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I am not sure what's going on. I have a 3 month old pair of MMGs and probably have 150 hrs on them. They are driven by an Audio Research preamp and an Odyssey amp. They are 40" from the rear wall in a12x14 room. They are in the lean back position and placed on carpet. On certain tracks with deep bass they vibrate/distort. It seems like a certain frequency throws them off. The volume is about 85db with up to 93db peaks.
The tracks I've noticed on are the lead track off the Twin Peaks soundtrack and All it Nothing at All on Diana Krall's Love Scenes. I never had this issue when I had 1.6qr.
Follow Ups:
"and placed on carpet." Could be a case of the speakers aren't making solid contact with the floor. Try playing them on a hard, solid surface to see if the problem persists.
From your description, it sounds like a delamination problem. Try playing some bass heavy music or better yet download a frequency generator.
There are several free programs available - I use a simple one that is available from Marchand - and find a frequency that replicates the problem. Then while playing, lightly press over the bass panel to see if you can suppress the vibration.
In any case the panels should not be doing this and you should either contact your dealer or Magnepan for warranty coverage.
Just to make sure... you are referring to your MMGs in the plural sense. So... both speakers are exhibiting what you call "vibrating"?
Yes, if both speakers are exhibiting the issue, then it's probably not a transducer failure or degradation. But, it could be. :)
Most likely the speakers are just being driven too hard and/or there's some low-frequency information in the program material they're just not capable of reproducing. The 1.6's have quite a bit more transducer area to create larger SPL's.
Dave.
They are both vibrating in the same manner. I switched sides anyway and the same. I think they just can't handle certain low frequencies, like the larger model. Do you think if I add a sub it would take some of the demand off the panel? I'm not ready to invest in a good sub but I have access to a Definitive Technology Prosub 100. It's a powered sub that takes speaker level connections so I would route the speaker cable from the amp to it first and then from the sub to the MMGs. It has adjustable crossover. Might that be a temporary fix?
sometimes it's hard to telll...
"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius
That would definitely take the load off the MMGs but you will lose clarity because the sub's crossover has a midling quality speaker level crossover. You should get a quality external crossover at line level if that loss of resolution bothers you. If you want to DIY the MMG's line level high pass filter it is very simple and dirt cheap. Any number of us can help you with it.
I don't know if this is relevant to MMGs, but my T-IVs had a similar symptom when I first got them. There was a buzzing/vibration when playing loud, low tones, around 30 HZ or so.
I called Magnepan about it and a technician told me to use the handle-end of a screwdriver to push on the staples that secure the bass panels to the MDF and tighten them up. Problem solved. Does Magnepan still use this primitive way to secure bass panels to the MDF?
I think they still use staples! My Tympani IIIA made in 1975 had its drivers glued and revited - no rattling.
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