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#1
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Speaker directivity
Provided that the model for a circular piston-type radiator is an adequate
tool for measuring the directivity of normal home or monitor speakers, how does one calculate an approximation of how the different frequencies are spread from the speaker cone? Is there any easy way of doing that, since I consider myself as a mathematically semi-challenged person? g I know the directivity is a by-product of the speaker cone's radius, however, some people say that "the radius of the cone must be at least 1/4th of the frequency's wavelenght in order for it to not radiate it spherically", while others say that the truth is closer to a situation where a normal speaker cone's radius has to be almost as large as the wavelenght itself in order for it to prevent radiating the frequency in all directions. Thanks for all the answers. |
#2
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Speaker directivity
Tommi wrote:
Provided that the model for a circular piston-type radiator is an adequate tool for measuring the directivity of normal home or monitor speakers, how does one calculate an approximation of how the different frequencies are spread from the speaker cone? Is there any easy way of doing that, since I consider myself as a mathematically semi-challenged person? g Nope. I know the directivity is a by-product of the speaker cone's radius, however, some people say that "the radius of the cone must be at least 1/4th of the frequency's wavelenght in order for it to not radiate it spherically", while others say that the truth is closer to a situation where a normal speaker cone's radius has to be almost as large as the wavelenght itself in order for it to prevent radiating the frequency in all directions. Sorry, we don't discuss that here because it might call into question the need for other kinds of precision we pride ourselves on. :-) Bob -- "Things should be described as simply as possible, but no simpler." A. Einstein |
#3
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Speaker directivity
Tommi wrote:
Provided that the model for a circular piston-type radiator is an adequate tool for measuring the directivity of normal home or monitor speakers, how does one calculate an approximation of how the different frequencies are spread from the speaker cone? Is there any easy way of doing that, since I consider myself as a mathematically semi-challenged person? g Nope. I know the directivity is a by-product of the speaker cone's radius, however, some people say that "the radius of the cone must be at least 1/4th of the frequency's wavelenght in order for it to not radiate it spherically", while others say that the truth is closer to a situation where a normal speaker cone's radius has to be almost as large as the wavelenght itself in order for it to prevent radiating the frequency in all directions. Sorry, we don't discuss that here because it might call into question the need for other kinds of precision we pride ourselves on. :-) Bob -- "Things should be described as simply as possible, but no simpler." A. Einstein |
#4
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Speaker directivity
Tommi wrote:
Provided that the model for a circular piston-type radiator is an adequate tool for measuring the directivity of normal home or monitor speakers, how does one calculate an approximation of how the different frequencies are spread from the speaker cone? Is there any easy way of doing that, since I consider myself as a mathematically semi-challenged person? g Nope. I know the directivity is a by-product of the speaker cone's radius, however, some people say that "the radius of the cone must be at least 1/4th of the frequency's wavelenght in order for it to not radiate it spherically", while others say that the truth is closer to a situation where a normal speaker cone's radius has to be almost as large as the wavelenght itself in order for it to prevent radiating the frequency in all directions. Sorry, we don't discuss that here because it might call into question the need for other kinds of precision we pride ourselves on. :-) Bob -- "Things should be described as simply as possible, but no simpler." A. Einstein |
#5
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Speaker directivity
Tommi wrote:
Provided that the model for a circular piston-type radiator is an adequate tool for measuring the directivity of normal home or monitor speakers, how does one calculate an approximation of how the different frequencies are spread from the speaker cone? Is there any easy way of doing that, since I consider myself as a mathematically semi-challenged person? g Nope. I know the directivity is a by-product of the speaker cone's radius, however, some people say that "the radius of the cone must be at least 1/4th of the frequency's wavelenght in order for it to not radiate it spherically", while others say that the truth is closer to a situation where a normal speaker cone's radius has to be almost as large as the wavelenght itself in order for it to prevent radiating the frequency in all directions. Sorry, we don't discuss that here because it might call into question the need for other kinds of precision we pride ourselves on. :-) Bob -- "Things should be described as simply as possible, but no simpler." A. Einstein |
#6
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Speaker directivity
Tommi wrote:
