What you say would be 100% best solution if I hadn't found the Atlas T10 (see #136), and also, it depends on the voltages that the amplifier can produce, discussed at the bottom of this post.
"suitable for use with amplifiers rated 150W RMS into 8 ohm"
I have been wondering why they keep using "8 Ohm system reference", but you've beautifully clarified that, also discussed at the bottom of this post along with max voltages.
Spec sheet is in #97, reproduced and discussed below.
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A genuine KSN-1165 is not available in the UK or EU from anywhere (including Amazon.co.uk and ebay.co.uk), and shipping to UK from CTS or Amazon.com or ebay.com is 100 USD !!! (no typo).
So I looked for an equivalent in Europe, which I think is the Monacor MPT-165. I looked for that at Blue Aran (who I've used before) and they sell the Monacor MPT-177, which I'm tempted to buy. Problem with both the MPT-165 and MPT-177 is the lack of info on the "typical impedance", but at that low price and high SPL, I'm willing to give the MPT-177 a try. Monacor MPT-177 Rectangular Dual Piezo Horn Tweeter from Monacor PS11.38
Using the "system reference" data for KSN-1165and MPT-177, I made a small table in Excel to get the voltages
Monacor actually state a max voltage "~ 30V" which is corroborated by that system ref data.
What is interesting is that the KSN-1165 works out at a max voltage of 56V !!!
Next, same thing for the amplifiers which I have at my disposal.
The Quad 405 went back into its box a few years ago, it's heavy, and it would be best to use the Quad 44 preamp (also back in its box). The reason they went back in their boxes is because someone gave me a Dennon UPA-F10 and although it's not a patch on the Quad in terms of power etc, I prefer it because it's lighter and takes up far less space. The Edge ED7300 is a car power amp that I've got knocking about.
The main issue is that I'll probably end up using the Edge car amp, mainly because it will run off a 12V car battery (or an SLA). Both the Denon and the Edge are limited in the voltages that they can put out.
Table below shows the impedance of the KSN-1165 using 0.3 uF and 30 Ohms from its datasheet. Using those impedances, and the voltages that the amplifiers give out, I'm not going to get much gain without using a transformer such as the Atlas T10.
Unless I can get hold of KSN-1165 at reasonable price in the UK, using the KSN-1165 as the focal point in the discussion could be a waste of time for me. But the analysis is still relevant for any piezo, just a different curve and voltages required.
I've been thinking about that table that I did in Excel.
The 3rd/4th/5th columns use Power = V² / R, where R is in the 2nd column, and V is the max voltage (RMS unclipped) that the amp in each column can give out.
I've always though of a Class A, B, or AB solid-state amp as more of a current device, in that if there's nothing there to take the current, then no volts are produced.
So if I were to connect a piezo that is >1k Ohm impedance directly to the amplifier (e.g. Monacor MPT-177) with nothing else connected, why would the amp produce its max volts ?
Assuming that the amp could at some point produce its max voltage across the piezo (with nothing else connected), and since piezos are mostly a voltage driven device, then is the "gain" above the 2.83V SPL just proportionate to the voltage ?
Either way, this is another reason why it's better to use a transformer, because I know that the amp will see a conventional load - and note that initially I will be putting an oscilloscope across both the primary and secondary to see what's happening.
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Well I decided to check and discovered that, on the Denon at least, the voltages are there without any load. Voltages varied proportionally with main volume control.
Setup is shown below (the load is a pair of Rogers Studio 1 speakers out of shot).
With load disconnected, max pk-to-pk voltage just before clipping was 60V, which comes out at 21V RMS.
In the pic you can also see some resistors, these are 1 Ohm (5%) 50W in series with each speaker, to measure current. I didn't measure volts at the same time, might try that tomorrow, but the max I dared take it to was 8A pk-to-pk (didn't want the amplifier to start clipping and damage the speakers). That's 2.8A RMS, into 8 + 1 Ohms = 70 Watts.
So it would be possible to get some reasonable SPL out of piezos without using a transformer, depending on the amplifier's PSU etc.
But what puzzles me about piezos, is that if the impedance varies with frequency, why is the SPL reasonably flat ?
Should it be just the resistance that is taken into account on SPL, which, in the case of the KSN-1165, is 30 Ohms ?
