COmputer program for determining acoustic centres

5th element · 13th March 2004, 09:22 PM

There was a thread not to long ago that specified a program that could do this. I tried a few searches but came up empty handed

Can anyone elighten me to either the location of the thread or what this program was called.

Cheers Matt

sreten · 13th March 2004, 09:59 PM

This may not help but illustrate the problem.

The pulse testing of a Thiel concentric unit revealed
that although they were physically aligned they were
not time aligned even with mechanical 1st order c/o's.

I suspect this is due to phase differences between the elements.

And its also certain a units "acoustic centre" is affected by
by the crossover, Bessel alignments being the most phase
linear and equivalently position stable as I understand it.

sreten.

5th element · 13th March 2004, 10:04 PM

The reason why I want to determine the acoustics centres is for the Z coodinate in LSPcad, this makes quite a considerable differnce when simulating.

Bill Fitzpatrick · 14th March 2004, 01:05 AM

I'd be interested in this software as well.

russbryant · 14th March 2004, 05:25 AM

Quote:

Originally posted by sreten

The pulse testing of a Thiel concentric unit revealed
that although they were physically aligned they were
not time aligned even with mechanical 1st order c/o's.

And its also certain a units "acoustic centre" is affected by
by the crossover, Bessel alignments being the most phase
linear and equivalently position stable as I understand it.

sreten.

It's the acoustic slope that determines the order of a crossover not the electrical slope. The acoustic slope is the summed response of the electrical slope and the drivers natural roll off. I think it was Dynaudio that used 17 component to acheive a true 1st order slope in one of their speakers.

The acoustic center of a driver is determined from raw measurements without a crossover. What is important is the acoustic center of one driver, say a woofer, relative to the acoustic center of another, the tweeter. This is what programs like LSPCad and SoundEasy need. I don't think there are any programs that can measure it directly.

Russ

Svante · 14th March 2004, 08:31 AM

Also, I think that the position of acoustic centre would vary with frequency, so it is not *one* number you are looking for. Possibly the number around the crossover frequency is the most interesting, though.

ergo · 14th March 2004, 09:56 AM

LspCad and JustMLS cobination has means to do what you want.

Check the Ugly Ducling project description on Ingemars web page..

www.ijdata.com

Ergo

5th element · 14th March 2004, 11:20 AM

I have looked at the ugly duckling several times before I guess its time to lookat it again!

Ron E · 14th March 2004, 01:19 PM

I am not sure how JustMLS or LspCAD work, but I know that in Speaker Workshop, if you measure the woofer and tweeter at the same distance and use those measurements without generating minumum phase data, the information about acoustic center (relative phase between woofer and tweeter) is contained in the data. Modeling will show the proper summation.

ergo · 14th March 2004, 01:30 PM

In LspCad exaclty the same technique is used...

Ergo

13th March 2004, 09:22 PM	#1
5th element diyAudio Member Join Date: Oct 2002 Location: England	COmputer program for determining acoustic centres There was a thread not to long ago that specified a program that could do this. I tried a few searches but came up empty handed Can anyone elighten me to either the location of the thread or what this program was called. Cheers Matt __________________ What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz! Droggon Attack!

13th March 2004, 10:04 PM	#3
5th element diyAudio Member Join Date: Oct 2002 Location: England	The reason why I want to determine the acoustics centres is for the Z coodinate in LSPcad, this makes quite a considerable differnce when simulating. __________________ What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz! Droggon Attack!

14th March 2004, 08:31 AM	#6
Svante diyAudio Member Join Date: Feb 2004 Location: Stockholm	Also, I think that the position of acoustic centre would vary with frequency, so it is not one number you are looking for. Possibly the number around the crossover frequency is the most interesting, though. __________________ Simulate loudspeakers: Basta! Simulate the baffle step: The Edge

14th March 2004, 11:20 AM	#8
5th element diyAudio Member Join Date: Oct 2002 Location: England	I have looked at the ugly duckling several times before I guess its time to lookat it again! __________________ What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz! Droggon Attack!

14th March 2004, 01:19 PM	#9
Ron E diyAudio Member Join Date: Jun 2002 Location: USA, MN	I am not sure how JustMLS or LspCAD work, but I know that in Speaker Workshop, if you measure the woofer and tweeter at the same distance and use those measurements without generating minumum phase data, the information about acoustic center (relative phase between woofer and tweeter) is contained in the data. Modeling will show the proper summation. __________________ 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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13th March 2004, 09:59 PM	#2
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	This may not help but illustrate the problem. The pulse testing of a Thiel concentric unit revealed that although they were physically aligned they were not time aligned even with mechanical 1st order c/o's. I suspect this is due to phase differences between the elements. And its also certain a units "acoustic centre" is affected by by the crossover, Bessel alignments being the most phase linear and equivalently position stable as I understand it. sreten.

14th March 2004, 01:05 AM	#4
Bill Fitzpatrick diyAudio Member Join Date: Jun 2001 Location: Eugene, OR	I'd be interested in this software as well.

14th March 2004, 09:56 AM	#7
ergo diyAudio Member Join Date: Mar 2001 Location: Tallinn, Estonia	LspCad and JustMLS cobination has means to do what you want. Check the Ugly Ducling project description on Ingemars web page.. www.ijdata.com Ergo

14th March 2004, 01:30 PM	#10
ergo diyAudio Member Join Date: Mar 2001 Location: Tallinn, Estonia	In LspCad exaclty the same technique is used... Ergo

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