Originally Posted by
Tom Loizeaux
After doing some more reading and research recently, I think my "4320s" may actually be 4331s! Check my photo to the left and see the cabinet in the lower right. They came with 2215 B woofers, 2420 compression drivers w/ 2307 horns and 2308 lenses and had no crossovers. I added the 2405s in new holes centered above the lenses and installed two pair of banana plugs and a 3106 in each cabinet. So now they are bi-amped with the 2405s running passively from the 3106 crossovers.
I have discovered that JBL made a few variations of the 4320 that hade a same cabinet, but used different port numbers and lengths depending on the woofers used. Some were passivly crossed over, some were bi-amped, some were 2-way, while some were 3-way. In any case, they were the beginning of JBL's studio monitor line.
Tom