Magnepan Tympani 1D Repair/Restoration: Part 2

I last left off my account of this project with the unfortunate revelation that the tweeter needed total replacement. Once the replacement tweeter had arrived from Magnepan, I could continue my work on fixing everything up:



The new tweeter turned out to be a little wider than the original unit, which meant we would have to widen the hole in the frame for it. This meant it was time to do some cutting. The damaged portions of the frame would have to be cut out as well and mended before the whole unit could go back together- not so much for structural integrity or aesthetics, but because I was worried leaving a hole in the frame might effect the sound of the tweeter. First up was drilling some holes to roughly mark out the corners of where the widened frame hole would lie:



Then, out came the jigsaw. Cutting was more of a pain than initially expected because the blade wanted to wander through the rather thin particle board, making carefully measured cuts wobble much more than I would have liked. It didn't exactly have to be pretty, though, because in the end the sock was going over it- it just had to hold together and not buzz. Anyways, after the new wider hole was cut we removed the damaged sections of frame:





Using some scrap from what was cut off of the frame I made a patch for the lower damaged portion:



For the upper portion, there was a lot more material missing and a scrap piece wasn't going to work. A quick trip to a hardware store and a cheap sheet of particle board later, I had cut out a piece that would serve as the backing piece of a 2-part repair:



Next up was a liberal application of wood glue and some clamps to keep everything steady while it set:





After that, I used another scrap piece from the original particle board to make sure the side of the tweeter had a nice flush surface to mount on:



After a little bit of fitting with a file to let the new tweeter sit flush in its hole, it was ready to mount to the frame. The tweeter itself came with adhesive on the sides, but the instructions recommended further attaching the tweeter to the frame with extra hardware. The use of bolts was considered for this job, but in the end the original factory attachment method of rivets was used:



A little bit of caulk was applied to seal up the smaller holes and cracks in the frame, and then it was time to handle the wiring. The existing tweeter wires were soldered onto the terminals of the new tweeter, and hot glued down in their new positions:



Then it was time to re-sock the whole assembly and put it all back together:



The fabric of the sock had actually shrunk a little while being off the frame- even 40 years of being held taut with staples was not sufficient to stretch the fabric out. I'm assuming that at the factory there was some sort of tool or weight to assist in the stretching process, since pulling manually took a lot of effort to get just barely enough fabric over the end. After a liberal application of staples we had the sock secured:



It was just a matter of soldering on the terminal plate again, and then reuniting the panel with the rest of the unit:



I checked the terminals once again with the multimeter to verify that all was well, and it was time to hook them up!

So, the final verdict? These sound simply amazing. They're not as sensitive as "normal" speakers, so to keep my center channel from overpowering them at a given volume level I had to tweak my receiver a little bit. Also, their bass response isn't as good as traditional speakers, but my woofer more than makes up for any deficiency in the low frequencies. I'm sure a well-trained audiophile with equipment could detect the difference between the left and right channel now, based on the age difference of the tweeters, but for me at least the difference is barely perceptible and possibly just placebo on my part. This was an awfully big project but I'm really, incredibly happy with how it turned out!