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In Reply to: RE: Difference between 3.7 and 3.7i's posted by Davey on April 03, 2014 at 17:16:31
I don't know that they are actually seeking a patent. But there is no more speculation than that.
I just respect their choice to keep mum in order to keep their advantage. It is definitely something they do routinely, or do you forget their refusal to let Stereophile review their speakers so that they don't reveal their tricks?
Follow Ups:
Magnepan has had speakers reviewed by Stereophile on numerous occasions. Anyways, a review wouldn't necessarily reveal any "tricks."
You're still implying there's some sort of technical upgrade here that needs to be kept secret from competitors. I don't know where you're getting that. :)
My belief is this whole affair is a (veiled) product recall of some sort and the ignition switch needs to be replaced. Prove me wrong. :)
Dave.
Well, the word from Wendell is "Some of it is trade secrets." He added this morning that eventually, some but not all of the tweaks will be discovered. (So it seems there's more than one -- who will be the first to open one up and find out?)Otherwise, neither I nor Steve have been able to chip away at their commitment to secrecy, and we must have driven Wendell crazy by now with our nagging. I continue to think that they're taking this too far -- I mean, I can understand withholding proprietary information that could be of use to a competitor, and I understand and appreciate the integrity that makes Wendell dislike hype and selling on the basis of tech lust rather than sonics. but what could it hurt to give people an overall view of what their $500 will buy them? I don't think anybody is asking for the nitty gritty, just a general idea.
I find it hard to believe that this is worth the bad publicity and the ire on the part of some of their most loyal customers, though Wendell says that the 3.7 customers he's spoken to have been happy with the arrangement, and thinks the sonic improvements will speak for themselves. I certainly don't think there's any kind of conspiracy, though if people believe that in the absence of solid information from the company, they (the company) have only themselves to blame.
Edits: 04/04/14
If there are indeed trade secrets involved, which might be useful to competitors, it sort of implies that whatever they are might be could usefully employed in other model Maggies. If that be true, then Mr. Diller ows to all their 'faithful' to be better informed about it.
IMO with all the secrecy on the part of Magnepan, it it would only be befitting if we gave it some code name, (as was done for the Manhattan Project at Los Alamos). Should Comrade Putin know if it was being discussed at the G7?
Interesting to speculate about, no? Will there be a 20.7i? Did some of the new technology already make its way into the improved MMG? I'll have to ask my contacts at the NSA . . .
We have been told that there will not be a 20.7i. This "i" thing is already there. If we can trust such a statement?
Knowing Magnepan, I imagine we can. So does this give us license to speculate? What's unique about the 20.7 that we know of? A lower mass midrange comes to mind. So -- a lower mass diaphragm in the 3.7i? That would be a major mod indeed.
Great to see you posting again.
I was thinking that the issue of the "i" upgrade would be unique to the 3.7 as the diaphragm's division into mid and bass does not give you much in the way of room to adjust treble vs midrange speed. Which you would be able to do with the MMG or 1.7 where the particulars of the mid and treble traces can be adjusted to provide transient speed where it is most significant.
In the 3.7 the shared membrane has to retain its strength for bass excursions so can't be made thinner as it was in the 20.7. Therefore transient speed - which is still far less than in the ribbon - and thus a significant concern for the design, would be the target of whatever new tricks Mark and co. came up with. The MMG and 1.7 would not gain much since the tweeter section already has lower mass due to the thinner foil on it.
The review indicates that was where things have improved; more articulation, less upper mid brightness (which would happen with either a lighter, or less stiff diaphragm, or better damping, and any combo thereof).
Thanks, Satie. Wish I could hang around but I'm traveling this weekend and then still have a bit of a slog ahead of me -- screwed up my back a month ago so wasn't able to get much accomplished.
Are you sure the 20.7 have a lower mass midrange? For sure the midrange of the Tympani IVa are low mass with its 6 µm Mylar, AWG 32 wiring and dividing strips. I think the mass of the glue could be higher. In order to lower the mass of the midrange in the 3.7, you need to use thinner Mylar even for the bass. If you decrease the wire gauge you loose effiency. Calls for stronger magnets, a costly route.
Yes, the lower mass midrange was mentioned in one of the reviews. (Of course, reviews are sometimes wrong.) Agree that they probably wouldn't reduce the foil thickness, what with the cost of neodynium magnets.
Josh wrote:
” Yes, the lower mass midrange was mentioned in one of the reviews. (Of course, reviews are sometimes wrong.)”Reviewers are often told facts that they never check. If we believe the reviews written over the years, Magneplanar drivers would have no moving mass at all. Truth is that it is still the same Mylar and wiring in most cases. Round wires or flat wires does not change the mass. I do not know why people believe the mass is less while going from round to rectangular wires. For exemple, the wiring of the 3.6 mids are about 2 gram, Mylar also 2 gram (but it is a part of the bass section...) and then some glue. Compared to an electrostatic this is a lot of moving mass.
For comparsion, the largest section of the Tympani IVa mids, the wiring is 0.5 gram and the Mylar 0.3 gram.
Here a picture of the T-IVa mids: http://www.twin-x.com/groupdiy/albums/userpics/IMG_0353.JPG
Edits: 04/05/14
I am still dreaming of a graphene conductor on a thin kaladex in a neodymium powered push pull driver that would be able to be as fast as an electrostat without its output limitations and arcing.
Unfortunately, the commercial graphene is still too high in resistivity to compete with Aluminum conductors since the lower density of the graphene does not compensate for the much higher resistance, so the practical driver would still end up with a higher mass with graphene. Even if you make the whole diaphragm from graphene it would still be heavier to conduct the same current as Al.
Perhaps interesting, headphones using graphene driver:
http://arxiv.org/abs/1303.2391
That is very cool
I have no way of knowing whether the reviewer was correct. They certainly aren't always. But I think Satie did a good job of describing the trades here. Assuming you want to maintain the Bl product, the wiring can't play a role unless you can find more powerful magnets that fit the budget. But of course there are other ways of reducing the mass. It's pure speculation until you look!
Interesting figures, BTW.
Outside of the glue wires and mylar there is the damping layer. You can use a lighter gauge membrane if you go for a stronger polyamide rather than a regular polyester. More expensive, but that is what BG did. The damping material would be something to look at. Maybe something that dries less stiff would make for lower final tension or for less mass if you can spray less of it and still get enough damping.
I tried pricing Neo magnets for the ribbon tweeters thinking that I could improve their efficiency but it was absurdly expensive. I think it was $300 just for the magnets. Then I had to have someone weld on stiffening strips on the tweeter frame so it won't buckle with the extra magnetic force. It all got very expensive very quickly.
Yeah, neo magnets are crazy, aren't they.
I recall reading a BG white paper in which they said they used Kapton on their smaller drivers because their small surface area required superior heat resistance.
Pic is of Kapton repeating unitKapton is a polyimide, BG used kaladex a cousin of PET, PEN Poly ethelene naphthalate (instead of terephthalate) good for high temp (180C continuous) film with 2.5X tensile strength of PET (of cola bottles fame) and great flex recovery. Makes for excellent capacitor film too. Also used for flexible printed circuit boards.
Edits: 04/04/14 04/04/14
None of the x.7 series nor the mini made it to Stereophile.
I do think they are being a little paranoid about these things since some of the folks here figured some of these out anyway and no one stepped in to use them commercially.
"My belief is this whole affair is a (veiled) product recall..."
Well, you are making me feel less dumb, thanks. That was a thought I did not feel like mentioning but one possibility is such. The reason I thought of it is that the 3.7s never showed me something that I would have expected from them after hearing it from a pair of lesser Maggies.
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