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In Reply to: RE: Magnepan MG3 posted by xfiler91158 on April 18, 2014 at 10:32:13
I am surprised anyone is asking over a grand for such old MG3s.
I have a twentyseven year old pair of IIIa's which I recently self repaired (Weldwood dap). I also got new black socks (much better than the old 60s looking gunny sack), stained the light wood dark cherry and painted the feet black to match. I wouldn't say mine play like new, but they look much better than new.
That said, I assume they are worth substantially less than a grand.
BTW, does anyone know if the newer tweeter is substantially better than the old one from the 3a?
Also, does anyone know if the tweeters lose anything as they age*? Mine seems to have less sparkle than I remember twenty plus years ago, but that could be me aging more than the speakers.
* the bass on the other hand seems to just keep getting better.
Follow Ups:
I replaced the tweeters in my IIIa's with the "newer" tweeter. This requires elongating the channel by 0.6" (using a router). Quite honestly there was only a slight difference which I attribute more to being able to toss the 1 ohm resistor (the original IIIa tweeter is a bit wider with a 2 ohm impedance v the "3.3-3.7" ribbon with a 3 ohm impedance). Of course since I am pretty much deaf over 13 kHz, I may be missing out on some of nuances.
Interesting, Neolith.
So replacing an old ribbon with a new and improved ribbon made only a slight difference.
I am ashamed to admit to one other odd practice.... I find my old speakers sound notably more dynamic when played backwards (Mylar facing out). The difference is dramatic. I frequently switch them back to normal, but am never as satisfied with the sound. I assumed it was an artifact of the age of my tweeter or something and how it integrates with the mids, but maybe I am just strange.
Hi guys. Not trying to thread jack and just have a quick question.
Do any of you also hear the differences when reversing these speakers?
I'm mounting my MG1's and SMGa's on my shops ceilings(mainly due to space constraints) and have the option of turning them around prior to installation. I was just curious as to what others thought about the perceived difference that Swamis Cat mentioned above. I feel that the imaging/depth takes a slight hit but they certainly seem slightly louder in the midrange.
Thanks
I hear a bit more clarity in the highest notes - don't know that it is the bars on the tweeter or the double layer of sock material when the tweeters face forwards. But lacking both it sounds distinctly more detailed and clear. Not by orders of magnitude, but obvious. I currently XO the tweeter at 6khz in traditional 1st order inverted polarity XO scheme, so the top end is in reverberation, high harmonics, cymbals, the sheen on trumpets and triangles.
The mids are push pull so have perforated plates on both sides. they don't suffer too badly from being covered by the sock. It dulls transients slightly. It is not that bad, but as Doug Schroeder noted, it matters. So I am thinking of finishing the mid/tweeter with a removable grill made from the sock cloth stretched on a frame rather than a sock.
They might sound more dynamic, but it's not physically possible for them to actually BE more dynamic. :)
As Neo said, if you do this it's vitally important to eliminate all other variables by switching the left and right speakers and reversing wires to create the same absolute polarity.
Cheers,
Dave.
Dave,
I cannot hear absolute polarity. I am careful of course to ensure my DWMs stay in phase (I reverse the polarity of them to match the reversed mains). But I cannot hear changes in polarity. I've tried a bunch of times blind, but simply cannot hear it.
Having reversed your panels, you will notice that there are no longer any 'bars' in front of the ribbon. Magnepan puts those bars at the front, IMO, simply for protection - but the way I see it, they must be causing diffraction of the ribbon sound. So much better to have a clear slot in front of the ribbon. :-))
And if you ever get round to replacing the stock MDF frames, put the rebate for the ribbon cage at the front of the frame - so that the surface of the ribbon cage flange is flush with the front of the frame.
Magnepan, with the 3.6:
a) increased the size of the mid panel (compared to previous models), and
b) flipped the bass-mid driver so the mylar was in front.
I believe the 2nd action directly followed on from the 1st - they thought to deliver more mid by making the mid part of the shared mylar sheet, wider ... and putting the mylar at the front, further enhanced the improved mid range.
Unfortunately, though, the bass driver shares that same sheet of mylar ... and there is good reason to have the magnets in front, for the bass panel. :-((
Regards,
Andy
In a conversation with Wendell in regards to my DWMs, I mentioned to him that I preferred my MG3a's backward. He scoffed at the idea, and if memory serves, mentioned something about comb filtering.
Trusting he knows infinitely more about his speakers than I do, I have repeatedly tried the recommended front firing position (Mylar back and tweeters barred). I always prefer them playing backwards, at least when the tweeters are inboard (less so when tweets are out). If there are cons of playing them backward, the pros seem to outweigh them, at least to these ears in my system in my rooms with my twenty plus year old tweeters.
As a follow up question, Andy, does this mean that the newer twenty series gets the best of both? Mylar forward for mids and push pull plates on both sides for the bass?
By the way, I think the DWMs have plates on both sides of the Mylar too.
AIUI, the MG-20 had magnets on both sides of the bass panel only - though I don't know how they placed the mid panel (mylar front or pole-piece front). As I'm sure you're aware, the reason why magnets both sides is good for the bass panel is that it stops the mylar/wire excurting into a region of lower magnetic strength, when it moves away from the magnets during a large bass transient.
However, with the 20.1, Magnepan moved to magnets on both sides of the whole mylar sheet ... I would suspect for mfrg reasons, rather than SQ, as the excursion of the mid panel mylar is so small, it never moves into a region of lower magnetic field strength. And I would suspect the 20.7 is the same.
Regards,
Andy
The MG-20 had magnets on the back of the Mylar. I am not sure they had the thinner Mylar of the Tympani IVa mids.
Here a customized version, http://media-audiogon-com.s3.amazonaws.com/uploads/image/image/345847/scaled_MG20.jpg
And here's some speculation on my part.
The newer ribbon might not be significantly superior to the old ribbon but by using a narrower ribbon the material costs should be less, although not by much. It also eliminated the need for a 1 ohm resistor which definitely reduced costs not only for the resistor but also for labor. I suspect the narrower ribbon would have less sensitivity (move less air) but this would be compensated by not ẅasting 3.5 db as heat in the resistor. Theoretically, the sound should be better as Rg (all the resistance in the speaker circuit not attributed to the driver itself) is never your friend.
I turned my mid-bass panels around (mylar in front) several years ago and never looked back. IMO the pole-piece was put in front to protect the speakers and not for acoustic advantage. All the "newer" models have the mylar in front. When switching remember to swap the left and right so the mids are adjacent to the tweeter and also reverse the polarity.
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