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New MMGs, Burned Tweeter? - Crossover Schematic or Picture?

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I have a pair of 4 month old MMGs and one has a strange problem, or it may just be a blown tweeter.

On the problem MMG the tweeter doesn't play and all the high frequencies are coming out of the bass panel as though the bass panel has no low pass filter.

On the good MMG if I pull the fuse, the bass panel definitely has a low pass filter, no high frequencies there.

Before I ship this thing off to Magnepan I'd love to look at the crossover and see how this thing is wired.

Any help is greatly appreciated.

Thanks

Jim

Follow Ups:

RE: New MMGs, Burned Tweeter? - Crossover Schematic or Picture? - rljammer@yahoo.com 19:40:44 04/03/19 (0)
MMG tweeter blown?
I bought a pair of MMGs off of Craigslist a while back--the seller thought that he had blown the tweeter. The way he explained it, I told him that the Magnepans don't work that way- he said he just wanted to get rid of them. For the price, they were too good to turn down and I thought they'd be a good summer project. When I took them out of the box, everything appeared new and the socks to have never been taken off. When I played them, I heard what people described in this thread.

I was going to remove the sock, but the side rails prevented me from doing that (I don't want to damage the rails). Does anyone have a suggestion on removing the rails or should I just cut the sock where the crossovers are located and go from there? Any suggestions are appreciated. What I'm looking for is help in finding the simplest solution(s) in making these speakers sound as good as possible.
Schematics will help.
Thanks
RE: New MMGs, Burned Tweeter? - Crossover Schematic or Picture? - Norman M 06:25:28 02/20/16 (1)
Four month old speakers screwed up and be told to pay the shipping charges (or negotiate same or open them up, etc.), hell no! I'd save all my paper work and dispute the charge with my Credit Card.
- RE: New MMGs, Burned Tweeter? - Crossover Schematic or Picture? - Jim-W 08:14:38 02/20/16 (0)
  Can't send them back now, already stripped out all the junk crossovers and rewired with Canare wire for bi-amp.
RE: New MMGs, Burned Tweeter? - Crossover Schematic or Picture? - Jim-W 19:01:49 02/08/16 (7)
Called Magnepan and the 100uf cap belongs there.
- RE: New MMGs, Burned Tweeter? - Crossover Schematic or Picture? - Davey 06:53:29 02/12/16 (6)
  Interesting. Clearly a major change to the MMG crossover network.
  I wish Magnepan would return to providing schematics for the speaker systems.
  
  Dave.
  - RE: New MMGs, Burned Tweeter? - Crossover Schematic or Picture? - Jim-W 18:41:25 02/15/16 (5)
    And, the inductors are .86.
    - RE: New MMGs, Burned Tweeter? - Crossover Schematic or Picture? - Davey 08:28:50 02/16/16 (4)
      Ah. Another considerable change from the previous version.
      
      Dave.
      - RE: New MMGs, Burned Tweeter? - Crossover Schematic or Picture? - Satie 07:00:33 02/17/16 (3)
        
        In Reply to: RE: New MMGs, Burned Tweeter? - Crossover Schematic or Picture? posted by Davey on February 16, 2016 at 08:28:50
        
        How did they change the elbow freq and likely acoustic XO freq ? Any idea of what they might have hoped to achieve that way?
        
        RE: New MMGs, Burned Tweeter? - Crossover Schematic or Picture? - Davey 09:09:40 02/17/16 (2)
        
        In Reply to: RE: New MMGs, Burned Tweeter? - Crossover Schematic or Picture? posted by Satie on February 17, 2016 at 07:00:33
        
        There may be a concurrent change to the panels themselves as well, so no way to know for sure without some actual measurements.
        
        It may even be a series crossover now. I've seen no close-up photo's that would allow to confirm that.
        
        Dave.
        
        RE: New MMGs, Burned Tweeter? - Crossover Schematic or Picture? - Jim-W 08:36:36 02/20/16 (0)
        
        In Reply to: RE: New MMGs, Burned Tweeter? - Crossover Schematic or Picture? posted by Davey on February 17, 2016 at 09:09:40
        
        @ Davey, they are definitely series crossovers.
        
        Thanks (nt) - Satie 11:14:05 02/17/16 (0)
        
        In Reply to: RE: New MMGs, Burned Tweeter? - Crossover Schematic or Picture? posted by Davey on February 17, 2016 at 09:09:40
        
        nt
Maybe a solution - neolith 11:23:41 01/21/16 (12)
Now that the MUG page is back up, I was able to look at the wiring diagram. If the white and blue wires on the left speaker were swapped, then all the signal would go to the woofer and none to the tweeter and this would mimic what you are describing. A pretty easy fix. Good luck.
- RE: Maybe a solution - Jim-W 13:16:15 01/21/16 (11)
  I can't find that link would you please repost it?
  
  I wonder if those wire were swapped it would cause amps to shutdown?
  
  Thanks!
  - RE: Maybe a solution - neolith 13:43:25 01/21/16 (10)
    Here is the official diagram from Magnepan:
    
    Note that speaker 1 (Left) is wired differently than speaker 2 (right) but it would be quite easy to switch the blue and white connections. This would send the signal through the woofer without a LP filter and leave the tweeter ~~unconnected~~ with a very sharp bandpass @ 1000 hz.
    As far as causing the amps to fart, I am not sure. The woofer is almost purely resistive so the impedance would be constant and independent of the frequency. The operative word is "almost" and it is possible that at some frequencies the impedance does drop causing an issue for some amps, especially integrated amps which are notorious for not being stable at low impedance. Normally the series inductor would raise the impedance at high frequencies and counter-act the drop. Another explanation might be that the DCR of the inductor (about 0.4 ohms) is just enough to keep some amps from crapping out and its loss is sorely missed.
    
    Edits: 01/21/16 01/21/16
    - RE: Maybe a solution - Jim-W 17:16:44 01/21/16 (9)
      That make perfect sense except, if I'm looking at this right, with the blue and white wires swapped, the woofer would have the fuse in the circuit. If I pull the fuse the woofer still plays.
      
      I did get the tweeter to make noise with an old analog ohm meter so it seems good.
      
      I have a miniDSP 10x10 Hd, tomorrow I'll set up a 2500hz high pass filter and send some audio through the tweeter and make sure it's ok, if it is I'll pull the grill cloth and see what the heck is going on... bye bye warranty.
      
      Thank!
      - RE: Maybe a solution - neolith 17:48:21 01/21/16 (8)
        
        In Reply to: RE: Maybe a solution posted by Jim-W on January 21, 2016 at 17:16:44
        
        You are right about pulling the fuse (or the attenuator jumper). Back to the drawing board : <. You may be able to see enough with just opening up the back panel without removing the socks. Good luck and let me know if you get a solution.
        There are several freeware function generators that you can use to play a specific sine (square, triangle, etc) wave to test the speakers. Click here to download a very basic app from Phil Marchand . I recently found a program from Daqarta that does all sorts of things for audio testing. If my theory had been correct the tweeter would play ok around 1000 hz but would drop off significantly at higher and lower frequencies.
        
        RE: Maybe a solution - Jim-W 14:57:41 01/22/16 (7)
        
        In Reply to: RE: Maybe a solution posted by neolith on January 21, 2016 at 17:48:21
        
        Wow, fried inductor! The wiring doesn't quite match that old drawing, guess they made changes since 1999.
        And it has a 12uF in parallel with a 100uF cap which at first glance that looks like a first order crossover at 350Hz for the tweeter. I'll have to sort out the wiring and see what's going on.
        Tweeter is good, that's a relief.
        I have an Outlaw Audio 5 channel amp I think I'm just going to bi-amp these.
        