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Can anyone help me build something from scratch? I don't know jack about audio and all of that stuff. Most of the info in this thread is technical as heck.
Anyone had success building something like this and deterring dogs?
Ideally, if someone could just let me know, yeah buy this, this and this, then hook them up together, it'd be great.
As for the audio apparantly there is a good view on YT that works.
I'm just talking about the hardware.
YouTube
Anyone had success building something like this and deterring dogs?
Ideally, if someone could just let me know, yeah buy this, this and this, then hook them up together, it'd be great.
As for the audio apparantly there is a good view on YT that works.
I'm just talking about the hardware.
YouTube
Adding an update has been on my to-do list since November 2018 !!
Basically
1. Piezo tweeters present a purely capacitive load
2. The data sheets for Piezo tweeters need to be carefully interpreted as to the max SPL you'll get
3. I found a research paper that someone did on dogs' hearing - according to dog breed their hearing is not much better than young humans, indeed some dog breeds are worse
4. When a dog barks, its bark will suppress any impact of the HF (try directing say 15kHz at yourself and shout loudly, you'll not hear the HF while you're shouting)
5. Getting a high SPL out of an array of tweeters is difficult as tweeters at 20 kHz become exceptionally directional, and an array of them would be a nightmare to set up to keep the beam in phase
6. HF does not travel well through the air, the higher the frequency, the more the molecules absorb the energy instead of simply pushing it onto the next molecule
7. Conclusion - using HF tones will not deter a barking dog
8. If you live in a country where the authorities take noise seriously, get the relevant authorities involved instead.
9. Note that an air-driven device such as an air-horn does stop them, but not always , and you won't find an air-driven device which is inaudible to humans - if you did succeed in creating an air-driven device at 20 kHz which emitted extremely high SPL (we're talking say 150 dB at 1 metre) it'll likely damage the hearing of the dogs and any humans
i'll try to give more detail on points 1, 2, 3, and 6 at a later date
Basically
1. Piezo tweeters present a purely capacitive load
2. The data sheets for Piezo tweeters need to be carefully interpreted as to the max SPL you'll get
3. I found a research paper that someone did on dogs' hearing - according to dog breed their hearing is not much better than young humans, indeed some dog breeds are worse
4. When a dog barks, its bark will suppress any impact of the HF (try directing say 15kHz at yourself and shout loudly, you'll not hear the HF while you're shouting)
5. Getting a high SPL out of an array of tweeters is difficult as tweeters at 20 kHz become exceptionally directional, and an array of them would be a nightmare to set up to keep the beam in phase
6. HF does not travel well through the air, the higher the frequency, the more the molecules absorb the energy instead of simply pushing it onto the next molecule
7. Conclusion - using HF tones will not deter a barking dog
8. If you live in a country where the authorities take noise seriously, get the relevant authorities involved instead.
9. Note that an air-driven device such as an air-horn does stop them, but not always , and you won't find an air-driven device which is inaudible to humans - if you did succeed in creating an air-driven device at 20 kHz which emitted extremely high SPL (we're talking say 150 dB at 1 metre) it'll likely damage the hearing of the dogs and any humans
i'll try to give more detail on points 1, 2, 3, and 6 at a later date
Caramello,
If you can elaborate on which equipment you discovered in the end worked, it would be helpful. Let people experiment for themselves and decide whether it works or not.
There is an anecdote from someone on Youtube who claims dogs "hid behind objects" when he tried this.
So far I understand I would require the following items:
1) Amplifier (in my case I would like to attempt it with 50 to 100 watts). I need something simple, preferably something inexpensive with only a volume control and preferably capable of bridging to mono (so I can save money by buying a 100w unit, where it's 2x50w bridged into one output)
2) Tweeter. One tweeter. I don't require an array of tweeters. My plan is to move my tweeter around the wall to see where it is best to locate it. The dog is in the room on the other side of the wall. All I need to do is find the right spot, as in, closest to the dog. I won't be leaving this on all day, just short bursts when the owner is present there as well, so the owner can take note of what's going on by observing either the dog desperate to get out of the room, or what have you.
