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What is a dual force canceling speaker?
What is a dual force canceling speaker?
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Old 1st October 2010, 05:30 PM   #1
audiothings is offline audiothings  India
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Default 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?

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Last edited by audiothings; 1st October 2010 at 05:47 PM.
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Old 1st October 2010, 05:35 PM   #2
chris661 is offline chris661  United Kingdom
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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
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Old 1st October 2010, 06:03 PM   #3
head_unit is offline head_unit  United States
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What is a dual force canceling speaker?
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).
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Old 1st October 2010, 06:15 PM   #4
sreten is offline sreten  United Kingdom
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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.
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Old 1st October 2010, 06:27 PM   #5
Charles Darwin is offline Charles Darwin  United Kingdom
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Quote:
Originally Posted by sreten View Post
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.
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Old 1st October 2010, 06:36 PM   #6
planet10 is offline planet10  Canada
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What is a dual force canceling speaker?
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

Click the image to open in full size.

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
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Old 1st October 2010, 06:43 PM   #7
planet10 is offline planet10  Canada
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What is a dual force canceling speaker?
Quote:
Originally Posted by Charles Darwin View Post
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
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File Type: png push-push-woofers.png (35.0 KB, 269 views)
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Old 1st October 2010, 07:46 PM   #8
Charles Darwin is offline Charles Darwin  United Kingdom
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No they are fully active. These little ones use 50w for the tweeter, 100w for midwoofer and 200w for the sub.
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Old 1st October 2010, 08:01 PM   #9
planet10 is offline planet10  Canada
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What is a dual force canceling speaker?
Cool, i only noted the 50W in the spec. How expensive are those?

dave
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Old 1st October 2010, 08:32 PM   #10
Charles Darwin is offline Charles Darwin  United Kingdom
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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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