Provided that the model for a circular piston-type radiator is an adequate tool for measuring the directivity of normal home or monitor speakers, how does one calculate an approximation of how the different frequencies are spread from the speaker cone? Is there any easy way of doing that, since I consider myself as a mathematically semi-challenged person? g Nope. I know the directivity is a by-product of the speaker cone's radius, however, some people say that "the radius of the cone must be at least 1/4th of the frequency's wavelenght in order for it to not radiate it spherically", while others say that the truth is closer to a situation where a normal speaker cone's radius has to be almost as large as the wavelenght itself in order for it to prevent radiating the frequency in all directions. Sorry, we don't discuss that here because it might call into question the need for other kinds of precision we pride ourselves on. :-) Bob -- "Things should be described as simply as possible, but no simpler." A. Einstein |
#7
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Speaker directivity
On Mon, 19 Apr 2004 01:44:07 +0300, "Tommi"
wrote: Provided that the model for a circular piston-type radiator is an adequate tool for measuring the directivity of normal home or monitor speakers, how does one calculate an approximation of how the different frequencies are spread from the speaker cone? Is there any easy way of doing that, since I consider myself as a mathematically semi-challenged person? g I know the directivity is a by-product of the speaker cone's radius, however, some people say that "the radius of the cone must be at least 1/4th of the frequency's wavelenght in order for it to not radiate it spherically", while others say that the truth is closer to a situation where a normal speaker cone's radius has to be almost as large as the wavelenght itself in order for it to prevent radiating the frequency in all directions. Try to find a copy of Martin Colloms' High Performance Loudspeakers, which contains all the information most people will ever need about loudspeakers. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#8
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Speaker directivity
On Mon, 19 Apr 2004 01:44:07 +0300, "Tommi"
wrote: Provided that the model for a circular piston-type radiator is an adequate tool for measuring the directivity of normal home or monitor speakers, how does one calculate an approximation of how the different frequencies are spread from the speaker cone? Is there any easy way of doing that, since I consider myself as a mathematically semi-challenged person? g I know the directivity is a by-product of the speaker cone's radius, however, some people say that "the radius of the cone must be at least 1/4th of the frequency's wavelenght in order for it to not radiate it spherically", while others say that the truth is closer to a situation where a normal speaker cone's radius has to be almost as large as the wavelenght itself in order for it to prevent radiating the frequency in all directions. Try to find a copy of Martin Colloms' High Performance Loudspeakers, which contains all the information most people will ever need about loudspeakers. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#9
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Speaker directivity
On Mon, 19 Apr 2004 01:44:07 +0300, "Tommi"
wrote: Provided that the model for a circular piston-type radiator is an adequate tool for measuring the directivity of normal home or monitor speakers, how does one calculate an approximation of how the different frequencies are spread from the speaker cone? Is there any easy way of doing that, since I consider myself as a mathematically semi-challenged person? g I know the directivity is a by-product of the speaker cone's radius, however, some people say that "the radius of the cone must be at least 1/4th of the frequency's wavelenght in order for it to not radiate it spherically", while others say that the truth is closer to a situation where a normal speaker cone's radius has to be almost as large as the wavelenght itself in order for it to prevent radiating the frequency in all directions. Try to find a copy of Martin Colloms' High Performance Loudspeakers, which contains all the information most people will ever need about loudspeakers. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#10
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Speaker directivity
On Mon, 19 Apr 2004 01:44:07 +0300, "Tommi"
wrote: Provided that the model for a circular piston-type radiator is an adequate tool for measuring the directivity of normal home or monitor speakers, how does one calculate an approximation of how the different frequencies are spread from the speaker cone? Is there any easy way of doing that, since I consider myself as a mathematically semi-challenged person? g I know the directivity is a by-product of the speaker cone's radius, however, some people say that "the radius of the cone must be at least 1/4th of the frequency's wavelenght in order for it to not radiate it spherically", while others say that the truth is closer to a situation where a normal speaker cone's radius has to be almost as large as the wavelenght itself in order for it to prevent radiating the frequency in all directions. Try to find a copy of Martin Colloms' High Performance Loudspeakers, which contains all the information most people will ever need about loudspeakers. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#11
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Speaker directivity
