The 168ez and the 166 can be used in a TQWT with added series resistance. The drawback is the lowered efficency. I have had the 168ez in a TQWT and even with series resistance the performance was not suited to my taste. The highs are almost painful and the only pratical answer was an EQ curve of sorts and i really dont like passive circuits in the signal path. I had the FE-166e in a BLH and the performance was exceptional, but i sold it when a friend made me an offer i could not refuse.The FE-167 has a higher Qts and will work in a pipe very well, it can even be used in a BR app but either both the BR and the pipe may still need some series resistance. ron
Right on! I do not like passive components in the signal path either. I got a high eff. driver for the efficiency, so there is no point in lowering the efficiency to get more bass. So the FE168EZ is in a proper back horn. The bass is still not acceptable, but the added efficiency in the mid band does compensate for the upper peaks (meaning that frequencies from 200 to 1KHz are on par with the 7.5KHz peak), so the overall feeling is that of a high eff. speaker with no deep bass. SO, I am saving money to add a proper pair of low Q subs to get things going under 60 or 80Hz. There is simply only two choices: flush efficiency to get more bass (in fact, there is no more bass, only LESS of the rest!) or keep the efficiency and ADD more bass with dedicated bass drivers.
I gave up on the new 168 and went to the 206e.A much better performing driver(less money also) and with the horn shown. I am getting a very strong FAST tight bass down to 45 Hz, no sub necessary. Horn rolls off at 300 hz and the baffle pickes it up at 300hz.No stuffing. ron