What is a dual force canceling speaker?

audiothings · 05:47 PM

Take a look at this.

I want to understand the "Dual force canceling subwoofers" they speak of... What is the principle? Is it some severe thing or something as simple as reversing the phase of one of the two subwoofer signals?

chris661 · 1st October 2010, 05:35 PM

The drivers are acoustically in phase (as they move out, they pressurise the room), but mechanically, they move in opposite directions.

I designed my last subwoofer and speakers with a similar thing in mind, as (being 16) I live with my parents, who don't enjoy bass comming through the ceiling.

Chris

head_unit · 1st October 2010, 06:03 PM

Imagine a subwoofer with a huge super heavy 18" cone on the front.

Sir Isaac Newton told us that for every action there is an equal and opposite reaction.

Therefore, as the cone moves in and out, the cabinet must rock back and forth slightly to compensate. This generates slight acoustic vibration into the air and probably into the floor.

Now if you mounted an identical cone on the back, with the same polarity, the mechanical motions cancel. When both cones move in or out, there is no net momentum and the cabinet won't rock (at least not due to the cone motion).

sreten · 1st October 2010, 06:15 PM

Hi,

If you mechanically link the two opposite drivers you can decouple
the driver mountings from the cabinet without any real effect.
This is the ideal way of doing it, reducing direct cabinet vibration.

rgds, sreten.

Charles Darwin · 1st October 2010, 06:27 PM

Quote:

Originally Posted by sreten

Hi,

If you mechanically link the two opposite drivers you can decouple
the driver mountings from the cabinet without any real effect.
This is the ideal way of doing it, reducing direct cabinet vibration.

rgds, sreten.

Which is exactly what Thomas Barefoot did here.

planet10 · 1st October 2010, 06:36 PM

Also call push-push. Mechanical linkage is important... some commercial designs that use the enclosure as the linkage miss the point.

KEF can possibly be credited with the 1st commercial implementations.

This concept shows an extreme implentation including a specially executed woofer.

toobz woofer

Whenever possible i use this technique as it can remove a very significant amount of energy from the box, dramatically reducing boxiness and the likelihood of resonance excitation.

dave

planet10 · 1st October 2010, 06:43 PM

Quote:

Originally Posted by Charles Darwin

Thomas Barefoot

From the info, those are powered speakers, not active... do they actually use a passive XO on the woofers?

From the attached image, these guys do a good job of the push-push.

dave

Charles Darwin · 1st October 2010, 07:46 PM

No they are fully active. These little ones use 50w for the tweeter, 100w for midwoofer and 200w for the sub.

planet10 · 1st October 2010, 08:01 PM

Cool, i only noted the 50W in the spec. How expensive are those?

dave

Charles Darwin · 1st October 2010, 08:32 PM

US$ 2747.50 each at Vintage King. There could be a waiting list, studios buy them quicker than Thomas can make them!

1st October 2010, 05:30 PM	#1
audiothings diyAudio Member Join Date: Aug 2005	What is a dual force canceling speaker? Take a look at this. I want to understand the "Dual force canceling subwoofers" they speak of... What is the principle? Is it some severe thing or something as simple as reversing the phase of one of the two subwoofer signals? Last edited by audiothings; 1st October 2010 at 05:47 PM.

1st October 2010, 05:35 PM	#2
chris661 diyAudio Member Join Date: Feb 2008 Location: Lancashire Blog Entries: 7	The drivers are acoustically in phase (as they move out, they pressurise the room), but mechanically, they move in opposite directions. I designed my last subwoofer and speakers with a similar thing in mind, as (being 16) I live with my parents, who don't enjoy bass comming through the ceiling. Chris __________________ "Throwing parts at a failure is like throwing sponges at a rainstorm." - Enzo My setup: http://www.diyaudio.com/forums/multi...tang-band.html

1st October 2010, 06:36 PM	#6
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 4	Also call push-push. Mechanical linkage is important... some commercial designs that use the enclosure as the linkage miss the point. KEF can possibly be credited with the 1st commercial implementations. This concept shows an extreme implentation including a specially executed woofer. toobz woofer Whenever possible i use this technique as it can remove a very significant amount of energy from the box, dramatically reducing boxiness and the likelihood of resonance excitation. dave __________________ community sites t-linespeakers.org, frugal-horn.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

1st October 2010, 08:01 PM	#9
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 4	Cool, i only noted the 50W in the spec. How expensive are those? dave __________________ community sites t-linespeakers.org, frugal-horn.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

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1st October 2010, 06:03 PM	#3
head_unit diyAudio Member Join Date: Feb 2004 Location: Los Angeles	Imagine a subwoofer with a huge super heavy 18" cone on the front. Sir Isaac Newton told us that for every action there is an equal and opposite reaction. Therefore, as the cone moves in and out, the cabinet must rock back and forth slightly to compensate. This generates slight acoustic vibration into the air and probably into the floor. Now if you mounted an identical cone on the back, with the same polarity, the mechanical motions cancel. When both cones move in or out, there is no net momentum and the cabinet won't rock (at least not due to the cone motion).

1st October 2010, 06:15 PM	#4
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, If you mechanically link the two opposite drivers you can decouple the driver mountings from the cabinet without any real effect. This is the ideal way of doing it, reducing direct cabinet vibration. rgds, sreten.

1st October 2010, 07:46 PM	#8
Charles Darwin diyAudio Member Join Date: Nov 2009 Location: Birmingham, UK	No they are fully active. These little ones use 50w for the tweeter, 100w for midwoofer and 200w for the sub.

1st October 2010, 08:32 PM	#10
Charles Darwin diyAudio Member Join Date: Nov 2009 Location: Birmingham, UK	US$ 2747.50 each at Vintage King. There could be a waiting list, studios buy them quicker than Thomas can make them!

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