(Thomas A) wrote in message . com...
(Svante) wrote in message . com...
(Thomas A) wrote in message

Look at the old Olsen measurements, should be a reference on the web
somewhere. Olle Mirsch should have an article in MoLT; No 1, 1994.

Yes, I will.

PS. Have you seen or heard the Mirsch Rondo? They are made as perfect
spheres and measured quite good, if I remember correctly. Articles in
EV, around 1993-1994. The Allegro NG8, around 1990, are beweled cubes,
also by Mirsch, to counteract diffraction. See

No I have not heard them. Mmm... As I am beginning to understand it,
diffraction cannot be avoided in ANY kind of (finite size) design. But
for sure the design of the baffle is very important, and not always
very intuitive (at least not to me). "Avoid symmetry" seems to be the
only simple advice that holds, so far.

http://hem.bredband.net/b113928/inde...r/image002.jpg

At the first look at the images, they may look asymmetrical, but when
I try to model this baffle shape in my little program it appears as if
diffraction would affect the response of this speaker a lot (well,
peaks and dips 3-4 dB apart). I think it is the symmetrical left-right
placement that is responsible for this.
Of course I cannot say anything about how they sound based on this
simulation, and the effects may be compensated for in some way, also,
I have only rough estimates of the sizes from the photo. But at a
first look I would say that the placement of the speakers on the
baffle is not optimal.

I made some simulations long time ago using the baffle diffraction
simulator, and it looks ok. The beweled edges act as "filters". I cite
from the baffle diffraction simulator manual:

"If you sharply turn a baffle corner, there is a pressure change that
sends a reflection back at the listener, which arrives late and causes
a comb filter frequency effect. If you turn that same corner, and
instead of finding a single 90 degree sharp turn you pass over two 45
degree sharp edges forming a bevel, you create two such filters. The
distance to the median point between those two edges is the center of
a notch-filtering band. The distance between those edges is a width of
notch effect. The item filtered by that notch filter is the
cancellation of the comb filter like warbling. In all actuality, it is
a beat frequency pattern, not a notch at all. The first nodal
destruction is a half wavelength sum and the periodicity is every
harmonic thereafter. But it still resembles a notch-filtered band, and
as that is the way it appears when you view its effects in the
frequency domain, so I improperly refer to it as a notch filter."

The actual measurements of the speakers are rather good. This is an
old measurement which I made (I have increased the response now in the
1-2 kHz region to take take care of lost energy in the extreme
angles). The drop 10 khz is due to microphone error. The peak at 1.2
kHz is not as bad as it looks at 3 meters listening.

Yes, you are probably right in that the speaker is good. As I said the
diffraction effects that DO exist may be compensated for in the
filter. If I try do trace the dimensions of the baffle for the tweeter
(gosh, I HAVE to do something about the user interface in my program)
I end up with a transfer function with a 2-3 dB dip at 3 kHz, which I
think I can see in your response graphs (not as deep though). I think
this dip can be made smaller by moving the tweeter slightly to either
side.
But, anyway, these are small effects, and the program does not take
the response or directivity of the driver into account etc, so
probably there is nothing to worry about.
Your edges have a greater angle than 90 degrees, which should decrease
the amplitude of the edge reflections, which is good. On the other
hand you will have a second edge reflection from the back of the box.


http://hem.bredband.net/b113928/spea...asurements.htm

The actual dimensions of the speaker is:

http://hem.bredband.net/b113928/ritning.htm

A sphere is bad in one sense, internal standing waves. But it could be
fixed by making asymmetric internal cabinet.

Yes, anyone who has hit a basketball knows the sound of standing waves
inside a sphere.

(Svante) wrote in message . com...
(Thomas A) wrote in message . com...
(Svante) wrote in message . com...
(Thomas A) wrote in message

Look at the old Olsen measurements, should be a reference on the web
somewhere. Olle Mirsch should have an article in MoLT; No 1, 1994.

Yes, I will.

PS. Have you seen or heard the Mirsch Rondo? They are made as perfect
spheres and measured quite good, if I remember correctly. Articles in
EV, around 1993-1994. The Allegro NG8, around 1990, are beweled cubes,
also by Mirsch, to counteract diffraction. See

No I have not heard them. Mmm... As I am beginning to understand it,
diffraction cannot be avoided in ANY kind of (finite size) design. But
for sure the design of the baffle is very important, and not always
very intuitive (at least not to me). "Avoid symmetry" seems to be the
only simple advice that holds, so far.

http://hem.bredband.net/b113928/inde...r/image002.jpg

At the first look at the images, they may look asymmetrical, but when
I try to model this baffle shape in my little program it appears as if
diffraction would affect the response of this speaker a lot (well,
peaks and dips 3-4 dB apart). I think it is the symmetrical left-right
placement that is responsible for this.
Of course I cannot say anything about how they sound based on this
simulation, and the effects may be compensated for in some way, also,
I have only rough estimates of the sizes from the photo. But at a
first look I would say that the placement of the speakers on the
baffle is not optimal.

I made some simulations long time ago using the baffle diffraction
simulator, and it looks ok. The beweled edges act as "filters". I cite
from the baffle diffraction simulator manual:

"If you sharply turn a baffle corner, there is a pressure change that
sends a reflection back at the listener, which arrives late and causes
a comb filter frequency effect. If you turn that same corner, and
instead of finding a single 90 degree sharp turn you pass over two 45
degree sharp edges forming a bevel, you create two such filters. The
distance to the median point between those two edges is the center of
a notch-filtering band. The distance between those edges is a width of
notch effect. The item filtered by that notch filter is the
cancellation of the comb filter like warbling. In all actuality, it is
a beat frequency pattern, not a notch at all. The first nodal
destruction is a half wavelength sum and the periodicity is every
harmonic thereafter. But it still resembles a notch-filtered band, and
as that is the way it appears when you view its effects in the
frequency domain, so I improperly refer to it as a notch filter."

The actual measurements of the speakers are rather good. This is an
old measurement which I made (I have increased the response now in the
1-2 kHz region to take take care of lost energy in the extreme
angles). The drop 10 khz is due to microphone error. The peak at 1.2
kHz is not as bad as it looks at 3 meters listening.

Yes, you are probably right in that the speaker is good. As I said the
diffraction effects that DO exist may be compensated for in the
filter. If I try do trace the dimensions of the baffle for the tweeter
(gosh, I HAVE to do something about the user interface in my program)
I end up with a transfer function with a 2-3 dB dip at 3 kHz, which I
think I can see in your response graphs (not as deep though). I think
this dip can be made smaller by moving the tweeter slightly to either
side.

The dip at 3.2 kHz could either be a small diffraction effect caused
by the edge, but the form of the 5 inch driver on the front baffle
could also account for the dip. The bevel edge is 12 cm at tweeter
axis and 17 cm at woofer axis and should have a good effect to
"cancel" diffraction effects from the tweeter. Nevertheless, the dip
is found only in the 0 deg axis, and is actually not doing very much
on the energy at 3 meters. On-axis measurements say little of the
total sound from the speaker. In addition there is a wish for me to
have a slight dip in the 3-4 kHz regions compared to 1-2 kHz, since
the ear is more sensitive in the direct sound vs diffuse fields in the
3-4 khz region. Listen to soprano voices at high volumes, and I think
you would prefer a slight dip in the 3-4 kHz region.

But, anyway, these are small effects, and the program does not take
the response or directivity of the driver into account etc, so
probably there is nothing to worry about.
Your edges have a greater angle than 90 degrees, which should decrease
the amplitude of the edge reflections, which is good. On the other
hand you will have a second edge reflection from the back of the box.

Well there will be a beat pattern from this arrangement where the
second edge which will cancel the effect of the first diffraction
edge. With two corners there are two comb filters. There will be a
destructive phase alignment of the two reflecting filters with a
center f and bandwith which is determined by the bevel edge size. I
have not seen your program (mac user) so I don't know if it calculates
on the two corners. Have you compared your result with the Excel
Spreadsheet at

http://www.pvconsultants.com

I've lost the direct link to the Spreadsheet, unfortunately.


http://hem.bredband.net/b113928/spea...asurements.htm

The actual dimensions of the speaker is:

http://hem.bredband.net/b113928/ritning.htm

A sphere is bad in one sense, internal standing waves. But it could be
fixed by making asymmetric internal cabinet.

Yes, anyone who has hit a basketball knows the sound of standing waves
inside a sphere.

(Svante) wrote in message . com...
(Thomas A) wrote in message . com...
(Svante) wrote in message . com...
(Thomas A) wrote in message

Look at the old Olsen measurements, should be a reference on the web
somewhere. Olle Mirsch should have an article in MoLT; No 1, 1994.

Yes, I will.

PS. Have you seen or heard the Mirsch Rondo? They are made as perfect
spheres and measured quite good, if I remember correctly. Articles in
EV, around 1993-1994. The Allegro NG8, around 1990, are beweled cubes,
also by Mirsch, to counteract diffraction. See

No I have not heard them. Mmm... As I am beginning to understand it,
diffraction cannot be avoided in ANY kind of (finite size) design. But
for sure the design of the baffle is very important, and not always
very intuitive (at least not to me). "Avoid symmetry" seems to be the
only simple advice that holds, so far.

http://hem.bredband.net/b113928/inde...r/image002.jpg

At the first look at the images, they may look asymmetrical, but when
I try to model this baffle shape in my little program it appears as if
diffraction would affect the response of this speaker a lot (well,
peaks and dips 3-4 dB apart). I think it is the symmetrical left-right
placement that is responsible for this.
Of course I cannot say anything about how they sound based on this
simulation, and the effects may be compensated for in some way, also,
I have only rough estimates of the sizes from the photo. But at a
first look I would say that the placement of the speakers on the
baffle is not optimal.

