Magnepan MG-IIA Rebuild

[-reverb-]

Read all the threads about rebuilding a set of Maggies and felt comfortable that I could accomplish this. Baco99's recent rebuild gave me the confidence I needed.

Both tweeters are out and there is some slight rattles in the bass. No problem. This is what I expected.

The original owner told the person I got them from that they had been back to Magnepan for rebuild a "few years ago". I do not believe this is true - someone has been in there however. First clue is there was only about 5 staples holding the cloth down at the bottom and they were not completely seated into the wood. I don't think Magnepan would ever leave staples like this.

The tweeter wires were broken and there is evidence that someone has tried to tack down the bass wires at the ends. Apparently they felt that if enough glue was good, the three times as much is three times better. Again, I don't think this looks like a Magnepan repair. What it is, is a nice mess, but I felt good knowing that it's just a matter of some Acetone, cotton balls, time and plenty of good ventilation :yes:

Here is where the nightmare begins!

 

[-reverb-]

What in hell did they use to repair these?

I tested a single end-wire to see what would happen. YIKES! Once Acetone hits the previously repaired area, it changes chemical composition into some kid of hard, white scale crud. :sigh:

Acetone will NOT remove this gunk and it is caked onto the bass wires at the end. The mechanical bond to the mylar is very strong. The mechanical bond to the wire is very strong. Oddly enough however, the bond between the mylar and wire is not very good. The wire will simply pull up off the mylar. I was able to get a little chip of it to release but no way I will be able to prep the panel properly with just acetone.

Luckily, only a thin layer was wiped onto a small section of the tweeter wire area.

After much acetone, rubbing and chipping it off with my fingernail, the tweeter panel area is salvageable.

I have no idea what to do about the bass wires.

To me, the crap looks like it may be some type of superglue product.

So the question is, other than acetone, what cleaner can be used that WILL NOT harm the mylar???

Anyone got a clue, cause I sure don't?

 

[jguzman21]

I saw those listed. Thought about it and figured it sounded too good. Hopefully you got a good deal on them. Good luck with the repair. I'm sure you'll bring them back to life :thmbsp:

 

[ejman]

It definitely doesn't look like anything magnepan would do. Interesting that acetone would not remove
the gunk (acetone dissolves super glue). I wonder if the stuff could be removed with water or alcohol

 

[-reverb-]

I saw those listed. Thought about it and figured it sounded too good. Hopefully you got a good deal on them. Good luck with the repair. I'm sure you'll bring them back to life :thmbsp:

Seemed like a deal at the time.... not sure now. Got them for about 1/2 the asking price.

Looks like a full rewire is in-store - both bass and tweeter sections. I broke the bass wire trying to clean the gunk off of it.

Not sure why I do this to myself

 

[-reverb-]

It definitely doesn't look like anything magnepan would do. Interesting that acetone would not remove
the gunk (acetone dissolves super glue). I wonder if the stuff could be removed with water or alcohol

ejman: is alcohol safe on mylar???

 

[ejman]

ejman: is alcohol safe on mylar???

According to the attached list from the manufacturer of mylar, the stuff is remarkably resistant to most solvents, including alcohol.
http://usa.dupontteijinfilms.com/informationcenter/downloads/Chemical_Properties.pdf

 

[Donkey Karma]

Maybe it would be worth the email/phone call to Magnepan, there is a chance they did have a hand and may be able to ID the Liquid Nail that was slapped on? Not likely but stranger things...

Either way, last year I Peter Gunned a pair of these, all the way to the caps.

If your going the route of a complete re-wire, I wonder if this particular module is worth the effort? I know this a complete "eye of the beholder". They can be very limited on their top end and of course need a nice fast sub with a PILE of power to reap the benefits of all your hard work.

They made leaps and bounds since this model.

Either way good luck, enjoy the journey and it will be fun to watch.

 

[-reverb-]

According to the attached list from the manufacturer of mylar, the stuff is remarkably resistant to most solvents, including alcohol.
http://usa.dupontteijinfilms.com/informationcenter/downloads/Chemical_Properties.pdf

Thanks for the link ejman. Called Magnepan this morning and they confirmed what you have pointed out; alcohol is safe on mylar. I wanted a project - looks like I have one now.

