Need advice on adding subs

Thank you all for the help.

There is a good thread currently running elsewhere on the site, under the simple title "Subwoofers" (I think). Duke of AudioKinesis and BDP24, among others, have made some valuable contributions, and it is worth reading. Here’s the link: https://forum.audiogon.com/discussions/subwoofer?highlight=subwoofers

That's a great thread. I had looked at that thread earlier and came away from it with some insights and some confusion.  My takeaway from that thread is this:

A sealed box gives the most musical and dynamic bass.  Using two subs instead one would let me crossover at a higher frequency.

That's why I was looking at a pair of Rythmik F12 or F12G. 

One thing that confuses me about that thread.  There appears to be a disagreement about aluminum vs paper driver.  That's the difference between the F12 and the F12G.  Can anyone clarify this for me?

Hello Martyki
Could you tell me more about the subs you used with the DeCapo

The deCapo is beautifully balanced as a stand-alone.  The presence thru treble is gently rolled off to balance the modest bass energy.  As a stand-alone monitor, it's really, really good and IMO one of the best values out there (which is why I bought mine).  When I added a subwoofer (for pretty much the same reasons stated in the OP), I loved the extra weight on the bottom end, but the sound as a whole went dull.  I tweaked it for a long time, but eventually moved on.  

  I agree the Decapo is a great speaker. Chamber music and jazz are great. But, I can't stand to listen to symphonic music on these speakers.

Hi BDP24
Wow. That's spooky.  I was looking at the Rythmik web site and the email notification with your post poped up on my screen.

You buy the DIY kit from GR Research or Rythmik Audio, the co-designers of the sub. It contains four 12" woofers (a pair for each of two subs) optimized for Open Baffle

Ok.  Open baffle? Is this a speaker with out a box?  Because that sounds like the opposite of everything I've read about subwoofers.  That is, that a closed box provides the best bass sound quality.  Ported boxes compromise sound quality to improve volume.

I want to thank everyone again for the help. Sorry for the late response. It's been a busy week at work.

As often happens when I post a question here, the answers expose me to the complexity of audio reproduction.

The other thread recommended some authors like Toole. I think I'm going to do some more reading on acoustics to better understand the nature of bass reproduction before I commit to a purchase.

 

  You buy the DIY kit from GR Research or Rythmik Audio, the co-designers of the sub. It contains four 12" woofers (a pair for each of two subs) optimized for Open Baffle

 I have some rudimentary DIY skills so I could probably manage a speaker assembly. I'm a bit cautious about the open baffle. I've noticed that a lot of people are experimenting with these type of speakers. But, audio has a history of technology fads that are initially celebrated but ultimately disappoint.   You have inspired me to get a little more serious about understanding acoustics. I think I need to study more before I start sinking even more money into audio.