I made some simulations long time ago using the baffle diffraction
simulator, and it looks ok. The beweled edges act as "filters". I cite
from the baffle diffraction simulator manual:

"If you sharply turn a baffle corner, there is a pressure change that
sends a reflection back at the listener, which arrives late and causes
a comb filter frequency effect. If you turn that same corner, and
instead of finding a single 90 degree sharp turn you pass over two 45
degree sharp edges forming a bevel, you create two such filters. The
distance to the median point between those two edges is the center of
a notch-filtering band. The distance between those edges is a width of
notch effect. The item filtered by that notch filter is the
cancellation of the comb filter like warbling. In all actuality, it is
a beat frequency pattern, not a notch at all. The first nodal
destruction is a half wavelength sum and the periodicity is every
harmonic thereafter. But it still resembles a notch-filtered band, and
as that is the way it appears when you view its effects in the
frequency domain, so I improperly refer to it as a notch filter."

The actual measurements of the speakers are rather good. This is an
old measurement which I made (I have increased the response now in the
1-2 kHz region to take take care of lost energy in the extreme
angles). The drop 10 khz is due to microphone error. The peak at 1.2
kHz is not as bad as it looks at 3 meters listening.

Yes, you are probably right in that the speaker is good. As I said the
diffraction effects that DO exist may be compensated for in the
filter. If I try do trace the dimensions of the baffle for the tweeter
(gosh, I HAVE to do something about the user interface in my program)
I end up with a transfer function with a 2-3 dB dip at 3 kHz, which I
think I can see in your response graphs (not as deep though). I think
this dip can be made smaller by moving the tweeter slightly to either
side.

The dip at 3.2 kHz could either be a small diffraction effect caused
by the edge, but the form of the 5 inch driver on the front baffle
could also account for the dip. The bevel edge is 12 cm at tweeter
axis and 17 cm at woofer axis and should have a good effect to
"cancel" diffraction effects from the tweeter. Nevertheless, the dip
is found only in the 0 deg axis, and is actually not doing very much
on the energy at 3 meters. On-axis measurements say little of the
total sound from the speaker. In addition there is a wish for me to
have a slight dip in the 3-4 kHz regions compared to 1-2 kHz, since
the ear is more sensitive in the direct sound vs diffuse fields in the
3-4 khz region. Listen to soprano voices at high volumes, and I think
you would prefer a slight dip in the 3-4 kHz region.

But, anyway, these are small effects, and the program does not take
the response or directivity of the driver into account etc, so
probably there is nothing to worry about.
Your edges have a greater angle than 90 degrees, which should decrease
the amplitude of the edge reflections, which is good. On the other
hand you will have a second edge reflection from the back of the box.

Well there will be a beat pattern from this arrangement where the
second edge which will cancel the effect of the first diffraction
edge. With two corners there are two comb filters. There will be a
destructive phase alignment of the two reflecting filters with a
center f and bandwith which is determined by the bevel edge size. I
have not seen your program (mac user) so I don't know if it calculates
on the two corners. Have you compared your result with the Excel
Spreadsheet at

http://www.pvconsultants.com

I've lost the direct link to the Spreadsheet, unfortunately.


http://hem.bredband.net/b113928/spea...asurements.htm

The actual dimensions of the speaker is:

http://hem.bredband.net/b113928/ritning.htm

A sphere is bad in one sense, internal standing waves. But it could be
fixed by making asymmetric internal cabinet.

Yes, anyone who has hit a basketball knows the sound of standing waves
inside a sphere.

(Svante) wrote in message . com...
(Thomas A) wrote in message . com...
(Svante) wrote in message . com...
(Thomas A) wrote in message

Look at the old Olsen measurements, should be a reference on the web
somewhere. Olle Mirsch should have an article in MoLT; No 1, 1994.

Yes, I will.

PS. Have you seen or heard the Mirsch Rondo? They are made as perfect
spheres and measured quite good, if I remember correctly. Articles in
EV, around 1993-1994. The Allegro NG8, around 1990, are beweled cubes,
also by Mirsch, to counteract diffraction. See

No I have not heard them. Mmm... As I am beginning to understand it,
diffraction cannot be avoided in ANY kind of (finite size) design. But
for sure the design of the baffle is very important, and not always
very intuitive (at least not to me). "Avoid symmetry" seems to be the
only simple advice that holds, so far.

http://hem.bredband.net/b113928/inde...r/image002.jpg

At the first look at the images, they may look asymmetrical, but when
I try to model this baffle shape in my little program it appears as if
diffraction would affect the response of this speaker a lot (well,
peaks and dips 3-4 dB apart). I think it is the symmetrical left-right
placement that is responsible for this.
Of course I cannot say anything about how they sound based on this
simulation, and the effects may be compensated for in some way, also,
I have only rough estimates of the sizes from the photo. But at a
first look I would say that the placement of the speakers on the
baffle is not optimal.

I made some simulations long time ago using the baffle diffraction
simulator, and it looks ok. The beweled edges act as "filters". I cite
from the baffle diffraction simulator manual:

"If you sharply turn a baffle corner, there is a pressure change that
sends a reflection back at the listener, which arrives late and causes
a comb filter frequency effect. If you turn that same corner, and
instead of finding a single 90 degree sharp turn you pass over two 45
degree sharp edges forming a bevel, you create two such filters. The
distance to the median point between those two edges is the center of
a notch-filtering band. The distance between those edges is a width of
notch effect. The item filtered by that notch filter is the
cancellation of the comb filter like warbling. In all actuality, it is
a beat frequency pattern, not a notch at all. The first nodal
destruction is a half wavelength sum and the periodicity is every
harmonic thereafter. But it still resembles a notch-filtered band, and
as that is the way it appears when you view its effects in the
frequency domain, so I improperly refer to it as a notch filter."

The actual measurements of the speakers are rather good. This is an
old measurement which I made (I have increased the response now in the
1-2 kHz region to take take care of lost energy in the extreme
angles). The drop 10 khz is due to microphone error. The peak at 1.2
kHz is not as bad as it looks at 3 meters listening.

Yes, you are probably right in that the speaker is good. As I said the
diffraction effects that DO exist may be compensated for in the
filter. If I try do trace the dimensions of the baffle for the tweeter
(gosh, I HAVE to do something about the user interface in my program)
I end up with a transfer function with a 2-3 dB dip at 3 kHz, which I
think I can see in your response graphs (not as deep though). I think
this dip can be made smaller by moving the tweeter slightly to either
side.

The dip at 3.2 kHz could either be a small diffraction effect caused
by the edge, but the form of the 5 inch driver on the front baffle
could also account for the dip. The bevel edge is 12 cm at tweeter
axis and 17 cm at woofer axis and should have a good effect to
"cancel" diffraction effects from the tweeter. Nevertheless, the dip
is found only in the 0 deg axis, and is actually not doing very much
on the energy at 3 meters. On-axis measurements say little of the
total sound from the speaker. In addition there is a wish for me to
have a slight dip in the 3-4 kHz regions compared to 1-2 kHz, since
the ear is more sensitive in the direct sound vs diffuse fields in the
3-4 khz region. Listen to soprano voices at high volumes, and I think
you would prefer a slight dip in the 3-4 kHz region.

But, anyway, these are small effects, and the program does not take
the response or directivity of the driver into account etc, so
probably there is nothing to worry about.
Your edges have a greater angle than 90 degrees, which should decrease
the amplitude of the edge reflections, which is good. On the other
hand you will have a second edge reflection from the back of the box.

Well there will be a beat pattern from this arrangement where the
second edge which will cancel the effect of the first diffraction
edge. With two corners there are two comb filters. There will be a
destructive phase alignment of the two reflecting filters with a
center f and bandwith which is determined by the bevel edge size. I
have not seen your program (mac user) so I don't know if it calculates
on the two corners. Have you compared your result with the Excel
Spreadsheet at

http://www.pvconsultants.com

I've lost the direct link to the Spreadsheet, unfortunately.


http://hem.bredband.net/b113928/spea...asurements.htm

The actual dimensions of the speaker is:

http://hem.bredband.net/b113928/ritning.htm

A sphere is bad in one sense, internal standing waves. But it could be
fixed by making asymmetric internal cabinet.

Yes, anyone who has hit a basketball knows the sound of standing waves
inside a sphere.

(Svante) wrote in message . com...
(Thomas A) wrote in message . com...
(Svante) wrote in message . com...
(Thomas A) wrote in message

Look at the old Olsen measurements, should be a reference on the web
somewhere. Olle Mirsch should have an article in MoLT; No 1, 1994.

Yes, I will.