        Edits: 01/22/16
        
        RE: Maybe a solution - neolith 08:20:09 01/23/16 (3)
        
        In Reply to: RE: Maybe a solution posted by Jim-W on January 22, 2016 at 14:57:41
        
        WTF! It is nearly impossible to fry a speaker inductor with an audio amplifier. Also as Davey says, that 100 uF cap does not belong there. Also at first glance it makes no sense that you can get sound out of the woofer if the inductor is open. First thing, check the other speaker to see if it is was modified as well. Since the speakers are new, I would call Magnepan on Monday and ask to talk to Wendell. He does visit this forum on rare occasions so he can take a look at the picture. Give him the serial numbers so he can trace the sales history on these speakrs. It's very weird because while Magnepan takes the MMG back on their 30 day program, they should have tested it before re-sale. They still may make good on the warranty and even pay for shipping or at least send you a new inductor if you are up for DIY. Finally if you do go DIY think about by-passing the fuse - it really serves no purpose and as you can tell your tweeter is able to take a lot of abuse as it is being driven as low 350 hz without damage.
        
        RE: Maybe a solution - Jim-W 10:23:34 01/23/16 (1)
        
        In Reply to: RE: Maybe a solution posted by neolith on January 23, 2016 at 08:20:09
        
        The other MMG has that 100uF cap in it too. I've found two other people that had that 100uF cap. I almost suspect Magnepan is adding these caps.
        
        The staples on the bottom look perfect, undisturbed, if these speakers were modded either Magnepan re-socked them or the guy that modded them hit every staple in the same hole.
        
        They didn't offer free shipping back and I forgot to ask, the 4-6 weeks turnaround time plus almost 2 weeks total shipping time got me in a tizzy. These are my only speakers. And, if they deem this as my fault the repair costs are outrageous.
        
        I've talked to Wendell a couple of times and he's been no help at all. He made it clear that he was marketing not technical and connected me to the returns dept.
        
        The inductor is not open it's just half melted down which no doubt drastically changed it's value.
        
        I'm just going to bi-amp them with a miniDSP 10x10 and an Outlaw 5 channel amp.
        
        I'm hoping to upgrade later this year but I doubt it'll include Magnepans.
        
        RE: Maybe a solution - Davey 08:43:37 01/24/16 (0)
        
        In Reply to: RE: Maybe a solution posted by Jim-W on January 23, 2016 at 10:23:34
        
        Well, if this is a Magnepan modification to the MMG's I'd like to understand it or at least have them acknowledge it.
        The evolution of your particular pair of speakers is puzzling, to say the least. :)
        
        Converting the MMG's to a generic electrical crossover has been done previously....but not in this way....to my knowledge.
        
        Cheers,
        
        Dave.
        
        Wiring errors - neolith 08:39:51 01/23/16 (0)
        
        In Reply to: RE: Maybe a solution posted by neolith on January 23, 2016 at 08:20:09
        
        The blue wire should have been going to where the brown wire is, not to the inductor, and the brown wire should have gone to the capacitor. The tweeter and woofer are wired in inverse polarity and the person who modded that crossover probably tried to put them in the same polarity (which would have been correct with the tweeter set at 350 hz).
        To correct things - lose the 100 uF cap, replace the inductor, connect the blue wire to the input post (where the red wire connects) and move the brown wire to the bottom of the 12 uF cap.
        
        RE: Maybe a solution - Davey 18:59:55 01/22/16 (2)
        
        In Reply to: RE: Maybe a solution posted by Jim-W on January 22, 2016 at 14:57:41
        
        Somebody has modified those speakers. :)
        That large a capacitor pushes the electrical HP way lower than it would have been stock. I don't understand the thinking of that modification.
        
        Dave.
        
