Apparently in reply to my post above, Timlub wrote: "Extension, dampning and efficiency are the tradeoffs. The vectors go in different directions. The op questions grip vs eff. The extension is not. as I understand. part of the query. But I'm all in for a free lunch of any kind. Elucidate."
Sorry for the late resopnse; I didn't check back in on this thread until just now.
First let me say that high damping is not necessarily desirable in and of itself; it is the in-room frequency response that we want to optimize because that is what correlates best with subjective preference. An overdamped speaker sounds... overdamped.
Suppose we have a fairly low-Q woofer in a considerably larger-then-optimum vented box. Let's say we're tuning to the upper 30's, giving us a -3 dB point in the upper 30's with a steep rolloff below that. With typical room gain, we're getting down to the mid 30's.
Now let's drive this same speaker with a low-damping-factor tube amp, but without changeing the tuning frequency. Boom! Quite literally - we now have a broad 2 dB hump across the middle of the bass region, and we've managed to push the -3 dB point south a little bit. So far this isn't a net improvement, but we're not done yet...
Let's drop the tuning frequency to the upper 20's, which elminates any peaking and gives us extension into the lower 30's before room gain. We're on the right track.
Now let's factor in room gain, and push the tuning down into the mid 20's. We get a nice gentle rolloff across the bass region that is approximately the inverse of room gain, and real-world extension into the upper 20's. In contrast, before our low-damping-factor amp came into play, we could have expected extension to the mid 30's after room gain.
This isn't hypothetical. I manufacture this speaker, and chose my woofer and box size and port system with all of this in mind. The scenario I've described doesn't necessarily play out with all high-efficiency speakers.
Duke
