An Introduction and Some Questions about Exponential Horns

[emgcr]

Hello Ethan,

I wonder if you know about the newly published definitive book of over one thousand pages which informs readers about every possible aspect of horns ? It is, understandably, not cheap but your local library might be able to assist you ? ISBN : 978-1-5272-4542-6.

Here is a review :

In 1919, Arthur Gordon Webster published his seminal paper on horn theory, which gave impetus to a large body of research work. Since then, many papers, patents and book chapters have been published on the topic, but during the century that has since elapsed, no book has been published that exclusively covers the subject of horns. Until now. After more than fifteen years, Bjørn and Thomas have consolidated their research covering the history, theory, and design of horns and horn loudspeakers. The subject has been examined thoroughly and scientifically, presented in a way that endeavours to make this esoteric and elusive information more easily available to acousticians, audio professionals and loudspeaker enthusiasts alike. Published exactly 100 years after Webster’s paper, “High Quality Horn Loudspeaker Systems”, by Bjørn Kolbrek and Thomas Dunker is the first genuinely comprehensive and detailed reference material on the subject.

More info available at https://hornspeakersystems.info/

[fran604g]

Hello Ethan,

I wonder if you know about the newly published definitive book of over one thousand pages which informs readers about every possible aspect of horns ? It is, understandably, not cheap but your local library might be able to assist you ? ISBN : 978-1-5272-4542-6.

Here is a review :

In 1919, Arthur Gordon Webster published his seminal paper on horn theory, which gave impetus to a large body of research work. Since then, many papers, patents and book chapters have been published on the topic, but during the century that has since elapsed, no book has been published that exclusively covers the subject of horns. Until now. After more than fifteen years, Bjørn and Thomas have consolidated their research covering the history, theory, and design of horns and horn loudspeakers. The subject has been examined thoroughly and scientifically, presented in a way that endeavours to make this esoteric and elusive information more easily available to acousticians, audio professionals and loudspeaker enthusiasts alike. Published exactly 100 years after Webster’s paper, “High Quality Horn Loudspeaker Systems”, by Bjørn Kolbrek and Thomas Dunker is the first genuinely comprehensive and detailed reference material on the subject.

More info available at https://hornspeakersystems.info/

^^^this! It's a real shame Amazon doesn't sell it in the states - the last time I looked - and given the sorry state of affairs the postal systems have become recently, I am hesitant to have it shipped from the EU.

Best,
Fran

[emgcr]

Hello Fran,

I have just emailed one of the authors who has replied as follows :

We have been in touch with PartsExpress and they were planning to take it in, but it has been put on hold for the moment. As Celestion sell through them, they have been very helpful in negotiating with them, and are following up. Perhaps if people sent them requests, asking if they plan to take in the book, things would move forward.

Otherwise, it is worth contacting Lean Business Audio and ask for a quote. They have to do it on a case-by-case basis for overseas customers, as the rates varies between states. But they do pack well, and I don't think the prices are too bad.

We stopped selling through Amazon due to the poor packaging. Several books were damaged and returned.

Hope this is helpful.

[fran604g]

Hello Fran,

I have just emailed one of the authors who has replied as follows :

We have been in touch with PartsExpress and they were planning to take it in, but it has been put on hold for the moment. As Celestion sell through them, they have been very helpful in negotiating with them, and are following up. Perhaps if people sent them requests, asking if they plan to take in the book, things would move forward.

Otherwise, it is worth contacting Lean Business Audio and ask for a quote. They have to do it on a case-by-case basis for overseas customers, as the rates varies between states. But they do pack well, and I don't think the prices are too bad.

We stopped selling through Amazon due to the poor packaging. Several books were damaged and returned.

Hope this is helpful.

Thank you very much, this helps me to be hopeful. I've been informed by friends to contact the author previously, but PartsExpress is a company I frequently do business. That would be most convenient.

Cheers,
Fran

[Ethan]

I hadn’t heard of that book before, but it certainly sounds as though it could be useful! I checked and my local library doesn’t have it, but I’ll be sure to keep it in mind if I decide to make another horn at some point—which seems fairly likely, as part of the fun, for me, is just in experimenting.

I did, however, find an interesting article to-day about horn design, which mentioned—among other things—that a papier mâché horn, if made according to a true exponential curve, will shrink to a close approximation of a Wilson modified horn as it dries on its former; has anyone else observed this? The mouth of the straight horn that I designed would have to shrink by about two inches in diameter if it shrank from true exponential to modified exponential, which seems as though it could push the horn up its former, possibly distorting it before it has time to harden completely.

[shoshani]

The 1929 book "Modern Gramophones and Electrical Reproduction" gives three designs for exponential horns one can build. It starts with an elaborate bifurcated horn setup, then moves on to simpler horns. Provided I've linked it correctly, it starts here: https://archive.org/details/ModernGramo ... 9/mode/2up

[fran604g]

The 1929 book "Modern Gramophones and Electrical Reproduction" gives three designs for exponential horns one can build. It starts with an elaborate bifurcated horn setup, then moves on to simpler horns. Provided I've linked it correctly, it starts here: https://archive.org/details/ModernGramo ... 9/mode/2up

Thanks for the link shoshani, a very interesting read!

Best,
Fran

[Ethan]

Hello,

Thank you to all those who have offered suggestions so far!

I’ve been rather busy lately doing my first spring-motor rebuild, but now that I have it rebuilt, I think that I am almost ready to begin construction of my horn; I just have a few last questions:

Will sturdy brown packing paper be suitable for the interior surface of the horn? It seems fairly rough to me, but emgcr says in his article about the fiberglass Xb Oversize horns (and also in reference to the Nimbus horn-Mark IX conversion) that the interior surface of a horn shouldn’t be glassily smooth at all, as it produces peaks in the frequency response, presumably due to internal reflections.

Also, what does anyone think of the following method for making a former for the curved part of the horn?

1. Make a “horn” from panels of a smooth, slippery fabric, such as polyester—basically a bent fabric morning-glory horn.
2. Fill the fabric “horn” with plaster.
3. Once dry, peel off the fabric.
4. Use the Inlow Sound method of sanding and polishing the plaster former.

I will try making a small mock-up today and report back with the results; in the mean time, any thoughts or advice are welcome!

- Ethan

[phonosandradios]

I came across this fascinating you tube video today about horn making and remembered this thread. Watch it as it goes into how the former for the horn was made - it might help you with making your own. Great sound too! I am very tempted to do a project like this myself now.

(Double-click the video above or click this link to watch the video on YouTube in HD.)

[dzavracky]

This is the video I’m basing my project of of

You’ll see in the comments he responded to me gave me all the measurements