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  #1  
Old 03-22-2011, 03:38 PM
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Altec MLTL with Model 19 drivers

This thread will document a large MLTL enclosure using the Altec 416-8b. The design of the cabinet was done by GM, an Altec user and installer with many years of experience in audio and a damn fine individual. The initial design considerations were discussed here on Todd White's Altec User Board. To summarize the goals: Raise the height of the woofer to accommodate my listening space and to improve upon the low position of the original Altec Model 19 alignment.

I will be using the Altec 811 horn and a Heil AMT1 tweeter on the top of the enclosure. The cabinet dimensions are 52 3/4" H x 30" W x 21" D, volume is 16 1/2 ft.^3.

Preliminary sketch using Google sketchup (without true scale, I'm not that good with the program, yet):



Note: At one time I bought six sheets of Birch plywood from my local lumber superstore. These turned out to be full of voids and the interior plies were probably not the same species. They were returned and 13 ply, 19mm Baltic Birch in 5' x5' sheets were purchased from my local hardwoods supplier.

I am about to start cutting and am sorting sheets. I'm going in.....
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Old 03-22-2011, 03:44 PM
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Ah, finally the Altec project cometh!

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Old 03-22-2011, 03:46 PM
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good on ya for getting the real deal, the Baltic Birch. It pretty amazing stuff most of it comes from Russia. In Canada all most all of it is imported through Thomes Canada and they have a great detailed explanation of how this stuff is made on their website. Pretty interesting read. They also specialize in importing Aircraft plywood and I've often wondered about using it for a set of enclosures. Too expensive though. Here's a link to the importer

http://www.thomescanada.com/

Those sheets are pretty heavy so don't strain yourself Eh!
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Old 03-22-2011, 04:07 PM
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Nice Lance. I'm excited for you to get this going.

Please don't bring back those ugly old fake Model 19 cabinets you took from me a while ago or I'll have to sick my wife on you.

Any thoughts on mounting the horn to a baffle to help dampen them?
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Old 03-22-2011, 04:28 PM
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Looks like your off to a good start Lance!

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Old 03-22-2011, 05:03 PM
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Looking forward to seeing this develop Lance. What are you using for the 811 driver? What crossover?
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  #7  
Old 03-22-2011, 07:10 PM
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Quote:
Originally Posted by ejfud View Post
Nice Lance. I'm excited for you to get this going.

Please don't bring back those ugly old fake Model 19 cabinets you took from me a while ago or I'll have to sick my wife on you.

Any thoughts on mounting the horn to a baffle to help dampen them?
Those cabinets went to another local AK'er that has more time and patience then myself. Please, don't let the wife at me!

Initial plans are an adjustable sled w/ mounting baffle. I found that I was not hearing any of the infamous ringing when the front flange of the horn is securely bolted to wood.

Quote:
Originally Posted by doucanoe View Post
Looks like your off to a good start Lance!

RC
Thanks Ron, at least it's a start.

Quote:
Originally Posted by djnagle View Post
Looking forward to seeing this develop Lance. What are you using for the 811 driver? What crossover?
I have been using 802-8g's with the original light aluminum 'phragms. I am already thinking about different hornage. I've been using active crossovers and don't know why I would change that, they just work so well.

Quote:
Originally Posted by shawnra View Post
good on ya for getting the real deal, the Baltic Birch. It pretty amazing stuff most of it comes from Russia. In Canada all most all of it is imported through Thomes Canada and they have a great detailed explanation of how this stuff is made on their website. Pretty interesting read. They also specialize in importing Aircraft plywood and I've often wondered about using it for a set of enclosures. Too expensive though. Here's a link to the importer

http://www.thomescanada.com/

Those sheets are pretty heavy so don't strain yourself Eh!
F*&k, I need a sheet crane, you're right they're heavy. The only way to deal with that is to start cutting!
These sheets would probably be a grade "B" according to the grading scale from Thomes. I do have access to some marine grade plywood but 1/2" dimension sheets 4' x 6', IIRC, are $110. They are made with phenoiic resin and are glassed on one surface. Heavy, straight, and expensive.
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Old 03-22-2011, 07:24 PM
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Great project!!! I love the great Heils. How are the diaphragms in yours? I have 5 pairs and when I hooked up a 4 a side array I found out that they were not all outputting the same SPL. What frequency are you crossing the Heils over at? I guess if it's high enough you wouldn't have to worry about any notching.

This makes me wonder if I should sub a Heil into my Valencias some time to hear what they sound like in there. I'm using 2404 Cheeks right now.

BTW what type of corner joint are you planning on using?

Cheers

Lar
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Last edited by diamondsouled; 03-22-2011 at 07:28 PM.
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  #9  
Old 03-22-2011, 08:21 PM
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Quote:
Originally Posted by diamondsouled View Post
Great project!!! I love the great Heils. How are the diaphragms in yours? I have 5 pairs and when I hooked up a 4 a side array I found out that they were not all outputting the same SPL. What frequency are you crossing the Heils over at? I guess if it's high enough you wouldn't have to worry about any notching.

