Medic5050
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Already done good sir. I did before I posted. I'm almost considering buying the book offered on eBay...almost.
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Loud horns
- Thread starter patracy
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jamesfrom180
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I would love to see an in-depth build write up on this. Where is my popcorn. I think I may play around with this a bit have a feeling I can get the initial design alittle more efficient on labor time.
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I wouldn't pay for it. They're very simple. I was almost ready to buy them until I found that diagram. I'm going to do a full photoshoot with the second build. I'll update the thread then. Labor isn't very difficult at all. The hardest part is trimming the diaphragm to fit it to the tube.
jamesfrom180
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I'm not sure but the individual who authored the attached diagrams article said that the closed rear air chamber muted the overall effect of the horn. I am really interested in getting some major performance out of a garage built horn
This unit uses a shopping bag...lol...a friend has a fog horn that uses a .2" brass diaphragm I'm wondering how these scale? Have you tried stiffer disk yet? or are you working with the .060" poly
This unit uses a shopping bag...lol...a friend has a fog horn that uses a .2" brass diaphragm I'm wondering how these scale? Have you tried stiffer disk yet? or are you working with the .060" poly
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I'm using a butter tub lid for mine in the one shown. I just can't see a plastic bag standing up to it for any length of time. Mine isn't closed in on the back section though. You need the diaphragm to be able to freely move.
jamesfrom180
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That was my thought. The bag reed is for a human powered version, but the concept is the same. I would have thought that HDPE (most food containers) would have been two supple. I want to up it a bit with shim material or sheet brass. I have a suspicion that the stiffer the read the faster the vibration and thus possibly the longer the horn. Really cool though to have something cheep to learn and play with.
by KennyJ on Astrosafari.com
Here's some notes on horn theory and design:
What makes a horn work is the way the expanding column of air in the horn couples the small movements of the relatively heavy diaphragm to much less dense air outside the horn. Think of it as an acoustic transformer coupling the high impedance diaphragm to the low impedance air. Horns have a very high acoustic efficiency which is why they can be so loud.
The opening of the nozzle at the diaphragm is the throat of the horn, and is typically smaller than the diaphragm. The ratio of the diaphragm area to the throat area is the compression ratio of the horn. This compression helps transfer the diaphragm's movement to the outside air, increasing efficiency. Some of the train horns I've looked at on the internet have a compression ratio as high as 25:1.
The length of the horn from the throat to the mouth, or bell, is the horn path. Depending on the frequency range to be covered different horn flares are desirable from a long exponential flare for a bass horn to a more rapidly expanding flare for higher frequencies.
The length of the horn path determines the low frequency cut-off and in an air horn is the frequency at which the horn resonates. The ideal horn length is one wavelength of the desired frequency, in other words for a 400 hz horn, the speed of sound traveling through air is approximately 1,130 feet per second, divided by 400 hz, one single sound wave would be 2.825 feet long. In actuality a horn can reproduce frequencies over a horn path of 1/4 or 1/2 a wavelength so that 2.825 foot horn can also reproduce 200 hz and 100 hz at lesser volumes.
In real terms you can estimate the frequency or note of your horn by dividing its length into 1,130, roughly the speed of sound in free air.
The size of the mouth, or bell, of the horn determines how well the lowest frequencies are reproduced. Ideally the area of the mouth should translate to one wavelength of the lowest frequency to be reproduced. This ideal mouth area can be very large for a given horn, and in reality smaller mouth sizes can be used at the expense of efficiency.
Well, that was a little long winded and kind of technical but may be of interest to some.
by KennyJ on Astrosafari.com
Here's some notes on horn theory and design:
What makes a horn work is the way the expanding column of air in the horn couples the small movements of the relatively heavy diaphragm to much less dense air outside the horn. Think of it as an acoustic transformer coupling the high impedance diaphragm to the low impedance air. Horns have a very high acoustic efficiency which is why they can be so loud.
The opening of the nozzle at the diaphragm is the throat of the horn, and is typically smaller than the diaphragm. The ratio of the diaphragm area to the throat area is the compression ratio of the horn. This compression helps transfer the diaphragm's movement to the outside air, increasing efficiency. Some of the train horns I've looked at on the internet have a compression ratio as high as 25:1.
The length of the horn from the throat to the mouth, or bell, is the horn path. Depending on the frequency range to be covered different horn flares are desirable from a long exponential flare for a bass horn to a more rapidly expanding flare for higher frequencies.
The length of the horn path determines the low frequency cut-off and in an air horn is the frequency at which the horn resonates. The ideal horn length is one wavelength of the desired frequency, in other words for a 400 hz horn, the speed of sound traveling through air is approximately 1,130 feet per second, divided by 400 hz, one single sound wave would be 2.825 feet long. In actuality a horn can reproduce frequencies over a horn path of 1/4 or 1/2 a wavelength so that 2.825 foot horn can also reproduce 200 hz and 100 hz at lesser volumes.
In real terms you can estimate the frequency or note of your horn by dividing its length into 1,130, roughly the speed of sound in free air.