On Mon, 19 Apr 2004 01:44:07 +0300, "Tommi"
wrote: Provided that the model for a circular piston-type radiator is an adequate tool for measuring the directivity of normal home or monitor speakers, how does one calculate an approximation of how the different frequencies are spread from the speaker cone? Is there any easy way of doing that, since I consider myself as a mathematically semi-challenged person? g I know the directivity is a by-product of the speaker cone's radius, however, some people say that "the radius of the cone must be at least 1/4th of the frequency's wavelenght in order for it to not radiate it spherically", while others say that the truth is closer to a situation where a normal speaker cone's radius has to be almost as large as the wavelenght itself in order for it to prevent radiating the frequency in all directions. Try to find a copy of Martin Colloms' High Performance Loudspeakers, which contains all the information most people will ever need about loudspeakers. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#12
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Speaker directivity
"Tommi" wrote in message ... Provided that the model for a circular piston-type radiator is an adequate tool for measuring the directivity of normal home or monitor speakers, how does one calculate an approximation of how the different frequencies are spread from the speaker cone? Is there any easy way of doing that, since I consider myself as a mathematically semi-challenged person? g I know the directivity is a by-product of the speaker cone's radius, however, some people say that "the radius of the cone must be at least 1/4th of the frequency's wavelenght in order for it to not radiate it spherically", while others say that the truth is closer to a situation where a normal speaker cone's radius has to be almost as large as the wavelenght itself in order for it to prevent radiating the frequency in all directions. Thanks for all the answers. It depends on a few assumptions.... What you mean by non-directional and what is satisfactorily non-directional.... are you refering to 45 degrees off axis? more? less? Unibox "suggests" 350Hz as being the "right" point for a 15" loudspeaker which is roughly D=1/4 wavelength Eminence recomends 700Hz for it's 15" speakers... r=1/4 wavelength... The "correct" answer is that it depends on your purposes.... For the 15" example, below 350Hz the response is excellent at 45 degrees off axis and up to 700Hz it's barely perceptible at 45 degrees... cb |
#13
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Speaker directivity
"Tommi" wrote in message ... Provided that the model for a circular piston-type radiator is an adequate tool for measuring the directivity of normal home or monitor speakers, how does one calculate an approximation of how the different frequencies are spread from the speaker cone? Is there any easy way of doing that, since I consider myself as a mathematically semi-challenged person? g I know the directivity is a by-product of the speaker cone's radius, however, some people say that "the radius of the cone must be at least 1/4th of the frequency's wavelenght in order for it to not radiate it spherically", while others say that the truth is closer to a situation where a normal speaker cone's radius has to be almost as large as the wavelenght itself in order for it to prevent radiating the frequency in all directions. Thanks for all the answers. It depends on a few assumptions.... What you mean by non-directional and what is satisfactorily non-directional.... are you refering to 45 degrees off axis? more? less? Unibox "suggests" 350Hz as being the "right" point for a 15" loudspeaker which is roughly D=1/4 wavelength Eminence recomends 700Hz for it's 15" speakers... r=1/4 wavelength... The "correct" answer is that it depends on your purposes.... For the 15" example, below 350Hz the response is excellent at 45 degrees off axis and up to 700Hz it's barely perceptible at 45 degrees... cb |
#14
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Speaker directivity
"Tommi" wrote in message ... Provided that the model for a circular piston-type radiator is an adequate tool for measuring the directivity of normal home or monitor speakers, how does one calculate an approximation of how the different frequencies are spread from the speaker cone? Is there any easy way of doing that, since I consider myself as a mathematically semi-challenged person? g I know the directivity is a by-product of the speaker cone's radius, however, some people say that "the radius of the cone must be at least 1/4th of the frequency's wavelenght in order for it to not radiate it spherically", while others say that the truth is closer to a situation where a normal speaker cone's radius has to be almost as large as the wavelenght itself in order for it to prevent radiating the frequency in all directions. Thanks for all the answers. It depends on a few assumptions.... What you mean by non-directional and what is satisfactorily non-directional.... are you refering to 45 degrees off axis? more? less? Unibox "suggests" 350Hz as being the "right" point for a 15" loudspeaker which is roughly D=1/4 wavelength Eminence recomends 700Hz for it's 15" speakers... r=1/4 wavelength... The "correct" answer is that it depends on your purposes.... For the 15" example, below 350Hz the response is excellent at 45 degrees off axis and up to 700Hz it's barely perceptible at 45 degrees... cb |
#15
