What am I doing wrong?

Good question... but was relying on other measured data before dismantling. I have only small space and limited time to work on this so was hoping to promote a quick and simple fix.
As Dave has kindly offered to measure in a few weeks time then we may have some better data 🙂

Meanwhile I lose nothing by experimenting 'seat of the pants style' ;-) and maybe learn enough to be 'dangerous'
 
Do remember that, the 'classic' twin-peaks of equal ohms is only ideal if the driver is in
the optimal box volume via Theil & Small calculations.
If your 8" is not in the ideal box volume, then 'twin-peaks' may not result in optimum results.
I seriously do suggest you try an - "Actively Assisted Passive Radiator" 🙂
( the system impedance (@ LF) can be above 4 ohms, depending on your inductor )
 
Last edited: