how to include the subwoofer?

I'd go with your last choice - separate x-over. If the high pass filter in your DD12 is the same as the one in my Velodyne SMS-1 controller - and I believe that it is - it ain't great. It subjects the main signal path to A/D/A processing and has a fixed turnover and slope. By contrast the low pass is incredibly flexible and IMO the A/D/A is much less objectionable way down there in the deep bass.

I use an NHT x-2 x-over to feed my SMS. It works like a charm, is inaudible (to my ear) AND it's inexpensive, to boot.

BTW, even though your main speakers have decent bass extension, you should experiment with crossing over at 80, 100, and 120 hz. This will allow the DRC in your sub to do its thing. I suspect you will be amazed by the improvement in sound.

Good Luck.

Marty

I recommended experimenting with higher x-over frequencies because my experience with room issues has usually revealed the most audible problems lie between 50hz and 150hz, especially 80ish to 120ish . These are pretty common and usually very, very audible.

I use bass busters which are pretty effective at knocking out the hump between 80hz and 120hz in my current room. I cross at app. 75hz and the DRC in the SMS-1 does the rest. Without bassbusters, I'd start at 120hz to judge the effects of the DRC, then directly compare the sound to a much lower, audiophile approved x-over point. You may be surprised.

Note: if you use bass busters (or similar treatments), you can probably safely cross as low as 70hz - 80hz and get most of the benefit of DRC in the DD subwoofer. If you cross any lower, the DRC won't get a crack at the worst nasties in the room.

Marty

Dgaylin,

If you're looking to maintain the "purity" of the main signal path,
what are your choices?

I can pretty much assure you that the high pass in the NHT is less audible
(and much more flexible) than the high pass in the SMS-1 as I have
extensively A-B'd the two. The Velo ain't terrible, but I knew it was there.
Also, the added flexibility of the NHT allowed for a better crossover function,
as I can high pass at my chosen turnover frequency and steeper slope than
the SMS allows. So, what can you do?

1) Use the active x-over of your choice (you might be more comfortable re:
transparency in the main path with Bryston or Marchand, but there's the $
issue) or

2) Run the Curves full range, bypassing the DD's high pass and try to
"snug up" the DD from below, using only it's internal high cut
filter. You might get a good x-over function, but you've blown the
opportunity to maximize the benefit of the DRC.

My point is: Cable adaptors won't improve "purity" in the main
path (DD's high cut ain't great) unless you forgo DRC (low x-over point). If
your question is: "Is DRC worth some slight (in my case, inaudible to me)
degradation of the main signal path?", my answer would be "Without
Question, Yes, Yes, Yes"

OTOH, YMMV.

Marty

Dgaylin,

Sorry I missed your intervening post re: the smooth bass response you're already getting from the Curves. My room makes such a result impossible. So, as Emily Litella once so aptly put it "Oh...never mind".

Marty

Good point. It never occurred to me to try this. That's probably because, IME with measuring system response in room, I've found that almost any speaker with extended bass response will produce significant excess energy somewhere above 80 hz - in most rooms. Taming this can't be done with DRC in your proposed set-up. You could use bassbusters or maybe you don't need to if your room/speaker system is different than any I've measured - which seems to be the case here.

Marty

BTW,

I'm pretty sure that the NHT X-2 is available direct (oand IIRC from AudioAdvisor.com for a few bucks less) with a money back guarantee for a home trial period. There's little at risk if you're tempted to check it out.

Marty

Dgaylin,

FYI - someone has just listed a used Museatex active/passive switchable high pass filter for sale at $275. I haven't heard this model first hand, but I knew a guy some years back (generally reliable) who swore by it. Just FYI.

Marty