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Speaker directivity
"Tommi" wrote in message ... Provided that the model for a circular piston-type radiator is an adequate tool for measuring the directivity of normal home or monitor speakers, how does one calculate an approximation of how the different frequencies are spread from the speaker cone? Is there any easy way of doing that, since I consider myself as a mathematically semi-challenged person? g I know the directivity is a by-product of the speaker cone's radius, however, some people say that "the radius of the cone must be at least 1/4th of the frequency's wavelenght in order for it to not radiate it spherically", while others say that the truth is closer to a situation where a normal speaker cone's radius has to be almost as large as the wavelenght itself in order for it to prevent radiating the frequency in all directions. Thanks for all the answers. It depends on a few assumptions.... What you mean by non-directional and what is satisfactorily non-directional.... are you refering to 45 degrees off axis? more? less? Unibox "suggests" 350Hz as being the "right" point for a 15" loudspeaker which is roughly D=1/4 wavelength Eminence recomends 700Hz for it's 15" speakers... r=1/4 wavelength... The "correct" answer is that it depends on your purposes.... For the 15" example, below 350Hz the response is excellent at 45 degrees off axis and up to 700Hz it's barely perceptible at 45 degrees... cb |
#16
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Speaker directivity
"Tommi" wrote in message ... Provided that the model for a circular piston-type radiator is an adequate tool for measuring the directivity of normal home or monitor speakers, how does one calculate an approximation of how the different frequencies are spread from the speaker cone? Is there any easy way of doing that, since I consider myself as a mathematically semi-challenged person? g I know the directivity is a by-product of the speaker cone's radius, however, some people say that "the radius of the cone must be at least 1/4th of the frequency's wavelenght in order for it to not radiate it spherically", while others say that the truth is closer to a situation where a normal speaker cone's radius has to be almost as large as the wavelenght itself in order for it to prevent radiating the frequency in all directions. Thanks for all the answers. It depends on a few assumptions.... What you mean by non-directional and what is satisfactorily non-directional.... are you refering to 45 degrees off axis? more? less? Unibox "suggests" 350Hz as being the "right" point for a 15" loudspeaker which is roughly D=1/4 wavelength Eminence recomends 700Hz for it's 15" speakers... r=1/4 wavelength... The "correct" answer is that it depends on your purposes.... For the 15" example, below 350Hz the response is excellent at 45 degrees off axis and up to 700Hz it's barely perceptible at 45 degrees... cb |
#17
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Speaker directivity
"Chris Berry" wrote in message ... It depends on a few assumptions.... What you mean by non-directional and what is satisfactorily non-directional.... are you refering to 45 degrees off axis? more? less? I guess my practical purpose is to find an equation for determining a "directional" frequency for a given speaker, in its widest sense; that being something like much over 100 degrees off axis. Say I have a cone with a 6" radius back against a wall. How do I calculate, roughly at which frequency it starts to radiate sound to the back? |
#18
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Speaker directivity
"Chris Berry" wrote in message ... It depends on a few assumptions.... What you mean by non-directional and what is satisfactorily non-directional.... are you refering to 45 degrees off axis? more? less? I guess my practical purpose is to find an equation for determining a "directional" frequency for a given speaker, in its widest sense; that being something like much over 100 degrees off axis. Say I have a cone with a 6" radius back against a wall. How do I calculate, roughly at which frequency it starts to radiate sound to the back? |
#19
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Speaker directivity
"Chris Berry" wrote in message ... It depends on a few assumptions.... What you mean by non-directional and what is satisfactorily non-directional.... are you refering to 45 degrees off axis? more? less? I guess my practical purpose is to find an equation for determining a "directional" frequency for a given speaker, in its widest sense; that being something like much over 100 degrees off axis. Say I have a cone with a 6" radius back against a wall. How do I calculate, roughly at which frequency it starts to radiate sound to the back? |
#20
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Speaker directivity
"Chris Berry" wrote in message ... It depends on a few assumptions.... What you mean by non-directional and what is satisfactorily non-directional.... are you refering to 45 degrees off axis? more? less? I guess my practical purpose is to find an equation for determining a "directional" frequency for a given speaker, in its widest sense; that being something like much over 100 degrees off axis. Say I have a cone with a 6" radius back against a wall. How do I calculate, roughly at which frequency it starts to radiate sound to the back? |
#21
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Speaker directivity
