My son and I are trying to fabricate a large horn to be used for a Gjallarhorn for his high school. We want to replicate a sound similar the new “War of the Worlds” tri-pod monster or the “ Helms Deep” horn from Lord of the Rings. My research says this is approximately 113hz (this was a starting point so it can change as needed.) We plan on using a pneumatic air horn for the driver ( still developing that as well, open to suggestions.) We want this to be LOUD! like feel it in your bones loud. It will be setup at the football stadium at one end where there is no seating to avoid concerns with hearing damage. The biggest question I need help with is the horn design. I want to fabricate it out of fiberglass. Ideally it would be portable, so 10’-15’, but we really want it to have the power and sound of a deep toned Viking war horn that envelops the stadium with intimidation…. Is there anyone who could provide the horn dimensions we should use? Thanks for any help.
113 Hz somewhat close to A2 for 110 Hz
Far as how loud it gets. depends on the air diaphragm and how much pressure you use.
Air horn on a car or truck, might be around 90 to 120 PSI
For really loud train horns can be 150 to 180 PSI
So if you have a air tank that can maintain 150 PSI
you will be close to train level.
Likewise you need a diaphragm that can handle 150 PSI
Most truck horns and compressor kits usually maintain 90 to 120 PSI
So probably dont wanna push most diaphragms over 120 PSI
Far as the pitch, the horn needs to be large enough for pitch wanted.
Then the right length for desired pitch.
Tuba horn is large enough for E1 or 41 Hz
or your goal of A2 110 Hz or octave lower A1 55 Hz
can be easily done with a Tuba sized horn.
Actual as mentioned a trombone can go down to E2
around 82 Hz so A2 110 Hz is feasible
Far as the actual length of the tube, the valves or slide change that.
believe the longest length is around 16 feet. But for a Tuba it is all
coiled up. What length for A2 or A1 not sure.
We have software that can give you a conical or exponential flare rate.
Just need to know the size you diaphragm exit starts at. then what size horn and length.
far as how loud...depends if your 90 to 120 PSI or 150 to 180 PSI and your diaphragm doesn't
blow at high pressure.
Far as how loud it gets. depends on the air diaphragm and how much pressure you use.
Air horn on a car or truck, might be around 90 to 120 PSI
For really loud train horns can be 150 to 180 PSI
So if you have a air tank that can maintain 150 PSI
you will be close to train level.
Likewise you need a diaphragm that can handle 150 PSI
Most truck horns and compressor kits usually maintain 90 to 120 PSI
So probably dont wanna push most diaphragms over 120 PSI
Far as the pitch, the horn needs to be large enough for pitch wanted.
Then the right length for desired pitch.
Tuba horn is large enough for E1 or 41 Hz
or your goal of A2 110 Hz or octave lower A1 55 Hz
can be easily done with a Tuba sized horn.
Actual as mentioned a trombone can go down to E2
around 82 Hz so A2 110 Hz is feasible
Far as the actual length of the tube, the valves or slide change that.
believe the longest length is around 16 feet. But for a Tuba it is all
coiled up. What length for A2 or A1 not sure.
We have software that can give you a conical or exponential flare rate.
Just need to know the size you diaphragm exit starts at. then what size horn and length.
far as how loud...depends if your 90 to 120 PSI or 150 to 180 PSI and your diaphragm doesn't
blow at high pressure.
Concert Tuba is rather large, Marching Tuba is downsized both are rather expensive.
Your best bet is to find a used Large Marching Bugle which is about the size
of a Marching Tuba
Or just find a used Trombone
those can be cheap around 50 to 120 dollars.
Using a Trombone just pull the slide all the way out
for around E2 82 Hz or almost all the way out for A2 110 Hz
basically you just need a threaded brass adapter that will thread into
your air diaphragm. Then where the trombone mouth piece usually goes.
Solder on your threaded adapter.
Also the slide should be soldered or held in place.
or it will fly out when you smack it with 120 to 150 PSI.
All done.
Also like a Truck or Fog horn its usually 2 or 3 notes.
Assume the War of the Worlds sound effect is likely
a chord using orchestra samples.
So you could make a A major or Minor chord to be really intimidating.
Hence 2 or 3 trombones. Set to a chord.
Find the notes with the normal mouthpiece, then solder the slides permanent.
or tap with screws so the horns go back into the case.
of course you need 2 or 3 diaphragms, and a tank/compressor
that will maintain 120 PSI
Your best bet is to find a used Large Marching Bugle which is about the size
of a Marching Tuba
Or just find a used Trombone
those can be cheap around 50 to 120 dollars.
Using a Trombone just pull the slide all the way out
for around E2 82 Hz or almost all the way out for A2 110 Hz
basically you just need a threaded brass adapter that will thread into
your air diaphragm. Then where the trombone mouth piece usually goes.
Solder on your threaded adapter.
Also the slide should be soldered or held in place.
or it will fly out when you smack it with 120 to 150 PSI.
All done.
Also like a Truck or Fog horn its usually 2 or 3 notes.
Assume the War of the Worlds sound effect is likely
a chord using orchestra samples.
So you could make a A major or Minor chord to be really intimidating.
Hence 2 or 3 trombones. Set to a chord.
Find the notes with the normal mouthpiece, then solder the slides permanent.
or tap with screws so the horns go back into the case.
of course you need 2 or 3 diaphragms, and a tank/compressor
that will maintain 120 PSI
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A study of train horns is enlightening.
https://en.wikipedia.org/wiki/Train_horn
http://locomotivehorns.info/
US train horns are higher pitch to differentiate from heavy truck horns. So maybe you want to shop the truck store. Same mechanism, different lengths.
https://en.wikipedia.org/wiki/Train_horn
http://locomotivehorns.info/
US train horns are higher pitch to differentiate from heavy truck horns. So maybe you want to shop the truck store. Same mechanism, different lengths.
Good point.
most air horns are higher in pitch
low horn 300 to 600 Hz
High tone 600 to 1800 Hz
So trying to make a horn down to 100 Hz can be done.
Just assume a typical diaphragm will be working harder.
Also it takes more pressure to produce bass frequencies.
Old military or marching band trick to have the loudest band possible.
was to tune brass instruments as high as possible.
Higher tones being louder more audible.
Having done some fun experiments with noise machines
using electric car horns. the low tones sounded better.
But the high tone horns were much louder.
Basically I mounted 12 car horns to a portable frame.
with a car battery and had 3 switches turning on 4 at a time.
went from loud, to very loud.
Actually I didnt think of the current. using pretty normal gauge wire
used for horns on cars.
each horn about 2.5 to 3 amps x 12 equals = first run sounded great
then wires melted LOL.
anyways I got rid of the low tones and used all high tones.
and got a lot louder. low tones sounded better though.
most air horns are higher in pitch
low horn 300 to 600 Hz
High tone 600 to 1800 Hz
So trying to make a horn down to 100 Hz can be done.
Just assume a typical diaphragm will be working harder.
Also it takes more pressure to produce bass frequencies.
Old military or marching band trick to have the loudest band possible.
was to tune brass instruments as high as possible.
Higher tones being louder more audible.
Having done some fun experiments with noise machines
using electric car horns. the low tones sounded better.
But the high tone horns were much louder.
Basically I mounted 12 car horns to a portable frame.
with a car battery and had 3 switches turning on 4 at a time.
went from loud, to very loud.
Actually I didnt think of the current. using pretty normal gauge wire
used for horns on cars.
each horn about 2.5 to 3 amps x 12 equals = first run sounded great
then wires melted LOL.
anyways I got rid of the low tones and used all high tones.
and got a lot louder. low tones sounded better though.