Regarding the tin can effect:
The Tectonic video said "oil can" not tin can. Tin can has negative connotations like a tin ear. All he meant by oil can was the physical size of the exciter contact point itself. The physical size of the piston pushing against the panel is a lower limit on how small the initial pulse can shrink. If you cluster exciters into a group the minimum "oil can" size increases.
Thus, you get beaming because you're playing higher (shorter) frequencies from a surface area larger than the frequency lengths. But can you actually hear it? No, because the modal radiation comes immediately after the initial oil can impulse. Measurement mics can make it visible on a graph but we can't hear it with our ears.
It's possible that any beaming that does occur is beyond our hearing anyway. IOW, not only can you not hear it, but you can't even hear it if you could hear it.
The Tectonic video said "oil can" not tin can. Tin can has negative connotations like a tin ear. All he meant by oil can was the physical size of the exciter contact point itself. The physical size of the piston pushing against the panel is a lower limit on how small the initial pulse can shrink. If you cluster exciters into a group the minimum "oil can" size increases.
Thus, you get beaming because you're playing higher (shorter) frequencies from a surface area larger than the frequency lengths. But can you actually hear it? No, because the modal radiation comes immediately after the initial oil can impulse. Measurement mics can make it visible on a graph but we can't hear it with our ears.
It's possible that any beaming that does occur is beyond our hearing anyway. IOW, not only can you not hear it, but you can't even hear it if you could hear it.
Burntcoil.
I read this paper some time ago and was not impressed,the last sentence of the paper says it all !!
He uses computer speakers and compares the sound.????
What a waste of time, I've read others like this,life is too short.
As for Gobel panels, yet another heavily damped panel ,I don't even need to hear it ,I know it will not satisfy me,I'm sure it sounds fine but that's not good enough.
He's using 9 layers of special materials ,glued together,slots cut into the panel and filled with damping material to control bad resonances and to extend fr ,say no more.
If I need to turn an empty milk carton into a speaker I might give it a re-read
I hope you understand that I'm just trying to make everyone aware that there is no free lunch when it comes to manipulating a panel.
Steve
I read this paper some time ago and was not impressed,the last sentence of the paper says it all !!
He uses computer speakers and compares the sound.????
What a waste of time, I've read others like this,life is too short.
As for Gobel panels, yet another heavily damped panel ,I don't even need to hear it ,I know it will not satisfy me,I'm sure it sounds fine but that's not good enough.
He's using 9 layers of special materials ,glued together,slots cut into the panel and filled with damping material to control bad resonances and to extend fr ,say no more.
If I need to turn an empty milk carton into a speaker I might give it a re-read
I hope you understand that I'm just trying to make everyone aware that there is no free lunch when it comes to manipulating a panel.
Steve
@Spedge
I am pretty certain that the poor lad who produced the paper has regretted putting that milk carton on the front page every day since it was published. I am sure he thought it was just a bit of fun, a nice way to add some personality to a dry topic. He might even had some 'advice' from his marketing flat mate who went on to form a PR consultancy and earn ten times more than an honest engineer. It would be a shame to ignore all his hard work for a foolish error. I did much worse when I was at uni and have not received anything like the brickbats he must have received although the way today is panning out that might just be a matter of time. Maybe Perfect Curve could find a role for me?
YouTube
I am pretty certain that the poor lad who produced the paper has regretted putting that milk carton on the front page every day since it was published. I am sure he thought it was just a bit of fun, a nice way to add some personality to a dry topic. He might even had some 'advice' from his marketing flat mate who went on to form a PR consultancy and earn ten times more than an honest engineer. It would be a shame to ignore all his hard work for a foolish error. I did much worse when I was at uni and have not received anything like the brickbats he must have received although the way today is panning out that might just be a matter of time. Maybe Perfect Curve could find a role for me?