3) Transformer, BP capacitor. So far I understand that I need to hook up a transformer in series to the tweeter. What am I aiming for here... What's the low side voltage here and the high side voltage. I understand I need to wind this myself since it's unusual. I'm fully capable of doing that. I'll probably also solder two capacitors together to make a BP cap to protect the tweeter. Can someone give me an approximation of the cap value please so that I can avoid the complicated math?
I will be generating the 20-25Khz tone with an Aliexpress generator. I picked one that exhibited very clean sinusoidal waves at high frequencies in Youtube reviews. I also purchased an inexpensive DIY frequency counter kit so I can dial it in.
Please, no concern trolls or ethicists. Imagine I am doing this for other reasons and not for a dog. I'm also only doing this through drywall and a brick wall that seperates our townhouse. Let me be an idiot for wasting my money on something that's not going to work. Just please help me with the technical aspect of it.
Also, please no lectures on how low and high frequency sound travels. I am a veteran of suffering from low-frequency foot fall (lived in a basement for many years) and am well versed in these subtleties. I have been wearing 31dBm rated ear plugs for more than 15 years when I sleep. I can still hear this miserable hound with them on.
If you can elaborate on which equipment you discovered in the end worked, it would be helpful. Let people experiment for themselves and decide whether it works or not.
There is an anecdote from someone on Youtube who claims dogs "hid behind objects" when he tried this.
So far I understand I would require the following items:
1) Amplifier (in my case I would like to attempt it with 50 to 100 watts). I need something simple, preferably something inexpensive with only a volume control and preferably capable of bridging to mono (so I can save money by buying a 100w unit, where it's 2x50w bridged into one output)
2) Tweeter. One tweeter. I don't require an array of tweeters. My plan is to move my tweeter around the wall to see where it is best to locate it. The dog is in the room on the other side of the wall. All I need to do is find the right spot, as in, closest to the dog. I won't be leaving this on all day, just short bursts when the owner is present there as well, so the owner can take note of what's going on by observing either the dog desperate to get out of the room, or what have you.
3) Transformer, BP capacitor. So far I understand that I need to hook up a transformer in series to the tweeter. What am I aiming for here... What's the low side voltage here and the high side voltage. I understand I need to wind this myself since it's unusual. I'm fully capable of doing that. I'll probably also solder two capacitors together to make a BP cap to protect the tweeter. Can someone give me an approximation of the cap value please so that I can avoid the complicated math?
I will be generating the 20-25Khz tone with an Aliexpress generator. I picked one that exhibited very clean sinusoidal waves at high frequencies in Youtube reviews. I also purchased an inexpensive DIY frequency counter kit so I can dial it in.
Please, no concern trolls or ethicists. Imagine I am doing this for other reasons and not for a dog. I'm also only doing this through drywall and a brick wall that seperates our townhouse. Let me be an idiot for wasting my money on something that's not going to work. Just please help me with the technical aspect of it.
Also, please no lectures on how low and high frequency sound travels. I am a veteran of suffering from low-frequency foot fall (lived in a basement for many years) and am well versed in these subtleties. I have been wearing 31dBm rated ear plugs for more than 15 years when I sleep. I can still hear this miserable hound with them on.
After buying the T10 transformers mentioned in #136 of the thread, I found out that they're not needed.
Most second-hand 100 Watt or even 50 Watt amplifiers on ebay selling for as little as 20 USD will provide the voltage to drive a Piezo tweeter. Piezo tweeters don't need power, just voltage, but without a good data sheet for the Piezo, it's not possible to interpret what the max voltage is. Basically, for a Piezo, the acoustic power out (aka Sound Pressure Level or SPL) is proportional to the ac voltage going into the Piezo, but there is a maximum voltage after which the Piezo crystal will crack.
For wire-wound it's similar, although they take current as well. Once you go beyond max voltage on a wire-wound (and hence max current) the voice-coil will burn out.
Either way, as you get close especially with continuous RMS, they won't stand it for more than a couple of seconds.
The type of data sheets to look for are on #97 in the thread.
I didn't buy the APT-80s because, after finding and buying a couple of the KSN 1165 on #97, I came to the conclusion that you can't ever reach high enough SPL from a single tweeter (a pair only increases it by 3 dB and an array will just cause bad fading).
