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Magnepan SMG

Bigkahuna

Bigkahuna

Well-Known Member
I just bought a pair of Magnepan SMG, well, actually traded them for a pair of Boston HD9 bookshelf speakers. I got them home and connected them to my SX 1250. Man these things sound horrible! It is OK I was expecting this. I am expecting a project here and may tomorrow get the socks off to start some evaluation. Hopefully I can still get the repair kits from Magnepan this time of year. When I went to look at these they were sitting in a basement in Maine about a block from the ocean which is probably the worst environment as I understand from research.
Hopefully the film is OK. I can feel the wires lifted under the socks but seems to be some crunching noise there which does not sound good! Any advice on these? Any specific place I should go for information?
 
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I'll be watching this one. Crunching noise is only good if it's from that fist full of Pringles you extorted from one of your kids' friends.
 
Got a pair also, one sounds great, the other dead. I also can feel the wires lifted and am considering diving in as well.
I'll be watching your progress.

I believe repair kits are available from Magneplaner for around 50 bucks from what I've read. I plan on watching repair videos as well.

Glenn
 
I will take them apart and report back this morning. I have always wanted a pair of Magnepans as I have listened to them briefly a few times. This might get emotional so get your popcorn out! :lurk:;)
 
GD70 said:
Got a pair also, one sounds great, the other dead. I also can feel the wires lifted and am considering diving in as well.
I'll be watching your progress.

I believe repair kits are available from Magneplaner for around 50 bucks from what I've read. I plan on watching repair videos as well.

Glenn
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Glen Nice to have met you last weekend? I think maybe we talked about Magnepans. Are yours SMG?
 
better call Magnepan ASAP as they wont ship their glue in the winter as its not freeze thaw stable.. Many have used another 3m product to fix . Some have used rubber cement for small repairs
 
OK, I have one of them apart on my kitchen counter so here is what I have. As I was pulling the sock off everything looked fine but when I got to the top of the speaker this is where I saw the issues. The glue is very dry and the wires are just starting to lift. I think the crunching I hear is the dried glued rubbing on mylar when I push on the wires. There is some corrosion you can see in one of the photos much of which is on the aluminum wire for the tweeter. Also a couple of holes through the mylar. This speaker certainly does not look as bad as I might have expected and in fact I am not sure why they sound so bad at this point. The bass wires are what is lifting and these have just started. I would say only some are lifted and the ones that are only maybe a 1/2" at the top of the loop. Listening to them I thought they might need cap replace in the crossover. However, it looks like this is a film cap. Of course this is my first experience with Magnepans so please chime in if you know something on these.

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Bigkahuna said:
OK, I have one of them apart on my kitchen counter so here is what I have. As I was pulling the sock off everything looked fine but when I got to the top of the speaker this is where I saw the issues. The glue is very dry and the wires are just starting to lift. I think the crunching I hear is the dried glued rubbing on mylar when I push on the wires. There is some corrosion you can see in one of the photos much of which is on the aluminum wire for the tweeter. Also a couple of holes through the mylar. This speaker certainly does not look as bad as I might have expected and in fact I am not sure why they sound so bad at this point. The bass wires are what is lifting and these have just started. I would say only some are lifted and the ones that are only maybe a 1/2" at the top of the loop. Listening to them I thought they might need cap replace in the crossover. However, it looks like this is a film cap. Of course this is my first experience with Magnepans so please chime in if you know something on these.

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I will be following your progress and procedures on this. Great pics!
I haven't opened mine up so have no clue if there's corrosion, or just lifted wires due to age.
 
I guess these are left and right and even has an L and R at the end of the serial number. I took the first one completely apart just to get the socks off which was a waste of time as I was definitely going to replace them. On the right speaker you can see I just cut out the rear portion to access the mylar and crossover.
So on to the evaluation:
Right speaker
I desoldered the capacitor to get it out of the circuit and also to test it with my cool little $13 transistor tester that also measures caps.
Cap measures at 19.15MF and it is a 17MF cap so not that far off but could be better.
Low Frequency wire measures 4.7 Ohms
High Frequency wire measures 5.1 Ohms

Left speaker
Cap measures at 19.65MF and it is a 17MF cap.
Low Frequency wire measures 4.7 Ohms
High Frequency wire measures open circuit. There is a photo in this post that shows the corroded crumbled wire.
So, looks like I have a project on my hands.