YouTube
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That milk carton paper is nothing new. After all that talk all he could say to improve on a DML panel is EQ. LOL
He also states this>In short, DML still has a long way to go to be as satisfiable as the conventional electro-magnetic loudspeaker in practice.
Which just proves his design sucks. LOL
There is some truth to his article though you just have to know which ones is truth and which ones are not. Since some of you act like you know it all you should be able to figure it out on your own especially since someone told me that I don't understand how DML's work. LOL
He also states this>In short, DML still has a long way to go to be as satisfiable as the conventional electro-magnetic loudspeaker in practice.
Which just proves his design sucks. LOL
There is some truth to his article though you just have to know which ones is truth and which ones are not. Since some of you act like you know it all you should be able to figure it out on your own especially since someone told me that I don't understand how DML's work. LOL
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Bradleypnw.
You are getting your primary drive mixed up with your tin can oops sorry oil can, the beeming from within the coil area is easy to hear and measure ,the centre is like a tweeter ,but a very bad tweeter ,there are a lot of cancellations and peaks causing distortions which are not very pleasant to listen to.
I regard this area within the coil foot or what ever he calls it, to be very important to the panel sound , causing a harshness to the sound and a lack of detail.
The primary drive area is the area that produces the initial pulse that radiates outwards through the panel ,the oil can radiates inwards from the coil.
Steve
You are getting your primary drive mixed up with your tin can oops sorry oil can, the beeming from within the coil area is easy to hear and measure ,the centre is like a tweeter ,but a very bad tweeter ,there are a lot of cancellations and peaks causing distortions which are not very pleasant to listen to.
I regard this area within the coil foot or what ever he calls it, to be very important to the panel sound , causing a harshness to the sound and a lack of detail.
The primary drive area is the area that produces the initial pulse that radiates outwards through the panel ,the oil can radiates inwards from the coil.
Steve
Gapmedia.
At last somebody has noticed the problem and tried to fix it,I did see a cheep computer type speaker with the centre area of the coil cut out,but that's about it,I have experimented with cutting the centre out but I found it caused more problems than it solved.
Thinner lighter panels have more of a problem in this area as you also have the cavity noise behind the panel within the exciter coil causing noise,so it's a double whammy,but ply does suffer too.
Steve
At last somebody has noticed the problem and tried to fix it,I did see a cheep computer type speaker with the centre area of the coil cut out,but that's about it,I have experimented with cutting the centre out but I found it caused more problems than it solved.
Thinner lighter panels have more of a problem in this area as you also have the cavity noise behind the panel within the exciter coil causing noise,so it's a double whammy,but ply does suffer too.
Steve
Steve,
The Blu Tack smoothes a bump/rise in the frequency responce around 300 - 400hz I think. I can't remember exactly, I'll see if I can find the measurements I made with REW at the time. The size of the 'blob' had a definite effect on the result. A flattened piece the size of a small marble worked best for me. It is slightly smaller than the internal circumference of the voicecoil. I tried different size blobs at different places on the (lighter) diaphragm when testing, and settled on a single blob at the centre of the voicecoil as the best option.
Maybe a circular piece of soft foam or similar placed snuggly in the centre of the voicecoil before mounting to the diaphragm might help? Possibly glued to the rear of the diaphragm as well? Sadly, I epoxy my exciters on to eliminate buzzing so removing and trying this out is not that easy on the panels I have.
The Blu Tack smoothes a bump/rise in the frequency responce around 300 - 400hz I think. I can't remember exactly, I'll see if I can find the measurements I made with REW at the time. The size of the 'blob' had a definite effect on the result. A flattened piece the size of a small marble worked best for me. It is slightly smaller than the internal circumference of the voicecoil. I tried different size blobs at different places on the (lighter) diaphragm when testing, and settled on a single blob at the centre of the voicecoil as the best option.