PS. Have you seen or heard the Mirsch Rondo? They are made as perfect
spheres and measured quite good, if I remember correctly. Articles in
EV, around 1993-1994. The Allegro NG8, around 1990, are beweled cubes,
also by Mirsch, to counteract diffraction. See

No I have not heard them. Mmm... As I am beginning to understand it,
diffraction cannot be avoided in ANY kind of (finite size) design. But
for sure the design of the baffle is very important, and not always
very intuitive (at least not to me). "Avoid symmetry" seems to be the
only simple advice that holds, so far.

http://hem.bredband.net/b113928/inde...r/image002.jpg

At the first look at the images, they may look asymmetrical, but when
I try to model this baffle shape in my little program it appears as if
diffraction would affect the response of this speaker a lot (well,
peaks and dips 3-4 dB apart). I think it is the symmetrical left-right
placement that is responsible for this.
Of course I cannot say anything about how they sound based on this
simulation, and the effects may be compensated for in some way, also,
I have only rough estimates of the sizes from the photo. But at a
first look I would say that the placement of the speakers on the
baffle is not optimal.

I made some simulations long time ago using the baffle diffraction
simulator, and it looks ok. The beweled edges act as "filters". I cite
from the baffle diffraction simulator manual:

"If you sharply turn a baffle corner, there is a pressure change that
sends a reflection back at the listener, which arrives late and causes
a comb filter frequency effect. If you turn that same corner, and
instead of finding a single 90 degree sharp turn you pass over two 45
degree sharp edges forming a bevel, you create two such filters. The
distance to the median point between those two edges is the center of
a notch-filtering band. The distance between those edges is a width of
notch effect. The item filtered by that notch filter is the
cancellation of the comb filter like warbling. In all actuality, it is
a beat frequency pattern, not a notch at all. The first nodal
destruction is a half wavelength sum and the periodicity is every
harmonic thereafter. But it still resembles a notch-filtered band, and
as that is the way it appears when you view its effects in the
frequency domain, so I improperly refer to it as a notch filter."

The actual measurements of the speakers are rather good. This is an
old measurement which I made (I have increased the response now in the
1-2 kHz region to take take care of lost energy in the extreme
angles). The drop 10 khz is due to microphone error. The peak at 1.2
kHz is not as bad as it looks at 3 meters listening.

Yes, you are probably right in that the speaker is good. As I said the
diffraction effects that DO exist may be compensated for in the
filter. If I try do trace the dimensions of the baffle for the tweeter
(gosh, I HAVE to do something about the user interface in my program)
I end up with a transfer function with a 2-3 dB dip at 3 kHz, which I
think I can see in your response graphs (not as deep though). I think
this dip can be made smaller by moving the tweeter slightly to either
side.

The dip at 3.2 kHz could either be a small diffraction effect caused
by the edge, but the form of the 5 inch driver on the front baffle
could also account for the dip. The bevel edge is 12 cm at tweeter
axis and 17 cm at woofer axis and should have a good effect to
"cancel" diffraction effects from the tweeter. Nevertheless, the dip
is found only in the 0 deg axis, and is actually not doing very much
on the energy at 3 meters. On-axis measurements say little of the
total sound from the speaker. In addition there is a wish for me to
have a slight dip in the 3-4 kHz regions compared to 1-2 kHz, since
the ear is more sensitive in the direct sound vs diffuse fields in the
3-4 khz region. Listen to soprano voices at high volumes, and I think
you would prefer a slight dip in the 3-4 kHz region.

But, anyway, these are small effects, and the program does not take
the response or directivity of the driver into account etc, so
probably there is nothing to worry about.
Your edges have a greater angle than 90 degrees, which should decrease
the amplitude of the edge reflections, which is good. On the other
hand you will have a second edge reflection from the back of the box.

Well there will be a beat pattern from this arrangement where the
second edge which will cancel the effect of the first diffraction
edge. With two corners there are two comb filters. There will be a
destructive phase alignment of the two reflecting filters with a
center f and bandwith which is determined by the bevel edge size. I
have not seen your program (mac user) so I don't know if it calculates
on the two corners. Have you compared your result with the Excel
Spreadsheet at

http://www.pvconsultants.com

I've lost the direct link to the Spreadsheet, unfortunately.


http://hem.bredband.net/b113928/spea...asurements.htm

The actual dimensions of the speaker is:

http://hem.bredband.net/b113928/ritning.htm

A sphere is bad in one sense, internal standing waves. But it could be
fixed by making asymmetric internal cabinet.

Yes, anyone who has hit a basketball knows the sound of standing waves
inside a sphere.

(Svante) wrote in message . com...
(Thomas A) wrote in message . com...
(Svante) wrote in message . com...
(Thomas A) wrote in message

Look at the old Olsen measurements, should be a reference on the web
somewhere. Olle Mirsch should have an article in MoLT; No 1, 1994.

Yes, I will.

PS. Have you seen or heard the Mirsch Rondo? They are made as perfect
spheres and measured quite good, if I remember correctly. Articles in
EV, around 1993-1994. The Allegro NG8, around 1990, are beweled cubes,
also by Mirsch, to counteract diffraction. See

No I have not heard them. Mmm... As I am beginning to understand it,
diffraction cannot be avoided in ANY kind of (finite size) design. But
for sure the design of the baffle is very important, and not always
very intuitive (at least not to me). "Avoid symmetry" seems to be the
only simple advice that holds, so far.

http://hem.bredband.net/b113928/inde...r/image002.jpg

At the first look at the images, they may look asymmetrical, but when
I try to model this baffle shape in my little program it appears as if
diffraction would affect the response of this speaker a lot (well,
peaks and dips 3-4 dB apart). I think it is the symmetrical left-right
placement that is responsible for this.
Of course I cannot say anything about how they sound based on this
simulation, and the effects may be compensated for in some way, also,
I have only rough estimates of the sizes from the photo. But at a
first look I would say that the placement of the speakers on the
baffle is not optimal.

I made some simulations long time ago using the baffle diffraction
simulator, and it looks ok. The beweled edges act as "filters". I cite
from the baffle diffraction simulator manual:

"If you sharply turn a baffle corner, there is a pressure change that
sends a reflection back at the listener, which arrives late and causes
a comb filter frequency effect. If you turn that same corner, and
instead of finding a single 90 degree sharp turn you pass over two 45
degree sharp edges forming a bevel, you create two such filters. The
distance to the median point between those two edges is the center of
a notch-filtering band. The distance between those edges is a width of
notch effect. The item filtered by that notch filter is the
cancellation of the comb filter like warbling. In all actuality, it is
a beat frequency pattern, not a notch at all. The first nodal
destruction is a half wavelength sum and the periodicity is every
harmonic thereafter. But it still resembles a notch-filtered band, and
as that is the way it appears when you view its effects in the
frequency domain, so I improperly refer to it as a notch filter."

The actual measurements of the speakers are rather good. This is an
old measurement which I made (I have increased the response now in the
1-2 kHz region to take take care of lost energy in the extreme
angles). The drop 10 khz is due to microphone error. The peak at 1.2
kHz is not as bad as it looks at 3 meters listening.

Yes, you are probably right in that the speaker is good.

I correct myself is that the measurements are made on my new speakers,
using approximately the same cabinet but with different drivers. The
original NG8 did not measure this flat.

T

(Svante) wrote in message . com...
(Thomas A) wrote in message . com...
(Svante) wrote in message . com...
(Thomas A) wrote in message

Look at the old Olsen measurements, should be a reference on the web
somewhere. Olle Mirsch should have an article in MoLT; No 1, 1994.

Yes, I will.

PS. Have you seen or heard the Mirsch Rondo? They are made as perfect
spheres and measured quite good, if I remember correctly. Articles in
EV, around 1993-1994. The Allegro NG8, around 1990, are beweled cubes,
also by Mirsch, to counteract diffraction. See

No I have not heard them. Mmm... As I am beginning to understand it,
diffraction cannot be avoided in ANY kind of (finite size) design. But
for sure the design of the baffle is very important, and not always
very intuitive (at least not to me). "Avoid symmetry" seems to be the
only simple advice that holds, so far.

http://hem.bredband.net/b113928/inde...r/image002.jpg

At the first look at the images, they may look asymmetrical, but when
I try to model this baffle shape in my little program it appears as if
diffraction would affect the response of this speaker a lot (well,
peaks and dips 3-4 dB apart). I think it is the symmetrical left-right
placement that is responsible for this.
Of course I cannot say anything about how they sound based on this
simulation, and the effects may be compensated for in some way, also,
I have only rough estimates of the sizes from the photo. But at a
first look I would say that the placement of the speakers on the
baffle is not optimal.

I made some simulations long time ago using the baffle diffraction
simulator, and it looks ok. The beweled edges act as "filters". I cite
from the baffle diffraction simulator manual:

"If you sharply turn a baffle corner, there is a pressure change that
sends a reflection back at the listener, which arrives late and causes
a comb filter frequency effect. If you turn that same corner, and
instead of finding a single 90 degree sharp turn you pass over two 45
degree sharp edges forming a bevel, you create two such filters. The
distance to the median point between those two edges is the center of
a notch-filtering band. The distance between those edges is a width of
notch effect. The item filtered by that notch filter is the
cancellation of the comb filter like warbling. In all actuality, it is
a beat frequency pattern, not a notch at all. The first nodal
destruction is a half wavelength sum and the periodicity is every
harmonic thereafter. But it still resembles a notch-filtered band, and
as that is the way it appears when you view its effects in the
frequency domain, so I improperly refer to it as a notch filter."

The actual measurements of the speakers are rather good. This is an
old measurement which I made (I have increased the response now in the
1-2 kHz region to take take care of lost energy in the extreme
angles). The drop 10 khz is due to microphone error. The peak at 1.2
kHz is not as bad as it looks at 3 meters listening.

Yes, you are probably right in that the speaker is good.

