PipeDream Subwoofers, I want to know more

I have been looking for information about the subwoofers that came with the Nearfield Acoustics PipeDream line array speakers.
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From what I read they contain two 18" woofers each.

Are these sealed acoustic suspension subs?

How do they sound?

What are the specs?

I also found pictures that look a bit different.....how are these different and did they also come with the PipeDream speakers?

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And fore completeness here is the whole set
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I’d guess sealed, push-push.

Top ones likely up and down firing, firt one with end mounted drivers, in the second, mounted in the middle firing out the slots. Cylinders are inherently stiff and coukd be cardboard, plastic, or one of the formed wooden cylinders. bCHeap and effective.

dave
 
So I actually own a set of pipedreams. I still have the subs but switched to REL 212SE subs. They sound great and go deep but just can't compete with newer technology. It was hard to get the Pipedream subs to really integrate well. They have 2 18" subs in each drum. Both point up. They are wired opposite of each other. The external crossover provides eq to help them get way low. I believe they are Eminence drivers. Whatever you're trying to do, good luck.
 
So I actually own a set of pipedreams. I still have the subs but switched to REL 212SE subs. They sound great and go deep but just can't compete with newer technology. It was hard to get the Pipedream subs to really integrate well. They have 2 18" subs in each drum. Both point up. They are wired opposite of each other. The external crossover provides eq to help them get way low. I believe they are Eminence drivers. Whatever you're trying to do, good luck.
That REL looks impressive.

I am working on the bass section of some high SPL omnidirectional speakers. I don't want them to need subs. Where I live all I can easily/affordably get are pro drivers. Some divers based on Italian drivers are really affordable here (rcf, b&c).

In what way can the pipedream subs not compete with modern technology? I will only use it for music so I am not that bothered about extension below 35 Hz.
 
The biggest challenges are related to the speed. There are so many small drivers in the pipedreams that they really don't need to move much to get output. This helps them be super dynamic and more efficient. It also makes 2 18 inch drivers struggle to keep up. Those Eminence drivers if I recall weren't really built for that either. The magic sauce was more in the crossover / EQ but that's still trying to overcome the driver choice itself.