[warnerwh]

Mike: You can run the 215 upto where you need. Now that it's finally sunk in my hard head what you need you're definitely on the right track.  You will only be augmenting your main speakers with the extra woofers.  A null at 120hz is a good place to have a null in a way as it's an area where if you have too much then the bass becomes muddy.  

I would think the Tact unit could deal with this very well. If I had the money I would have bought one myself.  If you're going to run your speakers full range could you give us your room response below 120hz?  Thanks

[Mike-48]

Mike: You can run the 215 upto where you need. Now that it's finally sunk in my hard head what you need you're definitely on the right track.  You will only be augmenting your main speakers with the extra woofers.  A null at 120hz is a good place to have a null in a way as it's an area where if you have too much then the bass becomes muddy.  

I would think the Tact unit could deal with this very well. If I had the money I would have bought one myself.  If you're going to run your speakers full range could you give us your room response below 120hz?  Thanks

Warner,

Well, I've thought of also running mains full-range, but right now, I'm planning to turn them off below the crossover frequency.

I've posted a graph of measured response from 20-2000 Hz (before digital correction).  From that you can see: (1) There is no lack of absolute bass in the room; (2) a huge peak at about 35 Hz in both channels; (3) a broad null in the R and L channels from 50-70 Hz; and (4) deep nulls in R and L channels at 210 Hz and 170 Hz respectively.  (I was wrong when I said 120.)

It seems an ideal crossover frequency would be about 300 Hz.

[warnerwh]

First I'd try to keep the crossover as low as possible.  Your in room response is actually very good so the treatments helped significantly.  Why not bring down the the response on both sides of the null a few db while increasing the the reponse at the dips.  I think your speakers could easily handle a 3 or 4 db boost in these frequencies if your power amp can.  The 215 sub will go that high but as I said earlier I'd be inclined to keep the crossover as low as is possible.

The dip in the 50-70hz range would be the range that the subs would really help.  That's where the impressive bass power that people like is.  That range will also improve the overall presentation of your speakers too.