Cast aluminum 808 multicellular horn.

Tsingtao_1903

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In the early 50's, Altec produced aluminum 808 horns that were casted in two pieces and bolted together.


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After only a few years, Altec went with an one-piece design. Upon closer inspection, the one-piece design appeared to be two halves welded together.
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After the "success" of the cast WP12027 project, I decided take a deep dive on designing a cast aluminum 808. From a casting perspective, the 808 was much more technically challenging. Casting requires certain minimum wall thicknesses, features and draft angles. After weeks of modeling efforts and a couple dozen models later - Voila.

Two pieces with tabs. Bolted together to form the final assembly.
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Two pieces. No tabs. Welded together to form the final assembly.
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The biggest drawback of the two piece with tabs design is the roundness of the throat. It's very difficult to maintain perfect roundness and concentricity where the two halves are machined with manufacturing variations/tolerances and then come together. Can pair up two halves, machined and maintain the pairing - not easy to do in practice. (I prefer the bolted together design. It looks so archaic and cool.:smoke) For the single piece design where the two halves are welded together, the throat roundness can be maintained by boring it out to dimension after welding.

Anyway, which of the two designs do you guys prefer?
 
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Yeah. bolt together is cool. But I gotta wonder about vibration resonances (if that's the correct terminology).
How large is it?
It's a concern. The horn has several features to minimize vibration resonances. The two mating surfaces will be machined flat and are co-planar to tight tolerances. The compression forces from the 4 bolts should hold the two halves together tightly. The cell walls have a minimum thickness of 4.5mm and angled out up to around 7mm for draft. The cell walls are also convex - that is to say each cell is massive and rigid. The complete horn will be around 6kgs. If all of that is not sufficient, one can always apply appropriate metal adhesive between the two halves, then, bolt them together. (Highly recommended).

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Size-wise, the horn is about 17" x 9" and 11.5" deep.
 
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Very impressive work. Are you thinking of having some of the 808s cast into working horns? Given the going rate for the vintage Altec made 808s, you could pretty much name your price and there is a small market. I'm sure there are a handful of us crazy Altec guys that would pony up for a set.
 
Very impressive work. Are you thinking of having some of the 808s cast into working horns? Given the going rate for the vintage Altec made 808s, you could pretty much name your price and there is a small market. I'm sure there are a handful of us crazy Altec guys that would pony up for a set.
I want to.... Reality is the market for modern interpretations of classic and beloved horns is teeny tiny. I am still an absolute unknown outside of the Haven. Coupled with the fact that costs for everything went up significantly post-Covid. Looking at around $900-$1000 a pair just to break even.

For the cast 808 horn, will need 4-5 brave souls to sign up just to get it started. The good news is the foundry had reviewed the design and deemed it manufacturable!
 
No need. No cash until you get the horns in your hands.

Thanks. Since you are number one, you get to pick the color for the lot: black or light grey?
Oh boy - let me sleep on that one. I have a pair of 808-8a's that have been waiting for horns like these.
 
Put me down for the number two pair if you go ahead and make some. It's such an Iconic horn design (pun intended). I would also be willing to front some money as I know molds would have to be made.

Exciting project!
 
Put me down for the number two pair if you go ahead and make some. It's such an Iconic horn design (pun intended). I would also be willing to front some money as I know molds would have to be made.

Exciting project!
Thanks. You are number two. No need for money until the horns are ready to go. You guys are willing to take a risk with me; I am willing to take the risk to get the project through the prototypes stage.

Will finalize the model and associated drawings to send to the foundry this week.
 
Thanks for the support guys. I will be stopping at number four. The four early adapters will also be receiving a pdf of the drawing showing the engineering notes to the foundry the specific requirements for the horn. My way of saying thanks.
 
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