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Author Topic: Can a horn speaker be made?  (Read 1186 times)
cossoft
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« on: February 26, 2017, 12:41:06 am »

Other than buying one, is it possible to make something like this of the order of 150mm long:-



Clearly this one was made (!) but would it be possible for an oaf to make it without a smithy and metallurgical skills?  I found http://brassgoggles.co.uk/forum/index.php/topic,36063.msg782629.html#msg782629 but the guy seems to have gone dark.  I use 3D modelling software so the geometry isn't a problem.  All I can think of is 3D printing it (pretty expensive for a SLS machine), but is there another way?  I wouldn't mind if it had flat surfaces like some traditional gramophone horns...
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von Corax
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« Reply #1 on: February 26, 2017, 12:50:25 am »

Making the curved goose-neck part as a working part of the horn would  be difficult. What you could do is make a Victrola-style straight horn, mount the driver speaker at the narrow end, and then mount the entire assembly on a gooseneck.
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« Reply #2 on: February 26, 2017, 01:28:10 am »

The goose neck (and possibly the horn in its entirety) could be rotational cast from epoxy resin; there are instructions on how to do this if you look for them. Then you would mount it on that lower cylindrical piece that contains some sort of electromagnetically vibrated tympanium, which could be custom built, or salvaged from an already existing speaker.

Can anyone advise on how well a horn speaker like this works? There has to be a reason by this design is no longer manufactured.
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steiconi
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« Reply #3 on: February 26, 2017, 03:24:54 am »

The bell part of that horn looks almost exactly like a cheap plastic flowerpot I have somewhere.  I think it's from the 1980s.  Shipping would probably be prohibitive, but maybe you should look at odd things just to get the shape.

Got a friendly potter nearby?  it could be done in ceramic, possibly thrown on the wheel, then curved to suit.
Other options could include air-dry or oven fired clay (like Fimo). 
I would build an armature from foil and/or paper, and lay the clay over it.
Papier mache could work the same way, but it would be tough to get that smooth surface.
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Banfili
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« Reply #4 on: February 26, 2017, 05:01:49 am »

Papier mache can be smoothed and polished to an extremely fine tolerance. Just look at all those Vicwardian trays! The Chinese and Japanese were masters of working it.
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James Harrison
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« Reply #5 on: February 26, 2017, 12:17:06 pm »

If you're happy with having it made up from a set of flats it might be relatively simple to make.  I say 'relatively' because at times even the simplest of ideas proves to be difficult  Cheesy

If you were to say build it as an octagonal type rather than circular there are templates for each section that can be found through a google image search- you could then alter the template as necessary for each of the eight sides to get the goose neck you're looking for. 

Or even build a master out of scraps of wood and cardboard and then as Banfili suggested use that to build up a papier-mache horn. 
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« Reply #6 on: February 26, 2017, 12:42:21 pm »

The first question that comes to mind is. Does it need to be functional, or are you just looking for the shape?
To actually beat the horn out of metal sheet would take quite a high level of skill.
However, if you are looking for something that is the right shape, at the size that you are describing, I would have thought that this would be a prime candidate for 3D printing. The horn and the "Spout" could be made separately, and then be glued together and then sanded and painted.
What I have done in the past is buy an old brass car horn, these can easily be dismantled by using a blow lamp to melt the solder. The tubes can then be cut, reconfigured, and then re-soldered.
In either case, it is a fairly simple job to fit a modern speaker into whatever you are using as the base.

+++EDIT+++

I just did a quick search on eBay for "Brass Car Horn". This was the first item to come up.


If you were to de-solder the second joint and cut off the pipe and rotate it so that the end faced straight down, it would not be exact, but it would be a fairly close match to the shape of the radio horn, and it would be fairly close to the size that you described.
If you don't like the brass finish, a simple coat of black paint could be applied.
« Last Edit: March 12, 2017, 10:03:21 am by Mr Addams » Logged
cossoft
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« Reply #7 on: February 26, 2017, 02:30:41 pm »

Duh!  I hadn't thought of a car horn - all I looked up was gramophone horn and those are much bigger and more expensive.  This computery internet thing is going to be big some day isn't it  Shocked  ?
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Mr Addams
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« Reply #8 on: February 26, 2017, 07:58:07 pm »

Duh!  I hadn't thought of a car horn - all I looked up was gramophone horn and those are much bigger and more expensive.  This computery internet thing is going to be big some day isn't it  Shocked  ?

Wheres the "LIKE" button when you need one?

I hope that you are going to post pictures of whatever you are making when you are finished.
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« Reply #9 on: March 08, 2017, 06:51:34 pm »

Any updates to this? I liked the idea of a smaller car horn or musical instrument horn as a solution.
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J. Wilhelm
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« Reply #10 on: March 09, 2017, 08:20:39 am »

Other than buying one, is it possible to make something like this of the order of 150mm long:-



Clearly this one was made (!) but would it be possible for an oaf to make it without a smithy and metallurgical skills?  I found http://brassgoggles.co.uk/forum/index.php/topic,36063.msg782629.html#msg782629 but the guy seems to have gone dark.  I use 3D modelling software so the geometry isn't a problem.  All I can think of is 3D printing it (pretty expensive for a SLS machine), but is there another way?  I wouldn't mind if it had flat surfaces like some traditional gramophone horns...


