@erik_squires wrote:
Then I’d really like to know what you think happens when your reach the maximum excursion of a driver. Either they have limited excursion, and therefore compression, or they have infinite excursion and no compression.
That’s indeed what I’m talking about in regards to mechanical compression, but how often do we reach, let alone exceed X-mech? My point is, before that happens the driver’s suspension has a range of motion within which compression per se as a mechanically induced phenomenon isn’t relevant. What’s arguably more relevant mechanically is hysteresis (or magnetically, hysteresis distortion) as that which happens through the range of cone movement, but that’s hardly a compression issue, no?
Although: smaller (<10"), low eff. woofers certainly makes their effort in reproducing the range <40Hz at elevated, but hardly prodigious levels be known, and when you’re used to a pair of corner loaded, high eff. tapped horns fitted with 15" pro woofers in 20cf. enclosures where the cones barely more than a few mm’s at bonkers SPL’s, it’s all the more obvious. With smaller hifi woofer cones working hard it’s likely a combo of mechanical noise and -compression, as well as the onset of thermally induced compression.
I wish I could find them but I remember seeing tone burst tests showing that thermal compression could happen in a tweeter in less than half a second. You could see the first tone burst perform perfectly, and then half way through the second compression sets in.
Interesting; I take it what could also be referred to as thermal modulation as a more dynamic phenomenon. It’s a shame this area isn’t more well documented, leaving us with the more general ’thermal compression’ description and correlation as heat build-up in the voice coils over longer time.
