I came across a web site that supposedly improves the performance of all Magnepan speakers. They have a .doc file that 'explains' how they improve the sound etc.
One section says
"Magnepan changed much of what it had done before suddenly and without explanation, (turning the pole piece rearward, changing the XO's and moving the panels generally more vertical) and I believe (and this is only my belief) that they did this to compete in the ever growing home theater market at a time when 2 channel was dying and HT growing and they had as yet no such dedicated HT models. Doing these things makes their speakers beam more, which makes them seem more falsely dynamic and "brighter", things certain to appeal to the home theater shopper who knows nothing and gives 20 second auditions. One can't blame them for doing what they had to to survive, and doing it was a Rubicon they can't go back over, even though they now have dedicated HT models. However I consider the reversing of the pole piece a ruse and I re-install them forward as they should be. Why? What makes maggies special is the rear wave, not the front one and with the pole piece in the back the bass wave cannot escape as freely as it should resulting in a loss of bass, ambience and over all musicality. (some argue it's also better this way because of the magnets interaction with the mylar (push vs pull) but I tend to discount this) In any case, the vast majority of people when they hear it both ways prefer the pole piece front. "
It doesn't seem to make any sense to me. Am I missing something ?
Open baffle planar speakers have identical front and rear wavefronts. How come the Maggies have a 'restrained' front wavefront and that the rear wavefront sounds better ? " Push vs pull "......?
One section says
"Magnepan changed much of what it had done before suddenly and without explanation, (turning the pole piece rearward, changing the XO's and moving the panels generally more vertical) and I believe (and this is only my belief) that they did this to compete in the ever growing home theater market at a time when 2 channel was dying and HT growing and they had as yet no such dedicated HT models. Doing these things makes their speakers beam more, which makes them seem more falsely dynamic and "brighter", things certain to appeal to the home theater shopper who knows nothing and gives 20 second auditions. One can't blame them for doing what they had to to survive, and doing it was a Rubicon they can't go back over, even though they now have dedicated HT models. However I consider the reversing of the pole piece a ruse and I re-install them forward as they should be. Why? What makes maggies special is the rear wave, not the front one and with the pole piece in the back the bass wave cannot escape as freely as it should resulting in a loss of bass, ambience and over all musicality. (some argue it's also better this way because of the magnets interaction with the mylar (push vs pull) but I tend to discount this) In any case, the vast majority of people when they hear it both ways prefer the pole piece front. "
It doesn't seem to make any sense to me. Am I missing something ?
Open baffle planar speakers have identical front and rear wavefronts. How come the Maggies have a 'restrained' front wavefront and that the rear wavefront sounds better ? " Push vs pull "......?
I was under the impression that ALL flat panels with magnets on them ( like B&G) had magnets on both sides of the diaphragm . So that would be identical looked at from both sides. Magnets on one side wouldn't make it linear travel...would it ? That would be like a normal loudspeaker with coil extension only on one side of the magnetic field.
Just realised that the magnets could be located on just one side as long as it had a magnetic path on the other side to bring it back to the front. That would mean a magnetic field perpendicular to the moving film. But that still made it uniform looking at it from either side.
Just realised that the magnets could be located on just one side as long as it had a magnetic path on the other side to bring it back to the front. That would mean a magnetic field perpendicular to the moving film. But that still made it uniform looking at it from either side.
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no the diaphragm has no effect. I am guessing that the single ended drive probably generates more second order harmonic distortion which probably accounts for how good Maggie's can sound. It is a weak motor system but that combined with a rather heavy moving mass (copper VC and adhesive) they can make good bass for a compact diaphragm area with the trade off being low efficiency. So the design flaws work for you and not against you making for a good set of compromises overall.
Double ended drive systems such as used in the Eminent Technology designs does bring the efficiency back up at the cost of more magnets and structure to hold them. ET's do have a good reputation for sound but you can't turn them around as with a Maggie and and listen to just the diaphragm. There is debate about listening off of the diaphragm side with some who prefer that sound (I do) and with some who like to have the metal pole piece facing forward. On paper the magnetic planar does not look all that impressive but one listen makes you re-evaluate things and the huge popularity of Maggie's stands as proof that they can and do deliver the goods as long as you have the watts to drive them or if you don't need to listen too loud. I think that the smaller Maggie's (MMG's SMG's and MG1's) with a stereo set of subs makes for an excellent compromise. They are compact and will preform well in smaller rooms yielding all the benefits of planar speakers in an easy to drive package. I would like to hear a stacked set of MMG's ala Acoustat 0ne plus 0ne's.