The link that you provided of that thread that has a great video, thanks to Mr. A. Pettyengineer:

I'll repost the video here for inspiration:



Now, if you look in the aethernet for Victrola Horns, there are various ways to reproduce this using other materials and techniques

BUILD: Victrola Style Passive Speaker


And there is one very very sneaky way to make one, which I will keep to myself, on account that there will be a new version of my Victorian Boombox soon enough  Roll Eyes I need to pay some bills  Undecided
« Last Edit: March 09, 2017, 08:25:01 am by J. Wilhelm » Logged

oldskoolpunk
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« Reply #11 on: March 09, 2017, 11:57:41 pm »

Can anyone advise on how well a horn speaker like this works? There has to be a reason by this design is no longer manufactured.
It works about as well as a bullhorn. Good efficiency, not so good audio quality. Modern speakers are not very efficient but have enough amplifier power behind them to shove the reproducing element around to follow the audio accurately.


Typical horn driver.

Public address speakers often work this way. This horn driver might be used in a high school gym. The horn screws on. Horn drivers are usually sized for large horns; small speakers don't need a horn.
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J. Wilhelm
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« Reply #12 on: March 10, 2017, 03:56:27 am »

Can anyone advise on how well a horn speaker like this works? There has to be a reason by this design is no longer manufactured.
Perhaps I can expound on the subject.

In acoustics theory the horn falls under the category of an "acoustic impedance matching device" its purpose is to maximize the energy transfer from the sound source (of a given impedance) to the human ear.

As an aside, the mathematical description in AC electric circuit theory is analogous to the mathematical description of the physics of sound waves (the differential equations that describe current flow in AC circuits are of the same form as those which describe cyclical pressure waves in an fluid. Hence the name "acoustic impedance matching."

Specifically, the horn takes low frequency sounds made by the speaker and channels that energy into middle range frequencies. Early speakers as has been pointed out were not very efficient. But they do radiate energy I  the form of a frequency range. If you sacrifice a little fidelity in the sound (frequency response curve) you can take advantage of certain "disposable energy" that would otherwise not be productive in that range. The reason for doing this is that the human ear can hear better those mid range frequencies, but is poor at detecting very low frequencies. So you can exploit any energy being radiated as low frequency sound.

So the horn is erroneously called a "passive amplifier." In reality, it's more like a "sound transformer." The opening shape of the horn is instrumental in moving the energy from low to mid frequencies. Equivalently, the shape of the horn minimizes the resistance to energy transfer in the acoustic circuit (speaker - air - human ear) to a minimum - thus impedance matching.
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Drew P
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« Reply #13 on: March 10, 2017, 12:51:30 pm »

Actually,  he stated that modern speakers are not efficient, um, yes they are.

And you are ruling out bass horns, be it Corner, Folded, "scoop", in multiple arrays or stand alone, output is enhanced not turned into midbass.

Just sayin'. Wink
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« Reply #14 on: March 10, 2017, 02:52:58 pm »

Actually,  he stated that modern speakers are not efficient, um, yes they are.

And you are ruling out bass horns, be it Corner, Folded, "scoop", in multiple arrays or stand alone, output is enhanced not turned into midbass.

Just sayin'. Wink

1. Indeed I misread. I read that "old" speakers were inefficient, instead of "new." I agree. That statement mat be moot then.

2. The question you need to answer is: Output is enhanced how, exactly? How did you "enhance it?" (see spoiler below)

3. A frequency range has an infinite number of sound wavelengths. "Low" Mid" and "high" frequencies is a qualitative definition more based on the human hearing system, rather than sound physics. You don't necessarily turn sound into "mid-range" (what is that circa 1 kHz?) for all designs in all conditions. You can use a very low frequency source and convert almost inaudible waves into what we consider "bass" (Say 100 Hz)

~ ~ ~

The Actual answer is a bit more complicated.

Spoiler (click to show/hide)
« Last Edit: March 24, 2017, 08:28:01 am by J. Wilhelm » Logged
RJBowman
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« Reply #15 on: March 12, 2017, 09:24:53 pm »

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Sludge Van Diesel
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« Reply #16 on: March 12, 2017, 09:44:54 pm »

Posting to keep tabs on the thread.

Carry on, nothing to see here
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cossoft
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« Reply #17 on: March 19, 2017, 02:15:25 am »

And there is one very very sneaky way to make one... I need to pay some bills.

Do tell.  I'll give you a shiny dollar (or a food parcel if you're really under the kosh).
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cossoft
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« Reply #18 on: March 19, 2017, 02:53:12 am »

Minimal functionality is all that's required.  Mine would only be producing a hiss.

