1803B horn plans available?

[Audiomind]

Hi There,

1803 guy here.

Just to answer a couple of things. First, all cells in the 1803B are identical. It's their configuration that makes them seem different. Second, as already mentioned, the 1803 is massive even in comparison with the 1505. The 1505 is probably better for home use but if you really want to be crazy, I'll see if I can find a way to measure the 1803's so you can do a take off. This will not be easy as they are hanging in the speaker room so if you say yes Audiomind, I want you to promise you will build them. I would love to see another build thread. The Petter Persson thread over at diyAudio was absolutely fascinating. His method of using rings that he slid down the horns to act as clamps was a stroke of genius. The finite detailing at the throat must have taken an incredible amount of patience. That was true craftsmanship. My hat was off to him.

My idea would be to make a pattern of one cell cutting out some sort of separate thin cardboard for each side of th inside walls. (maybe something like the large white foam sandwich pieces you can get at a craft store that go behind picture frames).

But the real challenge is the throat. I am sure there is an easy way to make a copy with some sort of casting materials that could be put inside.

Unless the guy on ebay will come down to $2500 from $7000 I am building them myself so that is a guarantee, they will be built, they already have a loving home.

[alancohen]

Just to answer a couple of things. First, all cells in the 1803B are identical. It's their configuration that makes them seem different. ...
...
The Petter Persson thread over at diyAudio was absolutely fascinating. His method of using rings that he slid down the horns to act as clamps was a stroke of genius. The finite detailing at the throat must have taken an incredible amount of patience. That was true craftsmanship. My hat was off to him.

S'up Cal . That's some juicy information that the cells are all identical. I would think from a prudent manufacturing perspective that that should be the case. If I had a dollar to bet, I would wager all the **03 cells are the same regardless of how many. Same with the **05s etc. They just add more.

Also, given the entry points are square as are the terminal openings, I'd bet another dollar that all cell walls are the same, meaning one template of the curve and length, along with the ID of both ends would be all that's required to build all the cells.

Like Audiomind mentions, the throats are a different matter and would need to be modeled.

It's a shame that the pics of Petter's build are not hosted any longer. I tried to PM him through DIY to see if he still might have them saved locally, but his mailbox is full and not accepting any more mesages.

[Cal Weldon]

Hey Alan,

You are correct in all points about the horn cells so all you have to do is get one side right.

We're not sure why Petters photos disappeared but I have left a note in that thread for him to maybe do something with his mailbox. I notice he was active as of a couple days ago so hopefully he will look in. I am highly reluctant to use my mod powers to attain his email address so let's just leave it where it is for the moment.

Audiomind, I agree using the foam core from your local dollar store is the way to go at least to start. We have been having a tom of fun experimenting with the Cornu style cabinets. Without the foam, those would be beyond many of our means. So what's it going to be, the 1803? I can give you all the dimensions of the waveguide as well if need be.

[Cal Weldon]

Let me rethink this. If you made all 4 sides the same you would need 45? mitres. That might be hard to do even with the clamping rings. You might want to go with a top and bottom that overlap the sides for ease of cutting and assembly. Either way, that doesn't change the actual measurements.

[bowtie427ss]

Let me rethink this. If you made all 4 sides the same you would need 45? mitres. That might be hard to do even with the clamping rings. You might want to go with a top and bottom that overlap the sides for ease of cutting and assembly. Either way, that doesn't change the actual measurements.

Exactly!

[Altec Best]

All cells are identical,just different lengths(805-803,etc..) ... If you make a jig for constructing one cell you will be good to go. Look at this photo you can see all the cells stacked on top of each other on the table.And what looks like a jig at the end of table.For sheet metal though.You can also see all the soldering irons at the end of table as well.

Click on the photo it is expandable.

LANSING MANUFACTURING

[alancohen]

Let me rethink this. If you made all 4 sides the same you would need 45? mitres. That might be hard to do even with the clamping rings. You might want to go with a top and bottom that overlap the sides for ease of cutting and assembly. Either way, that doesn't change the actual measurements.

Ah, good catch. I was planning on doing 45* miters. Either way, I probably wouldn't be using clamping rings. I would build a jig with outside formers that everything would squeeze into. Basically a big mold/clamp. The downside is I would only be able to glue up one at a time.



And considering all the shapes and bends of various Altec throat assemblies, it doesn't appear a perfectly direct soundwave path is mission critical:

http://altecpro.com/pdfs/vintage/Spe...ar%20Horns.pdf

[Cal Weldon]

All cells are identical,just different lengths(805-803,etc..)

Is that true? The only measuring thing I have with me at the moment is in cm and the mouth opening of the 1803 cell is 20.5 cm or about 8 inches. Does anyone have another horn they could check?

I like the chart on page 2 that shows you just how big the darn things are.

[Cal Weldon]

I will take many photos as well if I am doing the take off. I will email those directly as I can't post them all here.

[bowtie427ss]

IMO, an important detail to keep in mind is the thickness of the cell walls where the cells will come together at their throats. Ideally, each cell will need to be carefully sanded at the throat end to a thickness as close as possible to the thickness of the tin. The better sounding multicells i've heard(and i've only heard a few) had been carefully hand sanded to a nearly knife edge at the throat junction such that there's no surface left to reflect energy back toward the driver.