subwoofers with dual opposed drivers

[ryanosaur]

I think the thread is about having woofers on opposites sides of the enclosure, pushing/pulling at the same time.

Just to be clear, Dual Opposed and Push/Pull are two different concepts. Push/Pull is also Dual Opposed in a manner of speaking, but Dual Opposed is not Push/Pull.

The clearest definition in a modern Sub of Push Pull is the Perlisten and M&K models where one driver is facing outward as normally seen, and the other is magnet out. These drivers will be wired out of phase two each other but in phase for the purpose of how the motor moves in relation to the cabinet itself.
Dual Opposed on the other hand is two drivers mounted specifically directly opposite each other, either both magnets inside the cabinet or both outside, with no closed space between them other than the cabinet (with the cabinet being either vented or sealed). Specifically, in this latter arrangement, the cones simply play in phase opposite each other.
The prior example utilizes the opposing linearity of one driver pushing away from the magnet while the other pushes toeard the magnet, thus cancelling some nonlinear performance/distortion in the resulting output.
The latter example is almost purely about force cancelation as each drive negate the force of the other driver.

Here is the Perlisten Push/Pull:

This is the SVS 3000 Micro (dual opposed):

Though similar, the two are fundamentally very different.

Only because this keeps coming up in the thread, an isobaric design will have each driver coupled directly to the other via a small tube or compartment. The drivers can be clamshell (cone-to-cone), facing the same way (cone to magnet), or "reverse clamshell" (magnet to magnet). It is very important to note that in all three examples, the cones must move IN PHASE with outer driver! According to Dickason ans Alden, the Chamber linking the two drivers should be as minimal as possible without allowing parts of either driver to directly touch the other. Thus:

In this example, even "A" should have a smaller chamber directly linking the two drivers more similar to "B" and "C." In the Dickason and Alden books, they almost seem to recommend such as a sonotube as the joining compartment.
Regarding Phase, the "Inner" Driver must move in Phase with the Driver exposed to the outside of the Cabinet. They form a system that supports each other.

 

[sigbergaudio]

Ok,judging by your signature obviously you seem to know lot more than me.I only shared what I believe to be true. I am not in audio business. This was my understanding.

The illustrations below show isobaric loading (there are other variants as well, but these are the most typical). This is a rare configuration in home audio. Somewhat more common in car audio when space is restricted, but less common even there nowadays due to better drivers and more powerful amps. There are simply not any real advantages to this design.

While dual opposing on the other hand, simply have one driver on each side of the cabinet pointing in the opposite direction, either in a common internal enclosure (most common I believe) or dual / separate internal enclosures. They both play in the same phase , so both drivers go out at the same time and in the opposite direction, effectively eliminating cabinet vibrations.

 

[sigbergaudio]

@ryanosaur beat me to it.

 

[summersnow]

From my experience dual opposed driver subwoofers do exactly the opposite of what there supposed to do. Yes they do cancel out vibrations, but also cancel out a lot of the sound. I made the big mistake of buying one the XXL from Golden Ear and it's the worst sounding subwoofer I've ever heard, though I do love their tower speakers, I have their Triton Fives, Triton 2's and Triton Reference. I also listened to other brands like Power Sound, Martin Logan including other brands and frankly I just don't get it. You have to really turn them up to hear anything and when you do they sound like like 100 dollar subs. I'll stick to my single driver subwoofers like JTR Captivator 2400ULF's. It's Good Vibrations. Have a good one.

 

[sigbergaudio]

From my experience dual opposed driver subwoofers do exactly the opposite of what there supposed to do. Yes they do cancel out vibrations, but also cancel out a lot of the sound. I made the big mistake of buying one the XXL from Golden Ear and it's the worst sounding subwoofer I've ever heard, though I do love their tower speakers, I have their Triton Fives, Triton 2's and Triton Reference. I also listened to other brands like Power Sound, Martin Logan including other brands and frankly I just don't get it. You have to really turn them up to hear anything and when you do they sound like like 100 dollar subs. I'll stick to my single driver subwoofers like JTR Captivator 2400ULF's. It's Good Vibrations. Have a good one.

Sounds like you listened to a lot of subwoofers that were either poorly designed or more likely misconfigured somehow. This is not accurate at all. Dual opposed subwoofers do not cancel out any sound.

 

[jbattman1016]

Sounds like you listened to a lot of subwoofers that were either poorly designed or more likely misconfigured somehow. This is not accurate at all. Dual opposed subwoofers do not cancel out any sound.

I would agree, I have been using a sub with dual woofers for years and its great and also really small. The P1005 from Cambridge Soundworks in my case.

 

[summersnow]

Sounds like you listened to a lot of subwoofers that were either poorly designed or more likely misconfigured somehow. This is not accurate at all. Dual opposed subwoofers do not cancel out any sound.

Unfortunately in my experience it is accurate and yes they are misconfigured, as in a dual opposed driver configuration. Until they come up with a dual opposed driver sub that even sounds competitive to some extent, I have no interest in them at this time. Maybe silence is golden to some, but I want my house vibrating with great bass. No offense, it's just my experience. Have a good one.

