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mg20r buzzing, is it aluminum wire? how to pull socks?

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Posted on September 5, 2014 at 16:06:47
Blaine H
Audiophile

Posts: 60
Location: N New Jersey
Joined: February 2, 2004
 Well, I triamped last year, and it sounded great. But I've always had a "knock" coming from the bass panel when I push it with low stuff, I can avoid that by only sending 40hz and up at 18db slope. but sort of defeats purpose here of big Maggie. Anyway, now I get a loud buzzing from top of bass panel, also at low freqs, but sounds like around 70hz to me.
I haven't done a sweep, but its clear its the dreaded delamination. I had witnessed first hand the job on Tympani 1d at my buds house. I'm thinking 20r doesn't use the same aluminum wire, but rather looks like wide bands of some kind...but maybe that's the magnet. So, clearly I need a plan. not looking forward to buying boxes, paying heavy freight, and paying Maggie a ton of money to repair these. The worst part is the trying to move and box these. And these didn't come with boxes. Oh yes, I am using mye stands, and there is no torque whatsoever on the frames. And yes, the triamping really brought these guys into the next level. I'm using DEQX, with jenson transformer output board for xlr. Crown K2 for bottom, ICE power H20s250 for mids, and direct digital Newforce DDA-100 for tweets, and sometimes Nightshade NS-50 tubes for tweet using single ended connection. Has run nicely like this for a year. No fuses, direct to driver connections. The xover is DEQX latest HDP-4. They gave me a great deal to upgrade from my HDP-3.
So, could anyone please shed light on how to pull socks on 20r, maybe construction of bass panels conductors, repair hints, possible 2nd source to repair/upgrade besides Magnepan maybe? I'm in NJ USA area. Please? Thx

 

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RE: mg20r buzzing, is it aluminum wire? how to pull socks?, posted on September 5, 2014 at 19:08:46
Green Lantern
Audiophile

Posts: 16952
Location: San Diego, Ca
Joined: November 12, 2002
Contributor
  Since: June 17, 2003
 Sorry to hear this about your 20s!

This won't help you but from my understanding the bass panels are almost impossible to tackle due to the magnets being sandwiched together on each side with rivets. To undo them you'd essentially have to drill through each rivet; repair, then re-rivet.

And as my friend pictureguy noted in a previous post, the metal shavings from the drilling would have to be caught mid-air.

I spoke with Magnepan when I once thought I heard rattling/buzzing (turned out to be my amps were simply running out of steam, I bought a pair of Emotiva XPA-1s and no problems since); the nice lady basically said they scrap the old bass panels and build new ones since it would be economically unsound to to repair them.









 

RE: mg20r buzzing, is it aluminum wire? how to pull socks?, posted on September 5, 2014 at 20:15:22
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 The best thing to do with delam on the MG20.x bass panel is to have Magnepan repair them. The wires are between the magnet boards and it is tricky and dangerous to pry them apart and difficult to align them and reassemble. However, someone had documented his repair project somewhere on the forums here or elsewhere.. I don't recall where - search for it.

 

"So, could anyone please shed light on how to pull socks on 20r"?, posted on September 6, 2014 at 02:19:23
andyr
Manufacturer

Posts: 12548
Location: Melbourne
Joined: September 2, 2000
 I'll add my comment in case you're one of these people who don't want to listen to what's said ... but if 3 people say the same thing, it might sink in.

If you think "taking the socks" off is all you need to do ... you obviously haven't closely examined your MG-20Rs? So, press your hand against the socks, front & back. On the other side of the mid-line of the overall panels from the ribbon, you will feel something hard - both front & back. This is the 'pole piece' - the holey metal sheet which supports the magnet arrays.

As you can feel this sheet front & back (under the sock), you should realise that the mylar is sandwiched in between - this means that it is a major difficulty to deal with de-lam.

You should also feel that the mid panel only has magnets one side (for the 20Rs only - the 20.1s & 20.7s have magnets both sides of the mid panel as well as the bass panel). So re-laying mid wires on a 20R is definitely feasible for a DIYer.

You decided to go for the improved bass delivery of the 20.Rs which comes from having magnets both sides of the mylar ... the penalty for this is that you have to send them back to Magnepan, for repair. And, as someone else posted - probably, they bin them and give you new panels!

I suggest you shouldn't complain about this - being in 'Noo Joyzie', you are privileged, compared to Maggie owners in other parts of the world.


Good luck,

Andy

 

RE: mg20r buzzing, is it aluminum wire? how to pull socks?, posted on September 6, 2014 at 05:43:40
neolith
Audiophile

Posts: 4842
Location: Virginia
Joined: February 21, 2002
Contributor
  Since: December 2, 2004
 As everyone has said, you really can't make a DIY repair. If you are convinced that you have delamination, you should call Magnepan and see if they will ship you the bass panels without you having to ship the speakers. That would save you the hassle and cost of shipping and some labor costs.