If you really want to continue to use electrical power to get high SPL, you need amps and speakers that are used at rock concerts !! You need very high SPL leaving the speaker system so as to achieve a high enough SPL at the dog's ears (because the SPL falls away with distance especially at HF, and especially through walls). But I doubt if you'd find rock concert gear that achieves high SPL at 20 kHz.
The cheapest and simplest way to get high acoustic power is using air-horns
e.g. Super Loud 150DB 12V Single Trumpet Air Horn Compressor Truck Lorry Boat Train | eBay
I bought one of those, put it under a wooden box with a car battery and remote controlled relay, and it drove the dogs indoors (dogs had 24/7 use of a dog flap) - but only when the owners were out.
Each situation is different, but from my research, unless you have a LOT of money and time, forget using amplifiers and speakers, you can't get enough acoustic energy out of domestic equipment whether brand new or second-hand. Air driven horns give far better results for far less money and far less messing about. The problem is that you won't find air driven devices above 10 kHz or below 1 kHz because there's no demand. If i knew how to do either, I'd say that 15 Hz would be a safer bet, although it would be huge.
Regarding anything you've heard, or seen on youtube, forget it, it's a myth.
So, as per the thread title "Piezo Tweeter for Dogs" - nope - unless the dog is within a few metres with clear line of sight (and line of sound), then any tweeter, Piezo or conventional wire-wound, will not have any effect. When I've gone into detail on point 3 on #145 you'll see why.
Note that the way to interpret the info on KSN 1165 in #97 ---> 400 W (8 Ohm system reference) is 56 volts i.e. the max voltage that a KSN 1165 will take is 56 volts pk-to-pk , and you won't require a 400 W amp , a 100 W or even a 50 W will give that kind of voltage pk-to-pk into a non-resistive load (such as a Piezo).
Note also that it says sensitivity 93 dB 1m/1W ---> 1 W into an 8 Ohm system reference is 2.8 volts, so 2.8 volts gives 93 dB SPL at 1 metre.
Finally, 400 W is ~26 dB higher than 1 W, so at 56 volts the SPL should be 93 dB + 26 dB = 119 dB at 1 metre. But a 20 kHz tone is an RMS voltage so continuous 56 volts pk-to-pk at 20 kz will crack the KSN 1165 very quickly.
I can't remember the max power of the APT-80 but voltage does not come into the calculations for a conventional wire-wound voice-coil - other than that, max SPL calculation is same i.e. just add the difference between the 1 W reference and the max power, in dB, to the reference SPL
Most second-hand 100 Watt or even 50 Watt amplifiers on ebay selling for as little as 20 USD will provide the voltage to drive a Piezo tweeter. Piezo tweeters don't need power, just voltage, but without a good data sheet for the Piezo, it's not possible to interpret what the max voltage is. Basically, for a Piezo, the acoustic power out (aka Sound Pressure Level or SPL) is proportional to the ac voltage going into the Piezo, but there is a maximum voltage after which the Piezo crystal will crack.
For wire-wound it's similar, although they take current as well. Once you go beyond max voltage on a wire-wound (and hence max current) the voice-coil will burn out.
Either way, as you get close especially with continuous RMS, they won't stand it for more than a couple of seconds.
The type of data sheets to look for are on #97 in the thread.
I didn't buy the APT-80s because, after finding and buying a couple of the KSN 1165 on #97, I came to the conclusion that you can't ever reach high enough SPL from a single tweeter (a pair only increases it by 3 dB and an array will just cause bad fading).
If you really want to continue to use electrical power to get high SPL, you need amps and speakers that are used at rock concerts !! You need very high SPL leaving the speaker system so as to achieve a high enough SPL at the dog's ears (because the SPL falls away with distance especially at HF, and especially through walls). But I doubt if you'd find rock concert gear that achieves high SPL at 20 kHz.
The cheapest and simplest way to get high acoustic power is using air-horns
e.g. Super Loud 150DB 12V Single Trumpet Air Horn Compressor Truck Lorry Boat Train | eBay
I bought one of those, put it under a wooden box with a car battery and remote controlled relay, and it drove the dogs indoors (dogs had 24/7 use of a dog flap) - but only when the owners were out.
