Dual membrane planar magnetic (both active driven)

[neodymium]

I suspect, the mass reduction by alu, CCA wires (related to copper) well masked by mass of necessary membrane coating (glue, for example). Did you ever measure the mass of glue on membrane? At the Magnepans seems dominating part the glue and the Milloxan. Furthermore this layer make better mechanical coupling between wire and undriven foil sections, gives a better high-frequency response (paradoxically). Perhaps the copper can be enough good (against its higher specific mass)?

 

[båndsei]

Maybe your driven mass is too heavy for the magnets .Lack of control.
Have you tried to measure thiele small values .Too high Q value.
Underneeth here some measurements of my AMT´s . One with soft film PVDC Saran and one with mylar.
Might be different aluminium thickness too

Bernt Båndsei

 

[båndsei]

If you would increase magnet strength you could do like this.

Bernt

 

[AVWERK]

Here’s an interesting dual sided diaphragm and most likely have a symmetrical magnet arrangement on both sides of the screen

 

[esl 63]

When running double membranes you also have higher force factor pushing the air. So if you extend the baffle the bass response below 250Hz will increase.
So almost no adding cost you will get a huge bass boost with a wider and higher baffle.
I have tried it on ESL 63, important to NOT make a H frame rather a v shape where the baffle is pointing back wards.