Originally Posted by S_rangeBrew
There is a procedure for this? What does it measure? I've seen a few videos of it being done, but I must have missed the reasoning. Most of the videos are just kids doing it with car subs because it looks "cool". I don't think that's what you're talking about.
Someone on here said it would be a good test for IB subwoofers, but I never found out how to do this test.
Upon receiving any drivers, especially subwoofers, I like to test them with some signal prior to installation.
With IB drivers, and the manner in which they're excursion limited instead of thermally limited, it's important to know precisely where the limits exist,...especially within the gain structure you plan to implement. To discover this, you've got to ease the power to them, little by little until; a.)your amp runs out of power, or b.)your driver encounters it's excursion limits. With a frequency generator, like the various PC based tone generators available, one can explore power handling and excursion at different frequencies as well.
Well, if you were to install the driver, and then pursue these tests, you'd have to endure untold stress on your valuable hearing. This is where the free air element of this comes into play. In free air, the drivers acoustically null a significant amount of the potential energy,...thus easy on the ears. This way, with ample power you can easily hear when the driver begins to encounter the physical limit (VC former into the back plate, in the case of the IB3-18's).
By observing the clip lights, monitoring each gain stage position, EQ, etc, you can get a good feel for the overload characteristics of each element in the system,...make notes, etc, and proceed accordingly.
Each driver from each mfr enters into it's limitations in different ways. Other enthusiasts may or may not agree, however I've found its quite helpful not only for the reasons I stated above, but also for my own quality control that each drive unit operates similarly as it's exposed to equal amounts of drive voltage.
You can re-configure the load by paralleling, series, series-parallel, and bridging the amplifier. By doing this you can explore each combination of load impedance, and subsequent power output from your amplifier.
I hope this answers your question.
All the best