Each situation is different, but from my research, unless you have a LOT of money and time, forget using amplifiers and speakers, you can't get enough acoustic energy out of domestic equipment whether brand new or second-hand. Air driven horns give far better results for far less money and far less messing about. The problem is that you won't find air driven devices above 10 kHz or below 1 kHz because there's no demand. If i knew how to do either, I'd say that 15 Hz would be a safer bet, although it would be huge.
Regarding anything you've heard, or seen on youtube, forget it, it's a myth.
So, as per the thread title "Piezo Tweeter for Dogs" - nope - unless the dog is within a few metres with clear line of sight (and line of sound), then any tweeter, Piezo or conventional wire-wound, will not have any effect. When I've gone into detail on point 3 on #145 you'll see why.
Note that the way to interpret the info on KSN 1165 in #97 ---> 400 W (8 Ohm system reference) is 56 volts i.e. the max voltage that a KSN 1165 will take is 56 volts pk-to-pk , and you won't require a 400 W amp , a 100 W or even a 50 W will give that kind of voltage pk-to-pk into a non-resistive load (such as a Piezo).
Note also that it says sensitivity 93 dB 1m/1W ---> 1 W into an 8 Ohm system reference is 2.8 volts, so 2.8 volts gives 93 dB SPL at 1 metre.
Finally, 400 W is ~26 dB higher than 1 W, so at 56 volts the SPL should be 93 dB + 26 dB = 119 dB at 1 metre. But a 20 kHz tone is an RMS voltage so continuous 56 volts pk-to-pk at 20 kz will crack the KSN 1165 very quickly.
I can't remember the max power of the APT-80 but voltage does not come into the calculations for a conventional wire-wound voice-coil - other than that, max SPL calculation is same i.e. just add the difference between the 1 W reference and the max power, in dB, to the reference SPL
A “doggie defender” is only going to work at point blank range - sort of like using a snub nose .22 except it won’t get you arrested. I have a need for a new one now, and am considering bullet tweeters now because of the lack of good piezo. The old one with 50-ish volts at 3.5 kHz, gated on and off at a 2Hz rate worked pretty good. A 9 volt battery used to power it. A dynamic tweeter will take a LiFePO4 battery to get similar effect, but at least you can get those now. Being some 10dB more sensitive 10 or 20 volts with appropriate peak to average ratio to keep thermals in check ought to do it.
Going ultrasonic is of no value. Just make sure you’re not on the business end. It hurts. Bad. When it’s clearly audible, any human within earshot will know you mean business with the thing and not fooling a round with that stupid mutt when it’s deployed. The message needs to go all the way up the chain of command.
Going ultrasonic is of no value. Just make sure you’re not on the business end. It hurts. Bad. When it’s clearly audible, any human within earshot will know you mean business with the thing and not fooling a round with that stupid mutt when it’s deployed. The message needs to go all the way up the chain of command.
Has value if you don't want the dog-owner to know you're doing it, and only if it stops the dog barking - which it doesn't
So yes, ultrasonic is futile.
Ears (human, animal, whatever) have lots of resonances scattered all over the place, even into ultrasonics.
Hitting them HURTS.
Even if Ultrasonic, you feel very uncomfortable if they are present, that´s why sweeping/warbling in practice works much better than fixed ones which are hit o miss, at one moment or another they will hit the painful ones.
There are a couple circuits around (some with dual 555 , one for main frequency, the other sweeping it up-down) which are NASTY, then you feed them into any amp you have around and an array of Piezos.
Hitting them HURTS.
Even if Ultrasonic, you feel very uncomfortable if they are present, that´s why sweeping/warbling in practice works much better than fixed ones which are hit o miss, at one moment or another they will hit the painful ones.
There are a couple circuits around (some with dual 555 , one for main frequency, the other sweeping it up-down) which are NASTY, then you feed them into any amp you have around and an array of Piezos.
I swept the Gould generator at various rates between 15 to 20 kHz.
I found a frequency shifter and used that to shift a warbling sound up to 15 to 20 kHz.
I recorded them barking and shifted that up to 15 to 20 kHz.
No difference.
When you see the graphs of dogs' hearing response, you'll see why 20kHz is futile.
