Originally Posted by
Elac310
The rest of the system includes 2x15" per side, i.e. more than 100dB at 4 ohms impedance.
Working in passive filtering mode as I do, the 2445 in J version (16 ohm) has insufficient sensitivity in the HF region. In normal mode, it needs no attenuation at all to match the sensitivity of the bass section so I have no headroom that would allow to compensate the FR by lowering the driver's overall level. JBL themselves used on such cinema systems as the 4670 (also a 4ohm bass section with 2x15" in parallel) a HF boost circuit comprising a capacitor followed by a small inductor.
I also have heard of the reputation of harshness in some cases but I cannot really confirm this, even despite the extra boost I apply. I also found out that an old fashioned capacitor (Russian cap in metal can said to be paper in oil or something like that) has considerable positive influence on the overall smoothness (I never had very noticeable changes in the last 20 years with different types of capacitors).