 

[sigbergaudio]

Unfortunately in my experience it is accurate and yes they are misconfigured, as in a dual opposed driver configuration. Until they come up with a dual opposed driver sub that even sounds competitive to some extent, I have no interest in them at this time. Maybe silence is golden to some, but I want my house vibrating with great bass. No offense, it's just my experience. Have a good one.

Not offended, just saying you're mistaken.

 

[jbattman1016]

00

Unfortunately in my experience it is accurate and yes they are misconfigured, as in a dual opposed driver configuration. Until they come up with a dual opposed driver sub that even sounds competitive to some extent, I have no interest in them at this time. Maybe silence is golden to some, but I want my house vibrating with great bass. No offense, it's just my experience. Have a good one.

Maybe the particular device you had was more sensitive to placement over the single driver sub you moved to. I agree that you should get your system to how you like it. I will likely move over to a ported single driver setup once the AMP on this sub dies (if ever).

As note, the particular golden ear sub referenced is only rated down to 25Hz. at that's -6db already? So, you likely just didn't like this sub because it doesn't do what you want.

Frequency Response

25Hz–160Hz (-6dB on axis, anechoic)

SuperSub XXL | GoldenEar

SuperSub XXL Overview Housed within the gorgeous piano-gloss black enclosure are two horizontally-opposed 12˝ ultra-long-throw active drivers and two vertically-opposed 15˝ x 13˝ planar back-wave-driven radiators, driven by a 1600 watt Class D Digital amplifier. This dual-plane, patented*...

www.goldenear.com

While the JTR can clearly (18-inch woofer)... hit the earth-shaking frequencies:

Frequency +/- 3db - 12-165hz (in room response below 10hz)

JTR Captivator 2400ULF — JTR Speakers

www.jtrspeakers.com

 

[Ricardojoa]

Dual opposed subs are great but I would take a pair of subs any day . The biggest issue with resonance is the room. I would rather address that issue over a properly built single sub.

 

[Sancus]

Unfortunately in my experience it is accurate and yes they are misconfigured, as in a dual opposed driver configuration. Until they come up with a dual opposed driver sub that even sounds competitive to some extent, I have no interest in them at this time. Maybe silence is golden to some, but I want my house vibrating with great bass. No offense, it's just my experience. Have a good one.

This just isn't true. I have a pair of reasonably sized dual opposed subwoofers that are using up a bunch of overhead to let MSO smooth the FR and they still play, at the listening position, about 105dB @ 20hz and about 110dB @ 40hz without more than ~1dB of compression.

This would not be possible were there any significant "cancellation" happening.

Measurements:

Spoiler

Dual opposed subs are great but I would take a pair of subs any day . The biggest issue with resonance is the room. I would rather address that issue over a properly built single sub.

They're not a replacement for multiple subs at all really, they just let you get a little extra output out of a given cabinet size and eliminate physical vibrations which can be beneficial for certain use cases(like using the sub as an end table ).

Sub count and driver configuration aren't connected topics unless the sub has drivers that are individually addressable and separated by a significant distance, at least 3ft imo. Almost no subs work that way though.

 

[Ra1zel]

If someone thinks you can cancel wavelengths by a second in phase driver it's time for a physics course

 

[Chromatischism]

He may just prefer more rumble and hasn't explained very well what he's experiencing.

Our overall sense of perception (hearing and feeling) is greatly affected when the balance changes.

 

[jhaider]

Dual opposed subs are great but I would take a pair of subs any day . The biggest issue with resonance is the room. I would rather address that issue over a properly built single sub.

Different solution, different issue.

DO are great when you don’t want subs to walk, you’re using them as speaker stands, you use them as end tables and don’t want your coffee to shake, etc. They don’t otherwise perform substantially differently from other single subs.

 

[DACslut]

I used to have a Sony SA-WX700. Sadly it was a victim of bad capacitors on the plate amplifier. I believe it's design was of the "Perlisten Push/Pull" variety. I also remember it was a window rattler and house shaker before it gave up the ghost.

 

[kiwifi]

I used to have a Sony SA-WX700. Sadly it was a victim of bad capacitors on the plate amplifier. I believe it's design was of the "Perlisten Push/Pull" variety. I also remember it was a window rattler and house shaker before it gave up the ghost.

I have it's big brother, the SA-WX900. I upgraded the cabinet here...

 

[DACslut]

I have it's big brother, the SA-WX900. I upgraded the cabinet here...

That's quite an interesting thread about those SA-WX900 mods you posted here a while back:

Sony SA-WX900 Push-Pull Subwoofer (Pictures, Measurements & Mods)

I like push-pull subs, but I was unaware that Sony had made any, until I noticed one for sale on a local auction site. In fact Sony has made two models that I know of. A dual 10" 250W sub (SA-WX700) and the one that I found, which is a dual 12" sub with a 1000W B&O IcePower 1000A amplifier...

www.audiosciencereview.com

 

[ppataki]

One more use-case for DOS: when for any reason one cannot have multiple subs but wants to maximize cone surface area using just a single sub
Also DOS design allows a narrower speaker cabinet (when one has a space constraint re. baffle width)
(these were the reasons why this project and this project came to life)

 

[Count Arthur]

Why stop at dual opposed drivers?:

When you can have 4.

And when you really need the wub-wubzzzz:

 

[tinnitus]

Here is a comparison between 4x10" woofer in ripol arrangement (opposite) against 4x6.5" woofer front arrangement.