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.

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

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

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

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

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

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

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

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

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

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

"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

"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

"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

"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

"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

"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?

"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?

"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?

"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?

"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?

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

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

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

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

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

"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.

"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.

"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.

"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.

"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.

"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

"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

"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

"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

"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

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.

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.

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.

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.