Double ended drive systems such as used in the Eminent Technology designs does bring the efficiency back up at the cost of more magnets and structure to hold them. ET's do have a good reputation for sound but you can't turn them around as with a Maggie and and listen to just the diaphragm. There is debate about listening off of the diaphragm side with some who prefer that sound (I do) and with some who like to have the metal pole piece facing forward. On paper the magnetic planar does not look all that impressive but one listen makes you re-evaluate things and the huge popularity of Maggie's stands as proof that they can and do deliver the goods as long as you have the watts to drive them or if you don't need to listen too loud. I think that the smaller Maggie's (MMG's SMG's and MG1's) with a stereo set of subs makes for an excellent compromise. They are compact and will preform well in smaller rooms yielding all the benefits of planar speakers in an easy to drive package. I would like to hear a stacked set of MMG's ala Acoustat 0ne plus 0ne's.
The voice coil is Al. The mylar is 0.0005" thick and the adhesive is only used along the voice coil. The entire moving panel in the MG20.1 weighs only a fraction of the weight of a cone driver that is flat to 25Hz (-3dB). The efficiency is low, but I have heard the 20.1 play very loud with a pair of my 100W mono amps.
This thread begins with a quote from John, AKA~ Peter Gunn on the asylum.
His company is magnestand and I was his first customer.
Magnestand - Where Maggies Live And Breathe
The SMGA was the first maggie he modded and used as his model for the rest of his mods.
His statements can sometimes be interesting, and knowing John as I do I don't worry about it.
His stuff sounds fantastics, BTW, if maggies weren't amp killers I'd still have a pair.
Just wanted to try and put the opening quote into some personal context, FWIW.
His company is magnestand and I was his first customer.
Magnestand - Where Maggies Live And Breathe
The SMGA was the first maggie he modded and used as his model for the rest of his mods.
His statements can sometimes be interesting, and knowing John as I do I don't worry about it.
His stuff sounds fantastics, BTW, if maggies weren't amp killers I'd still have a pair.
Just wanted to try and put the opening quote into some personal context, FWIW.
We are trying to understand how the magnetic circuit works in a Magnepan . Some of the explanations seem to clarify what is in that 'blurb'.
However it would be very interesting to see a cross section of the panel. Did Magnepan ever publish such a diagram ?
Edit: OK I missed it the first time I looked for it.
Here it is. It is clear that the film is completely on one side of the magnet. So both sides are not identical. However it is not clear if the second side is also covered with a similar perforated panel as the one shown ? Wouldn't radiation be different from either side ? Is the frequency response different when taken with either side facing forwards ?
However it would be very interesting to see a cross section of the panel. Did Magnepan ever publish such a diagram ?
Edit: OK I missed it the first time I looked for it.
Here it is. It is clear that the film is completely on one side of the magnet. So both sides are not identical. However it is not clear if the second side is also covered with a similar perforated panel as the one shown ? Wouldn't radiation be different from either side ? Is the frequency response different when taken with either side facing forwards ?
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Magnepan did publish a cross section of the driver, but I do not have a link. I will attempt to find one.
Some models have the magnets and pole piece on both sides of the membrane. I have never turned mine around to listen to them, so I won't comment on that.
As for how they work, see SY'S post 7 drawing. The magnetic field is not a simple line. It is usually shown as a series of lines arcing from one pole to the other. At some point in this set of lines, the field is relatively uniform. If the conductor is center in the center of this uniform field, then it can move back and forth inside this field where the strength is the same. The tension on the mylar works to pull the VC back to the center from either direction. Remember the size of the membrane. Now, how far does a 200 sq. in. membrane need to move to generate 400Hz? The bass panels on my speakers are roughly 12 sq. ft., 24 for both sides together. That limits the excursion needed to generate 25Hz.
Some models have the magnets and pole piece on both sides of the membrane. I have never turned mine around to listen to them, so I won't comment on that.
As for how they work, see SY'S post 7 drawing. The magnetic field is not a simple line. It is usually shown as a series of lines arcing from one pole to the other. At some point in this set of lines, the field is relatively uniform. If the conductor is center in the center of this uniform field, then it can move back and forth inside this field where the strength is the same. The tension on the mylar works to pull the VC back to the center from either direction. Remember the size of the membrane. Now, how far does a 200 sq. in. membrane need to move to generate 400Hz? The bass panels on my speakers are roughly 12 sq. ft., 24 for both sides together. That limits the excursion needed to generate 25Hz.
For a given SPL, of course! My headphones can do 25Hz with very little movement, too. Not very loud, tho. Unless I put them on my ears.
The little pan was very impressive. It was a blind demo, we didn't know what we where listening to. Music suited to it, of course. The big bass panels must help. I was just surprised at the realism of the thing, and the size of the sound vs the size of the panel. . They seem to do strings very well. But that's a Maggy strong point.
Way back in the 80s a built a small panel based on the Show Pan. About 11x14". It worked. Magnets were not nearly strong enough, tho...
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