 

[-reverb-]

Maybe it would be worth the email/phone call to Magnepan, there is a chance they did have a hand and may be able to ID the Liquid Nail that was slapped on? Not likely but stranger things...

Either way, last year I Peter Gunned a pair of these, all the way to the caps.

If your going the route of a complete re-wire, I wonder if this particular module is worth the effort? I know this a complete "eye of the beholder". They can be very limited on their top end and of course need a nice fast sub with a PILE of power to reap the benefits of all your hard work.

They made leaps and bounds since this model.

Either way good luck, enjoy the journey and it will be fun to watch.

I hear ya brother. It's almost a "I will not admit defeat" mentality at this point.

I spoke to Magenepan this morning and ordered rebuild kits for the tweets and the bass panels. Just a smidge over 80 bucks for all that. It's too cold for them to ship it, so the kit will not include the 3M Fastbond 30NF adhesive. I can get a quart of that for about 30 bucks locally.

All said and done, I will have a rebuilt pair for right at 250. Not a scroe but not too bad a price to dip my toe into the Planar-Magnetic pool.

I think I have enough juice to push them? I have a Sansui B-2102 that is 200 wpc into 8 ohms and the Yamaha MX-1000 pushes about 295 wpc into 6 ohms.

I think that one of these will should be able to get the mylar vibrating!

 

[Donkey Karma]

I hear ya brother. It's almost a "I will not admit defeat" mentality at this point.

I spoke to Magenepan this morning and ordered rebuild kits for the tweets and the bass panels. Just a smidge over 80 bucks for all that. It's too cold for them to ship it, so the kit will not include the 3M Fastbond 30NF adhesive. I can get a quart of that for about 30 bucks locally.

All said and done, I will have a rebuilt pair for right at 250. Not a scroe but not too bad a price to dip my toe into the Planar-Magnetic pool.

I think I have enough juice to push them? I have a Sansui B-2102 that is 200 wpc into 8 ohms and the Yamaha MX-1000 pushes about 295 wpc into 6 ohms.

I think that one of these will should be able to get the mylar vibrating!

This is where ppl post they pushed them fine with 20wpc tubes and some were they pushing them with +200wpc and needed more....

Sounds like you will be more than fine. I was using 250 per with the lows subbed out.

Please do not get me wrong. When these were placed correctly and the right recording was on they were literally quite stunning and would leave listeners in aww more often than not.

They are just finicky, and needy.

It was as much about the journey for me as anything. Getting a set of them under my belt after piles of conventional boxes I was pumped as heck to work on these.

Careful with the Mylar, alcohol will be fine but it can take very little to puncture. I got lucky and scored two pair for $50. So I had room for error.


I wish you the best and will continue to watch the outcome. Im sure they will shine!

 

[ejman]

Maybe it would be worth the email/phone call to Magnepan, there is a chance they did have a hand and may be able to ID the Liquid Nail that was slapped on? Not likely but stranger things...

Either way, last year I Peter Gunned a pair of these, all the way to the caps.

If your going the route of a complete re-wire, I wonder if this particular module is worth the effort? I know this a complete "eye of the beholder". They can be very limited on their top end and of course need a nice fast sub with a PILE of power to reap the benefits of all your hard work.

They made leaps and bounds since this model.

Either way good luck, enjoy the journey and it will be fun to watch.

I bought Magnepan MGI I Imp back in 1980 and I still own them (I rebuilt them about 15 years ago). Sometimes the mellow top end can be a real asset. I use them in my TV room, powered by Emotiva UPA 1 (350 W into 4 ohms). For whatever reason, these particular speakers sound absolutely terrific with those monoblocks. The Emotiva's sounded a bit bright for my taste with my MMG's and 1.7's but it's the perfect combination with these old Maggies and they have enough power to bring out bass I didn't know existed in these ol' gals.

Rebuilding is not hard, just very time consuming and the OP has the extra challenge of the mystery goop. I agree it should be a great project!

 

[MexicoMiike]

Frankly, sometimes the best thing to do is admit you made a mistake. That's what dumpsters are for.

I am NOT badmouthing maggies; I have a pair of MGC2.6s and the wires ARE not all that difficult to rebond...IF you are starting with a pair of unmolested speakers. But what you have there were butchered by some hack and repairing those is a whole different level of PITA. I'd avoid the death march and just give it up.

OTOH, if you really just get into it as a project and figure "what the heck," accepting that they may be un-repariable at any reasonable cost, I suppose it could be an interesting "journey." Heck, people used to walk 1000 miles to Santiago de Compostela as penance. So this might make a good substitute.

 

[-reverb-]

Not sure what I would be doing penance for... I suppose the list could go on and on

I appreciate the dose of reality and somber reasoning but I got parts ordered, so the repairs will continue.

I figure if nothing else I will get the enjoyment of learning something new and maybe the satisfaction of bringing something back to life - or at least going down in flames trying.

As long as I don't rip the mylar, everything should be copasetic.

 

[Donkey Karma]

Not sure what I would be doing penance for... I suppose the list could go on and on

I appreciate the dose of reality and somber reasoning but I got parts ordered, so the repairs will continue.

I figure if nothing else I will get the enjoyment of learning something new and maybe the satisfaction of bringing something back to life - or at least going down in flames trying.

As long as I don't rip the mylar, everything should be copasetic.

Amen brother!

 

[ejman]

Not sure what I would be doing penance for... I suppose the list could go on and on

I appreciate the dose of reality and somber reasoning but I got parts ordered, so the repairs will continue.

I figure if nothing else I will get the enjoyment of learning something new and maybe the satisfaction of bringing something back to life - or at least going down in flames trying.

As long as I don't rip the mylar, everything should be copasetic.

Actually, even if you do rip the mylar the stuff is so amazing that rips don't propagate. A small rip can often times be fixed with a bit of tape (like the extra heavy duty clear tape from the post office) and you are good to go.

 

[-reverb-]

Stripping wires

Began removing the bass wires last night. Must say that it went a little better than I expected.

Lessons learned so far:

* Make sure you have GOOD ventilation. Breathing acetone fumes is bad juju.

* Mylar is pretty amazing stuff - incredibly strong and durable. It does have it's limits however. It's mindless, boring work prepping the panel but don't get complacent and careless. Stay sharp and attentive (the acetone fumes certainly don't help in this regard)

* Be especially careful in the areas of mylar that doesn't have magnets underneath, such as the end loops. The mylar can be pushed in further in because there is nothing to limits it's travel. Therefore the risk of puncture is greater in these areas.

* Pull as many wires as you can together as a group. The more wires pull, the more likely large chunks the bonding glue will come with it. Careful not to stress the mylar too much however.

* Before using acetone to remove the remaining gunk, try to use your fingernail to lift it off. It will cleave-off cleanly and leave the mylar almost pristine. Remember as a kid how when you found a mica rock and the layers would fleck-off?? Sort of like that. Again, careful not to damage the mylar. Be aware also that it will leave your fingernails very sore the next day. That's a lot of flecking :yes:

* Soak the area around the middle "button" with acetone to be able to pull the wires out from under it. Sheila at Magenepan says there is no need to remove the button. When you rewire, just go slightly around the button with the new wire runs. My problem is when I pulled the wires, my button split into 3 pieces. Magenepan is sending replacements - these guys are super helpful!.

Now a few pics. First is a pile of wire in the floor. That's the bass loop.

Second is the bottom of the panel where I used the fingernail approach.

Lastly is the top of the panel where I went straight the acetone. As you can see, the top has much more work to be done. Because I have used acetone, the sharp edges of the glue have been dissolved and there is no chance of using the fingernail trick to speed the process. I will have to complete that section of the panel using only acetone. Live and learn.

I'll try to get some better pics tonight. Those were taken quickly this morning on the way out the door.

 

[Blue Shadow]

I recognize that pile of aluminum wire. Did some IIc speakers a few years ago.

 

[bored184]

Great read! Please keep us updated with your progress. Over Christmas break I plan on tackling a pair original MG-IIs.

 

[Drugolf]

Ditto! I have MG IIa's also that I will be replacing the tweeter wires and probably the crossover this winter and have the kits already. Hopefully not the bass wire. Trying to figure out the crossover options now and have some posts on the MUG board pertaining to it. We are all in this together!

Great read! Please keep us updated with your progress. Over Christmas break I plan on tackling a pair original MG-IIs.