The size of the mouth, or bell, of the horn determines how well the lowest frequencies are reproduced. Ideally the area of the mouth should translate to one wavelength of the lowest frequency to be reproduced. This ideal mouth area can be very large for a given horn, and in reality smaller mouth sizes can be used at the expense of efficiency.
Well, that was a little long winded and kind of technical but may be of interest to some.
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mudguppy
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subscribing...
: popcorn :
: popcorn :
jamesfrom180
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Well after work I decided to try.
First we have the material I went with a twist and used for my first attempt the cheep plastic dust cap used for ground roughing. It is called a test cap and you can find it at most big box stores. had to sand off some lettering.
Second sanded out the bushing. Sanded the 3/4 pipe also. made for a nice tight fit. Then I cut a 2 inch section of 3" pipe and used it with the cover to make the diaphram assembly.
Third I added a nipple for the air fitting. and knocked it all toghter.
Last we apply the air and it make a wailing loud sound. Needs some tuning but I think its around the C note range.
Looks like it works.
First we have the material I went with a twist and used for my first attempt the cheep plastic dust cap used for ground roughing. It is called a test cap and you can find it at most big box stores. had to sand off some lettering.
Second sanded out the bushing. Sanded the 3/4 pipe also. made for a nice tight fit. Then I cut a 2 inch section of 3" pipe and used it with the cover to make the diaphram assembly.
Third I added a nipple for the air fitting. and knocked it all toghter.
Last we apply the air and it make a wailing loud sound. Needs some tuning but I think its around the C note range.
Looks like it works.
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I like that setup. Cheaper than what I made!
Medic5050
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Heck, I like ALL the setups. What's even better, I showed the wife the YouTube video that patracy posted in the first of the thread, and she flipped. I was told I needed to make aset for the M.V. (when I get one) and for her TrailBlazer.
I can see this might not turn out that well for my wallet and our insurance (tickets, tickets, tickets).
I can see this might not turn out that well for my wallet and our insurance (tickets, tickets, tickets).
jamesfrom180
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Update took the pressure to 200 psig! Held and man what a racket. I was unsure of the cheep dust cap diaphragm but it held until I destroyed it with the hammer. I want to play around with different material for the diaphragm, seems I can improve the sound. Also you can reduce alot of the bulk by trimming down the fittings. Found a Blitz brand black funnel that works well as the horn. IT IS LOUD!!
Digging around here at work found a 4"to2" reducer and found that the dust caps I've been playing with also come in 4". Guess now I will have to see if upping the chamber gives higher performance. For those following along with the math the 3" to 3/4" gives a compression ration of roughly 32:1 and the 4" to 3/4" is 57:1 giving these horns a relativity high efficiency. Not sure that translates into sound power.
Digging around here at work found a 4"to2" reducer and found that the dust caps I've been playing with also come in 4". Guess now I will have to see if upping the chamber gives higher performance. For those following along with the math the 3" to 3/4" gives a compression ration of roughly 32:1 and the 4" to 3/4" is 57:1 giving these horns a relativity high efficiency. Not sure that translates into sound power.
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mudguppy
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need video,
and
and
Flat Black
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would like to see the step by step build on this, but I found these cheap enough to not bother trying to make one:
Train Horn Diaphragm [0960212] : 75 Chrome Shop, Chrome Semi Truck accessories, parts, and service
Train Horn Diaphragm [0960212] : 75 Chrome Shop, Chrome Semi Truck accessories, parts, and service
jamesfrom180
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Oh what fun is that, I mean its only right down the road from me anyways.
Actually have really got a nice design I like just got a little carried away and ruptured another diaphragm. I'm hoping to get 180db out of these things.
Actually have really got a nice design I like just got a little carried away and ruptured another diaphragm. I'm hoping to get 180db out of these things.
colelkhunter
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you know I see this getting way out of hand in my shop. what is the correspondence to the diameter of the horn to the sound? Or Db level? Heres what i envision. Smallest out of the four made from say 6" PVC then one 8" and so on. so that when air was applied it would sound like a cruise ship docking or a bomb going off, whichever. What about one that was the size of one of those bazooka bass tubes. supersize those horns people!!!!!
jamesfrom180
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Yeah but PVC just does not have the "Timber" it sounds plasticy. LOL. The biggest limit is the amount of air flow into the horns. I've tried to up the pressure but have found you loose the diaphram. But by all means go nuts.
bugwugger
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Lex_Ordo
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Train horns are a good choice. Here is a great place to buy them. Yes, these are the real deal too. Micro Precision Group | Micro Precision Group Online Store
You can find them a lot cheaper on eBay, but this is where they are manufactured. Oh, and don't foget the 3/4" valve...
Graham White Manufacturing Co.
Cleptomaniac
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ok my wife wasnt too happy about this at 2am 
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Cool ! I just found this thread 
I've had a brass locomotive whistle stored away for a long time - NOW I'm going to dig it out and plumb it into the Deuce's air lines. I'm thinking I'll keep the original horn as primary, but add the whistle as a compliment for parades, etc.
I've had a brass locomotive whistle stored away for a long time - NOW I'm going to dig it out and plumb it into the Deuce's air lines. I'm thinking I'll keep the original horn as primary, but add the whistle as a compliment for parades, etc.