        RE: Maybe a solution - Jim-W 19:30:20 01/22/16 (1)
        
        In Reply to: RE: Maybe a solution posted by Davey on January 22, 2016 at 18:59:55
        
        Here's another guy that found a 100uF cap in his MMGs, note the year, 2014, I bought mine in Sept. 2015.
        http://www.audiocircle.com/index.php?topic=125012.0
        As crossovers go it makes more sense than a 12uf except that it's way too low of a crossover for the tweeter.
        2.2mh @ 4ohms is around 300hz low pass
        12uf @ 4ohms is around a 3300Hz high pass
        What about the frequencies between 300hz and 3300hz? Maybe the bass panel has a rise in SPL above 300hz?
        http://www.audiocircle.com/index.php?topic=125012.0 (Open in New Window)
        
        Edits: 01/22/16
        
        RE: Maybe a solution - Davey 20:11:00 01/22/16 (0)
        
        In Reply to: RE: Maybe a solution posted by Jim-W on January 22, 2016 at 19:30:20
        
        The 300Hz/3300Hz spread between the electrical filters is correct. The acoustic response of the drivers fills that "void" and yields a nice overall response.
        It appears that somebody decided the Magnepan network was incorrect because it deviated considerably from a "textbook" design and they decided to lower HP filter to "correct" it.
        It seems you've identified one issue, but other problems look likely.
        With the schematic at hand and continuity checks of the individual transducers you should able to deduce the other issues.
        I forgot about that thread on AudioCircle. :)
        Dave.
        
        Edits: 01/23/16
RE: New MMGs, Burned Tweeter? - Crossover Schematic or Picture? - Davey 07:46:40 01/14/16 (0)
This thread has quite an extensive discussion. (Schematics included.)

Unless new MMG's now utilize series networks. Although, based on your description, that doesn't appear to be the case.

Dave.
- http://www.audioasylum.com/forums/MUG/messages/16/168024.htm (Open in New Window)
RE: New MMGs, Burned Tweeter? - Crossover Schematic or Picture? - Jim-W 16:00:08 01/13/16 (3)
Also, at higher volume levels this speaker shuts down 3 different amps.

If that's all there is to the crossover they had to wire it wrong/backwards. I have a return auth, I get to pay for shipping and turnaround is 4-6 weeks.

If I was sure the tweeter wasn't blown I'd just void the warranty and fix it myself.

Thanks!
- RE: New MMGs, Burned Tweeter? - Crossover Schematic or Picture? - neolith 06:20:56 01/14/16 (1)
  I would contact Magnepan and negotiate the return shipping. It seems unreasonable that you should pay the shipping on a product that was defective and should never have left their shop in the first place.
  If you are set on repair yourself, you can find diagrams of the wiring by googling "Magnepan MMG schematics". The images you find link back to the MUG home page, which is currently down, but you can see enough to figure out the wiring. Just watch the connections to the speaker as the left and right are different.
  - RE: New MMGs, Burned Tweeter? - Crossover Schematic or Picture? - Jim-W 06:37:38 01/14/16 (0)
    Thanks but I've been googling Magnepan MMG schematics and similar searches but MUG / integracoustics.com has been down for like a week so I posted here.
    
    Thanks to everyone for your help and suggestions.
    
    Jim
- RE: New MMGs, Burned Tweeter? - Crossover Schematic or Picture? - j beede 18:03:19 01/13/16 (0)
  I wouldn't ship the speaker back to Magnepan given your situation. I doubt that opening the rear cover so you can apply an audio signal directly to the tweeter would violate your warranty. I guess you must have bought the MMGs from Magnepan, not from a dealer? If so call Magnepan and let them know that your are a DIYer and would prefer to repair the speaker with their guidance. They have a history of supporting DIYers. Worst they can do is say no...
RE: New MMGs, Burned Tweeter? - Crossover Schematic or Picture? - neolith 15:45:12 01/13/16 (0)
Unfortunately, the "Tweaks" page which has the diagram is down. Mart is working on the problem. The crossover is pretty simple: just a cap and coil in parallel to each other with the cap in series with the tweeter and a fuse and the coil in series with the woofer. I am not sure how they (Magnepan) could have screwed it up but as long as your speaker is under warranty, I would not mess around with it.
RE: New MMGs, Burned Tweeter? - Crossover Schematic or Picture? - Satie 13:45:59 01/13/16 (0)
I think you already know that the one speaker has a manufacturing defect and somehow had bypased the LP filter and the tweeter circuit. Just call up magnepan and arrange to have it replaced.

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