Between 10kHz and 20kHz, depending on breed of dog, some breeds (and most cats) do have a less steep roll-off than humans do, but not drastically different. So you may as well experiment on stopping humans from loudly shouting or arguing (the equivalent of barking) - ultrasound won't stop humans shouting or arguing. However, the dominant hearing band for humans and dogs is same as their dominant vocal range - which overlaps considerably and is mainly 1 kHz to 8 kHz. That is why air-horns work.
The major difference between humans and some dog breeds (and most cats) is that the roll-off continues at the same rate from 20 kHz to 30 kHz, whereas humans' hearing dives after 20 kHz.
For a poodle for example, their hearing is about 15 dB down at 30 kHz compared with 4 kHz - but why try to create something powerful at 30 kHz when it's a lot easier at 4 kHz.
The research paper that I found was from 1983, and was part of a long study of comparative hearing which had shown that the ability of different mammals to hear high frequencies was inversely related to the distance between the ears. In particular, the high frequency limit of hearing correlates with the functional distance between the ears, where functional distance is defined as the distance between the ears divided by the speed of sound in the ecological medium they occupy.
In this particular paper, they were looking at whether this variation applies within-species as well. In the screen shot below, 34 is an elephant, 14 is a human, 24 is a dolphin under water, and the result of the range of dogs showed that the cut-off is very close within-species (at around 45kHz).
Don't forget that it's the absolute threshold at high frequency that they were looking for, but there were considerable differences through the rest of the test range (relevant to use of tweeters etc in this forum thread). In the screenshot below, A is a 2 year old female Chihuahua, B is a 4 year old male Dachshund (tested with pinnae pinned back, and with pinnae in normal position, no difference found), C is a 2 year old male Poodle, and E is a 2 year old male Saint Bernard.
Unfortunately there is no 20 kHz test point, because test points start at 4 kHz and go down in octaves to 31.25 Hz, and up in octaves to 16 kHz, 32 kHz and 64 kHz (though they did have more intermediate points between 41 kHz to 47 kHz to find the ultimate cut-off for each of the 4 breeds of dog).
What they did was start by finding the threshold of hearing at 4 or 8 kHz, then find the threshold at the octaves either side by boosting the tone, and it's the boost in dB that's on the y-axis. It was a very sophisticated experiment, both technically, and in the way the dogs were tested.
I've "digitised" that graph and put it into an excel spreadsheet as a table, inverted it, and also put tables of human hearing curves for ITU-R 468, A-weighting, B-weighting, and C-weighting. Then made graphs - next post.
In this particular paper, they were looking at whether this variation applies within-species as well. In the screen shot below, 34 is an elephant, 14 is a human, 24 is a dolphin under water, and the result of the range of dogs showed that the cut-off is very close within-species (at around 45kHz).
Don't forget that it's the absolute threshold at high frequency that they were looking for, but there were considerable differences through the rest of the test range (relevant to use of tweeters etc in this forum thread). In the screenshot below, A is a 2 year old female Chihuahua, B is a 4 year old male Dachshund (tested with pinnae pinned back, and with pinnae in normal position, no difference found), C is a 2 year old male Poodle, and E is a 2 year old male Saint Bernard.
Unfortunately there is no 20 kHz test point, because test points start at 4 kHz and go down in octaves to 31.25 Hz, and up in octaves to 16 kHz, 32 kHz and 64 kHz (though they did have more intermediate points between 41 kHz to 47 kHz to find the ultimate cut-off for each of the 4 breeds of dog).
What they did was start by finding the threshold of hearing at 4 or 8 kHz, then find the threshold at the octaves either side by boosting the tone, and it's the boost in dB that's on the y-axis. It was a very sophisticated experiment, both technically, and in the way the dogs were tested.
I've "digitised" that graph and put it into an excel spreadsheet as a table, inverted it, and also put tables of human hearing curves for ITU-R 468, A-weighting, B-weighting, and C-weighting. Then made graphs - next post.
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In the curves of dogs' hearing in the previous post above, the 0dB reference point is 20 μN/m² (20 micro Newtons per square metre, which is 20 micro Pascals).
This is also the 0 dB reference in all the curves below.
There are several curves available for humans' hearing. These are:
From the last curves it's possible to conclude that
1. Dachsunds have worse hearing than humans
2. St Bernards aren't much better
3. Poodles and Chuhuahuas do have extended hearing but their hearing up to 20kHz is not excessively better than humans - depending on the comparison curves that you use
So if someone wants to build a "sonic weapon" to stop dogs from barking, it's fundamentally important to consider if the frequency range being considered would stop juvenile humans from shouting.
It's only when you get well beyond 20 kHz that the "sonic weapon" is going to be inaudible to ALL humans, but, the difficulty of creating such a "sonic weapon" that works are huge.
For example, 30 kHz (completely inaudible to any human) at a distance of e.g. 8 metres LoS from e.g. a chuhuahua, assuming that the dog barks at 90 dB where its own ears are, is going to require a power at 1 metre from the device of over +120 dB to reach the dog's ears at higher SPL than its own bark is to itself. Getting that SPL out of any device at 30 kHz, in a beam that will carry through the air over just 8 metres, is the stuff of science-fiction IMO.
More on the KSN-1165 to follow later (I obtained 4)
This is also the 0 dB reference in all the curves below.
There are several curves available for humans' hearing. These are:
- ISO 226:2003 equal-loudness curves (revised Fletcher–Munson curves of 1933). These curves are almost always illustrated with dotted lines estimating a complete dive at 20 kHz
2. A, B, C, D weighting curves (also originally based on Fletcher–Munson curves). Note that weighting curves are the inverse of threshold of hearing curves.
3. ITU-R 468 weighting filter curve (originally developed by the BBC and still used in the UK, Europe, and countries such as Australia and South Africa).
The graphs below compare the lowest of the ISO 226:2003 curves (red) with A-weighting (blue) and with ITU-R 468 (black)
Note that in the avove 3 curves the x-axis is logarithmic whereas in the following Excel graphs the x-axis is linear
From tables available online, I've reconstructed the weighting curves of A, B, C, and ITU-R 468 in Excel, shown below.
From the dogs' hearing curves I've created a table in Excel and produced the graphs below (inverted to compare with the weighting curves)
Finally, a comparison of the dogs' hearing with ITU-R 468 and A-weighting
From the last curves it's possible to conclude that
1. Dachsunds have worse hearing than humans
2. St Bernards aren't much better
3. Poodles and Chuhuahuas do have extended hearing but their hearing up to 20kHz is not excessively better than humans - depending on the comparison curves that you use
So if someone wants to build a "sonic weapon" to stop dogs from barking, it's fundamentally important to consider if the frequency range being considered would stop juvenile humans from shouting.
It's only when you get well beyond 20 kHz that the "sonic weapon" is going to be inaudible to ALL humans, but, the difficulty of creating such a "sonic weapon" that works are huge.
For example, 30 kHz (completely inaudible to any human) at a distance of e.g. 8 metres LoS from e.g. a chuhuahua, assuming that the dog barks at 90 dB where its own ears are, is going to require a power at 1 metre from the device of over +120 dB to reach the dog's ears at higher SPL than its own bark is to itself. Getting that SPL out of any device at 30 kHz, in a beam that will carry through the air over just 8 metres, is the stuff of science-fiction IMO.
More on the KSN-1165 to follow later (I obtained 4)
Caramello, thanks for your fantastic information, you saved me a lot of money.
I was going to get an air horn, but I wanted something better than a tiny compressor thay they come with. So I looked into a 120V compressor and tank, for more capacity, but concluded that price/quality ratio just wasn't there. All the reviews suggested that modern compressors just don't last like they used to.
So I settled on the small 12V compressor the air horn kits come with, but I wanted something better than a 12v SLA battery. So I looked into a power supply... Apparently, these tiny compressors draw an immense amount of current initially, nothing any reasonably economical PSU could offer...
I was going to head to the hardware store yesterday but voila, somehow word got around to the neighbour that this was incredibly irritating, and they moved their dog somewhere else in the house. So I can only hear it barking very faintly now from the depths of its abode.
Again, I want to thank you and I will keep referencing this thread for future posts from you. The air horn is still something I plan on building. But I can take my time now to build something of better quality by shopping around in the used market for quality components. Cheers.
