Magnepan SMGa - Printable Version

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Magnepan SMGa - EdHolland - 12-17-2018

I have had these for about 10 years, bought second hand. At that time, they needed a complete rebuild of the wires glued to the Mylar diaphragm.

Amazingly, the company still supplies kits to repair a product produced in 1988! At the time, I replaced the wiring on both panels, and they have worked brilliantly untill last night. Alas, the right tweeter (very fine enameled aluminum wire) has failed. I will have to open up the speaker strip the old wire and re adhere a new run.

I will share some pictures of the construction and process... but it will have to wait a couple of weeks until after the holidays.

Cheers

Ed

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RE: Magnepan SMGa - EdHolland - 01-13-2019

This weekend's other project was to replace the wiring on the tweeter panel on the SMGAs

First job is to -carefully- strip the old wires away from the diaphragm using acetone to dissolve the adhesive layers, and clean the surface in preparation for the new wires

After that, spray adhesive is applied (masking areas where this is not wanted). 3M Super77 is the order of the day. Apparently the inventor (Jim Winey) was a 3M employee, and on seeing Mylar film and various adhesive products he was inspired to experiment with loudspeakers. Once the glue is ready, It takes a steady hand to lay out the wire pattern:

   

The whole speaker consists of a bass/treble section of heavier gauge wire, and a slender section for high frequencies:

   

A simple crossover (one inductor, one capacitor) takes care of dividing the audio between the two circuits.

Once the glue is dry, an over-coat of water based adhesive is applied, per the factory instructions.

Then the wire tails can be soldered to the tag strip. Here is where things get tricky, because the wire is enamel coated Aluminum (for light weight). Even with aluminum solder and good flux, it isn't easy to get a good joint.

All done now!

Cheers

Ed

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