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Author Topic: any experience building br-218's?  (Read 6092 times)

bryan holroyd

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any experience building br-218's?
« on: December 15, 2006, 09:42:24 am »

leaning towards these... not a real fan of horn loaded subs so i've been selling off my eaw la400's to replace with this combination: 18 sound 18" (18lw1400?) and the br-218 classic type front loaded enclosure.

i've seen drawings and spec from various websites but i had a few other questions... (having never built our own cab's before...)

1. if the design is for two individually ported enclosures in one unit, is it ok to simply split the design in half to create a few single 18" units? (or vice versa)

2. i want a good wood, atleast 11 ply. where can i find that (in southern NJ)

3. is stapled and glued strong enough construction?

4. can i use regular store bought pvc to make the porting? will it change the port characteristics vs. cardboard tube?

5. if i wanted to make these for a smaller truck pack (i.e. 90" width instead of 96") does the math work if i just extend the rear of the cabinet a little deeper (based on how much volume i reduce by shrinking the width?)
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bryan holroyd

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Re: any experience building br-218's?
« Reply #1 on: December 15, 2006, 09:46:46 am »

our other option is to use flat porting which would be much easier i think.
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Tony "T" Tissot

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Re: any experience building br-218's?
« Reply #2 on: December 15, 2006, 01:48:31 pm »

Just a few comments on construction for cabinets:

18MM void-free plywood (3/4" rough equivalent) as a minimum for subs.  11 mm will probably resonate, unless ultra-engineered.

Home Depot sometimes has near-void-free birch faced stuff.. You'll have to judge if that is acceptable (has been for me). Specialty wood guys can get it easily. It is expensive.

They should be built like a tank and absolutely rigid.

For construction, top of the line glue, counter sunk screws and battens in addition + reinforcement pieces to add stiffness.

Staples will not serve you long-term.

Commercially available ports are actually quite cheap - although for your subs - you may find that just cutting them in the face - without the tubes - may be sufficient to tune properly.

Eminence and Selenium have design specs available free for single 18 subs.


Duatex, Duratex, Duratex to finish professionally - unless you want to take them to a LINEX shop.

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MNGS
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bryan holroyd

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Re: any experience building br-218's?
« Reply #3 on: December 18, 2006, 09:43:53 am »

i hear ya on the duratex.

as far as single vs. double i want a few singles in stock for sidefill/ drum fill purposes but otherwise we are looking at mostly double 18"s for FOH. atleast 6 double, 4 single. figure that'll be a good starting point. i'll take a peek at home depot for the wood. so you figure 3/8 crown staples won't hold up? i'll admit to having issues with them in the past but i figured it was from a bad glue set or something... most repairs i've made to my cases have held for years... not that it really matters, i'm just not a fan of screws for various reasons but i'll use them if necessary
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peter.golde

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Re: any experience building br-218's?
« Reply #4 on: December 18, 2006, 12:30:11 pm »

I have never heard of staples failing, in fact quite the opposite. If your glue joints are put together tight, you should not have a problem. I would rather have a staple than a screw which could potentially back out. Either way, the fasteners are there to hold the wood while the glue sets, assuming the wood is properly fit.
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Elliot Thompson

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Re: any experience building br-218's?
« Reply #5 on: December 18, 2006, 03:34:58 pm »

Hello Bryan.

As with builders, materials will vary.

When I built my Double Eighteens (Can't believe it was 11 years ago) I used one tube of GE Silicone and one box of drywall screws per cabinet.

I do have some older cabinets that are stapled and glued they hold up just fine.

Best Regards,  



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Elliot

Tony "T" Tissot

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Re: any experience building br-218's?
« Reply #6 on: December 18, 2006, 04:03:46 pm »

Yes - staples will hold if properly glued (especially with battens).

Screws give me the added benfit of a full "dry-assembly" of everything for fit
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Duane Massey

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Re: any experience building br-218's?
« Reply #7 on: December 18, 2006, 05:13:21 pm »

Everything we build uses screws and glue. Use a carpenter's glue (yellow stuff) rather than the cheaper general-purpose (white) stuff. The glue is what holds everything together, but screws properly installed will clamp everything tighter than staples or nails. If you do use staples, clamp the wood together until the glue dries, as staples will allow the joints to "flex" a bit if you move the cabinets around before the glue sets up.

Definitely second the Duratex. We've tried several different coatings over the past 15 years, and it's the best all-around coating so far, especially for small production runs. Not as durable as a "bed-liner" coating, but the lack of fumes coupled with an easy clean-up and the ease of getting a consistent finish make it a great choice.
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Antone Atmarama Bajor

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Re: any experience building br-218's?
« Reply #8 on: December 18, 2006, 06:38:57 pm »

      Another option I've used with Screws but I'm sure staple/nail guns should work fine. (I've never used "staples")  Just pneumatic finishing nails.

    If you use wood flooring adhesive (very messy) you can still torsion things for a while if you didn't get it quite right.  The one thing that sucks about the flooring adhesive is it ruins your sanding heads pretty quick.  But So does filler like bondo.

    You will for any cabinet project need lots of good large clamps.  Pipe Clamps, and quick release types.  Clamp till glue sets.

Duratex has been pretty good though they recommended 3 coats I did mine with a texture roller.  3 coats seems a little thin.
Though I've heard you can get really great results with a hopper gun.

    I'm not sure why you want to get rid of the LA400's for a direct radiator?  Are you doing smaller venues where audience is closer to the drivers.

    You should see if you can do a side by side comparison of the LA400's with a dual 18cab.  You are going to loose a lot of headroom and eat a lot more power,  The Dual 18 isn't likely to give you much more low extension unless the box is quite large.

    To bad EAW doesn't post half space charts of the LA's I'd like to see its response.

    Good Luck

Antone-
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bryan holroyd

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Re: any experience building br-218's?
« Reply #9 on: December 19, 2006, 10:48:44 am »

the la400's don't couple well past 3 or 4 per side. we are doing larger events up to about 5000 folks so the la's aren't nearly enough. they are awesome sounding horns, don't get me wrong. i can just sell them and easily upgrade to dual 18's with cash left over. (by the way i only have 2 left if anyone is looking) plus with the 18's i get more pop instead of wump. although both are desired, a little processing and i'll be set.

i have a full function woodshop, and have made many cases etc. before, just never used it to do a production run of cabinets. that's why the screws comment set off a few questions, i love using wood glue and crown staples. yeah it takes a little more time and work, but you get smooth lines and a great bond. rarely do any staples back out, and i don't have to worry about stripped threads or anything when repairs may be needed... thanks

edit: as far as the side by side, i have done it. we do mostly outdoor camping/ music festivals and what not, with the opccasional indoor concert thrown in for good measure. i had one where the client grossly underestimated his attendance, and with only 2 850 tops and 2 la400 bottoms per side it wasn't nearly enough low end. (the tops covered well, but we threw up another on top for the long throw.) the client had 2 sb 1000's nearby (it was a theme park) so we added 1 per side on a 5k... the difference was night and day. but together was something else. since i had the subs on an aux i sent that back into the console and ran a split matrix. one send for the horns, another for the 1000's. combining the two was amazing. i had the punch and pop of the dual 18's, plus the warmth of the horns.

i'm just more a fan of the dual 18's in large format situations.
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