Magnepan Tympani 1D Repair/Restoration: Part 1

Recently I acquired a pair of super cool, high end Magnepan planar speakers that were provided free of charge, but with the caveat that the left channel's tweeter was intermittently buzzing. Far be it from me to turn such a find down, considering how neat they were. Unlike conventional speakers, they rely on a voice coil embedded in a diaphragm to produce sound, which allows them to have excellent response at higher frequencies. These speakers are big, though. One channel consists of 3 panels approximately as tall as I am, and each panel is 16 inches wide. That's a lot of real estate, so I actually had to tear my room apart and rearrange everything so that they would fit next to my TV.

They looked pretty imposing, even in the maelstrom of moved furniture, lamps, and just about everything in the room:



When all was said and done and I hooked them up for a test run, it appeared as though the move had finally administered the coup de grace on the left channel's tweeter- everything else was responsive and sounded great, including the left channel's other two panels. Unfortunately, the tweeter was thoroughly unresponsive- not even an errant buzz could be brought forth from jiggling connectors. I took out my trusty multimeter and measured the resistance across each speaker's terminal, and confirmed that the tweeter was indeed dead. There had to be a break in the wire somewhere.

Alas, it was time to take the panel back to the "operating room," also known as my dad's lab. After detaching the stands, separating the tweeter panel from the rest, and removing the sock, we got to survey the guts for the first time:



There was no obvious break in a wire or something of the like, so we knew the problem had to lie somewhere in the tweeter itself. Out came the multimeter again, and measuring directly across the terminals of the tweeters yielded the same result. It would have been a lucky break if the problem had turned out to be one crappy little corroded wire or solder joint, but no such luck. The next step was to take apart the tweeter itself and see what the problem was.

We desoldered the terminals to the tweeter, flipped the speaker over, and neatly taped off the grille to make sure no foreign material got inside:



Then we drilled out the rivets holding in the speaker:





The speaker was separated from the housing now, but the adhesive that originally held the tweeter in place for assembly was holding fast. I tried to gently pry the assembly apart from the frame, and a lot of it separated easily with a little bit of gentle encouragement from a putty knife and some car trim removal tools, with the occasional tap from a hammer.

What I failed to take into account, though, was the fact that the particleboard of the frame and the adhesive were now nigh 40 years old, and their bond was starting to get about as strong as the material itself. The tweeter released from the frame, but with a sickening crunch it brought some of the particleboard along for the ride:



I'm no expert, but I think it's safe to say that's not good.

A little bit came off near the top and bottom of the tweeter, which would have to be repaired before reassembly. Fortunately, upon closer inspection the structural integrity of the speaker itself was not affected whatsoever and all I was actually looking at was some cosmetic damage. It would still have to be repaired, but I wasn't fighting for a lost cause just yet:



I'm getting ahead of myself, though. It was time for the postmortem on the tweeter unit. I was hoping it could be saved- Magnepan themselves said that as long as the Mylar wasn't buggered up it could be revived. Alas, there was a tear in the Mylar and the speaker coil itself had snapped in a few places. It was remarkably thin wire, making it extremely hard to see where the breaks were. The tweeter was beyond repair at this point, so a call to Magnepan and $250 later, a replacement tweeter for the unit was in the mail. Once it arrived, we'd get down to repairing the frame's damage and mating the new tweeter to it!