metric. The Murphy ply is 18mm + the 2 maple veneer layers they add.

dave
 
For relativly "thin" wall construction:

1/4 in. x 48 in. Wood Round Dowel-HDDH1448 - The Home Depot

1/4" dowels irregularly (semi "random" placement on boards to supress modes) connected to interior opossing walls (with wood screws from outside of cabinet) of:

Underlayment (Common: 7/32 in. x 4 ft. x 8 ft.; Actual: 0.196 in. x 48 in. x 96 in.)-431178 - The Home Depot

1/4" cheap plywood wraped with:

27 in. x 8 ft. Steel Lath-2.5 METAL LATH - The Home Depot

metal lath w/ several coats of:

Rapid Set 25 lb. Stucco Patch-71020025 - The Home Depot

Stucco.

(you will need to build a wood frame to screw the panels onto.)

Waddell 1/2 in. x 36 in. American Basswood Square Dowel-8308U - The Home Depot
 
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_At HomeDepot, a 4x8 sheet of 0.75" cabinet grade Birch plywood is $53 -$72, based upon manufacturer.
_Even generic Birch plywood is a much better cabinet material than MDF.
_Select cabinet dimensions which fit one 48" x 96" sheet. You may need to glue together the bracing from separate boards.
_If you woodscrew one or two 4" ABS plastic pipe ports to the baffle, it will be easy to remove and change port length if you change rooms.
_One horizontal "window frame" brace, plus one vertical narrow interlocking brace should be adequate.

You can find several clever cabinet construction threads for "light-woofers" like the 3012LF. For bracing, low cost plywood or pine strips are adequate.
 

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@ LineSource ... That is more like what I was planning. I have used the void free cabinet grade before. While not BB, I can't imagine it not being enough with a "light" woofer. And you nailed it too ... I've built tons of subwoofers. This is my first experience using what you refer to as a "light" woofer.

I know I can build a dead. heavy cabinet. Done it many times. But wasn't sure if this type of cabinet/woofer combo called for that really. And I'm not at all opposed to getting a separate 1/4" sheet of hardboard, or cab grade ply, if they have it that thin, and making a 1" thick cabinet, IF it would help. I will buy a half sheet for making braces.
 
Huh? thin wall. I apologize. My explaining skills couldn't be much worse. This thread is sooo far away from what I was thinking.
I'm sure I will be okay.

It's that: "each to their own". ;)

A thin wall constuction can have it's modes more easily suppressed with the right kind of spot-bracing.

On top of that (literally),

I like a heavy rigid well-sealed enclosure to spress sound transmission THROUGH the cabinet walls.

Finally, I like a very rigid interface between driver and baffle. (..and cementious stucco does that in addition to blocking sound transmission.)


-ideally I'd prefer a sand-damped box, but that's not very "thin" (and it's a lot more complex). What I described you can achieve well with something slightly less than an inch thick. ;)


Both are heavy.. heavy is GOOD! :D
 
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If you have extra "cheap" 0.75" plywood around, you could construct a second outside front baffle from the expensive plywood, and use the cheaper plywood for the rear panel. This extra thick front baffle will allow you to counter-sink the woofer into the front baffle without any loss in strength. Extra 0.75" plywood would also allow you to easily cut a clever set of horizontal and vertical braces(like 4-pane window brace, or multi-hole X-Y matrix braces)

PORTS: simulation of 44Hz Qtc=0.7 tuning shows:
_one 4" diameter "flat edges" port is 4" long
_two 4" diameter "flat edges" ports are each 11" long
_one 6" diameter "flat edges" port is 11.3" long

SO, a screw-in interchangable port pipe would allow you to experiment with "bass shelf" tuning like 40Hz:
_one 4" diameter "flat edges" port is 5.5" long
_two 4" diameter "flat edges" ports are each 14" long
_one 6" diameter "flat edges" port is 14.6" long

The port length is measured from the front-edge of the front baffle.
 
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.
 
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Thank you, LineSource! The screw in port baffle section is GOLDEN in my particular application. My listening area is SOOOOOOO odd, no really! LOL
This allows me to fine tune before the DSP takes over. I love it.

Is there a way to cover a port, without affecting it's performance? Like, super flowing grill cloth, or similar? I hate round holes staring at me. :eek::eek:
 
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.

2.8 cubes is not a large cabinet.

IMO, stiffness is more important than mass. Your cabinet will probably be 50-80 lb anyway. Dado in some 2" long (deep) ribs every 4" or so along the length of any panel. No need to double up the baffle or treat the corners specially. You can tie opposite panels together if you like.

Try it with cheap ply just for the fun of it...you might be surprised how stiff it is.
 
Thanks everyone. I have been able to gain the answers I was seeking.I am going to use the cabinet grade 18mm void free ply we have locally. I will brace it very, very well. I will make the baffle doubled.

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.

What does having a narrow baffle, say maybe only an inch wider than they each are, do to the sound coming your way? Does it have ANY drawbacks?
 
-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.

Ex. for a long AMT tweeter think cylinder in shape with a bit of rounding at the top and bottom.
 
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