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Room Treatments for Maggies

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Posted on April 24, 2017 at 22:24:28
rw11
Audiophile

Posts: 12
Location: OR
Joined: March 16, 2017
 Can anyone help me understand what room treatments are typically used for planar speakers, like the 3.7i Magnepans I have?

... just a general guide re absorption, bass trapping, diffusion based on the dipole radiation characteristics

Thx!

 

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RE: Room Treatments for Maggies, posted on April 25, 2017 at 07:09:10
Green Lantern
Audiophile

Posts: 16952
Location: San Diego, Ca
Joined: November 12, 2002
Contributor
  Since: June 17, 2003
 Although every room is different, generally speaking it's almost always diffusion in the rear of the panels and absorption towards the front.









 

Depends..., posted on April 25, 2017 at 12:38:13
grantv
Manufacturer

Posts: 7728
Location: B.C.
Joined: January 15, 2002
 If your speakers are very far away from the front wall, you can do with less front treatment (my preference = diffusion). If you are far away from side walls, you can do with less treatment there (where I prefer absorption). The closer to the walls, the more the need IME.
I use home-made deeper wood diffusors up front, and 2 absorbing panels per side of room; one at each reflection point.



Behind me I use nothing as the rear wall is 8-9 feet away, with a raised couch...



But if you are close to the rear wall I'd recommend absorption there as well.

 

Sofas are bass traps, posted on April 25, 2017 at 13:47:56
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 The sofas act as bass traps so having their locations setup to have a positive effect (like against both sidewalls or on the front wall or the back wall.

 

RE: Room Treatments for Maggies, posted on April 25, 2017 at 21:12:20
rw11
Audiophile

Posts: 12
Location: OR
Joined: March 16, 2017
 Thx - I have plenty of room behind me. The real issue is the 2st and 2nd reflections on the LH side - part of a picture window and then another full picture window. I cannot use drapes and a diffusor would block my window.

 

RE: Depends..., posted on April 25, 2017 at 21:39:58
rw11
Audiophile

Posts: 12
Location: OR
Joined: March 16, 2017
 I should add... the sofa is in the near center of the room.

The RH speaker is far from the nearest side wall and fires back into a sort of alcove with the nearest rear wall maybe 8 ft away.

The room is very asymmetrical...

 

RE: Room Treatments for Maggies, posted on April 26, 2017 at 00:27:43
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 Can you change the system orientation? having a window on one side is rather hard to overcome without treatments on it.

How are the speakers positioned and aimed?

 

RE: Room Treatments for Maggies, posted on April 26, 2017 at 06:16:36
Green Lantern
Audiophile

Posts: 16952
Location: San Diego, Ca
Joined: November 12, 2002
Contributor
  Since: June 17, 2003
 you could try placing a fake ficus tree (or hanging vine plant/s)in front of the window to prevent direct waves from striking it.









 

Can you post a picture or 3? NT, posted on April 26, 2017 at 06:48:16
grantv
Manufacturer

Posts: 7728
Location: B.C.
Joined: January 15, 2002

 

RE: Can you post a picture or 3? NT, posted on April 26, 2017 at 14:06:18
rw11
Audiophile

Posts: 12
Location: OR
Joined: March 16, 2017



ok here is a room diagram and a photo ( despite the clumsy drawing attempt the 3.7i's are usually about 3 ft or more from the front wall on the LH side and there is the open are on the RH side)

I can't change them to the long wall - a fake ficus is about all I've come up with; it wold have to go behind the LH speaker and I'm not sure how well it would diffuse the back wave (??)

I can swap the tweeters to the outside, and am continuing to play with moving them around slightly. I usually aim the panel to point just behind my head.

The big gray block on the room diagram is a chimney and fire place. There is a leather couch that sits behind the chair a few feet.

Thanks much for your help and comments!

 

RE: Room Treatments for Maggies, posted on April 26, 2017 at 14:07:45
rw11
Audiophile

Posts: 12
Location: OR
Joined: March 16, 2017



Here is the photo - taken just to the right of the listening chair.


 

RE: Room Treatments for Maggies, posted on April 27, 2017 at 07:54:06
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 You have too much of a dissimilarity between the two channel's loading by the front wall vs. opening. And the speakers are placed too close to the front walls. But it looks like you have plenty of space to the sidewalls so you might want to swap to tweeters out.

So i would suggest pulling the speakers well away from the front wall (5 ft or more) and place a tall real or fake plant behind each speaker to diffuse the backwave.

Try tweeters out at the pulled out position, and consider an additional tall plant to diffuse the window reflections at the 1st reflections point. When positioning with toe in try to aim the dipole null at the window first and then adjust toe in to see if it is beneficial or not.

