Dual Opposed Subwoofers - how is the performance compared to a ported sub? - AVS Forum
Forum Jump: 
 
Thread Tools
Old 09-04-2014, 04:40 PM - Thread Starter
Senior Member
 
video1's Avatar
 
Join Date: Sep 2001
Location: NorCal Sierra Foothills
Posts: 251
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 28 Post(s)
Liked: 12
Dual Opposed Subwoofers - how is the performance compared to a ported sub?

I've read a few reviews of speakers using dual opposed woofers. The reviewers stated that while they could feel "chest slam" they felt almost no vibration when placing their hand on a the speaker due to the wave canceling effect of the opposing woofers.

So is there any benefit to a dual opposed subwoofer, especially as it pertains to minimizing vibration effects and improving the efficiency of sound isolation?

And how is the performance of such a design compared to a vented design like a mini-marty?
video1 is offline  
Sponsored Links
Advertisement
 
Old 09-04-2014, 05:02 PM
AVS Special Member
 
tuxedocivic's Avatar
 
Join Date: Feb 2010
Location: Ladysmith, BC
Posts: 5,101
Mentioned: 11 Post(s)
Tagged: 1 Thread(s)
Quoted: 572 Post(s)
Liked: 660
As you note, dual opposing drivers reduces cab vibrations. This isn't the same as panel resonances, as Bill F rightly points out often. Thankfully panel resonances aren't an issue with subs usually. So what it is doing is reducing/eliminating the shaking and rocking and vibrations that the driver puts into the cab. For myself, I found this to be quite significant as my sub cabs were fairly light.

Dual opposed isn't a box alignment like ported is. You can have a dual opposed ported sub if you want. It's just more common with sealed as the box size for sealed can often accommodate two drivers. This is what I do myself.
tuxedocivic is offline  
Old 09-04-2014, 08:08 PM
AVS Special Member
 
BassThatHz's Avatar
 
Join Date: Apr 2008
Location: East side of NW Cascades
Posts: 3,275
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 382 Post(s)
Liked: 444
Dual opposed is great for stacking sonotubes in the corners (boundary gain), or when mechanical vibrations need to be zero,
or in cases where space is tight and high SPL is needed; the disadvantage is that they usually rolloff higher because their boxes aren't ideally-sized.
BassThatHz is offline  
Old 09-04-2014, 09:57 PM - Thread Starter
Senior Member
 
video1's Avatar
 
Join Date: Sep 2001
Location: NorCal Sierra Foothills
Posts: 251
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 28 Post(s)
Liked: 12
So the benefit is mainly for the other drivers if any within the speaker cabinet.

Are there any benefits as far as limiting the amount of low bass that passes through the walls to outside of the HT?

Quote:
Originally Posted by tuxedocivic View Post
As you note, dual opposing drivers reduces cab vibrations. This isn't the same as panel resonances, as Bill F rightly points out often. Thankfully panel resonances aren't an issue with subs usually. So what it is doing is reducing/eliminating the shaking and rocking and vibrations that the driver puts into the cab. For myself, I found this to be quite significant as my sub cabs were fairly light.

Dual opposed isn't a box alignment like ported is. You can have a dual opposed ported sub if you want. It's just more common with sealed as the box size for sealed can often accommodate two drivers. This is what I do myself.
video1 is offline  
Old 09-04-2014, 10:00 PM - Thread Starter
Senior Member
 
video1's Avatar
 
Join Date: Sep 2001
Location: NorCal Sierra Foothills
Posts: 251
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 28 Post(s)
Liked: 12
Does this means less low bass leaks out of the HT?

As for rolloff, how bad is it? Are we talking about rolling at 25 Hz down to the point that there is no performance or are we talking about it rolling off as compared to the mega subs that the DIYers are used to building here?

Quote:
Originally Posted by BassThatHz View Post
Dual opposed is great for stacking sonotubes in the corners (boundary gain), or when mechanical vibrations need to be zero,
or in cases where space is tight and high SPL is needed; the disadvantage is that they usually rolloff higher because their boxes aren't ideally-sized.
video1 is offline  
Old 09-04-2014, 10:12 PM
Advanced Member
 
mtg90's Avatar
 
Join Date: Aug 2011
Location: Millbrook, IL
Posts: 916
Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 82 Post(s)
Liked: 244
The only real difference between a cabinet with dual opposed drivers and one of identical volume and dual front firing woofers would be the forces exerted on the cabinet by the moving woofers. In each designs the woofers both move in and out together, displacing the same amount of air and generating the same SPL, so there would be no difference in how the subwoofer sounds or how the bass waves move through (or out of) a room.
LTD02 and chalugadp like this.
mtg90 is online now  
Old 09-04-2014, 10:48 PM - Thread Starter
Senior Member
 
video1's Avatar
 
Join Date: Sep 2001
Location: NorCal Sierra Foothills
Posts: 251
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 28 Post(s)
Liked: 12
Got it. That makes sense.


Quote:
Originally Posted by mtg90 View Post
The only real difference between a cabinet with dual opposed drivers and one of identical volume and dual front firing woofers would be the forces exerted on the cabinet by the moving woofers. In each designs the woofers both move in and out together, displacing the same amount of air and generating the same SPL, so there would be no difference in how the subwoofer sounds or how the bass waves move through (or out of) a room.
video1 is offline  
Old 09-04-2014, 10:53 PM
Member
 
MDST's Avatar
 
Join Date: Mar 2014
Posts: 64
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 27 Post(s)
Liked: 20
With dual opposed: More down low SPL and more upper SPL?? Or I'm wrong??
MDST is offline  
Old 09-05-2014, 12:10 AM
AVS Addicted Member
 
LTD02's Avatar
 
Join Date: Oct 2003
Posts: 16,852
Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 566 Post(s)
Liked: 1170
as matt (mtg90) just said, dual opposed is simply an arrangement of drivers. functionally, the performance is identical to two independent subwoofers built large enough not to vibrate when bass is played, placed back-to-back. no more or less upper or lower bass spl than would occur with two independent subs.

Listen. It's All Good.
LTD02 is offline  
Old 09-05-2014, 06:46 AM
AVS Addicted Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 10,214
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1684
Quote:
Originally Posted by tuxedocivic View Post
As you note, dual opposing drivers reduces cab vibrations. This isn't the same as panel resonances, as Bill F rightly points out often.
+1. You'll often see it claimed that dual opposed cancels out the internal pressures that cause the panels of the cab to vibrate. It doesn't. The only way that would happen is if the drivers were wired with reverse polarity. That would eliminate panel flexing, but it would also eliminate sound output. What dual opposed does eliminate is the actual movement of the speaker across the floor, commonly referred to as dancing.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is online now  
 
Thread Tools


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off