Maybe a circular piece of soft foam or similar placed snuggly in the centre of the voicecoil before mounting to the diaphragm might help? Possibly glued to the rear of the diaphragm as well? Sadly, I epoxy my exciters on to eliminate buzzing so removing and trying this out is not that easy on the panels I have.
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Gapmedia.
The problems I'm talking about are mainly in the 8k to go to 20k depending on the panel,I do wonder if this is why tectonic xo below this fr on their main panels?
I used to use blu tack on my eps panels, but only a very small amount ,even tried using thin strips.
The coil ring and foot are the main culprits plus the cavity resonance.
Exciting the panel from a single point would be a better option ,but that would mean 're-designing the exciter.
Steve
The problems I'm talking about are mainly in the 8k to go to 20k depending on the panel,I do wonder if this is why tectonic xo below this fr on their main panels?
I used to use blu tack on my eps panels, but only a very small amount ,even tried using thin strips.
The coil ring and foot are the main culprits plus the cavity resonance.
Exciting the panel from a single point would be a better option ,but that would mean 're-designing the exciter.
Steve
In my case, the I.D. of the exciter voice coil measures 19mm. That means it would have the potential to beam above 18,000hz. However, adults can't hear anything over 15-17,000hz range.
If you were going to get audible beaming you'd need a surface larger than the wavelength of frequencies you could hear. Consequently, the beaming would have to come from the panel surface driven by the exciter.
Of course, the panel surface is heavier than a typical tweeter membrane. I'd guess that means the modal radiation dominates at those frequencies. Plus, the modal radiation comes immediately after the initial pulse so you wouldn't be able to distinguish one from the other anyway.
If you were going to get audible beaming you'd need a surface larger than the wavelength of frequencies you could hear. Consequently, the beaming would have to come from the panel surface driven by the exciter.
Of course, the panel surface is heavier than a typical tweeter membrane. I'd guess that means the modal radiation dominates at those frequencies. Plus, the modal radiation comes immediately after the initial pulse so you wouldn't be able to distinguish one from the other anyway.
Bradleypnw.
Are you seriously saying that a 19mm tweeter only beams above 18k ,and it doesn't matter because we can't hear it!!
All those people complaining about tweeters beaming and they don't realise they can t hear it,amazing.
Not that it has anything to do with the distortions causes by what I call the tin can effect.
Stdve
Are you seriously saying that a 19mm tweeter only beams above 18k ,and it doesn't matter because we can't hear it!!
All those people complaining about tweeters beaming and they don't realise they can t hear it,amazing.
Not that it has anything to do with the distortions causes by what I call the tin can effect.
Stdve
Burnt,
I assume you mean you can test for yourself what frequency is the highest you personally can hear, right?
From using tone generators and testing panels I can tell my top end is close to about 12 Khz. Over that, the mic and FFT will be picking up a strong signal sometimes, but I don't hear it.
Nearby in Philadelphia they use high frequency noise (17.4 kHz) to keep vandals out of the parks at night. Apparently they assume the vandals are all under 25 years old and can still hear that frequency.
Eric
No. I said a diameter of 19mm can only beam at frequencies above 18,000hz. Below 18,000hz the frequencies are longer than the radiation surface. In addition, adults can't hear anything above 15-17,000hz.
In other words, all I'm saying is people are either imagining things or they are misidentifying whatever it is they are hearing. If someone doesn't accurately identify the problem they'll keep running around in circles.
In other words, all I'm saying is people are either imagining things or they are misidentifying whatever it is they are hearing. If someone doesn't accurately identify the problem they'll keep running around in circles.
Or play a tone above 17,000hz and watch your dog's ears perk up while you don't hear a thing. Just don't play it too loud.
Yes. I don’t hear anything over 12kHz either so you may find me in a park at night. 😊
Burnt
I had to look that up. If I ever need to usher youngn's away I'll know what to do. Wait a moment, I'm wondering if I should do this with my car.
Sonic Devices Target Teenagers In Philadelphia : NPR