"Chris Berry" wrote in message ... It depends on a few assumptions.... What you mean by non-directional and what is satisfactorily non-directional.... are you refering to 45 degrees off axis? more? less? I guess my practical purpose is to find an equation for determining a "directional" frequency for a given speaker, in its widest sense; that being something like much over 100 degrees off axis. Say I have a cone with a 6" radius back against a wall. How do I calculate, roughly at which frequency it starts to radiate sound to the back? |
#22
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Speaker directivity
On Mon, 19 Apr 2004 18:08:13 +0300, "Tommi"
wrote: "Chris Berry" wrote in message ... It depends on a few assumptions.... What you mean by non-directional and what is satisfactorily non-directional.... are you refering to 45 degrees off axis? more? less? I guess my practical purpose is to find an equation for determining a "directional" frequency for a given speaker, in its widest sense; that being something like much over 100 degrees off axis. Say I have a cone with a 6" radius back against a wall. How do I calculate, roughly at which frequency it starts to radiate sound to the back? You also need to consider whether the *effective* radius of the cone is the same as the physical radius. Many drivers (such as B&W Kevlar cones) are designed to move into bending mode as frequency increases, thereby reducing their effective radius and maintaining dispersion. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#23
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Speaker directivity
On Mon, 19 Apr 2004 18:08:13 +0300, "Tommi"
wrote: "Chris Berry" wrote in message ... It depends on a few assumptions.... What you mean by non-directional and what is satisfactorily non-directional.... are you refering to 45 degrees off axis? more? less? I guess my practical purpose is to find an equation for determining a "directional" frequency for a given speaker, in its widest sense; that being something like much over 100 degrees off axis. Say I have a cone with a 6" radius back against a wall. How do I calculate, roughly at which frequency it starts to radiate sound to the back? You also need to consider whether the *effective* radius of the cone is the same as the physical radius. Many drivers (such as B&W Kevlar cones) are designed to move into bending mode as frequency increases, thereby reducing their effective radius and maintaining dispersion. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#24
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Speaker directivity
On Mon, 19 Apr 2004 18:08:13 +0300, "Tommi"
wrote: "Chris Berry" wrote in message ... It depends on a few assumptions.... What you mean by non-directional and what is satisfactorily non-directional.... are you refering to 45 degrees off axis? more? less? I guess my practical purpose is to find an equation for determining a "directional" frequency for a given speaker, in its widest sense; that being something like much over 100 degrees off axis. Say I have a cone with a 6" radius back against a wall. How do I calculate, roughly at which frequency it starts to radiate sound to the back? You also need to consider whether the *effective* radius of the cone is the same as the physical radius. Many drivers (such as B&W Kevlar cones) are designed to move into bending mode as frequency increases, thereby reducing their effective radius and maintaining dispersion. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#25
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Speaker directivity
On Mon, 19 Apr 2004 18:08:13 +0300, "Tommi"
wrote: "Chris Berry" wrote in message ... It depends on a few assumptions.... What you mean by non-directional and what is satisfactorily non-directional.... are you refering to 45 degrees off axis? more? less? I guess my practical purpose is to find an equation for determining a "directional" frequency for a given speaker, in its widest sense; that being something like much over 100 degrees off axis. Say I have a cone with a 6" radius back against a wall. How do I calculate, roughly at which frequency it starts to radiate sound to the back? You also need to consider whether the *effective* radius of the cone is the same as the physical radius. Many drivers (such as B&W Kevlar cones) are designed to move into bending mode as frequency increases, thereby reducing their effective radius and maintaining dispersion. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#26
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Speaker directivity
On Mon, 19 Apr 2004 18:08:13 +0300, "Tommi"
wrote: "Chris Berry" wrote in message ... It depends on a few assumptions.... What you mean by non-directional and what is satisfactorily non-directional.... are you refering to 45 degrees off axis? more? less? I guess my practical purpose is to find an equation for determining a "directional" frequency for a given speaker, in its widest sense; that being something like much over 100 degrees off axis. Say I have a cone with a 6" radius back against a wall. How do I calculate, roughly at which frequency it starts to radiate sound to the back? You also need to consider whether the *effective* radius of the cone is the same as the physical radius. Many drivers (such as B&W Kevlar cones) are designed to move into bending mode as frequency increases, thereby reducing their effective radius and maintaining dispersion. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#27
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Speaker directivity
"Tommi" wrote in message . ..