 

RE: Diffusion is your friend..., posted on April 27, 2017 at 13:23:10
BigguyinATL
Manufacturer

Posts: 3475
Joined: April 10, 2002



I'd add some absorption out of the way.

I has inch foam above and ceiling tile on th perimeter. Equipment and software rack add some diffusion as well as the corner
"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius

 

RE: see my MMG pic., posted on April 28, 2017 at 06:19:03
BigguyinATL
Manufacturer

Posts: 3475
Joined: April 10, 2002
 Try more toe in and spread the speakers a little out. The left speaker rear energy needs to be diffused - so let it fire more into the corner. set the right to match. The right speaker doesn't have that rear energy so you might need a slight balance adjustment.

"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius

 

RE: Room Treatments for Maggies, posted on April 28, 2017 at 06:50:23
grantv
Manufacturer

Posts: 7728
Location: B.C.
Joined: January 15, 2002
 Just backing what others have already said, you need to play with room treatments. The left being so close, right 100% open...
I'd experiment with diffusion and or absorption behind the left speaker.

 

RE: see my MMG pic., posted on April 28, 2017 at 11:04:56
rw11
Audiophile

Posts: 12
Location: OR
Joined: March 16, 2017
 Toe them in so they point in front of my head?

I'll move them further out - I often do that when "really" listening anyway.

 

RE: see my MMG pic., posted on April 28, 2017 at 11:44:51
BigguyinATL
Manufacturer

Posts: 3475
Joined: April 10, 2002



Yes, I have my tweeters in and the MMG's angle 45 degrees while their positions and I are roughly equilateral. There is an off axis listening benefit to this - the two side seats benefit from not needing a center channel for TV listening.
A secondary benefit is I find the MMG's a little too bright on axis - I use to use a more flat (geometrically) tweeters out layout and I had to roll of the high frequencies above 5kHz a bit.

Nice thing is Maggies are not too hard to move about.

Oh and you see one of my two subs on the floor below bottom right corner of the picture. The second sub is on the other side wall. Both are at the "dipole null" - on the side wall where the edge of the panel points - this seems to work very well for an excellent integration.


"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius

 

RE: Can you post a picture or 3? NT, posted on April 28, 2017 at 13:07:44
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002



Thinking of how to distance the speakers from the front wall.

Yes, a nice large plant behind the left speaker will help balance things out, but you also need more distance to the front wall and that should do more together to get the speakers balanced and get the front wall reflections to lower level so they don't interfere.

 

RE: Can you post a picture or 3? NT, posted on April 28, 2017 at 13:21:16
rw11
Audiophile

Posts: 12
Location: OR
Joined: March 16, 2017
 Thanks for all the help - esp. the taking the trouble to modify the diagram!

I am a little confused about distance to the front wall - I've always assumed that is for bass wave superposition to enhance the SPL for those frequencies, and does not affect the highs (much).

Right now, the tweeter is about 2 ft. from the wall (measuring at 90 degrees to the panel, not straight back across the room itself). The mid/bass panel's center is about 32" so just under 3 feet. If I put it on the added circle in the diagram, I should easily be able to get it at about a 5 ft distance from the corner of the 2 windows.

It seems like the distance form the front wall should depend on the room size, maybe the length. I guess I can move it back and forth to test.

I'm also trying to figure out the density and leaf size for a fake plant -- if it's not too spendy I can at least try it out and toss it when it gets dusty. (no real plants - had to replace the floors when they got wet from watering)

 

RE: Can you post a picture or 3? NT, posted on April 28, 2017 at 21:21:02
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 The rear wave from a planar dipole speaker is in reverse polarity to the front radiation. So the closer to the front wall you put it the weaker the bass. The reflections from the front wall in the mid and high frequencies are not well separated from the direct radiation by the ear till the reflections are delayed by 1ms or more. That requires that the backwave reflections travel to the fron wall and back to the plane of the speakers a distance greater than 10 ft. So the speakers need to be placed 5 ft or more from the reflective area on the front wall. It is less of an issue with severe toe in. But that adds in front radiation reflecting off the front wall, ,which is equally problematic.

Bass reinforcement by the front wall only works for box speakers. To get wall reinforcement of bass of a planar dipole you place it close to the sidewalls and dead perpendicular to them..

Do try it out to get your impression of what particular placement variation does to the speaker's performance. Keep notes and mark up the placements you try out.

There are particular placement schemes that rely on the dimensions of the room. But your open plan does not really make for a standard room. The right speaker in free space is getting a more favorable placement for mid and tweeter performance, particularly in detail resolution, the left speaker is getting some corner bass boost but otherwise it is having the mids and treble muddied with early reflections.

 

RE: Diffusion is your friend..., posted on April 29, 2017 at 11:48:36
Norman M












I use my MMGs to augment the sound from the front R/L channels when listening/watching BDs, particularly those involving classical music performances.

 

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