I have been purchasing used Carver amazing drivers for some time. Today I put my collection of original hex cone drivers to the test in a full six driver dipole configuration. The drivers are connected in two sets of three wired in series, the two sets then wired in parallel. Each driver has a DCR of 3.5 ohms, so the net impedance is a reasonable 5.3 ohms.
Test configuration is a ground plane measurement at 2 meters. I also did a similar measurement with the 4×15″ driver dipole panel I built with Goldwood drivers.
I know what you are thinking, these are the same speaker measured twice. Nope! I have added some silicon to the cones of the 15″ drivers to decrease their resonance to 24 Hz / raise their Qts to about 3.5. They are very close in specs to the original Carver drivers at 24 Hz / Qts = 3.0. Note the baffles are even different – the baffle is 24″ wide for the 4×15 and 15″ wide for the 6×12 – so maybe that compensates a little for the small difference in Qts.
For reference, consider a close mic measurement of one of the 15″ drivers (blue) compared to the array 2 meter ground plane measurement (green). You can see that the dipole bass cancelation is -15 dB at 24 Hz. You can also see multiple dips at 35, 57, 121, and 141 Hz. I had the speakers facing into the garage, so I am wondering if these dips were due to the finite baffle, or a garage Helmholtz resonance.
So another test I tried was to put the 6×12″ on its side and compare to the standing array.
A little bit of gain, but otherwise the same response.