Thanks for the reply, but perhaps I should have used the term "limiter" instead of compression ration. What I was curious to know was how agressive the limiter is on the signal as it reaches it's excursion limits. I believe that it was either one of your techies(maybe Curt?) that threw out that 8:1 ratio(at the predetermined excursion limit, for every 8dbl of spl signal increase, only 1 dbl gets thru)or some of the "basshead" folks over at Home Theater Forum had tested some of them, I forgot which. Of course, this is to protect the driver from over excursion damage and/or too much distortion, but as I said, some folks thought that the concern for that ultra low distortion on the bottom end came at a little bit of a sacrifice of ultimate volume. Perhaps the increase in driver excursion in the new models will ameliorate that concern. I'm looking forward to a demo of these new models. Congrats on such a high-tech approach.
Yes, there are gain limiters on every sub we sell. We've always believed strongly that a driver should be carefully matched with its amplifier and control circuitry for exactly the reasons you've stated - protecting the driver from over excursion and damage. The exact formulas we use for gain limitation differ from sub to sub - I can show you code in DD for example that accounts for the mass of the cone, the size of the cabinet, and other factors as they differ between the 10, 12, 15 and 18 in determining what parameters need to be fed into the digital gain limiting filters.
We do care about distortion but don't limit output to minimize it, as some might believe. We limit output only when the cone is reaching its maximum travel limits. The main job of the limiter is to protect against rogue signals that could bottom out the woofer violently. Distortion comes when a cone travels beyond its point of linearity ? that is, travels near the edge of the suspension limits and/or nears the outside of the magnetic gap. The box designs, servos, dual coils, and other design factors we use for our subs do more to limit distortion (i.e. maximize accuracy) than any gain limiter might do. Of course, a sub must have lots of output, which is why we use very heavy magnets, long throw drivers and lots of power - to provide the cleanest, loudest output possible.
Hope this helps to clarify this...