Now here is the kicker. In checking out the crossovers I found the fuse for the high frequency wire blown on both speakers. DOH! The right speaker is in better shape as it has the working tweeter and non crunchy contact cement. The left has an open circuit tweeter and the crunchy sounding contact cement. So at least I do hear the potential in these with the one tweeter and one speaker working. I won't say it is bass lacking but very different and I think I really like that. I have it connected to my SX1250 but might just try this one speaker on my Kenwood KR 9600 and see how that sounds. I have a Dave Brubeck CD playing now. This is a Telarc CD so the quality is pretty decent. It is very real sounding and vocals are excellent. I did try to listen to an MP3 file and it sounds horrible so these are very sensitive to source material. I wish the left speaker worked correctly I could certainly listen to these for a while.
 
Just ordered the kit to replace the tweeter wire and some new socks $129 including shipping. Not sure when I will have time but should be a pretty easy little project.
 
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.
 

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Excellent write up and photos. I was thinking another way to hold down the wires while the adhesive dries is lay a strip of wax paper across the area and weight it. The adhesive won't stick to the wax paper.

I know how you think I'll just work on this for another 15 minutes, and 3 hours is gone!

Glenn
 
Here is an update to my last post. In my last post I had the wires glued down at the ends. I wanted to let the contact adhesive set up before applying the new adhesive supplied by Magnepan to cover the rest of the wires. Everything was good until I applied this adhesive where I had two problems.

The tweeter wires are almost as thin as hair which made it very difficult to work with. They were straight with tension before applying the adhesive. However, just the brushing action and the viscosity of the adhesive moved the wires around. I would say that probably 30% of the tweeter wires are not centered between the magnets after applying the adhesive. I had read about applying a low amperage power supply to the tweeter wires that would center the wires. Maybe I need to look more into this.

I had little to no lifting on the woofer wires but did have some brown and dried adhesive. For the woofer wires Magenpan recommended that I apply one coat of the new adhesive directly over the old adhesive which I believe at that time they were using Miloxane. What happened was after about 1-2 minutes the new adhesive ate right into the old adhesive and I ended up with some globs coming off. This was like the new adhesive was the solvent for the old adhesive. I worked as fast as I could and just put down the new adhesive down because touching it with the brush after the adhesive was applied would pull up globs. So the end result is one speaker had some areas where there are globs and the other less so. Kind of looks like an 8th grade science project which was disappointing. I have included some photos to show you the worst.

After letting the adhesive set up a couple of days I decided to hook them up for a listen. I had very low expectations being somewhat disappointed in how my project looked when done. Wow! What a surprise! These things are awesome! I am literally giddy listening to them! I am not sure if there would be any sonic improvement to be had by getting back into these because they sound great now.

Here are some listening impressions for anyone reading this this. First off these are smaller SMG Magnepans and reading the specs on these they are 100WPC max. Comparing these to other Magnepans this is quite a bit less and recommended equipment is also lower wattage in the 20-100WPC range. This afternoon I was listening to some Santana, Mozart on CD and some Fleetwood Mac on vinyl and had a huge smile on my face. I have them in my cluttered basement connected to a 45WPC Pioneer SX-780 (yes I have better) and they sound very remarkable. They are so realistic it is a surreal experience to listen to how musical these are. Soundstage, and imaging are very remarkable and they are brutally honest about poor source material like MP3s. Vocals are so clear and accurate I feel like the stage is right in front of me. They are very focal and sound different just standing up. These speakers do not seem bass lacking but perhaps bass accurate. They certainly do not have big booming bass and these are not party rock and roll piss off your neighbors speakers. They are not for large rooms but for the average living room should be just fine as any 100WPC speaker would be. These are sit down and enjoy critical listening speakers. These are unlike anything I have heard before. This is my first experience listening to Magnepans and I think I will be a big fan! Glen you have a pair of these and I recommend this be your next project...

Now here is another reason why I really like these speakers. I like my hobby but I like it to be cheap. I like to get the stuff I could never afford when I had kids and other obligations. I want great results using stuff that I have obtained fairly inexpensively and perhaps had to fix like these speakers. When reading about Magnepans I read a lot about requiring big clean (expensive) power amps. This makes me feel like I am jumping into a real rabbit hole. However, I believe this applies mostly to the larger Magnepans. I have only listened to these on a 45 watt Pioneer receiver and expect things to get better going up the chain to some of my better equipment but I am thoroughly impressed already.
 

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Glad to hear you like them. All Magnepans like lots of current. I suspect you may like yours even more when they are fed more power.
 
I just bought a set of SMGa's at an estate sale, no stands and I have not hooked them up yet, supposedly they were tested and work but should I be prepared for the worst?
 
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