I was going to get an air horn, but I wanted something better than a tiny compressor thay they come with. So I looked into a 120V compressor and tank, for more capacity, but concluded that price/quality ratio just wasn't there. All the reviews suggested that modern compressors just don't last like they used to.
So I settled on the small 12V compressor the air horn kits come with, but I wanted something better than a 12v SLA battery. So I looked into a power supply... Apparently, these tiny compressors draw an immense amount of current initially, nothing any reasonably economical PSU could offer...
I was going to head to the hardware store yesterday but voila, somehow word got around to the neighbour that this was incredibly irritating, and they moved their dog somewhere else in the house. So I can only hear it barking very faintly now from the depths of its abode.
Again, I want to thank you and I will keep referencing this thread for future posts from you. The air horn is still something I plan on building. But I can take my time now to build something of better quality by shopping around in the used market for quality components. Cheers.
Although those compressors are tiny, those air-horns do not require a lot of pressure or flow-rate, because they have a very high efficiency of air in vs SPL out. Indeed, church organs similarly don't have a high pressure. If you were to replace the compressor that comes with the air-horn, with a large tank, you'd need to source a regulator that could regulate to a very low pressure - if you didn't it would probably destroy the diaphragm inside the horn. A good analogy is with volts and amps, where air pressure is volts, and flow-rate is current - the horn is low volts and low current. If you exceed the pressure (volts) you'll destroy it - just as with a piezo tweeter. Also, if you lengthen the pipe that comes with the air-horn kit, it won't work - this would be like using extremely long and thin wire to a piezo tweeter. The point is that the compressor and pipe and horn are all "matched" very precisely.
This Homemade PVC air ship horn probably does have a high pressure and certainly a high flow-rate, but the diaphragm is probably bigger and more rigid - that's how you get a deeper note and extreme SPL.
Going back to "Super Loud 150DB 12V Single Trumpet Air Horn Compressor" note that when they claim "150 dB", well that's probably in the throat of the horn. I measured a narrow peak of 105 dB at 4 metres, which is still very loud. The other thing to point out is that those small compressors are very inefficient when it comes to electrical-power-in versus air-power-out. I don't know what the actual air-power-out is, but the electrical current draw is about 20 Amps, so electrical-power-in is around 240 Watts. I did source a 12 volts SLA on ebay, the one I found was a Power Sonic PS-1270 which was 7 Ah, and the spec sheet says Max Discharge Current (7 Minutes) 21 Amps. The cost of an SLA like that, plus a simple "old-fashioned" car trickle-charger (no fancy lights and gizmos), is far less than the cost of a home-brew PSU that can deliver true 20 Amps DC at 12 Volts.
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I ought to point out that "up to 20 kHz" applies to 1 and 2 and 3, and in 3 by "extended" I really mean "elevated".
I'll add more on the KSN-1165 when I've collated the pictures and thoughts (I should have written this up in November 2018 when I'd started to conclude that it's all a myth)
This Homemade PVC air ship horn probably does have a high pressure and certainly a high flow-rate, but the diaphragm is probably bigger and more rigid - that's how you get a deeper note and extreme SPL.
Going back to "Super Loud 150DB 12V Single Trumpet Air Horn Compressor" note that when they claim "150 dB", well that's probably in the throat of the horn. I measured a narrow peak of 105 dB at 4 metres, which is still very loud. The other thing to point out is that those small compressors are very inefficient when it comes to electrical-power-in versus air-power-out. I don't know what the actual air-power-out is, but the electrical current draw is about 20 Amps, so electrical-power-in is around 240 Watts. I did source a 12 volts SLA on ebay, the one I found was a Power Sonic PS-1270 which was 7 Ah, and the spec sheet says Max Discharge Current (7 Minutes) 21 Amps. The cost of an SLA like that, plus a simple "old-fashioned" car trickle-charger (no fancy lights and gizmos), is far less than the cost of a home-brew PSU that can deliver true 20 Amps DC at 12 Volts.
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I ought to point out that "up to 20 kHz" applies to 1 and 2 and 3, and in 3 by "extended" I really mean "elevated".
I'll add more on the KSN-1165 when I've collated the pictures and thoughts (I should have written this up in November 2018 when I'd started to conclude that it's all a myth)