I correct myself is that the measurements are made on my new speakers,
using approximately the same cabinet but with different drivers. The
original NG8 did not measure this flat.

T

(Svante) wrote in message . com...
(Thomas A) wrote in message . com...
(Svante) wrote in message . com...
(Thomas A) wrote in message

Look at the old Olsen measurements, should be a reference on the web
somewhere. Olle Mirsch should have an article in MoLT; No 1, 1994.

Yes, I will.

PS. Have you seen or heard the Mirsch Rondo? They are made as perfect
spheres and measured quite good, if I remember correctly. Articles in
EV, around 1993-1994. The Allegro NG8, around 1990, are beweled cubes,
also by Mirsch, to counteract diffraction. See

No I have not heard them. Mmm... As I am beginning to understand it,
diffraction cannot be avoided in ANY kind of (finite size) design. But
for sure the design of the baffle is very important, and not always
very intuitive (at least not to me). "Avoid symmetry" seems to be the
only simple advice that holds, so far.

http://hem.bredband.net/b113928/inde...r/image002.jpg

At the first look at the images, they may look asymmetrical, but when
I try to model this baffle shape in my little program it appears as if
diffraction would affect the response of this speaker a lot (well,
peaks and dips 3-4 dB apart). I think it is the symmetrical left-right
placement that is responsible for this.
Of course I cannot say anything about how they sound based on this
simulation, and the effects may be compensated for in some way, also,
I have only rough estimates of the sizes from the photo. But at a
first look I would say that the placement of the speakers on the
baffle is not optimal.

I made some simulations long time ago using the baffle diffraction
simulator, and it looks ok. The beweled edges act as "filters". I cite
from the baffle diffraction simulator manual:

"If you sharply turn a baffle corner, there is a pressure change that
sends a reflection back at the listener, which arrives late and causes
a comb filter frequency effect. If you turn that same corner, and
instead of finding a single 90 degree sharp turn you pass over two 45
degree sharp edges forming a bevel, you create two such filters. The
distance to the median point between those two edges is the center of
a notch-filtering band. The distance between those edges is a width of
notch effect. The item filtered by that notch filter is the
cancellation of the comb filter like warbling. In all actuality, it is
a beat frequency pattern, not a notch at all. The first nodal
destruction is a half wavelength sum and the periodicity is every
harmonic thereafter. But it still resembles a notch-filtered band, and
as that is the way it appears when you view its effects in the
frequency domain, so I improperly refer to it as a notch filter."

The actual measurements of the speakers are rather good. This is an
old measurement which I made (I have increased the response now in the
1-2 kHz region to take take care of lost energy in the extreme
angles). The drop 10 khz is due to microphone error. The peak at 1.2
kHz is not as bad as it looks at 3 meters listening.

Yes, you are probably right in that the speaker is good.

I correct myself is that the measurements are made on my new speakers,
using approximately the same cabinet but with different drivers. The
original NG8 did not measure this flat.

T

(Svante) wrote in message . com...
(Thomas A) wrote in message . com...
(Svante) wrote in message . com...
(Thomas A) wrote in message

Look at the old Olsen measurements, should be a reference on the web
somewhere. Olle Mirsch should have an article in MoLT; No 1, 1994.

Yes, I will.

PS. Have you seen or heard the Mirsch Rondo? They are made as perfect
spheres and measured quite good, if I remember correctly. Articles in
EV, around 1993-1994. The Allegro NG8, around 1990, are beweled cubes,
also by Mirsch, to counteract diffraction. See

No I have not heard them. Mmm... As I am beginning to understand it,
diffraction cannot be avoided in ANY kind of (finite size) design. But
for sure the design of the baffle is very important, and not always
very intuitive (at least not to me). "Avoid symmetry" seems to be the
only simple advice that holds, so far.

http://hem.bredband.net/b113928/inde...r/image002.jpg

At the first look at the images, they may look asymmetrical, but when
I try to model this baffle shape in my little program it appears as if
diffraction would affect the response of this speaker a lot (well,
peaks and dips 3-4 dB apart). I think it is the symmetrical left-right
placement that is responsible for this.
Of course I cannot say anything about how they sound based on this
simulation, and the effects may be compensated for in some way, also,
I have only rough estimates of the sizes from the photo. But at a
first look I would say that the placement of the speakers on the
baffle is not optimal.

I made some simulations long time ago using the baffle diffraction
simulator, and it looks ok. The beweled edges act as "filters". I cite
from the baffle diffraction simulator manual:

"If you sharply turn a baffle corner, there is a pressure change that
sends a reflection back at the listener, which arrives late and causes
a comb filter frequency effect. If you turn that same corner, and
instead of finding a single 90 degree sharp turn you pass over two 45
degree sharp edges forming a bevel, you create two such filters. The
distance to the median point between those two edges is the center of
a notch-filtering band. The distance between those edges is a width of
notch effect. The item filtered by that notch filter is the
cancellation of the comb filter like warbling. In all actuality, it is
a beat frequency pattern, not a notch at all. The first nodal
destruction is a half wavelength sum and the periodicity is every
harmonic thereafter. But it still resembles a notch-filtered band, and
as that is the way it appears when you view its effects in the
frequency domain, so I improperly refer to it as a notch filter."

The actual measurements of the speakers are rather good. This is an
old measurement which I made (I have increased the response now in the
1-2 kHz region to take take care of lost energy in the extreme
angles). The drop 10 khz is due to microphone error. The peak at 1.2
kHz is not as bad as it looks at 3 meters listening.

Yes, you are probably right in that the speaker is good.

I correct myself is that the measurements are made on my new speakers,
using approximately the same cabinet but with different drivers. The
original NG8 did not measure this flat.

T

(Thomas A) wrote:

: have not seen your program (mac user) so I don't know if it calculates
: on the two corners. Have you compared your result with the Excel
: Spreadsheet at
:
: http://www.pvconsultants.com
:
: I've lost the direct link to the Spreadsheet, unfortunately.

http://www.pvconsultants.com/audio/d...ownloadbds.htm
linked from
http://www.pvconsultants.com/audio/frdgroup.htm

(Not very easy to find from the main page ;-))

(Thomas A) wrote:

: have not seen your program (mac user) so I don't know if it calculates
: on the two corners. Have you compared your result with the Excel
: Spreadsheet at
:
: http://www.pvconsultants.com
:
: I've lost the direct link to the Spreadsheet, unfortunately.

http://www.pvconsultants.com/audio/d...ownloadbds.htm
linked from
http://www.pvconsultants.com/audio/frdgroup.htm

(Not very easy to find from the main page ;-))

(Thomas A) wrote:

: have not seen your program (mac user) so I don't know if it calculates
: on the two corners. Have you compared your result with the Excel
: Spreadsheet at
:
: http://www.pvconsultants.com
:
: I've lost the direct link to the Spreadsheet, unfortunately.

http://www.pvconsultants.com/audio/d...ownloadbds.htm
linked from
http://www.pvconsultants.com/audio/frdgroup.htm

(Not very easy to find from the main page ;-))

(Thomas A) wrote:

: have not seen your program (mac user) so I don't know if it calculates
: on the two corners. Have you compared your result with the Excel
: Spreadsheet at
:
: http://www.pvconsultants.com
:
: I've lost the direct link to the Spreadsheet, unfortunately.

http://www.pvconsultants.com/audio/d...ownloadbds.htm
linked from
http://www.pvconsultants.com/audio/frdgroup.htm

(Not very easy to find from the main page ;-))

Look at the old Olsen measurements, should be a reference on the web
somewhere. Olle Mirsch should have an article in MoLT; No 1, 1994.


Yes, I will.



A good article at True Audio by John Murphy, based on Harry Olson's work:

http://www.trueaudio.com/st_diff1.htm


HTH,

Edu Silva
ES2 Audio

Look at the old Olsen measurements, should be a reference on the web
somewhere. Olle Mirsch should have an article in MoLT; No 1, 1994.


Yes, I will.



A good article at True Audio by John Murphy, based on Harry Olson's work:

http://www.trueaudio.com/st_diff1.htm


HTH,

Edu Silva
ES2 Audio

Look at the old Olsen measurements, should be a reference on the web
somewhere. Olle Mirsch should have an article in MoLT; No 1, 1994.


Yes, I will.



A good article at True Audio by John Murphy, based on Harry Olson's work:

http://www.trueaudio.com/st_diff1.htm


HTH,

Edu Silva
ES2 Audio

Look at the old Olsen measurements, should be a reference on the web
somewhere. Olle Mirsch should have an article in MoLT; No 1, 1994.


Yes, I will.



A good article at True Audio by John Murphy, based on Harry Olson's work:

http://www.trueaudio.com/st_diff1.htm


HTH,

Edu Silva
ES2 Audio

(Thomas A) wrote in message
(Svante) wrote in message
But, anyway, these are small effects, and the program does not take
the response or directivity of the driver into account etc, so
probably there is nothing to worry about.
Your edges have a greater angle than 90 degrees, which should decrease
the amplitude of the edge reflections, which is good. On the other
hand you will have a second edge reflection from the back of the box.

Well there will be a beat pattern from this arrangement where the
second edge which will cancel the effect of the first diffraction
edge. With two corners there are two comb filters. There will be a
destructive phase alignment of the two reflecting filters with a
center f and bandwith which is determined by the bevel edge size.

