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In Reply to: RE: Laugh it up..... posted by josh358 on April 04, 2014 at 19:00:09
The tizziness is a feature I thought we had to accept. I'm not sure it's much reduced in the 3.7 over the 3.6 - at least, I still hear it. Oddly enough, it seems less audible with the MMGs. Then again, I don't crank the MMGs as hard - single, near-field listener in a small space (in the house). If they've figured out a way to address that without ruining the speaker in other ways, then I see the value in it, but I still can't understand the absolute secrecy. Is this some kind of game? Can 'we' figure how they sound different and how the manufacturer accomplished that feat? It appears that we're already moving in that direction. So, if it is a game, we'll win it. If it isn't a game, being so tight-lipped is only going to drive us to the discovery all the quicker.
I'll say it again and then I promise to shut up about it. I hate to be critical of Magnepan, but I don't understand the handling of this upgrade. What should excite me is only annoying me and I'm not alone in that reaction.
The first real clue about this upgrade is that shot from the rear on page four. By no means can we infer that is all which is changed, but it is an obvious difference. It won't be long before somebody exposes exactly what that is. As soon as someone is willing to do an exploratory on their improved version, I'm ready to do the same on my originals.
More and more, as time goes by, I feel myself drawn to replacing the midranges, a la Satie's example. I have visions of a future woodworking project that will transform my 3.7s. Okay, I am starting to get excited.
Follow Ups:
And here I thought the tizziness was my crappy framing job on my MMGs, and/or my old amp.
I fixed mine by relocating the MMGs to the storage closet.
If you want a new project, instead of trying to reinvent the wheel, why not build a pair of Linkwitz LX-521s? R&D, plans already laid out, excellent support through the Linkwitz forum.
I was thinking of it myself, but my room size was marginally too small, and financially it would of taken much longer to get "there", then the route I took (mini monitors).
Might be hard to change the midrange, given that the mid and woofer are sections of the same diaphragm but have to be as close as possible to one another for the best polar response. I think it would actually be more practical with a 3.6.
...the midrange section of the planar panel were integrated with the woofer section? Is it the same foil? There are a few things I need to research in order to gauge the feasibility of this maneuver, but I am coming to terms with the reasoning behind it.
I would build a new set of frames. It could be a fun project, but it would probably take a while. I'm only half-serious right now, but the more I think about it, the more I like it. ;-)
Check out the tuning dots on this picture that Roger posted:http://www.twin-x.com/groupdiy/albums/userpics/mg_3_7.JPG
There are now tuning dots at the border of the woofer and midrange, which used to have a clamp. There's no way of knowing precisely what frequencies the segments are tuned to without more information. But my guess is that they're using acoustical equalization to make it a 2.5 way -- a necessity because with a single-pole crossover, each driver has to cover a wider frequency range, and for good polar response you need to keep driver width small compared to wavelength. If so, the 3.7 isn't a very good candidate for an add-on midrange. You're either going to have too much of a gap (if you put it next to the old midrange) or you're going to have it on the side opposite the acoustical EQ. Both could exacerbate lobing.
But the first step I think would be to get more information. You could get the frequencies of the resonant sections with a microphone, an RTA, and a pink noise generator -- just move the mic along the grille cloth and see what happens to the frequency response.
Edits: 04/10/14
...it would be simple enough to swap the left and right panels. That would put the unused midrange section on the opposite side from the midrange and tweeter. I imagine that it would be good to mechanically damp the non-driven section. As I said, this is just an idea that I'm beginning to entertain. Lots of research would have to be done before venturing down this path, and this is a start - thanks. ;-)
Mechanical damping might work. You'd want to leave the bottom part undamped, e.g., imitate a 3.6 with its solid clamp. This would shift the acoustical center of the bass frequencies back towards the center of the woofer section. It would also reduce the output at the frequency of the full width of the speaker. This would definitely require some experimentation and measurement.
OK, so here's another idea -- put a line-source electrostatic midrange (an Acoustat, say) between the woofer and the ribbon.
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