My brother has had 20.7s for almost 3 years, and he tells me in his setup they extend to 20Hz. I don’t know if he’s actually measured, but when I’ve listened, and he turns off his 2 large RELs, the 20.7s still seem to have plenty of low bass to my ear. In fact, the biggest difference I could hear with his subs engaged wasn’t so much an increase in LF extension as it was a general rounding out of the soundstage. Keep in mind, though, that those impressions are from someone who only hears that system once or twice a year, and it’s almost always on music unfamiliar to me (extreme avant-garde classical).
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To check the phase is simple, just swap the + and - on ONE of your speakers. Don’t change the cables at the amplifier, just the speakers. Now listen to some music. If it sounds better then you have it correct.
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Thanks much for sharing precisely your experience. I am a bit puzzled about reading you first got too much bass, that’as a bit irony compared to my longing for it ^^ Dare I ask what range of bass you’re talking about ? I’ve got someting quite satisfying for 100-500Hz (even if not totally mastered now = a bit fussy & muddy). Did you listened easily low frequencies 20-100 Hz at the beginning ?
I note that it took nearly 6 months for burn-in.
For phase, I will answer in a message below.
Yep, I just read this amazingly detailed review.
And there is a hope for my case : “Those membranes need to be played—and played hard—to loosen up and acquire the flexibility to show their best stuff on large excursions, particularly in the bass where large excursions are common. There is nothing unusual about this. All speakers require “break-in”; the Maggies just need a little more than some, although the upside is that you will hear how they are improving with every additional hour of play.”
I hope so much that could be true.
I believe that my ETALON amp is high current but i am not sure : two versions where launched but this small-scale production in Hungary is pretty secrete about specifications,
I have no budget now to buy another amp, but sure will do in 12-15 months.
I tried to borrow amps from local dealers, but they don’t have anything matching, as they said, and they don’t rent for a test, except there is a perspective of purchase.
I tried to increase the distance from the front wall. I got more medium, but same bass.
Thanks for message. Do you know if your brother got the bottom bass (20-100Hz) at the beginning or after burn-in ?
For phase, I tried with the advice from my dealer. I switched ± on each panel.
Not a huge difference, but the sound seems more straightforward, and a bit more deeper.
So I will keep this phase for burn-in.
Sorry I did not undertake measurements until after I installed the tube traps. The traps made such a big difference there is no precise way to state what was the range of excess bass, but it extended into the mid bass as well as real bass. Given that the dip at 50 Hertz is certainly due to my room dimensions I am sure that dip was there right from the beginning. There was therefore certainly excess bass from 70 to 150 and MAYBE from 25 to 40.
Your room is certainly big enough, especially long enough, for these speakers so I am sure you will see some improvements with time. Good luck!
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If you changed the speaker connections on both speakers and you were already out of phase, you’re still out of phase.
You have to switch only a single speaker to see if you have a phase problem.
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Yes of course, I tried this (switching only 1 panel), but tthen I got flat and weird sonic image), so phase is ok. Anyway the cables are specified with different colors for + and -, and they were correctly pluged in.
He had bass problems at the start, but I don’t think he (or I) would call it a lack of bass response. What drove him crazy for quite a while was excessive boominess, like the bass lacked precision and control. Part of the fix was burn-in I’m sure, but a larger part was positioning and room surfaces (managing diffusion).
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I would encourage you to email Wendell Dillar at Magnepan. My guess is he would take the time to talk to you personally in a virtual environment and give you appropriate tips on placement, amplifiers and whatever.else may help your Audio journey. I listened to both the 3.7 and the 20.7 and it was a no brainer for me to get 20.7.
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My experience was similar to Craig’s brother. Blobby uncontrolled bass, overwhelming on certain recordings (I still cringe at the memory of Jaap van Zweden’s recoding of Beethoven 5 with the New York Philharmonic - the bass drove me out of the room. Today I can listen to this recording with pleasure.)
My starting position was not that different from where I have them today, so I believe the corner tube traps provided at least 50% of the solution. I’d estimate positioning provided 25% and the break-in time the remainder. (But this is not to say that the positioning is not extremely important - if my starting position had been less favorable these percentages would be different.)
The nice thing about tube traps is they afford immediate relief. But they have to be of wide diameter for them to absorb lower frequencies. My ASC tube traps are oriented so that the surface facing away from the wall also diffuses higher frequencies while the Helmholtz resonators inside absorb bass and convert it to heat.
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I believe I got the explanation…
I stood behind each speaker, hearing organ with xlow bass.
On speaker 1, I can listen very low frequencies, under 40 Hz, radiating from the rubbon side opposite to the tweeter.
On speaker 2, this same part of the panel is… silent.
I switched plug of the amp to check if there is another issue, but the prb is located in the speaker 2 itself;
So I believe that i got the key for my “bass problem”, but the solving won’t be easy. And I doubt my dealer will agree with it.
O please, what shall I do ?!?! 
Sounds like a call to your dealer might be needed. A bad speaker won’t fix itself.
But first, did you check the fuse? It should be visible near the speaker terminals, but I’m sure to inspect it you’ll need to remove it.
A small pick should do the trick.
Shall i remove the fuse ?
But only the bass part of my panel doesn’t work.
If the fuse was burnt out, the whole speaker won’t speak at all, not just the bass part. Am I right ?
Actually, there are 2 fuses, one for tweeter, one for mid-range.
But no fuse for bass.
If the same fuse is for medium and bass, I believe there is no prb about fuse,
because on the speaker, the medium part speaks well, but the bass panel doesn’t.
In any case, I noticed that the (silent) bass part of the panel generates a strange sound, like humming.
The other speaker that works ok doesn’t hums…
Sounds like… time to call your dealer.
Concur. If the non-fuse-protected bass panel is not responding, there is likely an issue. Swap right-for-left first to ensure that it’s not an upstream issue. (If you haven’t already… I am not following the thread all that closely.)
Unfortunately, it’s Sunday, and shop opens next Tuesday.
I must wait 2 days, and the dealer is 200 km afar, so won’t be so easy…
Is this type of failure common on these models?
I knew the tweeters are fragile, but the bass panel…
Besides, I read that the bass is not protected by fuse (only medium and treble).