Questions Regarding Horn Design and Dimensions

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CarlosV
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Re: Questions Regarding Horn Design and Dimensions

Post by CarlosV »

TN Allen wrote: Wed Nov 24, 2021 10:21 am Remarkably the video made it onto YouTube. It is rough but gives a sense of the sound. The 60Hz. hum is the shop electrical system. I moved around trying to get a sense of the sound at different angles and distances. As I explain in the text accompanying the video, the shop acoustics are awful.

https://www.youtube.com/watch?v=6hoKI7mJFyA
Remarkable outcome! it sounds great, congratulations! - and yours is a very nice shop.

TN Allen
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Re: Questions Regarding Horn Design and Dimensions

Post by TN Allen »

Thank you for the complements. The more I listen to the video sound, the more I think the horn has promise. I don't know enough about Wilson and Webb, but suspect that they not only relied upon mathematics but a robust intuitive sense of experiment and design. I wish I had known them. I was concerned that adapting their dimensions to a spiral horn might not work out well, but their guidance on bends in transmission lines seems as good as their cross section and length data. Does anyone know if they designed and built a spiral horn? I suspect they may have.

The shop is not mine. I teach in it, but it is part of Maine Maritime Academy in Castine, Maine. It is indeed a very nice shop, and I am fortunate to have it as a "second home".

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emgcr
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Re: Questions Regarding Horn Design and Dimensions

Post by emgcr »

TN Allen wrote: Wed Nov 24, 2021 2:57 pm Does anyone know if they designed and built a spiral horn? I suspect they may have.
I have never come across one but they might well have done...............a great number of experiments were carried out.

CarlosV
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Re: Questions Regarding Horn Design and Dimensions

Post by CarlosV »

emgcr wrote: Thu Nov 25, 2021 3:48 am
TN Allen wrote: Wed Nov 24, 2021 2:57 pm Does anyone know if they designed and built a spiral horn? I suspect they may have.
I have never come across one but they might well have done...............a great number of experiments were carried out.
I have never seen a spiral horn neither, but a spiral tone arm was built. It was made of wood, and looked very well done, on a English cabinet machine I tried to buy years ago, but unfortunately I was the underbidder. I never saw another, so that one may be a unique model.

TN Allen
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Re: Questions Regarding Horn Design and Dimensions

Post by TN Allen »

I searched the subject and found this discussion:

viewtopic.php?t=1190

Is the Pugh phonograph the machine you decribed with the spiral tonearm?

CarlosV
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Re: Questions Regarding Horn Design and Dimensions

Post by CarlosV »

TN Allen wrote: Fri Nov 26, 2021 8:04 am I searched the subject and found this discussion:

viewtopic.php?t=1190

Is the Pugh phonograph the machine you decribed with the spiral tonearm?
Exactly! I had forgotten about that old thread. I remember having bidded for that machine but did not get it at the end.

neilmack
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Re: Questions Regarding Horn Design and Dimensions

Post by neilmack »

Would pointing your 'oyster' horn at a wall, or into a corner, provide some extra range or volume?

TN Allen
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Re: Questions Regarding Horn Design and Dimensions

Post by TN Allen »

It probably would. The shop space is 50'X150' and about 12' high, and with concrete walls, floor, ceiling and machinery, it no doubt detracts from the sound.

I suspect in a residence it might have sufficient volume. Your idea is interesting, when the entire assembly is easier to move, I'll try a corner.

TN Allen
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Re: Questions Regarding Horn Design and Dimensions

Post by TN Allen »

"Exactly! I had forgotten about that old thread. I remember having bidded for that machine but did not get it at the end."

That machine would have been not only expensive but time consuming to build. Even now with CAD and CNC machining it would be time consuming, and quite expensive if one were to pay the hourly rate for the design and machine. It is beautifully made though.

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Re: Questions Regarding Horn Design and Dimensions

Post by TN Allen »

I plan to return to the horn project soon. I've had a few interruptions for shoulder surgery and finishing teaching the past semester, but have some new ideas for turning the bell. These require assembling a lathe based upon an old spindle I took from an early Pratt & Whitney lathe. I'm also thinking about a numerically controlled X-Y table that directs a long spindle to "cut" the interior bell shape to dimensions from the Wilson and Webb data I used for the spiral part of the horn. Rather than a cutter mounted in the spindle I probably will use a grinding wheel dressed to an appropriate radius as I've found grinding produces a better surface finish. All of this may seem too much to produce a bell for the horn, but the lathe and particularly building a numerically controlled table interest me. The cost of stepper motors and drivers, and a PCB to read G-code is remarkably inexpensive, and the technology opens up all sorts of possibilities for interesting home shop work.

The bell will be assembled from 18 trapezoid shaped 2" X 24" pieces of insulation foam, cut to the correct angles and glued together before turning.

In the mean time, does anyone know of people adapting numerical control devices for acoustic horn building?
As always, I'm interested in suggestions and comments regarding this project.
W&W Full Horn2 with Bell.jpg

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