Polar pattern for different diameter drivers?

mefistofelez · 12th February 2007, 08:25 AM

I was wondering whether there exist some data or even better software that would alow determining polar pattern for a driver of a given diameter as a function of frequency.

If so, could you please point me to it?

Thank you,

M

sreten · 12th February 2007, 11:43 AM

Hi,

It doesn't work like that - dispersion being exactly related to diameter.

Its far more complicate depending on cone / dome materials and profiles.

/sreten.

ente · 12th February 2007, 11:43 AM

... pls look here

Arta

and here

http://www.fesb.hr/~mateljan/arta/Ap...r-Rev01Ger.pdf

Regards
Heinrich

Dag · 12th February 2007, 11:47 AM

check out "The Edge" baffle diffraction simulator at www.tolvan.com/

Geoff H · 12th February 2007, 01:08 PM

I have to agree with sreten on that.

The simulators don't allow for different cone shapes or contours of stiffness. A deep, rigid cone will have a narrower high freq. pattern than a curvilinear cone. Stiffening the apex will increase the upper limit, however it it stiffens too far up the apex, will beam it.

I am doing right now, in fact.

Geoff.

edit. If the beam was down to 10 deg, is a flat baffle going to make it wider? Say 40 degrees. Be handy if it did.

pinkmouse · 12th February 2007, 01:10 PM

Exactly, the only way is to measure in your own box.

mefistofelez · 12th February 2007, 04:18 PM

Thank you very much to everyone who replied.

Dear serten, Geoff H, and pinkmouse,

I do realize that models have limitations. And some of the variables may even be of a second or lower order.

I do not expect a quantitative analysis, more of a qualitative one, and insight, if you will. Staying with Richard W. Hamming's qoute "The purpose of computing is insight, not numbers."

Kindest regardes,

M

MJK · 12th February 2007, 04:31 PM

M,

The newest versions of my MathCad worksheets are going to show a polar plot of the driver in the enclosure. Right now it is set up as a free field polar plot but it will give the user some idea of how much sound energy is being reflected off the back or side walls and how directional the speaker is as a function of frequency. The polar plot accounts for the driver, port, or TL opening directivity as a function of size and shape and also the rectangular baffle edge sources. This is a work in progress and will continue to be developed. The OB worksheets were made available this weekend and hopefully a few more will follow every week or two depending on my time constraints at home.

mefistofelez · 13th February 2007, 07:44 AM

Dear Martin,

thank you for the reply. I will have to dust-off my MathCad skills and try your worksheets.

Kindest regards,

M

Ron E · 13th February 2007, 10:45 PM

Do a search for a tool called ARPE at the FRD consortium.

Alternatively I can send you a spreadsheet if you wish. It is based on The math at Art Ludwig's sound page. Art did a test of modeled vs. actual vs diameter based and found that shape matters very little in the farfield. Shape does matter for how the driver performs outside of the pistonic range, however....

12th February 2007, 08:25 AM	#1
mefistofelez diyAudio Member Join Date: Apr 2002	Polar pattern for different diameter drivers? I was wondering whether there exist some data or even better software that would alow determining polar pattern for a driver of a given diameter as a function of frequency. If so, could you please point me to it? Thank you, M

12th February 2007, 11:43 AM	#3
ente diyAudio Member Join Date: Aug 2004 Location: NNW of Rome	ARTA for directivity measurements ... pls look here Arta and here http://www.fesb.hr/~mateljan/arta/Ap...r-Rev01Ger.pdf Regards Heinrich

12th February 2007, 01:10 PM	#6
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	Exactly, the only way is to measure in your own box. __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

13th February 2007, 10:45 PM	#10
Ron E diyAudio Member Join Date: Jun 2002 Location: USA, MN	Do a search for a tool called ARPE at the FRD consortium. Alternatively I can send you a spreadsheet if you wish. It is based on The math at Art Ludwig's sound page. Art did a test of modeled vs. actual vs diameter based and found that shape matters very little in the farfield. Shape does matter for how the driver performs outside of the pistonic range, however.... __________________ Our species needs, and deserves, a citizenry with minds wide awake and a basic understanding of how the world works. --Carl Sagan Science is a way of thinking much more than it is a body of knowledge. --Carl Sagan

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12th February 2007, 11:43 AM	#2
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, It doesn't work like that - dispersion being exactly related to diameter. Its far more complicate depending on cone / dome materials and profiles. /sreten.

12th February 2007, 11:47 AM	#4
Dag diyAudio Member Join Date: Feb 2005 Location: Goteborg	check out "The Edge" baffle diffraction simulator at www.tolvan.com/

12th February 2007, 01:08 PM	#5
Geoff H diyAudio Member Join Date: Oct 2006	I have to agree with sreten on that. The simulators don't allow for different cone shapes or contours of stiffness. A deep, rigid cone will have a narrower high freq. pattern than a curvilinear cone. Stiffening the apex will increase the upper limit, however it it stiffens too far up the apex, will beam it. I am doing right now, in fact. Geoff. edit. If the beam was down to 10 deg, is a flat baffle going to make it wider? Say 40 degrees. Be handy if it did.

12th February 2007, 04:18 PM	#7
mefistofelez diyAudio Member Join Date: Apr 2002	Thank you very much to everyone who replied. Dear serten, Geoff H, and pinkmouse, I do realize that models have limitations. And some of the variables may even be of a second or lower order. I do not expect a quantitative analysis, more of a qualitative one, and insight, if you will. Staying with Richard W. Hamming's qoute "The purpose of computing is insight, not numbers." Kindest regardes, M

12th February 2007, 04:31 PM	#8
MJK Account disabled at member's request Join Date: Feb 2002 Location: Clifton Park, NY	M, The newest versions of my MathCad worksheets are going to show a polar plot of the driver in the enclosure. Right now it is set up as a free field polar plot but it will give the user some idea of how much sound energy is being reflected off the back or side walls and how directional the speaker is as a function of frequency. The polar plot accounts for the driver, port, or TL opening directivity as a function of size and shape and also the rectangular baffle edge sources. This is a work in progress and will continue to be developed. The OB worksheets were made available this weekend and hopefully a few more will follow every week or two depending on my time constraints at home.

13th February 2007, 07:44 AM	#9
mefistofelez diyAudio Member Join Date: Apr 2002	Dear Martin, thank you for the reply. I will have to dust-off my MathCad skills and try your worksheets. Kindest regards, M

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