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Thread: Suggestions - Making directional speaker - annoying neighbors

  1. #1
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    Default Suggestions - Making directional speaker - annoying neighbors



    Google was not able to give me the answers i neede, so I ask the highly skilled crew of PL once again. :-)
    I have a neighbor about 30 meters (100 feet) away, and they are playing quite high music every evening/night. We have tried the friendly chat a couple of times, but they just don`t give a fu**. So i was starting wondering about answering in the same way by starting giving back what they send. Noise!!! (They play a lot of Bangla/techno and it is not my cup of tea).

    As i don`t want to disturb my other neighbors by setting up the full PA and blast away, i was thinking in doing a quick build of a very directional speaker. What comes first to mind is using a Plastic pipe and mount a speaker in the rear of it. Then point and shoot.

    Anybody who have experience in building something like this? Im looking for something quick and dirty to build for more or less a one time use.

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    ... a directed EMP could help too

    Viktor
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    A conventional approach would involve a parabolic reflector, but I'm not sure that would be terribly effective or efficient over 30m. It would probably need to be quite large (with a chonky PA feeding into it) to reach real nuisance levels, though, and a certain amount of sound will always be spread in undesired directions (difficult to get around the fact that you're inducing pressure waves into a surrounding homogeneous medium). Commercial directional speakers (including weaponized ones like LRAD) use modulated ultrasound driving a planar array of transducers. These take advantage of the fact that planar arrays of approximate point sources tend to be strongly directional*. This has a good overview of how they work: https://www.explainthatstuff.com/dir...dspeakers.html


    * This is why you don't see actual walls of speakers at concerts, but line arrays. A linear array of speakers has a linear dispersion pattern at 90° to the axis of the array, so a vertical array has a dispersion pattern that is wide in the horizontal axis and narrow in the vertical axis--exactly what you want in a big arena.

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    Another way to make speakers directional is to make a large wall of them all the same and fed with the same signal. The height and width of the whole thing creates constructive interference, the same exact way a line array cancels vertical dispersion, but in both axis.
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  6. #6
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    Quote Originally Posted by JohnYayas View Post
    The cool trick with a soundlazer or the much better commercial unit it emulates is to bounce it off a wall so they can't see the array... The older commercial unit has a really cool DSP in it that takes the edgy roughness out of the demodulated sound in your ear by applying some FM and other tricks. Range is optimistically 7-10 meters at best.

    "Hi There, I'm the Lord Your God, See that Girl over There, Go Meet your Wife", is what my one employer did to me with the museum grade model and a bounce. Well before the Hebrew National hotdog commercial on TV with the similar line. If you keep the message ultra short, the psychological effect is amazing, it falls apart of you repeat the message or play music.

    So when I worked for the competitor of LRAD, I learned much about arrays. While a four or seven element line array in a simple MDF box will more then do what you want, I suggest a three by four array of piezo horn tweeters or three inch mids. This gives you elegant brute force in the two to four Kilohertz range. It has some lobes and really nice distortion if you use the mid range speakers. I'd suggest the sounds of crying babies and a slow sweep from two to four KC over about ten seconds. Don't bother with Bass, it just spreads out without some really careful cabinetry and huge boxes or very tall arrays. Just build it into the center of a thick piece of plywood roughly the size of a Roman shield. The shield size piece of wood or thick plastic aids in reducing the lobes. For a short range array, you do not have to do the fancy spacing calculations or time align the drivers by curving or slanting the speaker face.

    You'll need the shield when they come over to try to beat the crap out of you for using it on them. That is when you go from 20 watts of drive to 100. Multilayer carbon fiber replaces the wood or plastic quite nicely. A close fitting cover on the back is all that is needed, with a tiny vent port.

    I cant go into much more detail, because how you get a safe front to back ratio to protect the operator is covered by NDA and patents. Except in the kind of population that disturbs neighbors like that, arrays have a bad habit of making them angry the next day, after the ringing stops in their ears, and to a certain extent, yours.

    The smaller products I worked on ended up being sold more for urban rescue communications , air to ground communications for rescue aircraft, and attack warnings for incoming fire, or as directional warning sirens for trains, then for dispersing crowds. The larger products, using arrays and acoustic lenses, however, did excellent dispersing. If you have not noticed that less then lethal acoustics use is usually backed up by a large anti riot team, there is a reason for that. In other words, DONT.

    This is one time I REALLY suggest intervention by a civil lawyer, local government , landlords, the local EPA or cops. Forget the array and take the higher moral ground.

    Steve
    Last edited by mixedgas; 06-17-2020 at 20:32.
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    Default Thanks for all answers

    Thanks folks. A lot of answers in a short time. I really like the answer Steve are giving me. A more or less full recipy, and a kind remark on why not to bake that cake! .

    I am quite lucky living in Norway - and the need for lawyers and personal protection in such cases are rarely necessary.

    I have quite a few Piezo horns laying around, so i think I`ll try to build a 4 or 6 array on a piece of MDF just to try it out. If it works nice, I will consider trying it out on my noisy neighbor. Not in with a volume to stun them, but just enough to blend in with the music they are playing. What noise to use are to be tested. I like the idea of using a crying infant, but don`t want to start a search and rescue operation from the police to find the "missing mysterious infant".

    Another aproach is to use what is known as "swedish dance music" (Google "vikingarna") and play that on a loop.

    I asked for a quick and dirty solution, and have received answers and ideas for just that. Big thanks to the PL crowd again.


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    ... if you're in search for an appropriate "sound" -- howling wolves could be worth a try

    Viktor
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    Quote Originally Posted by VDX View Post
    ... if you're in search for an appropriate "sound" -- howling wolves could be worth a try

    Viktor
    If you have the Euro equivalent of a "70 Volt Line" transformer... That makes driving the piezo easier, by running in reverse for step up from the usual 8 ohm source.

    Steve
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  10. #10
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    If I really wanted to mess with them I would throw back what they throw at me with an adjustable delay.. Ouch....


    Steve
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