Provided that the model for a circular piston-type radiator is an adequate tool for measuring the directivity of normal home or monitor speakers, how does one calculate an approximation of how the different frequencies are spread from the speaker cone? Is there any easy way of doing that, since I consider myself as a mathematically semi-challenged person? g I know the directivity is a by-product of the speaker cone's radius, however, some people say that "the radius of the cone must be at least 1/4th of the frequency's wavelenght in order for it to not radiate it spherically", while others say that the truth is closer to a situation where a normal speaker cone's radius has to be almost as large as the wavelenght itself in order for it to prevent radiating the frequency in all directions. Thanks for all the answers. You might want to try to simulate it numerically. Spread out a number of point sources over the piston surface and take the different source-listener distances into consideration for the different listening positions. Complex math is the key to doing the addition of sources manageable. In the real world, the cone does not behave like a piston, but it seems as if you have already realised this. In principle, the point sources could be given different amplitudes and phases to model this behaviour, but finding out the appropriate phase and amplitude values will definitely be tricky. |
#28
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Speaker directivity
"Tommi" wrote in message . ..
Provided that the model for a circular piston-type radiator is an adequate tool for measuring the directivity of normal home or monitor speakers, how does one calculate an approximation of how the different frequencies are spread from the speaker cone? Is there any easy way of doing that, since I consider myself as a mathematically semi-challenged person? g I know the directivity is a by-product of the speaker cone's radius, however, some people say that "the radius of the cone must be at least 1/4th of the frequency's wavelenght in order for it to not radiate it spherically", while others say that the truth is closer to a situation where a normal speaker cone's radius has to be almost as large as the wavelenght itself in order for it to prevent radiating the frequency in all directions. Thanks for all the answers. You might want to try to simulate it numerically. Spread out a number of point sources over the piston surface and take the different source-listener distances into consideration for the different listening positions. Complex math is the key to doing the addition of sources manageable. In the real world, the cone does not behave like a piston, but it seems as if you have already realised this. In principle, the point sources could be given different amplitudes and phases to model this behaviour, but finding out the appropriate phase and amplitude values will definitely be tricky. |
#29
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Speaker directivity
"Tommi" wrote in message . ..
Provided that the model for a circular piston-type radiator is an adequate tool for measuring the directivity of normal home or monitor speakers, how does one calculate an approximation of how the different frequencies are spread from the speaker cone? Is there any easy way of doing that, since I consider myself as a mathematically semi-challenged person? g I know the directivity is a by-product of the speaker cone's radius, however, some people say that "the radius of the cone must be at least 1/4th of the frequency's wavelenght in order for it to not radiate it spherically", while others say that the truth is closer to a situation where a normal speaker cone's radius has to be almost as large as the wavelenght itself in order for it to prevent radiating the frequency in all directions. Thanks for all the answers. You might want to try to simulate it numerically. Spread out a number of point sources over the piston surface and take the different source-listener distances into consideration for the different listening positions. Complex math is the key to doing the addition of sources manageable. In the real world, the cone does not behave like a piston, but it seems as if you have already realised this. In principle, the point sources could be given different amplitudes and phases to model this behaviour, but finding out the appropriate phase and amplitude values will definitely be tricky. |
#30
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Speaker directivity
"Tommi" wrote in message . ..
Provided that the model for a circular piston-type radiator is an adequate tool for measuring the directivity of normal home or monitor speakers, how does one calculate an approximation of how the different frequencies are spread from the speaker cone? Is there any easy way of doing that, since I consider myself as a mathematically semi-challenged person? g I know the directivity is a by-product of the speaker cone's radius, however, some people say that "the radius of the cone must be at least 1/4th of the frequency's wavelenght in order for it to not radiate it spherically", while others say that the truth is closer to a situation where a normal speaker cone's radius has to be almost as large as the wavelenght itself in order for it to prevent radiating the frequency in all directions. Thanks for all the answers. You might want to try to simulate it numerically. Spread out a number of point sources over the piston surface and take the different source-listener distances into consideration for the different listening positions. Complex math is the key to doing the addition of sources manageable. In the real world, the cone does not behave like a piston, but it seems as if you have already realised this. In principle, the point sources could be given different amplitudes and phases to model this behaviour, but finding out the appropriate phase and amplitude values will definitely be tricky. |
#31
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Speaker directivity
"Tommi" wrote in message . ..
