DCAudioDIY.com

WOOHOO!

They are playing music, just without the super tweeters!

Since one super tweeter foil element is open circuit, did the DSP crossover to run as we 3-way adding the servo subs. The tweeter run 400Hz to 20KHz. Also added time alignment for the 3 planars and main panels to subs to finish it up.

Also figured out both the servo amp and the Class D amps are inverting polarity. The dspNexus 2x8 has an inverter for inputs, so just used the inverted USB setting. All drivers now in the same polarity.

First song, RUSH : 2112, that sounded very good!

Crazy thing happened.

Found another pair of Magnepan 1.7's with the right speaker with problems and my right speaker is good. This way I can make one good pair for cheaper than getting one repaired.

Not totally sure what is wrong with the one speaker, as they said it was intermittent.

Will be picking them up soon to start the conversion.

WOOHOO!

The second pair of Magnepan 1.7's are picked up and will be home tomorrow. Now one mirror image pair is working!

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.

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

This one has a break in the woofer foil that has 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.

Now that CAF2024 packup is completed, time to go back to the 1.7's to see if I can find the break in the foil.

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 along the foil path.

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.

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.

_________________
Walt

Since this foil is directly on the mylar film, do not want to take any chances in melting the polyester.

Found something possibly better. Flexible nickel adhesive is compatible with aluminum, so have a small pen of that coming.

Need to take it outside to use the acetone to remove the paint and cover layer over the foil for the repair.

_________________
Walt

Agree. The wire was easy compared to 1 micron aluminum foil!