Ah, for those not familiar with the SB-1 subwoofer, it is passive: The power amp's speaker output goes into the Sub where it passes through the sub's crossover. The upper and mid signals then comes out of there to the full range panels. Inside the sub there's a crossover but it has no adjustment, no internal amp. On the back of the sub, there's a volume control. Unfortunately I never had the proper manual, only the manual for the SB-2 which says it was selectable between 60 and 80Hertz so I'm guessing the SB-1 was at one of those two points. BTW the Acoustats by themselves are pretty gutless down low.
@millercarbon: 5 subs? LOL I've visited your virtual system. Perhaps in our next home I'll have a single-purpose music room but for now, a 'swarm' of subs is out of the question. (Besides, I rather enjoy my current wife.) However I must disagree with your implication that bass is non-directional. I have moved the subwoofer in the past to different locations and please believe me when I say that I could tell you where it was (and wasn't) in the soundstage.
@rego: I'm encourage by your statement that two 8" drivers move as much air as a single 16" driver. I will research that a bit further.