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Hey Guys,
I purchased a pair of Magnepan 3.7i's recently and struggled to accomodate them in a oddly shaped room with terrible acoustics. Here is my set up...
The speakers are run in series with the subwoofer to enable use of the subwoofer's low pass filter.
Peachtree Grand Pre X1 => SVS Ultra SB13 =>Parasound Halo A21 => Magnepan 3.7i
I've tried multiple different configurations and positions of the sub/speakers, but couldn't eliminate a lot of the standing waves. Finally I tried switching the phase of one of my Magnepans. The measurements look slightly improved to me and I actually prefer the sound in this unusual configuration.
That being said, I wanted to get the opinions and criticisms of some experienced audiophiles on this configuration.
The orange is w/ correct polarity, the blue is w/ my R magnepan polarity reversed.
Follow Ups:
One OTHER thing to try is to 'flip' the panels around and listen to the 'wrong' side.
maggies might be symmetric, but do NOT sound exactly the same front and rear, espeically the single sided models. This is everybody EXCEPT the 20 series which is push/pull and double sided.
Too much is never enough
So after alot of tinkering I realized, I simply wasn't going to improve the standing wave problem. FWIW I don't think the subwoofer was the problem, but thats all beside the point....
I fixed my issues by purchasing a MiniDSP DDRC22-D and implementing Dirac Live. I formerly had tried an AntiMode Dual Core which really struggled to get rid of the standing waves so I had sold it. Dirac Live on the other hand has done a phenomenal job and the system sounds amazing to my ears. Here are some updated measurements.
Did you do a shorter span impulse response? I am curious about the significance of the secondary peaks on the long time window test. If it were a time difference between the reaction of each driver I would have expected it to be corrected by Dirac Live as DEQX does.. Is it not one of Dirac Live's functions?
MANY years ago, I had a pair of MG-1 panels I bought used. This was early 80s. From the factory they were marked LEFT / RIGHT. And I used 'em that way except in ONE awful room.
It was a very small room and with the speakers in the usual spot, there was an audio 'image' in the upper LEFT corner of the room.
Swapping the speakers L/R fixed it.
Kooky.
Too much is never enough
Unrelated question but can the 3.7i's be biwired? I currently have 3.6r's that I have bi-wired and was thinking of moving to 3.7i's and am curious if I will be able to use my same kubala sosna cables if I switch.
Thanks.
No!
thanks.
How about these options
The second is probably going to give you the best results but it is in a narrow area and might need some backwall absorption to balance out the open side. Try it out and see...
I have a room similar to the OP (L-shaped app. 20x23 with a 6x8 "cutout") and I use a setup similar to the one you propose. I have a chair rather than a couch but the center of the couch would be where the chair is. The speakers are about 4-1/2' from the front wall and the chair is about 10' from the speakers.
Here's a picture from the chair - the sub is hidden behind the right speaker.
and looking behind the chair:
and the resulting waterfall plot with a sub
There is a room mode peak around 40 Hz and a slow fall off (about 5 db) from 500 to 20000 hz which Wendell Dillar said was exactly what Magnepan was trying to achieve.
I married the perfect woman. The downside is everything that goes wrong is my fault.
Edits: 08/30/16 08/30/16
Does the output waterfall look the same for both speakers playing separately?
My concern with using the long wall for an L shaped room is the asymmetry in the bass from the opened vs closed sides. When I was in such a space I had the bass carefully adjusted for symmetry by location and the slightly closer placement to the sidewall on the open side compensated for the lack of loading by the enclosing wall. The result was tuned with mono bass signals played at both speakers and then confirmed with mono jazz (contrabass) and Bach cello suites (Casals).
I have DIY absorbers behind the speakers and opposite the right speaker (short side) as well as at the corners on the short side. This seems to help some. There is a peak in the bass around 40-45 hz which roughly corresponds to the long side distance of 23'. Since 40 hz notes are fairly rare in acoustic music - what I mostly listen to (jazz, classical) - it is not a real issue.
Now when I think about it I have never tried putting the sub on the left side (open side). I'll have to do that this afternoon to see if that peak resolves -- or buy another sub when the boss is not looking :).
I married the perfect woman. The downside is everything that goes wrong is my fault.
That is a good idea on the bass balancing front.
I don't think the absorption is going to be effective in curbing bass discrepancies that well. You need bass traps and those rarely do more than a couple db's worth. The absorption I was suggesting was to balance the overall lower mid to bass output if you can't get it balanced out with placement asymmetry complementing the boundary loading asymmetry.
I agree with you about the panels and deep bass but they do seem to reduce harmonics of the ~40 Hz in the mid-bass and higher frequencies. I did not do waterfalls of the separate speakers but I believe the fs where similar. I didn't get around to moving the sub but maybe today -- nice being retired as there is always tomorrow.
I married the perfect woman. The downside is everything that goes wrong is my fault.
Try the Sub at the corner near the couch- try 45 degree toe in tweeters in and you can be closer to them.
"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius
I would rotate the whole setup 90 degrees to the right and put the speakers on the 22.5" wall. At least that would create a better symmetrical configuration.
Even if your left and right measurements (with one speaker in opposite polarity) look better, it's an unusable setup. You will not get any type of centering imaging capability with that configuration.
I suggest to forget about the subwoofer for the time being and experiment with just the speakers themselves.
Dave.
Hard to get good sound no matter what you do, IMO.
i.e you are screwed with that room!
The best Magnepan rooms are "Shoe boxed" shaped (but not too large).
From my experience, having the 6 foot maggies, in many rooms, over 40 years.
Can you put the speakers at the other end of the room, behind where the couch is now? At least then each speaker will be looking at the same situation in the room.
Do you have the distances and toe in to the maggies lined up correctly? You should have had some cancellation higher up if you did have them aligned correctly on one of the two polarities. As it is the speakers just seem out of sync.
Yea after I while I started to realize the image was very distorted, which prompted me to get the MiniDSP
Have you tried the sub ahead of the right speaker along the wall?
No I haven't, but for aesthetic reasons I can't really place it there.
Try bringing the subwoofer closer up to the acoustic center of the maggies (midrange) and then point its driver either left or right, across the soundstage--like pointing at the other speaker or pointing away from both.
Unusual, but can sometimes help standing waves.
Try not using the subs crossover. Run the Maggies full top to bottom and then adjust the subs xover as low as possible and bring up volume so you just hear it
Alan
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