# Dual-opposed subs



## fish (Jun 30, 2007)

I've been contemplating using two cabinets, both housing sealed dual-opposed subs. Searching the net it seems like some say you need volume for only ONE sub, while others say you need the space for TWO. Does anyone know which it is?

Also, I don't have a receiver yet, but if I choose one with only one sub output will Audysey have a problem running it's EQ function if the two cabinets are equal distance from the listening position, using a Y-splitter?


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## danno14 (Sep 1, 2009)

Look up isobaric and see if that fits what you are talking about. You will find all the pros and con's pretty easily if that's it.


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## fish (Jun 30, 2007)

danno14 said:


> Look up isobaric and see if that fits what you are talking about. You will find all the pros and con's pretty easily if that's it.


Not isobaric, but two drivers facing opposite of each other (magnet-to-magnet, but not touching of course) on either side of the enclosure. When I googled it I came across a description saying an advantage is only using the airspace necessary for a single driver, but I was told differently by a tech @ Parts Express.


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## danno14 (Sep 1, 2009)

based upon the air volume between the two and where the main air chamber is. If the air volume between is small and there is another chamber that they "see" it would be isobaric. Otherwise it may just be a simple enclosure with two woofers. 

Now what you may be thinking of is when one is mounted forward and one backwards. The combined suspension distortion is supposed to negate and net zero. Look too at plenum info on the cult of the infinitely baffled website.


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## 07azhhr (Dec 28, 2011)

I am thinking you mean something like this?


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## jim walter (Apr 10, 2010)

You need double the volume of one ideal sealed box. Vibration isolated or opposed drivers don't compliment the motor force and act isobarically (not a word, I know), instead they attempt to minimize vibration in the enclosure and act like a pressure transducer of sorts. 

Audessy will try to cooperate with the two, but this situation will not be ideal and I'd recommend against it, unless the Audyssey system supports dual/stereo subs. 

Jim


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## fish (Jun 30, 2007)

My original thoughts were it would just be a typical sealed box with two woofers, but then I start reading **** on the internet  & I get my hopes up that I can save on significant space.

And yes, that diagram is exactly what I was referring to.

Thanks for clarifying & answering my questions... back to the drawing board.


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## 07azhhr (Dec 28, 2011)

fish said:


> My original thoughts were it would just be a typical sealed box with two woofers, but then I start reading **** on the internet  & I get my hopes up that I can save on significant space.
> 
> And yes, that diagram is exactly what I was referring to.
> 
> Thanks for clarifying & answering my questions... back to the drawing board.


Just to give you something else to chew on. When you run isobaric or some type of push-pull setup that lets you run 2 subs in a box that would normally be for only 1 of said subs, you trade some things for this. First is that you need 2x the power then you would need for the one sub and second is you still only get the output of the single driver by it self. What you gain is the reduced air space needs and in some of the designs you gain a reduction in certain types of harmonic distortion. 

But again, to do this, you need 2 subs and the wattage for both yet you only get the output of one sub.

There is one version that I know of that gives you more output and that is when you have both subs on the same baffle or pannel with one facing in and one facing out. You run these IN phase and the force of one helps push the other one. This one will net more output and should have reduced distorion. Not sure if this one allows for a smaller box size though.


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## stereo_luver (Oct 30, 2007)

It can be done. I run a pair of Polk Audio PSW1000 subs that are as you describe. They use two 10" drivers mounted in the cabinets firing outwards from each side.

Chuck


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## fish (Jun 30, 2007)

stereo_luver said:


> It can be done. I run a pair of Polk Audio PSW1000 subs that are as you describe. They use two 10" drivers mounted in the cabinets firing outwards from each side.
> 
> Chuck


Would you say the enclosure size is on par with what you would see for a single 10" or does it accommodate fir both?


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## fish (Jun 30, 2007)

07azhhr said:


> Just to give you something else to chew on. When you run isobaric or some type of push-pull setup that lets you run 2 subs in a box that would normally be for only 1 of said subs, you trade some things for this. First is that you need 2x the power then you would need for the one sub and second is you still only get the output of the single driver by it self. What you gain is the reduced air space needs and in some of the designs you gain a reduction in certain types of harmonic distortion.
> 
> But again, to do this, you need 2 subs and the wattage for both yet you only get the output of one sub.
> 
> There is one version that I know of that gives you more output and that is when you have both subs on the same baffle or pannel with one facing in and one facing out. You run these IN phase and the force of one helps push the other one. This one will net more output and should have reduced distorion. Not sure if this one allows for a smaller box size though.



I've read up on this design in the past, but not very economical.


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## stereo_luver (Oct 30, 2007)

fish said:


> Would you say the enclosure size is on par with what you would see for a single 10" or does it accommodate fir both?


Both.

Chuck


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