Errhh... I don't think I understand this. In my world edge reflections
will add up regardless of if they come from the first edge or the
second edge. It may very well be that a reflection from the first edge
and some direction, con occur at the same time as another reflection
in some other direction from the second edge. It does not matter if
the reflections come from the first or the second edge, only the time
(and amplitude) in important. Add up the source, it's mirror and all
reflections (regardless of origin) and you will have an impulse
response. The fourier transform of this impulse response would be the
transfer function of the system (and include the baffle step and
ripple).
This is what my program does. I could include a second border for the
second edge, we'll see about that.

I have not seen your program (mac user) so I don't know if it calculates
on the two corners.

No. If you desperately want to run it I have heard of windows
emulators for mac, but I know nothing about them. But the program is
very simple and mostly a test to try if the baffle "step" can be
calculated by means of edge sources. It should not be seen as a "end
user product". I posted it to get real measurements to compare with,
and input from others (which I have, thank you all). In several cases
I have been positively surprised to see features of the real
measurements coincide with the model. Since I wrote it, I have also
learned that others have written similar things too, both more and
less complicated.

Have you compared your result with the Excel
Spreadsheet at

http://www.pvconsultants.com

No, I can't find anything about loudspeakers there. Is the link
correct?

(Thomas A) wrote in message
(Svante) wrote in message
But, anyway, these are small effects, and the program does not take
the response or directivity of the driver into account etc, so
probably there is nothing to worry about.
Your edges have a greater angle than 90 degrees, which should decrease
the amplitude of the edge reflections, which is good. On the other
hand you will have a second edge reflection from the back of the box.

Well there will be a beat pattern from this arrangement where the
second edge which will cancel the effect of the first diffraction
edge. With two corners there are two comb filters. There will be a
destructive phase alignment of the two reflecting filters with a
center f and bandwith which is determined by the bevel edge size.

Errhh... I don't think I understand this. In my world edge reflections
will add up regardless of if they come from the first edge or the
second edge. It may very well be that a reflection from the first edge
and some direction, con occur at the same time as another reflection
in some other direction from the second edge. It does not matter if
the reflections come from the first or the second edge, only the time
(and amplitude) in important. Add up the source, it's mirror and all
reflections (regardless of origin) and you will have an impulse
response. The fourier transform of this impulse response would be the
transfer function of the system (and include the baffle step and
ripple).
This is what my program does. I could include a second border for the
second edge, we'll see about that.

I have not seen your program (mac user) so I don't know if it calculates
on the two corners.

No. If you desperately want to run it I have heard of windows
emulators for mac, but I know nothing about them. But the program is
very simple and mostly a test to try if the baffle "step" can be
calculated by means of edge sources. It should not be seen as a "end
user product". I posted it to get real measurements to compare with,
and input from others (which I have, thank you all). In several cases
I have been positively surprised to see features of the real
measurements coincide with the model. Since I wrote it, I have also
learned that others have written similar things too, both more and
less complicated.

Have you compared your result with the Excel
Spreadsheet at

http://www.pvconsultants.com

No, I can't find anything about loudspeakers there. Is the link
correct?

(Thomas A) wrote in message
(Svante) wrote in message
But, anyway, these are small effects, and the program does not take
the response or directivity of the driver into account etc, so
probably there is nothing to worry about.
Your edges have a greater angle than 90 degrees, which should decrease
the amplitude of the edge reflections, which is good. On the other
hand you will have a second edge reflection from the back of the box.

Well there will be a beat pattern from this arrangement where the
second edge which will cancel the effect of the first diffraction
edge. With two corners there are two comb filters. There will be a
destructive phase alignment of the two reflecting filters with a
center f and bandwith which is determined by the bevel edge size.

Errhh... I don't think I understand this. In my world edge reflections
will add up regardless of if they come from the first edge or the
second edge. It may very well be that a reflection from the first edge
and some direction, con occur at the same time as another reflection
in some other direction from the second edge. It does not matter if
the reflections come from the first or the second edge, only the time
(and amplitude) in important. Add up the source, it's mirror and all
reflections (regardless of origin) and you will have an impulse
response. The fourier transform of this impulse response would be the
transfer function of the system (and include the baffle step and
ripple).
This is what my program does. I could include a second border for the
second edge, we'll see about that.

I have not seen your program (mac user) so I don't know if it calculates
on the two corners.

No. If you desperately want to run it I have heard of windows
emulators for mac, but I know nothing about them. But the program is
very simple and mostly a test to try if the baffle "step" can be
calculated by means of edge sources. It should not be seen as a "end
user product". I posted it to get real measurements to compare with,
and input from others (which I have, thank you all). In several cases
I have been positively surprised to see features of the real
measurements coincide with the model. Since I wrote it, I have also
learned that others have written similar things too, both more and
less complicated.

Have you compared your result with the Excel
Spreadsheet at

http://www.pvconsultants.com

No, I can't find anything about loudspeakers there. Is the link
correct?

(Thomas A) wrote in message
(Svante) wrote in message
But, anyway, these are small effects, and the program does not take
the response or directivity of the driver into account etc, so
probably there is nothing to worry about.
Your edges have a greater angle than 90 degrees, which should decrease
the amplitude of the edge reflections, which is good. On the other
hand you will have a second edge reflection from the back of the box.

Well there will be a beat pattern from this arrangement where the
second edge which will cancel the effect of the first diffraction
edge. With two corners there are two comb filters. There will be a
destructive phase alignment of the two reflecting filters with a
center f and bandwith which is determined by the bevel edge size.

Errhh... I don't think I understand this. In my world edge reflections
will add up regardless of if they come from the first edge or the
second edge. It may very well be that a reflection from the first edge
and some direction, con occur at the same time as another reflection
in some other direction from the second edge. It does not matter if
the reflections come from the first or the second edge, only the time
(and amplitude) in important. Add up the source, it's mirror and all
reflections (regardless of origin) and you will have an impulse
response. The fourier transform of this impulse response would be the
transfer function of the system (and include the baffle step and
ripple).
This is what my program does. I could include a second border for the
second edge, we'll see about that.

I have not seen your program (mac user) so I don't know if it calculates
on the two corners.

No. If you desperately want to run it I have heard of windows
emulators for mac, but I know nothing about them. But the program is
very simple and mostly a test to try if the baffle "step" can be
calculated by means of edge sources. It should not be seen as a "end
user product". I posted it to get real measurements to compare with,
and input from others (which I have, thank you all). In several cases
I have been positively surprised to see features of the real
measurements coincide with the model. Since I wrote it, I have also
learned that others have written similar things too, both more and
less complicated.

Have you compared your result with the Excel
Spreadsheet at

http://www.pvconsultants.com

No, I can't find anything about loudspeakers there. Is the link
correct?

(Edu Silva) wrote in message . com...
Look at the old Olsen measurements, should be a reference on the web
somewhere. Olle Mirsch should have an article in MoLT; No 1, 1994.


Yes, I will.



A good article at True Audio by John Murphy, based on Harry Olson's work:

http://www.trueaudio.com/st_diff1.htm


HTH,

Edu Silva
ES2 Audio

Yes, thanks.

That's a good example.

T

(Edu Silva) wrote in message . com...
Look at the old Olsen measurements, should be a reference on the web
somewhere. Olle Mirsch should have an article in MoLT; No 1, 1994.


Yes, I will.



A good article at True Audio by John Murphy, based on Harry Olson's work:

http://www.trueaudio.com/st_diff1.htm


HTH,

Edu Silva
ES2 Audio

Yes, thanks.

That's a good example.

T

(Edu Silva) wrote in message . com...
Look at the old Olsen measurements, should be a reference on the web
somewhere. Olle Mirsch should have an article in MoLT; No 1, 1994.


Yes, I will.



A good article at True Audio by John Murphy, based on Harry Olson's work:

http://www.trueaudio.com/st_diff1.htm


HTH,

Edu Silva
ES2 Audio

Yes, thanks.

That's a good example.

T

(Edu Silva) wrote in message . com...
Look at the old Olsen measurements, should be a reference on the web
somewhere. Olle Mirsch should have an article in MoLT; No 1, 1994.


Yes, I will.



A good article at True Audio by John Murphy, based on Harry Olson's work:

http://www.trueaudio.com/st_diff1.htm


HTH,

Edu Silva
ES2 Audio

Yes, thanks.

That's a good example.

T

(Svante) wrote in message . com...
(Thomas A) wrote in message
(Svante) wrote in message
But, anyway, these are small effects, and the program does not take
the response or directivity of the driver into account etc, so
probably there is nothing to worry about.
Your edges have a greater angle than 90 degrees, which should decrease
the amplitude of the edge reflections, which is good. On the other
hand you will have a second edge reflection from the back of the box.

Well there will be a beat pattern from this arrangement where the
second edge which will cancel the effect of the first diffraction
edge. With two corners there are two comb filters. There will be a
destructive phase alignment of the two reflecting filters with a
center f and bandwith which is determined by the bevel edge size.

Errhh... I don't think I understand this. In my world edge reflections
will add up regardless of if they come from the first edge or the
second edge. It may very well be that a reflection from the first edge
and some direction, con occur at the same time as another reflection
in some other direction from the second edge. It does not matter if
the reflections come from the first or the second edge, only the time
(and amplitude) in important. Add up the source, it's mirror and all
reflections (regardless of origin) and you will have an impulse
response. The fourier transform of this impulse response would be the
transfer function of the system (and include the baffle step and
ripple).
This is what my program does. I could include a second border for the
second edge, we'll see about that.


