[HAL]

The 12 H-Frames are at the paint shop for finishing.

Until then time for some 1.7's with the AK4499EX EA dspNexus 2x8 system for DSP crossover and two 2x12 modular OB servo subs.

Time to interface the Oracle Delphi MKI for some phono listening.

[HAL]

Just picked up another pair of 1.7's that has the opposite speaker not working.

So now I have one working pair of mirror image 1.7's to convert for the dspNexus DSP crossover! 

Pictures will be coming later.

[mix4fix]

First: aren't the speakers identical?

Second: what about the two broke ones? Fix?

[HAL]

The 1.7s are mirror image pairs with the tweeter planars on opposite sides of the baffle.

Fix is TBD.

[HAL]

Magnepan 1.7 pair #2 have the silver side stiles as compared to pair #1 with the black side stiles.

Now to remove the sock and passive crossover and install the replacement wiring and connector plate.

[HAL]

The side stiles were removed and sock on the intermittent 1.7 speaker had the staples pulled, so easy to pull up the sock.

This one has a break in the woofer foil that had a repair that is not holding. The bigger problem is the foil is delaminating in areas and the mylar is wrinkled. This would need a complete rebuild, so putting it aside.

I looked through the sock with a light on the working speaker and see a bit of the same foil delamination problem, but no wrinkles in the mylar. Once I remove the side stiles and staples, will be time to see if some glue cleaning and reapplication will fix the areas of problems.

[studiotech]

This is unfortunate. I thought the days of delam were over once Magnepan moved to full foil traces instead of the mid/bass wires.   

[HAL]

The bigger problem is the warped mylar than the delaminated foil.  If it were only delamination, you could just replace the foil traces.

To me, looks more like overdriven, overheated, stretched the mylar and foil and the glue gave out.  The entire mylar diaphragm and foil has to be replaced. 

[HAL]

Here is a closeup of the diaphragm where the trace broke and the mylar tore to cause the tension to release and wrinkle.

This entire planar has to be rebuilt.  This is not the one I need to use and that is the next to investigate for the conversion to DSP crossover.

[HAL]

Now that the pack-up for CAF2024 is completed, time to try some ideas for repairing the 1.7's.

I wired up a 12VAC toroidal power transformer to a 250Ohm resistor.  Wired the resistor to the positive side of the foil.  Only using the InPhase lead of the toroid with my ELFIX to see where the AC field stops. 

The foil break seems to be at one of the folds close to the negative terminal of the supertweeter.  Will use some acetone to remove the paint and glue to inspect the fold.
I purchased some grounding paint that is carbon based to see if it will complete the foil circuit.  I thought about silver, but that and aluminum are not a good combination, so the flexible carbon paint might work.  If I paint the carbon trace first, I do have some silver conductive paint that could go over the carbon to increase the conductivity, but not directly contact the aluminum foil.

I do have a ribbon replacement kit from Magnepan, but that is not an easy project from watching the Magnepan LRS build video on YouTube.