Hello, I am looking for powerful tweeters to reproduce sound at 30KHz, 40KHz, 50KHz. I would hope to be able to push at least 20W on each tweeter. I do not care about voltages, as I use a custom transformer so I can modify the output of the amplifier to produce the voltages needed.
I know that audio tweeters have a rapidly dropping response over 20KHz or so. If you happen to know of any that can go up to 60KHz without terrible power losses please let me know.
I know that audio tweeters have a rapidly dropping response over 20KHz or so. If you happen to know of any that can go up to 60KHz without terrible power losses please let me know.
Just to check: you want 130-140dB SPL at 50kHz? A pneumatic siren would seem a straightforward way to do it.
Is it correct to call 30KHz and above sound ... Is sound not something we hear???.. Maybe a plasma tweeter can do that frequency ??
Since some other animals seem to be able to hear or perceive pressure waves at those frequencies then it seems reasonable enough to call it sound. I certainly don't think it would be straining the meaning to use the term in this way, after all we humans are not the only beings capable of this kind of perception.
I see so it is correct to call it sound. Other animals do not know what sound is .. And if it is to be used to scare away animals how would you like to be sat in a room with 130db of 1 kHz blasted at you .. Remember we created the barriers not defenceless animals ..
I never said anything about how we should or should not treat other animals, but at least if we think if those things as sounds it may prompt us to ask about the kinds of consequences our actions may have for other animals in just the manner that you have outlined, and that could well be a good thing (at least for other animals). 😉
I did not mention dogs barking anywhere, did I?
I have found by searching on the internet, that there is a lot of research, projects, whole web sites, dedicated to ultrasonic dog repellers, some are really very sophisticated with automatic bark detection over a period of time, automatic stop when dog stops barking, frequency switching and so on.
Within a couple of hours searching I have found posts from Holland, Italy, Texas, Canada, UK. The problem of neighbours and their barking dogs (or their trees in my case) is very prevalent.
A web site I just visited informs that the problem many times is the dog owner and not the dog, so you can adjust the machine to hit the owner (lower frequencies).
I just tried some cheap piezo tweeters from ebay, really rubbish, because I cannot hear it I have no way of telling if they are producing a nice wave or completely distorting it, so I do not know what power level to feed them with. I tried 1W and 7W at my cat at 40KHz and 60KHz, she runs away at 3-4 metres, but does not get bothered at 8 metres.
I have found by searching on the internet, that there is a lot of research, projects, whole web sites, dedicated to ultrasonic dog repellers, some are really very sophisticated with automatic bark detection over a period of time, automatic stop when dog stops barking, frequency switching and so on.
Within a couple of hours searching I have found posts from Holland, Italy, Texas, Canada, UK. The problem of neighbours and their barking dogs (or their trees in my case) is very prevalent.
A web site I just visited informs that the problem many times is the dog owner and not the dog, so you can adjust the machine to hit the owner (lower frequencies).
I just tried some cheap piezo tweeters from ebay, really rubbish, because I cannot hear it I have no way of telling if they are producing a nice wave or completely distorting it, so I do not know what power level to feed them with. I tried 1W and 7W at my cat at 40KHz and 60KHz, she runs away at 3-4 metres, but does not get bothered at 8 metres.
Whut? You have a problem with your neigbour's trees?
I don't think these things work as tree repellers.
Your best bet might be an array of ultrasonic transducers like the ones used for parking aids, ultrasonic alarms etc. Murata is one manufacturer of those but there are others as well. They can achieve quite high SPLS and in an array they will be highly directive.
Regards
Charles
Edit: Forgot to mention that they are narrow bandwidth.
Regards
Charles
Edit: Forgot to mention that they are narrow bandwidth.
From what I see these are tiny devices with an effective range of a couple of metres at best. The "commercial" repelers I have seen use arrays of cheap piezo tweeters, like 16 or more. I need a way to determine how much power those tweeters can deliver at a given frequency without distorting. I think the only way to do that is to have a microphone pick up the emitted sound and check the curve on the scope. And the microphone and mic amp must have a flat frequency response all the way up to 60KHz.
There are some +/- 3 dB out to 40 kHz. But do you want any resolution to go with that, like specific restricted frequencies, whether changing or simple constant tone? Or would you be happy just blatting out some hi-F noise? Anything operating in the range you mention and doing anything useful is using ultrasonic transducers, not "sound" drivers.
The Murata MA40S4S for instance can generate about 110 dB @ 1m with 10 Volts of input. In a large array this would give quite some SPL.
Apart from that you cant't transmit sound too far at ultrasonic frequencies due to absorbtion in the air.
One thing you could try at ultrasonic frequncies is running the piezo tweeter(s) without the horn - or even use the bare piezo element only.
Regards
Charles
Apart from that you cant't transmit sound too far at ultrasonic frequencies due to absorbtion in the air.
One thing you could try at ultrasonic frequncies is running the piezo tweeter(s) without the horn - or even use the bare piezo element only.
Regards
Charles
One of the sonic weapons developed used just that kind of array, I believe 48 piezo elements clustered on a flat baffle to approximate a planar wave front. However the production model LRAD fires 2.5 kHz due to said absorption.
This question is asked annually in one forum or another and nobody ever seems to get a good enough answer to develop anything useful, so I'd have to conclude the answer is "no".
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