This makes me wonder if I should sub a Heil into my Valencias some time to hear what they sound like in there. I'm using 2404 Cheeks right now.

BTW what type of corner joint are you planning on using?

Cheers

Lar
Hey, Lar. The Heil pair I have seem very well matched, I've never measured them (don't have the gear yet) but they always seemed balanced. I plan to cross them at about 9Khz or so.

I had pondered what kind of joinery I was going to use on these and expedience and practicality won the day. They will be butt-jointed with a ledger (gusset) in each corner. I have a lot of faith in Titebond III, I guess. Everything I've built using that adhesive is still together, including my sliding tool boxes in the truck which get a lot of abuse. I plan to embellish the exterior of the cabs when I have them all together. I have ideas, oh yeah.
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  #10  
Old 03-22-2011, 08:44 PM
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cutting tutorial

Thought I would show this since I read about some guys having difficulty with cutting panels and they shy away from speaker builds or use Home Depot's panel cutter and the results aren't always good.

Firstly, I have a good table saw, fence, and out feed tables, more than enough gear to cut these 5' x5" panels. I choose to cut them, however, using my trusty Makita 7 1/4" circular saw and a straight edge. Some folks will tell you that you can't get a good quality of cut with a circular saw and the pictures, here, should dispel that. I will be using the table saw when I have the panels cut to some smaller dimensions for good repeatability.

As said, Makita 7 1/4" 5007NB (been dropped and thrown around for many years and keeps ticking), Freud Diablo 7 1/4" 48 tooth finishing blade with a very small kerf (1/16" or so), E Emerson 8' clamping straightedge, metal rule.

After assessing the squareness of the panel, I mark my cut line, measure the distance of the saw blade tooth to the edge of the saw table (in this case it is close to 5 1/16" in.). The clamping straightedge is positioned back from the cut line the aforementioned dimension (5 1/16"). Adjust the saw until the blade will cut 1/16" deeper than the sheet. I use a piece of MDF under the sheet I'm cutting and it is a sacrificial table that is steady and doesn't impede the blade. Position the saw at the straightedge and push it down the sheet with the edge of the circular saw table against the straightedge. At about mid cut, I look to see if the cut is trying to close and, if so, throw a little wedge in there to keep the cut open. Take a look at the pictures and you'll see the results.

This is an easy way to get accurate cuts in sheet goods and saves some laborious lifting and setup with the table saw.
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  #11  
Old 03-22-2011, 09:09 PM
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Only way to break down a sheet of plywood in my eyes. A circular saw and a good straight edge. Beatuiful cut line. That Frued blade is great. I've used this technique for many years. The only thing that's changed is I was given an amazing Festool circular saw/guide rail setup that makes quick work of this job.

Keep the educational stuff coming Lance. I always learn from your techniques.
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Old 03-22-2011, 09:15 PM
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Quote:
Originally Posted by ejfud View Post
Only way to break down a sheet of plywood in my eyes. A circular saw and a good straight edge. Beatuiful cut line. That Frued blade is great. I've used this technique for many years. The only thing that's changed is I was given an amazing Festool circular saw/guide rail setup that makes quick work of this job.

Keep the educational stuff coming Lance. I always learn from your techniques.
Hey Gary, try a red diablo thin kerf wet lumber blade. They are like a lazer beam. I bought one for my skillsaw and now have them on the table and mitre saws. Frueds are good too though.

OOPS, just noticed the Diablo in the post above. Didn't know they were made by Frued.
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Last edited by jaymanaa; 03-22-2011 at 09:24 PM.
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  #13  
Old 03-22-2011, 09:25 PM
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Quote:
Originally Posted by jaymanaa View Post
Hey Gary, try a red diablo thin kerf wet lumber blade. They are like a lazer beam. I bought one for my skillsaw and now have them on the table and mitre saws. Frueds are good too though.

OOPS, just noticed the Diablo in the post above. Didn't know they were made by Frued.
I need a new blade for my table saw. I'll be heading to the home store this weekend. Thanks for the tip Jay.
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Old 03-22-2011, 09:30 PM
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Great project Lance, I'll be watching!

Would you mind pointing me to your BB source? I have a little project in the works......
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Old 03-22-2011, 10:12 PM
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Looks like another great project, if I keep reading these DIY threads I might get the urge to shitcan my speakers and amps just to have the fun of building something else again.

Saw something about horn damping, if your horns aren't exposed you might consider using Plasti Clay. I used on my 24" alum horns and on my Electro Voice tweeters and they are dead when you tap them, don't look so hot though.

I also thought about using a rubber strip product that's used for waterproofing around windows/doors after install before siding. Home Depot has it, about 6" wide made by Grace, sticky on one side( sticks like hell after putting down) thought it might be good to line interior cabinet surfaces(about 1/8" thick) and cut down panel resonances seems like it would cost alot less than some of the producs sold for that purpose.

Hope the panel wrestling match cut down went ok, once you get to the table saw the real fun begins.
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