Acoustic null test?

electroaudio · 23rd March 2009, 09:51 PM

If i put two subs facing eachother where one has a reversed phase to see how different they are.
Are there any restrictions on how far apart they must be or anything else i have to think of?

chris661 · 24th March 2009, 08:34 PM

make sure they are reasonably close, but not touching

This line up is called Iso-brarik, where the effective Fs of the speaker is lowered, the motor power of the speaker is increased

Apparently, you can use a far smaller box to produce the same sound as just one driver.

Never tried it though.

Good luck.

Ron E · 25th March 2009, 03:12 AM

This is not about isobarik, this is about testing for dissimilarity. Quad does this with their ESL's AFAIK.
I would think, within reason, the closer the better. You will want to make some sort of fixture to hold them with the microphone dead center.
IIRC Quad puts the panels at an angle ( A V shape) and puts the mike on a line bisecting the angle.

23rd March 2009, 09:51 PM	#1
electroaudio diyAudio Member Join Date: Mar 2004 Location: stockholm	Acoustic null test? If i put two subs facing eachother where one has a reversed phase to see how different they are. Are there any restrictions on how far apart they must be or anything else i have to think of?

24th March 2009, 08:34 PM	#2
chris661 diyAudio Member Join Date: Feb 2008 Location: Lancashire Blog Entries: 6	make sure they are reasonably close, but not touching This line up is called Iso-brarik, where the effective Fs of the speaker is lowered, the motor power of the speaker is increased Apparently, you can use a far smaller box to produce the same sound as just one driver. Never tried it though. Good luck. __________________ iPod Touch (playing LossLess) > 4th order LR crossover @80Hz > Amp-6b > Fostex FE126eN in folded ML-Voigt Pipes ------------------------------------------------------------> Samson Servo 240 > W6-1139SG Tapped Horns

25th March 2009, 03:12 AM	#3
Ron E diyAudio Member Join Date: Jun 2002 Location: USA, MN	This is not about isobarik, this is about testing for dissimilarity. Quad does this with their ESL's AFAIK. I would think, within reason, the closer the better. You will want to make some sort of fixture to hold them with the microphone dead center. IIRC Quad puts the panels at an angle ( A V shape) and puts the mike on a line bisecting the angle. __________________ 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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