The links for the Excel spreadsheet and the manual is given by another
person in the thread. At the moment I am a little overworked, but I
cite a little more from the Baffle Diffraction Simulator manual. Maybe
it helps:

"If you sharply turn a baffle corner, there is a pressure change that
sends a reflection back at the listener, which arrives late and causes
a comb filter frequency effect. If you turn that same corner, and
instead of finding a single 90 degree sharp turn you pass over two 45
degree sharp edges forming a bevel, you create two such filters. The
distance to the median point between those two edges is the center of
a notch-filtering band. The distance between those edges is a width of
notch effect. The item filtered by that notch filter is the
cancellation of the comb filter like warbling. In all actuality, it is
a beat frequency pattern, not a notch at all. The first nodal
destruction is a half wavelength sum and the periodicity is every
harmonic thereafter. But it still resembles a notch-filtered band, and
as that is the way it appears when you view its effects in the
frequency domain, so I improperly refer to it as a notch filter.

So. If you sharply turn a baffle corner there is a reflection that
comb filters. If you turn that same corner with a two sharp edges
forming a bevel you create two filters. The distance to those two
edges is the center of a notch-filtering band. The item filtered by
that notch filter is the cancellation warbling. For that narrow region
there is significant cancellation of the comb filtering effect because
there is a destructive phase alignment of the two reflecting filters.
Above that frequency and below that frequency you see increased
evidence of the combing effect. Below that region the phase difference
is not significant (they remain correlated) so the two reflections sum
more or less. Above that region the phase difference is again changing
with frequency and so appear to be uncorrelated, so they sum and
difference at the harmonics of the notch but for only tiny frequency
windows and with only a modest amplitude effect in total. "

(Svante) wrote in message . com...
(Thomas A) wrote in message
(Svante) wrote in message
But, anyway, these are small effects, and the program does not take
the response or directivity of the driver into account etc, so
probably there is nothing to worry about.
Your edges have a greater angle than 90 degrees, which should decrease
the amplitude of the edge reflections, which is good. On the other
hand you will have a second edge reflection from the back of the box.

Well there will be a beat pattern from this arrangement where the
second edge which will cancel the effect of the first diffraction
edge. With two corners there are two comb filters. There will be a
destructive phase alignment of the two reflecting filters with a
center f and bandwith which is determined by the bevel edge size.

Errhh... I don't think I understand this. In my world edge reflections
will add up regardless of if they come from the first edge or the
second edge. It may very well be that a reflection from the first edge
and some direction, con occur at the same time as another reflection
in some other direction from the second edge. It does not matter if
the reflections come from the first or the second edge, only the time
(and amplitude) in important. Add up the source, it's mirror and all
reflections (regardless of origin) and you will have an impulse
response. The fourier transform of this impulse response would be the
transfer function of the system (and include the baffle step and
ripple).
This is what my program does. I could include a second border for the
second edge, we'll see about that.


The links for the Excel spreadsheet and the manual is given by another
person in the thread. At the moment I am a little overworked, but I
cite a little more from the Baffle Diffraction Simulator manual. Maybe
it helps:

"If you sharply turn a baffle corner, there is a pressure change that
sends a reflection back at the listener, which arrives late and causes
a comb filter frequency effect. If you turn that same corner, and
instead of finding a single 90 degree sharp turn you pass over two 45
degree sharp edges forming a bevel, you create two such filters. The
distance to the median point between those two edges is the center of
a notch-filtering band. The distance between those edges is a width of
notch effect. The item filtered by that notch filter is the
cancellation of the comb filter like warbling. In all actuality, it is
a beat frequency pattern, not a notch at all. The first nodal
destruction is a half wavelength sum and the periodicity is every
harmonic thereafter. But it still resembles a notch-filtered band, and
as that is the way it appears when you view its effects in the
frequency domain, so I improperly refer to it as a notch filter.

So. If you sharply turn a baffle corner there is a reflection that
comb filters. If you turn that same corner with a two sharp edges
forming a bevel you create two filters. The distance to those two
edges is the center of a notch-filtering band. The item filtered by
that notch filter is the cancellation warbling. For that narrow region
there is significant cancellation of the comb filtering effect because
there is a destructive phase alignment of the two reflecting filters.
Above that frequency and below that frequency you see increased
evidence of the combing effect. Below that region the phase difference
is not significant (they remain correlated) so the two reflections sum
more or less. Above that region the phase difference is again changing
with frequency and so appear to be uncorrelated, so they sum and
difference at the harmonics of the notch but for only tiny frequency
windows and with only a modest amplitude effect in total. "

(Svante) wrote in message . com...
(Thomas A) wrote in message
(Svante) wrote in message
But, anyway, these are small effects, and the program does not take
the response or directivity of the driver into account etc, so
probably there is nothing to worry about.
Your edges have a greater angle than 90 degrees, which should decrease
the amplitude of the edge reflections, which is good. On the other
hand you will have a second edge reflection from the back of the box.

Well there will be a beat pattern from this arrangement where the
second edge which will cancel the effect of the first diffraction
edge. With two corners there are two comb filters. There will be a
destructive phase alignment of the two reflecting filters with a
center f and bandwith which is determined by the bevel edge size.

Errhh... I don't think I understand this. In my world edge reflections
will add up regardless of if they come from the first edge or the
second edge. It may very well be that a reflection from the first edge
and some direction, con occur at the same time as another reflection
in some other direction from the second edge. It does not matter if
the reflections come from the first or the second edge, only the time
(and amplitude) in important. Add up the source, it's mirror and all
reflections (regardless of origin) and you will have an impulse
response. The fourier transform of this impulse response would be the
transfer function of the system (and include the baffle step and
ripple).
This is what my program does. I could include a second border for the
second edge, we'll see about that.


The links for the Excel spreadsheet and the manual is given by another
person in the thread. At the moment I am a little overworked, but I
cite a little more from the Baffle Diffraction Simulator manual. Maybe
it helps:

"If you sharply turn a baffle corner, there is a pressure change that
sends a reflection back at the listener, which arrives late and causes
a comb filter frequency effect. If you turn that same corner, and
instead of finding a single 90 degree sharp turn you pass over two 45
degree sharp edges forming a bevel, you create two such filters. The
distance to the median point between those two edges is the center of
a notch-filtering band. The distance between those edges is a width of
notch effect. The item filtered by that notch filter is the
cancellation of the comb filter like warbling. In all actuality, it is
a beat frequency pattern, not a notch at all. The first nodal
destruction is a half wavelength sum and the periodicity is every
harmonic thereafter. But it still resembles a notch-filtered band, and
as that is the way it appears when you view its effects in the
frequency domain, so I improperly refer to it as a notch filter.

So. If you sharply turn a baffle corner there is a reflection that
comb filters. If you turn that same corner with a two sharp edges
forming a bevel you create two filters. The distance to those two
edges is the center of a notch-filtering band. The item filtered by
that notch filter is the cancellation warbling. For that narrow region
there is significant cancellation of the comb filtering effect because
there is a destructive phase alignment of the two reflecting filters.
Above that frequency and below that frequency you see increased
evidence of the combing effect. Below that region the phase difference
is not significant (they remain correlated) so the two reflections sum
more or less. Above that region the phase difference is again changing
with frequency and so appear to be uncorrelated, so they sum and
difference at the harmonics of the notch but for only tiny frequency
windows and with only a modest amplitude effect in total. "

(Svante) wrote in message . com...
(Thomas A) wrote in message
(Svante) wrote in message
But, anyway, these are small effects, and the program does not take
the response or directivity of the driver into account etc, so
probably there is nothing to worry about.
Your edges have a greater angle than 90 degrees, which should decrease
the amplitude of the edge reflections, which is good. On the other
hand you will have a second edge reflection from the back of the box.

Well there will be a beat pattern from this arrangement where the
second edge which will cancel the effect of the first diffraction
edge. With two corners there are two comb filters. There will be a
destructive phase alignment of the two reflecting filters with a
center f and bandwith which is determined by the bevel edge size.

Errhh... I don't think I understand this. In my world edge reflections
will add up regardless of if they come from the first edge or the
second edge. It may very well be that a reflection from the first edge
and some direction, con occur at the same time as another reflection
in some other direction from the second edge. It does not matter if
the reflections come from the first or the second edge, only the time
(and amplitude) in important. Add up the source, it's mirror and all
reflections (regardless of origin) and you will have an impulse
response. The fourier transform of this impulse response would be the
transfer function of the system (and include the baffle step and
ripple).
This is what my program does. I could include a second border for the
second edge, we'll see about that.


The links for the Excel spreadsheet and the manual is given by another
person in the thread. At the moment I am a little overworked, but I
cite a little more from the Baffle Diffraction Simulator manual. Maybe
it helps:

"If you sharply turn a baffle corner, there is a pressure change that
sends a reflection back at the listener, which arrives late and causes
a comb filter frequency effect. If you turn that same corner, and
instead of finding a single 90 degree sharp turn you pass over two 45
degree sharp edges forming a bevel, you create two such filters. The
distance to the median point between those two edges is the center of
a notch-filtering band. The distance between those edges is a width of
notch effect. The item filtered by that notch filter is the
cancellation of the comb filter like warbling. In all actuality, it is
a beat frequency pattern, not a notch at all. The first nodal
destruction is a half wavelength sum and the periodicity is every
harmonic thereafter. But it still resembles a notch-filtered band, and
as that is the way it appears when you view its effects in the
frequency domain, so I improperly refer to it as a notch filter.