As to why they're not used these days, I'm no acoustics /sound engineering expert but some observations are:-

Well, they are used all the time.  Piezo horn tweeters are used for treble reproduction.
A gramophone only has one speaker so it's immediately  an acoustic compromise in dynamic range and power spectral density.
A gramophone has no electrical amplification, therefore the speaker diaphragm can only be moved by the needle travel.  Further mechanical amplification (by say a lever arrangement) would cause intolerable pressure onto the (originally) wax cylinder or shellac disc.
That's why they sound tinny.
They'll also reverberate as they're very thin walled, adding more tinny.
Reverberation is minimised by rigidity and mass.  That's why speaker cabinets are made of thick chipboard or particle board.
A base woofer (or even sub-woofer) is huge in order to convert large amounts of electrical power into waves of air.  The non linear spectral sensitivity of the human ear also means that even more kinetic energy has to be imparted to the air mass to make it loud enough for teenagers.
You can't shift that much undistorted air through a tiny hole at one end of the horn.  With smaller wavelengths, a tweeter can.
They're big and long.
They look old compared to Apple ear buds and my lad wouldn't be seen dead stood by one.  How would AC/DC look rocking in front of a set of gramophone horns?  They'd be killed.
In summary, they're crap for listening to.

I guess to make an audio device work with such a horn, you'd have the horn on top and a mid range /woofer somewhere else on the box, possibly disguised.  You might still have reverberation issues though.
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Drew P
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« Reply #19 on: March 19, 2017, 03:06:32 pm »

They are still available, if you have massive amounts of throw-away money....
To name just 2: Cessaro and the better known Avantgarde.

and I, too, am curious of this "sneaky" way to make one.... Wink
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« Reply #20 on: March 24, 2017, 08:00:29 am »

Minimal functionality is all that's required.  Mine would only be producing a hiss.

As to why they're not used these days, I'm no acoustics /sound engineering expert but some observations are:-

Well, they are used all the time.  Piezo horn tweeters are used for treble reproduction.
A gramophone only has one speaker so it's immediately  an acoustic compromise in dynamic range and power spectral density.
A gramophone has no electrical amplification, therefore the speaker diaphragm can only be moved by the needle travel.  Further mechanical amplification (by say a lever arrangement) would cause intolerable pressure onto the (originally) wax cylinder or shellac disc.
That's why they sound tinny.
They'll also reverberate as they're very thin walled, adding more tinny.
Reverberation is minimised by rigidity and mass.  That's why speaker cabinets are made of thick chipboard or particle board.
A base woofer (or even sub-woofer) is huge in order to convert large amounts of electrical power into waves of air.  The non linear spectral sensitivity of the human ear also means that even more kinetic energy has to be imparted to the air mass to make it loud enough for teenagers.
You can't shift that much undistorted air through a tiny hole at one end of the horn.  With smaller wavelengths, a tweeter can.
They're big and long.
They look old compared to Apple ear buds and my lad wouldn't be seen dead stood by one.  How would AC/DC look rocking in front of a set of gramophone horns?  They'd be killed.
In summary, they're crap for listening to.

I guess to make an audio device work with such a horn, you'd have the horn on top and a mid range /woofer somewhere else on the box, possibly disguised.  You might still have reverberation issues though.

Or just do what I did. Cheat by using the horn as mere adornment Grin

I don't know. I wager some people would like to use decorative horns for showmanship effect. Especially if someone makes a "Ragtime" version of their Rap Grin

Eminem: "Without Me." Re-mixed as Ragtime Piano.
https://www.youtube.com/watch?v=qCjtUcip-hg

The truth is that If I had used acosutically correct horns in my boombox, they'd have been way too long and fragile. Instead, the subwoofer is the body of the boombox, and the mid-range satellites fit comfortably in two short stubby horns.

In theory, hypothetically, based on my acoustics theory classes (a two part elective course in mechanical engineering) I could have taken out the speaker drivers from the satellite enclosures, and properly designed the horns, But after all that work then you get stuck with the same problem of how to build them cones. I opted instead on leaving the speakers as they were and just embedding them in the cones.



« Last Edit: March 24, 2017, 09:08:46 am by J. Wilhelm » Logged
J. Wilhelm
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« Reply #21 on: March 24, 2017, 08:16:54 am »




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J. Wilhelm
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« Reply #22 on: March 24, 2017, 08:54:22 am »

They are still available, if you have massive amounts of throw-away money....
To name just 2: Cessaro and the better known Avantgarde.

and I, too, am curious of this "sneaky" way to make one.... Wink

Soon. Very soon my preeties! *wrings palms of hands* I may post here again after I make them.
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RJBowman
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« Reply #23 on: March 24, 2017, 04:27:13 pm »

Here's another possible source for the horn:

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SeVeNeVeS
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« Reply #24 on: March 24, 2017, 05:22:38 pm »

Here's another possible source for the horn:


Why stop there when you can go bigger? Tongue

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