"Our head is round in order to allow our thoughts to change direction." Francis Picabia

 

RE: "So, could anyone please shed light on how to pull socks on 20r"?, posted on September 6, 2014 at 09:41:55
Roger Gustavsson
Audiophile

Posts: 2054
Location: Huskvarna
Joined: February 12, 2010
 AndyR wrote:
"So re-laying mid wires on a 20R is definitely feasible for a DIYer."

I doubt, think there are some crossbars across (some parts of the sheet metal is left there) the midrange driver, not giving easy access to the foil conductor. I have a picture somewhere...

To open these push-pull driver(s) some re-engineering will be need. Some sort of jig that hold the two halves (front and rear perforated sheet metal with the magnets) in position while the rivets are drilled out and then let you pry the two halves apart. Without the rivets, the two halves will slide sideways and probably destroy the Mylar. I have no idea of how to hold the halves in place on a suitable jig. Magnepan use a jig with hinges in production. I think Magnepan just pry them apart and rebuild the driver with new Mylar/wiring. I would be surpriced if they just send you a new driver without the old driver in exchange. They will not do that for any other model as far as I know, except the ribbon tweeters. It would make rebuilding old Magnepan speakers a lot easier if we could just change the driver without sending the whole speaker! The drivers can be placed in a rigid box giving tesl protection, not the cardboard boxes Magnepan uses...

 

RE: mg20r buzzing, is it aluminum wire? how to pull socks?, posted on September 6, 2014 at 11:29:30
macmagman
Audiophile

Posts: 501
Location: NW Indiana
Joined: October 17, 2010
 I'm not sure on the 20's if you have access to the mid panel but if your buzz is coming from the bass the only alternative would be to send them back to Magnepan for replacement. They will NOT send you the panels till they have your old ones, I tried. The midrange in one of my 20.1's went out and that was my only alternative.

I did take mine apart and sent them only the panel, saved a ton on shipping and they aren't that hard to remove. I think the cost of the new panel was about $1400.00. If I were you I would send both of them and see if they will upgrade them to 20.1 panels, then for around 3K or so you will have a new set of 20.1's, as long as the new panels will fit into the existing frames.

 

RE: mg20r buzzing, is it aluminum wire? how to pull socks?, posted on September 6, 2014 at 12:56:13
Roger Gustavsson
Audiophile

Posts: 2054
Location: Huskvarna
Joined: February 12, 2010


A picture of a MG 20. Not very impressive alignment of the foil conductors....

Magnepan will only upgrade 3.7 to 3.7i. They will not upgrade anything else. That is the answer you get from them.

 

RE: mg20r buzzing, is it aluminum wire? how to pull socks?, posted on September 6, 2014 at 13:43:51
Davy
Audiophile

Posts: 500
Location: London
Joined: July 20, 2001
 As many have said the only really viable solution is to send back the sealed bass panel to Magnepan for repair. This is why a 20 or 20.1 is not really a sensible buy if you are outside the USA as the push pull panels are not easily DIY repairable if delineation occurs unlike the 3 series or tympanis. Would love a set of 20s or 20.1s but this issue puts me off as I'm in the uk. Can't afford the 20.7s!

I very much doubt Magnepan would be able to upgrade a 20 to 20.1 spec. Even if they could you'd need to send them back the whole speaker as the crossover values are slightly different between the two.

 

as a band-aid, posted on September 6, 2014 at 14:48:57
Green Lantern
Audiophile

Posts: 16952
Location: San Diego, Ca
Joined: November 12, 2002
Contributor
  Since: June 17, 2003
 or if one were strapped for cash I supposed you could by-pass the bass panel all together and wire a DWM in it's place.









 

RE: as a band-aid, posted on September 6, 2014 at 15:07:51
Davy
Audiophile

Posts: 500
Location: London
Joined: July 20, 2001
 Good idea! Might not sound quite the same though ...

It's a shame Magnepan don't have a repair centre in Europe somewhere. I can do most stuff myself but not a mg20 bass panel repair.

 

drivers can be placed in a rigid box, posted on September 8, 2014 at 05:26:12
neolith
Audiophile

Posts: 4842
Location: Virginia
Joined: February 21, 2002
Contributor
  Since: December 2, 2004
 I did exactly that when I shipped my IIIa mid-bass panels to Magnepan about 10 years ago for delam repairs. Made a box from 1/4" luan plywood and 1x2's. Note the notches in the frames for the crossbars. I put the frame in a MMG box as it was only 1-1/2" thick. Saved a bundle in shipping costs.





"Our head is round in order to allow our thoughts to change direction." Francis Picabia

 

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