MG 20 Delamination repair.
nooshinjohn
Posts: 25,447
Starting this thread to document and discuss what is by far the most ambitious and extensive restoration of a speaker I have ever done. My new(to me) Magnepan MG-20 right channel speaker exhibits the notorious Maggie buzz. Performing the few external tweeks that were suggested by Magnepan were unable to address the problem. With nothing else to loose(except 3500.00 for Maggie to rebuild both!!!:eek:), I decided to grow some cajones and rip into a 12k speaker to see what I could do with it.
The MG20 driver panel consists of not one, but TWO magnetic plates acting upon a single mylar diaphram suspened between the two. The plates are fastened together using some 50 rivets, and each one needed to be drilled out to gain access to the goodies inside. The wire voicecoil is secured to the mylar plate using a water-based contact cement called Fastbond NF30, made by 3M. In my speaker, these wires look like they were never bonded at all. They are EVERYWHERE! I am amazed this speaker even made a sound.
The suggestion from Magnepan is to send them in and have new drivers installed, and I can understand why. So far, I am about 11 hours into the work and there is so much yet to do. I begin by removing all traces of the old adhesive(if it can be called that) with acetone, followed by wiping down the area with a diluted 50/50 mix of water and windex to eliminate residue from the acetone. Then I use DAP contact cement to replace the lifted sections of wire back between the magnets and secure them to the mylar. Each lifted section gets a topcoat of DAP and is allowed to dry before moving to the next section.
I am working in sections 12 inches long and 5 inches wide. For a speaker of this size and given that I am working with the flagship of the Maggie line, each section is taking 45 minutes to an hour to work. This is going to take a long time to get right... After all the realignment and repairs are complete, the entire driver will be recoated with the Fastbond to complete the repairs. I will start taking pics and post them as I go along.
Thanks for reading, and if any of you guys have done similar repairs to Magnepans, please chime in with some tips and advice.
The MG20 driver panel consists of not one, but TWO magnetic plates acting upon a single mylar diaphram suspened between the two. The plates are fastened together using some 50 rivets, and each one needed to be drilled out to gain access to the goodies inside. The wire voicecoil is secured to the mylar plate using a water-based contact cement called Fastbond NF30, made by 3M. In my speaker, these wires look like they were never bonded at all. They are EVERYWHERE! I am amazed this speaker even made a sound.
The suggestion from Magnepan is to send them in and have new drivers installed, and I can understand why. So far, I am about 11 hours into the work and there is so much yet to do. I begin by removing all traces of the old adhesive(if it can be called that) with acetone, followed by wiping down the area with a diluted 50/50 mix of water and windex to eliminate residue from the acetone. Then I use DAP contact cement to replace the lifted sections of wire back between the magnets and secure them to the mylar. Each lifted section gets a topcoat of DAP and is allowed to dry before moving to the next section.
I am working in sections 12 inches long and 5 inches wide. For a speaker of this size and given that I am working with the flagship of the Maggie line, each section is taking 45 minutes to an hour to work. This is going to take a long time to get right... After all the realignment and repairs are complete, the entire driver will be recoated with the Fastbond to complete the repairs. I will start taking pics and post them as I go along.
Thanks for reading, and if any of you guys have done similar repairs to Magnepans, please chime in with some tips and advice.
The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD
“When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson
“When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson
Post edited by nooshinjohn on
Comments
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Should have kept the SDA's.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Should have kept the SDA's.
LMAO!:cheesygrin:
SDA's are nice, and I could have rebuilt a hundred crossovers by now, but these Maggies sound better in every respect. They are more than worth the time being put into them. I may come back around to SDA's some day, but for now I am happy to try new things.The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD
“When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson -
Lots of pics or it didnt happen....."....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)
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One suggestion is to check out the Planar Asylum on AudioAsylum, but it looks like you're already there.
Sounds like a big project :eek:"Science is suppose to explain observations not dismiss them as impossible" - Norm on AA; 2.3TL's w/sonicaps/mills/jantzen inductors, Gimpod's boards, Lg Solen SDA inductors, RD-0198's, MW's dynamatted, Armaflex speaker gaskets, H-nuts, brass spikes, Cardas CCGR BP's, upgraded IC Cable, Black Hole Damping Sheet strips, interior of cabinets sealed with Loctite Power Grab, AI-1 interface with 1000VA A-L transformer -
Too much **** to list....
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Magnepan is sending out new "Quasi" film for the midrange section. There are a couple spots that don't look quite right to me so I will be replacing it on this speaker along with the other work I am doing. I will be doing exactly the same thing with the other speaker, and just for fun, replacing the ribbon tweets in both after the rebuild on them has been completed. This should give me a speaker ready for another decade or two of service. A lot of work, but considering what I picked them up for, they are well worth the price. Ironically, the work I am doing on them is exactly the same job I had to do that summer I worked there before I joined the 'Corps.The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD
“When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson -
An update and some pictures...
The repairs so far have been 100% sucessful. I had my first test of the delaminated panel tonight and everything performed perfectly at all power ranges and on all types of music or movie soundtracks. Reassembly will be a major PITA, but that is a small frustration compared to knowing that I will not have to come out of pocket a few grand to have Magnepan do it for me. This has been a lot of fun!The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD
“When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson -
Nice work. Did I read the other has some small issues as well?Too much **** to list....
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deleted.. will repost later, but the repair was completely successful.
The sound is simply superb, though they sound restrained in my small room. I am looking forward to get them into a better room. The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD
“When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson -
FYI... Magnepan no longer uses the milloxane adhesive for their speakers. They now use a "reformulated" 3M product called 30NF contact cement. It has added UV blockers which prevents the glue from breaking down from UV exposure. It is also moisture resistant (which is why humidity was an issue with Maggies). According to Magnepan, this new adhesive has been in use for the past five years or so and they do not expect that delamination will be an issue now (but the real world is not a test environment).
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Sorry I mised this Jon... I used 30NF when I put these back together. I have had the big girls in storage now for a few weeks, but soon they will have a room of their own.The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD
“When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson
