So, this all happened last night. Messing around with some stuff in the basement and connected my stacked large Advents to a Nikko NR 1219 I have. Having finished the 8th speaker of my 10 speaker project I look at he Magnepans and decided to just get started by cleaning one of them.
The MDF actually had some mold on it so that is where I started. Then I decided to just clean the Mylar using acetone and removing the tweeter wire. That worked really well by folding a paper towel to the width of the tweeter wires soaked in acetone then simply work back and forth over a 12" area. This also helps to soften the old adhesive to remove the tweeter wire. At the ends of the tweeter wire where the contact adhesive is used holding the paper towel there for a while help to soften that up. You can get the Mylar really clean no problem just be patient.
So, 11 o'clock time for bed. Well maybe I will try to lay down one wire. 3M 77 sprayed on just as much as Magnepan does less than 2". I have seen guys put the contact adhesive on several inches down and I suspect that is a mistake as I believe it must effect the sonic capabilities of the Mylar. I probably spent more than 2 hours on that first wire and after 3 attempts I got it.
So, here are a few tips to help you get this wire down and straight. Let the contact adhesive set up for a while maybe 10 minutes. I did a first coat that went maybe 2" down then did a second coat just 1" down. This helps hold the wire down on the turns and gives you a decent amount of adhesive to push the wire into. These were very thin coats. You are going to need to put just the slightest amount of tension on the wire to get it to stay straight and if the contact adhesive is too soft the wire will move. This is 32 gauge aluminum wire so great care must be taken to not make sharp bends or stretch the wire too much. I used a little nylon tool to push the wire into the adhesive. You will get good at making the turns around the ends of the magnets by very gently pushing the wire into the adhesive. It is imperative that the wire be between the magnets that are under the Mylar. The second speaker to 15 minutes to put the wire down. It is just how these things go.
I still have to coat the tweeter wires with the supplied adhesive from Magnepan and will update when I do.
I then installed my new caps and soldered in the tweeter wire. The kit included a new terminal block which I thought was not necessary. I do regret not replacing that as I did have a hard time with the soldering. This might be due to some contamination or the old aluminum wire corroded in the solder.
Was not planning to do all this in one sweep but finished at 3:30AM and there might be a nap in my future today!
A little bit about the kit from Magnepan. It comes with everything you will need to do this project with exception to the 3M 77 which can be found about anywhere. There is enough material to do several speakers and I certainly have a ton of the tweeter wire left. So, if you mess up it is just your time.
Also, I would like to mention that 3M 77 seems like it is the correct adhesive to use. It is commonly use for fabrics and remains flexible for long periods. It also is somewhat aerated when it comes out of the nozzle so just a quick spray is all that is needed for quick build up. I have used it when re felting pool tables and also use it when replacing speaker grill cloth. No staples needed. It is not just an adhesive it is a "contact adhesive" read and trust the instructions on the can and you will be fine.
I had some slight lifting on one speaker with the thicker woofer wires. Shiela at Magnepan suggested just applying the supplied adhesive over the wires. She said this is what really holds those wire down. So I asked her how I was going to keep the wires down while the adhesive was setting up and she said the guys in the shop have some steel bars coated with teflon they use. The magnets pull the steel bar down to create a slight clamping force. Well I did not have teflon coated steel bars. So, I cleaned off most of the dried contact adhesive sprayed a little 3M 77 down let that dry a bit then used a small round pipe which had little surface contact to the adhesive. After 45 minutes or so I took a razor blade to cut the adhesive away from the pipe and was all set with woofer wires glued down well.