So. If you sharply turn a baffle corner there is a reflection that
comb filters. If you turn that same corner with a two sharp edges
forming a bevel you create two filters. The distance to those two
edges is the center of a notch-filtering band. The item filtered by
that notch filter is the cancellation warbling. For that narrow region
there is significant cancellation of the comb filtering effect because
there is a destructive phase alignment of the two reflecting filters.
Above that frequency and below that frequency you see increased
evidence of the combing effect. Below that region the phase difference
is not significant (they remain correlated) so the two reflections sum
more or less. Above that region the phase difference is again changing
with frequency and so appear to be uncorrelated, so they sum and
difference at the harmonics of the notch but for only tiny frequency
windows and with only a modest amplitude effect in total. "

Svante wrote:

Interesting! Could you share these measurements, if possible?

I'll try to remember this as something to come back to - possibly on my
website - in case I resume development of system8, but they will be
unconclusive because the baffle measured is "non-simple", consequently
the cabinet effects are eqally non-simple.

Thx.

--
*******************************************
* My site is at: http://www.muyiovatki.dk *
*******************************************

Svante wrote:

Interesting! Could you share these measurements, if possible?

I'll try to remember this as something to come back to - possibly on my
website - in case I resume development of system8, but they will be
unconclusive because the baffle measured is "non-simple", consequently
the cabinet effects are eqally non-simple.

Thx.

--
*******************************************
* My site is at: http://www.muyiovatki.dk *
*******************************************

Svante wrote:

Interesting! Could you share these measurements, if possible?

I'll try to remember this as something to come back to - possibly on my
website - in case I resume development of system8, but they will be
unconclusive because the baffle measured is "non-simple", consequently
the cabinet effects are eqally non-simple.

Thx.

--
*******************************************
* My site is at: http://www.muyiovatki.dk *
*******************************************

Svante wrote:

Interesting! Could you share these measurements, if possible?

I'll try to remember this as something to come back to - possibly on my
website - in case I resume development of system8, but they will be
unconclusive because the baffle measured is "non-simple", consequently
the cabinet effects are eqally non-simple.

Thx.

--
*******************************************
* My site is at: http://www.muyiovatki.dk *
*******************************************

(Thomas A) wrote in message . com...
(Svante) wrote in message . com...
(Thomas A) wrote in message
(Svante) wrote in message
But, anyway, these are small effects, and the program does not take
the response or directivity of the driver into account etc, so
probably there is nothing to worry about.
Your edges have a greater angle than 90 degrees, which should decrease
the amplitude of the edge reflections, which is good. On the other
hand you will have a second edge reflection from the back of the box.

Well there will be a beat pattern from this arrangement where the
second edge which will cancel the effect of the first diffraction
edge. With two corners there are two comb filters. There will be a
destructive phase alignment of the two reflecting filters with a
center f and bandwith which is determined by the bevel edge size.

Errhh... I don't think I understand this. In my world edge reflections
will add up regardless of if they come from the first edge or the
second edge. It may very well be that a reflection from the first edge
and some direction, con occur at the same time as another reflection
in some other direction from the second edge. It does not matter if
the reflections come from the first or the second edge, only the time
(and amplitude) in important. Add up the source, it's mirror and all
reflections (regardless of origin) and you will have an impulse
response. The fourier transform of this impulse response would be the
transfer function of the system (and include the baffle step and
ripple).
This is what my program does. I could include a second border for the
second edge, we'll see about that.


The links for the Excel spreadsheet and the manual is given by another
person in the thread. At the moment I am a little overworked, but I
cite a little more from the Baffle Diffraction Simulator manual. Maybe
it helps:

I can understand that, don't worry. I found the program, it seems to
do good stuff. I have not found out how to place the driver on the
baffle, but I guess that would be found in the documentation.


"If you sharply turn a baffle corner, there is a pressure change that
sends a reflection back at the listener, which arrives late and causes
a comb filter frequency effect. If you turn that same corner, and
instead of finding a single 90 degree sharp turn you pass over two 45
degree sharp edges forming a bevel, you create two such filters. The
distance to the median point between those two edges is the center of
a notch-filtering band. The distance between those edges is a width of
notch effect. The item filtered by that notch filter is the
cancellation of the comb filter like warbling. In all actuality, it is
a beat frequency pattern, not a notch at all. The first nodal
destruction is a half wavelength sum and the periodicity is every
harmonic thereafter. But it still resembles a notch-filtered band, and
as that is the way it appears when you view its effects in the
frequency domain, so I improperly refer to it as a notch filter.

So. If you sharply turn a baffle corner there is a reflection that
comb filters. If you turn that same corner with a two sharp edges
forming a bevel you create two filters. The distance to those two
edges is the center of a notch-filtering band. The item filtered by
that notch filter is the cancellation warbling. For that narrow region
there is significant cancellation of the comb filtering effect because
there is a destructive phase alignment of the two reflecting filters.
Above that frequency and below that frequency you see increased
evidence of the combing effect. Below that region the phase difference
is not significant (they remain correlated) so the two reflections sum
more or less. Above that region the phase difference is again changing
with frequency and so appear to be uncorrelated, so they sum and
difference at the harmonics of the notch but for only tiny frequency
windows and with only a modest amplitude effect in total. "

I realise that this is not your explanation, but BDS's. I have some
problems with this viewpoint, I think it is confusing. For sure, if we
think of a circular baffle with the driver at the centre, the
situation outlined above would occur. There would be one reflection
from the first edge, and one from the second edge. And possibly this
could be viewed as two separate comb filters working in parallel. But
I think this explanation is unnessecarily complicated, combining two
filters that run in parallel is not a very intuitive task. Some zeroes
may be cancelled, that is easy to realise, but new would occur when
the two signals are of equal magnitude but opposite phase. The model
seems especially non-intuitive in the case of a non-circular baffle,
where the durations of the two impulse responses would overlap. Since
the only difference between the first and the second reflection is the
time at which they occur, and that this also is the difference between
different loactions along the (possibly non-circular) edge, it is IMO
easiest thought of as ONE impulse response, and the fourier transform
of this single impulse response would correspond to the frequency
response. It makes little sense to separate the two reflections and
then combine the filters. It is not wrong, but IMO confusing.

But of course, for those who like that viewpoint, it is OK, and
possibly it can also help to understand things from different aspects.

Thanks for your input!

(Thomas A) wrote in message . com...
(Svante) wrote in message . com...
(Thomas A) wrote in message
(Svante) wrote in message
But, anyway, these are small effects, and the program does not take
the response or directivity of the driver into account etc, so
probably there is nothing to worry about.
Your edges have a greater angle than 90 degrees, which should decrease
the amplitude of the edge reflections, which is good. On the other
hand you will have a second edge reflection from the back of the box.

Well there will be a beat pattern from this arrangement where the
second edge which will cancel the effect of the first diffraction
edge. With two corners there are two comb filters. There will be a
destructive phase alignment of the two reflecting filters with a
center f and bandwith which is determined by the bevel edge size.

Errhh... I don't think I understand this. In my world edge reflections
will add up regardless of if they come from the first edge or the
second edge. It may very well be that a reflection from the first edge
and some direction, con occur at the same time as another reflection
in some other direction from the second edge. It does not matter if
the reflections come from the first or the second edge, only the time
(and amplitude) in important. Add up the source, it's mirror and all
reflections (regardless of origin) and you will have an impulse
response. The fourier transform of this impulse response would be the
transfer function of the system (and include the baffle step and
ripple).
This is what my program does. I could include a second border for the
second edge, we'll see about that.


The links for the Excel spreadsheet and the manual is given by another
person in the thread. At the moment I am a little overworked, but I
cite a little more from the Baffle Diffraction Simulator manual. Maybe
it helps:

I can understand that, don't worry. I found the program, it seems to
do good stuff. I have not found out how to place the driver on the
baffle, but I guess that would be found in the documentation.


"If you sharply turn a baffle corner, there is a pressure change that
sends a reflection back at the listener, which arrives late and causes
a comb filter frequency effect. If you turn that same corner, and
instead of finding a single 90 degree sharp turn you pass over two 45
degree sharp edges forming a bevel, you create two such filters. The
distance to the median point between those two edges is the center of
a notch-filtering band. The distance between those edges is a width of
notch effect. The item filtered by that notch filter is the
cancellation of the comb filter like warbling. In all actuality, it is
a beat frequency pattern, not a notch at all. The first nodal
destruction is a half wavelength sum and the periodicity is every
harmonic thereafter. But it still resembles a notch-filtered band, and
as that is the way it appears when you view its effects in the
frequency domain, so I improperly refer to it as a notch filter.