Provided that the model for a circular piston-type radiator is an adequate tool for measuring the directivity of normal home or monitor speakers, how does one calculate an approximation of how the different frequencies are spread from the speaker cone? Is there any easy way of doing that, since I consider myself as a mathematically semi-challenged person? g I know the directivity is a by-product of the speaker cone's radius, however, some people say that "the radius of the cone must be at least 1/4th of the frequency's wavelenght in order for it to not radiate it spherically", while others say that the truth is closer to a situation where a normal speaker cone's radius has to be almost as large as the wavelenght itself in order for it to prevent radiating the frequency in all directions. Thanks for all the answers. You might want to try to simulate it numerically. Spread out a number of point sources over the piston surface and take the different source-listener distances into consideration for the different listening positions. Complex math is the key to doing the addition of sources manageable. In the real world, the cone does not behave like a piston, but it seems as if you have already realised this. In principle, the point sources could be given different amplitudes and phases to model this behaviour, but finding out the appropriate phase and amplitude values will definitely be tricky. |
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Speaker directivity
"Tommi" wrote in message .. . "Chris Berry" wrote in message ... It depends on a few assumptions.... What you mean by non-directional and what is satisfactorily non-directional.... are you refering to 45 degrees off axis? more? less? I guess my practical purpose is to find an equation for determining a "directional" frequency for a given speaker, in its widest sense; that being something like much over 100 degrees off axis. 100 degrees off axis is behind the speaker... you really mean that? Say I have a cone with a 6" radius back against a wall. How do I calculate, roughly at which frequency it starts to radiate sound to the back? It's only the cabinet resonance that gets radiated to the back so it's a pretty moot point. The only other way you'll get sound radiated behind the speaker is using open back cabs or have something reflect the sound back at the speaker - Only the open back cab will do this effectively and then you're stumped for high frequencies... Care to hint at what you're trying to do? cb |
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Speaker directivity
"Tommi" wrote in message .. . "Chris Berry" wrote in message ... It depends on a few assumptions.... What you mean by non-directional and what is satisfactorily non-directional.... are you refering to 45 degrees off axis? more? less? I guess my practical purpose is to find an equation for determining a "directional" frequency for a given speaker, in its widest sense; that being something like much over 100 degrees off axis. 100 degrees off axis is behind the speaker... you really mean that? Say I have a cone with a 6" radius back against a wall. How do I calculate, roughly at which frequency it starts to radiate sound to the back? It's only the cabinet resonance that gets radiated to the back so it's a pretty moot point. The only other way you'll get sound radiated behind the speaker is using open back cabs or have something reflect the sound back at the speaker - Only the open back cab will do this effectively and then you're stumped for high frequencies... Care to hint at what you're trying to do? cb |
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Speaker directivity
"Tommi" wrote in message .. . "Chris Berry" wrote in message ... It depends on a few assumptions.... What you mean by non-directional and what is satisfactorily non-directional.... are you refering to 45 degrees off axis? more? less? I guess my practical purpose is to find an equation for determining a "directional" frequency for a given speaker, in its widest sense; that being something like much over 100 degrees off axis. 100 degrees off axis is behind the speaker... you really mean that? Say I have a cone with a 6" radius back against a wall. How do I calculate, roughly at which frequency it starts to radiate sound to the back? It's only the cabinet resonance that gets radiated to the back so it's a pretty moot point. The only other way you'll get sound radiated behind the speaker is using open back cabs or have something reflect the sound back at the speaker - Only the open back cab will do this effectively and then you're stumped for high frequencies... Care to hint at what you're trying to do? cb |
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Speaker directivity
"Tommi" wrote in message .. . "Chris Berry" wrote in message ... It depends on a few assumptions.... What you mean by non-directional and what is satisfactorily non-directional.... are you refering to 45 degrees off axis? more? less? I guess my practical purpose is to find an equation for determining a "directional" frequency for a given speaker, in its widest sense; that being something like much over 100 degrees off axis. 100 degrees off axis is behind the speaker... you really mean that? Say I have a cone with a 6" radius back against a wall. How do I calculate, roughly at which frequency it starts to radiate sound to the back? It's only the cabinet resonance that gets radiated to the back so it's a pretty moot point. The only other way you'll get sound radiated behind the speaker is using open back cabs or have something reflect the sound back at the speaker - Only the open back cab will do this effectively and then you're stumped for high frequencies... Care to hint at what you're trying to do? cb |
