1803B horn plans available?

**alancohen** · February 1st, 2013, 12:57 PM

Originally Posted by Cal Weldon

Just had a nice long chat with Audiomind. Sounds like the project is a go. Can't wait to see pics of the progress. I'll have to go home now to see if I have some inside callipers to measure the inside of the waveguide.

Speaking of "inside the waveguide", if I make a multicell horn I'll be using my 802G drivers. I assume all Altec multicells were made for large format CDs. How does this affect me?

**Cal Weldon** · February 1st, 2013, 01:26 PM

Someone recently discussed this and I thought they had mentioned the 800 series horns but all I can find is adapters to take it down to 1"

**Audiomind** · February 1st, 2013, 01:28 PM

Originally Posted by alancohen

Speaking of "inside the waveguide", if I make a multicell horn I'll be using my 802G drivers. I assume all Altec multicells were made for large format CDs. How does this affect me?

I think it might be easier and maybe more helpful down the line to make or buy some the 30166 waveguide adapters and keep them stock with a 1.4" throat and then just use a 1" to 1.4" metal adapter.

You might want 288's with tangerine phase plugs down the line as they can get up there and you might be able to squeak by without a super tweeter so I personally would not limit myself by making a 1" only waveguide.

Hope this helps.

**Cal Weldon** · February 1st, 2013, 01:37 PM

Aha! The 808 is a 1" horn, but indeed a rare bird. It is a cast multicell. Yes, you read that right.

Vintage Altec Lansing 8 Cell Cast Aluminum 808H Horn H 808 Western Electric RARE | eBay

**martyh45** · February 1st, 2013, 04:10 PM

Originally Posted by Audiomind

Yes, it would make the angle fine if you were using individual metal cells but with wood construction the much less time consuming and better way to make thicker walls is to have to large curved wood plates and add the airplane wing shaped dividers on top of these plates.

You may find that the shape of those dividers is too complex to fabricate from a single block of wood with any degree of accuracy. unless you have access to a CNC router and can calculate then program the piece you will probably want to stick to the single cell construction method others have used in the past.

Cal, I tried plotting the curves you posted and can't get them to work. Have you tried measuring a radius from the outside of the horn?

**alancohen** · February 1st, 2013, 04:38 PM

Originally Posted by martyh45

You may find that the shape of those dividers is too complex to fabricate from a single block of wood with any degree of accuracy. unless you have access to a CNC router and can calculate then program the piece you will probably want to stick to the single cell construction method others have used in the past.

Cal, I tried plotting the curves you posted and can't get them to work. Have you tried measuring a radius from the outside of the horn?

The numbers worked for me, Marty. You just need to take into account that the lateral measurements are the entire cross section. You need to cut them in half to get the correct profile. If I can figure out how to get Excel to scale I'd have something!

**martyh45** · February 1st, 2013, 05:22 PM

HI,
I looked at in AutoCad and I see sections where the curve goes negative. These are the wobbles in your plot. In my experience with smaller horns a constant radius will fit to the expansion within tolerances anyone is likely to hold during construction. I don't know if that holds true for these big boys but measuring a curve from the outside of the horn should be easier. All you need is a straight board with a center mark and a ruler.

BTW, if you need them I can make printable templates and email them to you but we will need to get the curve plotted accurately first.

**Cal Weldon** · February 1st, 2013, 06:42 PM

Hi Marty,

I measured them on the outside but with the unevenness of the aquaplas coating, it was difficult to interpolate what the ID was. I mentioned the points, when plotted, would need smoothing. I'm glad to see Alan's curve is actually not that bad. There would be no way to use calipers like I did on the waveguide. Very interesting to see the slight compression on the side angle view of the waveguide up to the 2" point. I guess I have to post that here. I did a scan as Audiomind found my measurements difficult to read.

**Audiomind** · February 1st, 2013, 06:52 PM

Originally Posted by alancohen

The numbers worked for me, Marty. You just need to take into account that the lateral measurements are the entire cross section. You need to cut them in half to get the correct profile. If I can figure out how to get Excel to scale I'd have something!

I am assuming you are referring to the fact your line on the graph is a little longer than the 24.5" inches the cell should be?

**Audiomind** · February 1st, 2013, 06:55 PM

Originally Posted by Cal Weldon

Hi Marty,

I measured them on the outside but with the unevenness of the aquaplas coating, it was difficult to interpolate what the ID was. I mentioned the points, when plotted, would need smoothing. I'm glad to see Alan's curve is actually not that bad. There would be no way to use calipers like I did on the waveguide. Very interesting to see the slight compression on the side angle view of the waveguide up to the 2" point. I guess I have to post that here. I did a scan as Audiomind found my measurements difficult to read.

Hey Cal,

What about the calipers you made for the waveguide? Can you get some measurements at least part way down the cell with them as there seems to be a bad bump between 4 and 5 inches down the cell.

Audiomind...