I only cited the KH150 as an example of a good front BR port design. Did not mean to equate a 6'' woofer LS with an 8'' woofer LS - obviously
My point is the KH150 port was optimized under vastly different constraints.
Again, KH150 has basically equivalent bass output of the much smaller 705P (especially in install form; the powered one is comically deep) per SuR’s measurements, but with a much larger cabinet. So there's just more room to play with the port design. Furthermore, while this speaker is larger, if you accept JBL’s relative specifications 708 has
7dB greater output capability than 705, and thus a 7dB output advantage thus KH150.
It's also worth noting that none of this is new information. People have been kvetching about the 7-series port resonances for as long as I've been reading about these speakers, because JBL provided reasonable data from the start. Most of these kvetchers through all that time, it should be said, have not tried to personally evaluate the audible significance of these port issues. Dr. Toole often writes about features in graphs that are more offensive to the eye than the ear. I think this is one of those features.
I have no idea of course if it is correct or complete but seems interesting on how Harman chose to use EQ.
I’ve measured the frequency response of the hacked file screenshots as well as of the undisturbed tuning file, on a BSS BLU-50. The crack is complete as to FR (did not test limiting, etc.)
on a BSS device. Caveat is BSS defines some filters differently from, e.g. miniDSP. So a plug and chug in a different processor will yield different results. That said, the differences do not manifest as severely on 708 as on 705. On that speaker one can basically ignore the hacked file screenshots, except as a trace of the target curve.