So. If you sharply turn a baffle corner there is a reflection that
comb filters. If you turn that same corner with a two sharp edges
forming a bevel you create two filters. The distance to those two
edges is the center of a notch-filtering band. The item filtered by
that notch filter is the cancellation warbling. For that narrow region
there is significant cancellation of the comb filtering effect because
there is a destructive phase alignment of the two reflecting filters.
Above that frequency and below that frequency you see increased
evidence of the combing effect. Below that region the phase difference
is not significant (they remain correlated) so the two reflections sum
more or less. Above that region the phase difference is again changing
with frequency and so appear to be uncorrelated, so they sum and
difference at the harmonics of the notch but for only tiny frequency
windows and with only a modest amplitude effect in total. "

I realise that this is not your explanation, but BDS's. I have some
problems with this viewpoint, I think it is confusing. For sure, if we
think of a circular baffle with the driver at the centre, the
situation outlined above would occur. There would be one reflection
from the first edge, and one from the second edge. And possibly this
could be viewed as two separate comb filters working in parallel. But
I think this explanation is unnessecarily complicated, combining two
filters that run in parallel is not a very intuitive task. Some zeroes
may be cancelled, that is easy to realise, but new would occur when
the two signals are of equal magnitude but opposite phase. The model
seems especially non-intuitive in the case of a non-circular baffle,
where the durations of the two impulse responses would overlap. Since
the only difference between the first and the second reflection is the
time at which they occur, and that this also is the difference between
different loactions along the (possibly non-circular) edge, it is IMO
easiest thought of as ONE impulse response, and the fourier transform
of this single impulse response would correspond to the frequency
response. It makes little sense to separate the two reflections and
then combine the filters. It is not wrong, but IMO confusing.

But of course, for those who like that viewpoint, it is OK, and
possibly it can also help to understand things from different aspects.

Thanks for your input!

(Thomas A) wrote in message . com...
(Svante) wrote in message . com...
(Thomas A) wrote in message
(Svante) wrote in message
But, anyway, these are small effects, and the program does not take
the response or directivity of the driver into account etc, so
probably there is nothing to worry about.
Your edges have a greater angle than 90 degrees, which should decrease
the amplitude of the edge reflections, which is good. On the other
hand you will have a second edge reflection from the back of the box.

Well there will be a beat pattern from this arrangement where the
second edge which will cancel the effect of the first diffraction
edge. With two corners there are two comb filters. There will be a
destructive phase alignment of the two reflecting filters with a
center f and bandwith which is determined by the bevel edge size.

Errhh... I don't think I understand this. In my world edge reflections
will add up regardless of if they come from the first edge or the
second edge. It may very well be that a reflection from the first edge
and some direction, con occur at the same time as another reflection
in some other direction from the second edge. It does not matter if
the reflections come from the first or the second edge, only the time
(and amplitude) in important. Add up the source, it's mirror and all
reflections (regardless of origin) and you will have an impulse
response. The fourier transform of this impulse response would be the
transfer function of the system (and include the baffle step and
ripple).
This is what my program does. I could include a second border for the
second edge, we'll see about that.


The links for the Excel spreadsheet and the manual is given by another
person in the thread. At the moment I am a little overworked, but I
cite a little more from the Baffle Diffraction Simulator manual. Maybe
it helps:

I can understand that, don't worry. I found the program, it seems to
do good stuff. I have not found out how to place the driver on the
baffle, but I guess that would be found in the documentation.


"If you sharply turn a baffle corner, there is a pressure change that
sends a reflection back at the listener, which arrives late and causes
a comb filter frequency effect. If you turn that same corner, and
instead of finding a single 90 degree sharp turn you pass over two 45
degree sharp edges forming a bevel, you create two such filters. The
distance to the median point between those two edges is the center of
a notch-filtering band. The distance between those edges is a width of
notch effect. The item filtered by that notch filter is the
cancellation of the comb filter like warbling. In all actuality, it is
a beat frequency pattern, not a notch at all. The first nodal
destruction is a half wavelength sum and the periodicity is every
harmonic thereafter. But it still resembles a notch-filtered band, and
as that is the way it appears when you view its effects in the
frequency domain, so I improperly refer to it as a notch filter.

So. If you sharply turn a baffle corner there is a reflection that
comb filters. If you turn that same corner with a two sharp edges
forming a bevel you create two filters. The distance to those two
edges is the center of a notch-filtering band. The item filtered by
that notch filter is the cancellation warbling. For that narrow region
there is significant cancellation of the comb filtering effect because
there is a destructive phase alignment of the two reflecting filters.
Above that frequency and below that frequency you see increased
evidence of the combing effect. Below that region the phase difference
is not significant (they remain correlated) so the two reflections sum
more or less. Above that region the phase difference is again changing
with frequency and so appear to be uncorrelated, so they sum and
difference at the harmonics of the notch but for only tiny frequency
windows and with only a modest amplitude effect in total. "

I realise that this is not your explanation, but BDS's. I have some
problems with this viewpoint, I think it is confusing. For sure, if we
think of a circular baffle with the driver at the centre, the
situation outlined above would occur. There would be one reflection
from the first edge, and one from the second edge. And possibly this
could be viewed as two separate comb filters working in parallel. But
I think this explanation is unnessecarily complicated, combining two
filters that run in parallel is not a very intuitive task. Some zeroes
may be cancelled, that is easy to realise, but new would occur when
the two signals are of equal magnitude but opposite phase. The model
seems especially non-intuitive in the case of a non-circular baffle,
where the durations of the two impulse responses would overlap. Since
the only difference between the first and the second reflection is the
time at which they occur, and that this also is the difference between
different loactions along the (possibly non-circular) edge, it is IMO
easiest thought of as ONE impulse response, and the fourier transform
of this single impulse response would correspond to the frequency
response. It makes little sense to separate the two reflections and
then combine the filters. It is not wrong, but IMO confusing.

But of course, for those who like that viewpoint, it is OK, and
possibly it can also help to understand things from different aspects.

Thanks for your input!

(Thomas A) wrote in message . com...
(Svante) wrote in message . com...
(Thomas A) wrote in message
(Svante) wrote in message
But, anyway, these are small effects, and the program does not take
the response or directivity of the driver into account etc, so
probably there is nothing to worry about.
Your edges have a greater angle than 90 degrees, which should decrease
the amplitude of the edge reflections, which is good. On the other
hand you will have a second edge reflection from the back of the box.

Well there will be a beat pattern from this arrangement where the
second edge which will cancel the effect of the first diffraction
edge. With two corners there are two comb filters. There will be a
destructive phase alignment of the two reflecting filters with a
center f and bandwith which is determined by the bevel edge size.

Errhh... I don't think I understand this. In my world edge reflections
will add up regardless of if they come from the first edge or the
second edge. It may very well be that a reflection from the first edge
and some direction, con occur at the same time as another reflection
in some other direction from the second edge. It does not matter if
the reflections come from the first or the second edge, only the time
(and amplitude) in important. Add up the source, it's mirror and all
reflections (regardless of origin) and you will have an impulse
response. The fourier transform of this impulse response would be the
transfer function of the system (and include the baffle step and
ripple).
This is what my program does. I could include a second border for the
second edge, we'll see about that.


The links for the Excel spreadsheet and the manual is given by another
person in the thread. At the moment I am a little overworked, but I
cite a little more from the Baffle Diffraction Simulator manual. Maybe
it helps:

I can understand that, don't worry. I found the program, it seems to
do good stuff. I have not found out how to place the driver on the
baffle, but I guess that would be found in the documentation.


"If you sharply turn a baffle corner, there is a pressure change that
sends a reflection back at the listener, which arrives late and causes
a comb filter frequency effect. If you turn that same corner, and
instead of finding a single 90 degree sharp turn you pass over two 45
degree sharp edges forming a bevel, you create two such filters. The
distance to the median point between those two edges is the center of
a notch-filtering band. The distance between those edges is a width of
notch effect. The item filtered by that notch filter is the
cancellation of the comb filter like warbling. In all actuality, it is
a beat frequency pattern, not a notch at all. The first nodal
destruction is a half wavelength sum and the periodicity is every
harmonic thereafter. But it still resembles a notch-filtered band, and
as that is the way it appears when you view its effects in the
frequency domain, so I improperly refer to it as a notch filter.

So. If you sharply turn a baffle corner there is a reflection that
comb filters. If you turn that same corner with a two sharp edges
forming a bevel you create two filters. The distance to those two
edges is the center of a notch-filtering band. The item filtered by
that notch filter is the cancellation warbling. For that narrow region
there is significant cancellation of the comb filtering effect because
there is a destructive phase alignment of the two reflecting filters.
Above that frequency and below that frequency you see increased
evidence of the combing effect. Below that region the phase difference
is not significant (they remain correlated) so the two reflections sum
more or less. Above that region the phase difference is again changing
with frequency and so appear to be uncorrelated, so they sum and
difference at the harmonics of the notch but for only tiny frequency
windows and with only a modest amplitude effect in total. "

I realise that this is not your explanation, but BDS's. I have some
problems with this viewpoint, I think it is confusing. For sure, if we
think of a circular baffle with the driver at the centre, the
situation outlined above would occur. There would be one reflection
from the first edge, and one from the second edge. And possibly this
could be viewed as two separate comb filters working in parallel. But
I think this explanation is unnessecarily complicated, combining two
filters that run in parallel is not a very intuitive task. Some zeroes
may be cancelled, that is easy to realise, but new would occur when
the two signals are of equal magnitude but opposite phase. The model
seems especially non-intuitive in the case of a non-circular baffle,
where the durations of the two impulse responses would overlap. Since
the only difference between the first and the second reflection is the
time at which they occur, and that this also is the difference between
different loactions along the (possibly non-circular) edge, it is IMO
easiest thought of as ONE impulse response, and the fourier transform
of this single impulse response would correspond to the frequency
response. It makes little sense to separate the two reflections and
then combine the filters. It is not wrong, but IMO confusing.

But of course, for those who like that viewpoint, it is OK, and
possibly it can also help to understand things from different aspects.

Thanks for your input!