Altec DIY Build Finally Done

Howdy folks. Wanted to post a pic of the Altec DIY build I've been working on for the last year since first acquiring a pair of 416-8Bs. I had initially planned on building the Hiraga Onken 360s but decided in the end that a slightly beefed up 620A cabinet would work best in my space.

Some of you may remember when I posted asking for crossover advice but the idea was to have an interchangeable front baffle in case I ever wanted to try different drivers (Tannoys, 604s, JBLs) and I also wanted to be able to swap horns and compression drivers up top. I liked the design and look of the Model 17 and the 620A cabinets but decided to go 2" deeper and 2" wider to gain a little more volume which ended up being about 10 cubic feet.

I'm lucky enough to have a friend who is an amazing speaker builder and woodworker who mentored me along the way and helped with certain elements of my build.

We bought some of the last Baltic Birch we could get our hands on and after some woofer sweeps, lots of back and forth, some drawing and some more drawing in Sketchup, we got to work.

Due to my work schedule, I could only attack this project whenever I had spare time which is why it ended up taking a year. In the long run, I'm glad I didn't rush the build (as much as I may have wanted to at times).

Needless to say, I'm very happy with how they've turned out though I haven't quite had as much time as I'd like to just listen and enjoy them. I know that will come and they do sound excellent. Will try to post some more pics and info soon but just wanted to share this pic we took before they left the shop last week.



PS More images on IG here if you want to check it out.
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Versatile setup. How are you porting the cabinet? Have you made arrangements for easy crossover changes?
Versatile setup. How are you porting the cabinet? Have you made arrangements for easy crossover changes?
We went with a rear port near the bottom. It's 4" on the inside flared to 5" on the outside using 3/4" Baltic Birch. The upper 3/4 are lined with a firm 1" wool felt and the bottom has 1 bag of Polyfill. Tuning frequency is 28.25Hz.

The crossover is the Heathkit AS-101 800Hz (thanks, Adam Guy) mounted externally above the cabinet crossing to Altec 808-8A drivers and 511B horns with Belden 9497.

The original plan was to use JBL 2446h drivers with 2380A horns which I still have but these horns came with my drivers. I painted the drivers with a couple light quotes of Duplicolor bed liner and hit the horns with a couple quick coats of Rustoleum Painter's Touch 2 in 1 paint and primer.

I also have a MiniDSP 2x4 but haven't used it yet.

Here are a couple more pics from the woodshop showing the port and a couple pics of the XO20231005_145019.jpg20231004_132248.jpg20231007_095530.jpg20231007_095511.jpg20231007_095457.jpg
Nice work.
More cabinet details for us curious folks please 😏
Thank you. The cabinets are 40" H x 26W x 20D with an internal volume of around 10³. They measure 51H with the 511s.

The entire box is 3/4" Baltic Birch which is doubled up at the base and mitered in the top front corners. This required some careful work with a chisel, a Japanese handsaw and a hand planer but was definitely worth it aesthetically and to me, gives the cabinets more of a furniture grade look and feel.

The baffle is doubled up 1" MDF and the internal bracing is also 1"MDF. There are 4 braces in each cabinet which alternate between window frame style and randomized circles which were cut using a jig saw and a hole saw respectively and then routered smooth and hand sanded.

Each cab is finished with 5 coats of Eagle Brand water based polyurethane and the baffles (which were a bit of a nightmare to finish) eventually ended up being roller finished with Bear brand white paint and primer. I also individually painted each screw white as I didn't want to have black screws in a white baffle.

The speaker terminal is also routered to be flush mounted and both they and the terminals themselves are from Dayton Audio.

I should also say that I owe a huge debt of gratitude to my buddy Raf_Hifi who helped immensely with patient guidance in all aspects of this build, particularly in the woodshop. My skills were ok going in but thanks to him, were much stronger coming out.

Here's a couple more build pics of Raf and I in the shop working on some of those elements. I would have posted more originally but was pretty wiped when I posted this so kept it short and sweet.


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Beautiful work!!! Do you find you need a tweeter?
Thanks so much. Honestly, no. I have heard Altecs and JBLs with well implemented super tweeters and have a pair of JBL 2405s ready to go but I just don't really feel the need as this seems to be hitting the right notes as a two way. I will likely give it a go at some point because... ADHD but for now, I think I'm just going to enjoy these as they are.