Hey, Widget...posted by Mr. Widget
Shooting the system with my RTA confirmed ... a broad bump centered between 200Hz and 300Hz. ... my problem ... was the mutual coupling of the woofers and the 2202!
I've been pondering this all week-end, since the Friday taste-test. (Nice!)
If I'm deciphering your "3155 Modified" schematic correctly, you are running all transducers off the 3155 as Red input to Red transducer terminal post. Right? If so, they are all running JBL convention, negative polarity.
I'm guessing your LF's (2235's) are also running JBL convention negative (Red input to Red terminal). So, the area of frequency overlap between the LF and the 2202 would be summed, not cancelled. That is not what JBL do with the 4343 and 4345.
Both the 3143 and the 3145, when either biamped or four-way passive, run the LF negative (Red input to Red terminal post), and the "uppers" (MF, HF, UHF) all opposite polarity, positive (Red input to Black transducer terminal).
I'm wondering if the troubling 200-300Hz "hump" could be obviated or lessened by reversing polarity between the transducer groups (i.e, LF and others), and simplifying your active crossover configuration.
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