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Speaker directivity
"Tommi" wrote in message .. . "Chris Berry" wrote in message ... It depends on a few assumptions.... What you mean by non-directional and what is satisfactorily non-directional.... are you refering to 45 degrees off axis? more? less? I guess my practical purpose is to find an equation for determining a "directional" frequency for a given speaker, in its widest sense; that being something like much over 100 degrees off axis. 100 degrees off axis is behind the speaker... you really mean that? Say I have a cone with a 6" radius back against a wall. How do I calculate, roughly at which frequency it starts to radiate sound to the back? It's only the cabinet resonance that gets radiated to the back so it's a pretty moot point. The only other way you'll get sound radiated behind the speaker is using open back cabs or have something reflect the sound back at the speaker - Only the open back cab will do this effectively and then you're stumped for high frequencies... Care to hint at what you're trying to do? cb |
#37
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Speaker directivity
In article ,
Chris Berry wrote: Say I have a cone with a 6" radius back against a wall. How do I calculate, roughly at which frequency it starts to radiate sound to the back? It's only the cabinet resonance that gets radiated to the back so it's a pretty moot point. The only other way you'll get sound radiated behind the speaker is using open back cabs or have something reflect the sound back at the speaker - Only the open back cab will do this effectively and then you're stumped for high frequencies... With a monopole speaker the rear output will essentially match the front once your wavelengths are 3X baffle width, and there's some effect with wavelengths as short as 1/3 width. In free-space you get a 6dB drop in on-axis SPL when this happens. This is why speakers need baffle step compensation. -- a href="http://www.poohsticks.org/drew/"Home Page/a Life is a terminal sexually transmitted disease. |
#38
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Speaker directivity
In article ,
Chris Berry wrote: Say I have a cone with a 6" radius back against a wall. How do I calculate, roughly at which frequency it starts to radiate sound to the back? It's only the cabinet resonance that gets radiated to the back so it's a pretty moot point. The only other way you'll get sound radiated behind the speaker is using open back cabs or have something reflect the sound back at the speaker - Only the open back cab will do this effectively and then you're stumped for high frequencies... With a monopole speaker the rear output will essentially match the front once your wavelengths are 3X baffle width, and there's some effect with wavelengths as short as 1/3 width. In free-space you get a 6dB drop in on-axis SPL when this happens. This is why speakers need baffle step compensation. -- a href="http://www.poohsticks.org/drew/"Home Page/a Life is a terminal sexually transmitted disease. |
#39
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Speaker directivity
In article ,
Chris Berry wrote: Say I have a cone with a 6" radius back against a wall. How do I calculate, roughly at which frequency it starts to radiate sound to the back? It's only the cabinet resonance that gets radiated to the back so it's a pretty moot point. The only other way you'll get sound radiated behind the speaker is using open back cabs or have something reflect the sound back at the speaker - Only the open back cab will do this effectively and then you're stumped for high frequencies... With a monopole speaker the rear output will essentially match the front once your wavelengths are 3X baffle width, and there's some effect with wavelengths as short as 1/3 width. In free-space you get a 6dB drop in on-axis SPL when this happens. This is why speakers need baffle step compensation. -- a href="http://www.poohsticks.org/drew/"Home Page/a Life is a terminal sexually transmitted disease. |
#40
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Speaker directivity
In article ,
Chris Berry wrote: Say I have a cone with a 6" radius back against a wall. How do I calculate, roughly at which frequency it starts to radiate sound to the back? It's only the cabinet resonance that gets radiated to the back so it's a pretty moot point. The only other way you'll get sound radiated behind the speaker is using open back cabs or have something reflect the sound back at the speaker - Only the open back cab will do this effectively and then you're stumped for high frequencies... With a monopole speaker the rear output will essentially match the front once your wavelengths are 3X baffle width, and there's some effect with wavelengths as short as 1/3 width. In free-space you get a 6dB drop in on-axis SPL when this happens. This is why speakers need baffle step compensation. -- a href="http://www.poohsticks.org/drew/"Home Page/a Life is a terminal sexually transmitted disease. |
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