# Magnepan - 80+100-400hz being sucked out and looking for advice



## scot (Dec 26, 2006)

Something about my room is sucking out 100-400hz. I have corner traps in the front corners, and corner over the speakers, and 2" panels behind my Maggie 3.5s to tame the worst of the rear reflections. I also have some material behind the seating position to tame reflections from behind.

Room is not a perfect rectangle. 

26ft x 19'9"ft with a 10x20 chunk out of the back left. Speakers wall the long wall and on the right side of center, with the right speaker about 8' from the right wall and 5' from the speaker wall. Left speaker is 8' to the left. 

Seating position is 10' from speaker positions and centered. 

Room is a basement, concrete under laminate. Walls are drywall over insulation/wood with a 2" gap to foundation poured cement. 

I've tried moving the speakers back and forth, left and right. Up to the wall, and out as far as they can go (but can't stay.) Moved my absorber panels all over and.. Just not getting anywhere. 

Audessey just gives up and moves the crossover point for my maggies to 200hz  Sub is a DIY using ye' olde 18" tempest from many moons ago.


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## bpape (Sep 14, 2006)

Can you post a sketch of the room along with your head position in relation to the wall you are facing?


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## scot (Dec 26, 2006)

Not perfect, but I had done a sketchup diagram a long time ago and re-used it. Close to accurate.


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## bpape (Sep 14, 2006)

Thanks. And the distances?


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## scot (Dec 26, 2006)

Right speaker (from the listeners viewpoint) is 8' (to the middle of the panel) from the right wall and 5' from the back. Left speaker is 8.5' from the right speaker and also 5' from the wall behind it.

Listener position is 10' from speakers and equidistant.

Listener position can move forward a foot or so, but not laterally. Room is also a home theater and the tv is mounted with no possible way to convince anyone that moving is even a remote possibility 

Speakers are as far out in the room that they can go, they can move laterally out from center and back towards the wall. Keep in mind they are magnepans so wall interactions can become a separate issue. 

Sub is in the right corner, but my preferred crossover frequency is 60hz or below (40hz is ideal) so it really doesn't play into this too much. The tempest is great super low, but not so much for higher frequencies. 

Mic is an old generation ECM8000 pointing at the ceiling. I tried to use a canned calibration but it is not right above 10khz, so you need to ignore the drop off unfortunately. All of my speakers show the same pattern even near field and in another room. Low end seems to be accurate.


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## bpape (Sep 14, 2006)

Got it. But how far straight line are you from the wall you are facing?


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## scot (Dec 26, 2006)

12'6" from wall to head position


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## bpape (Sep 14, 2006)

Try moving forward with the seat about 6" and then put the speakers 1' closer together. Do each one one at a time.


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## scot (Dec 26, 2006)

bpape said:


> Try moving forward with the seat about 6" and then put the speakers 1' closer together. Do each one one at a time.


Wish I could, but the speakers can't come forward any more. Literally up against the couch at 5'2". I could move both the speakers and couch back 6" but I'm running on the edge of my households nerves as it is, plus the screen is 65" so it's getting far away. 

Moving them closer together is also a no go as it becomes an issue with the tv, I have them as close together now as possible while providing most of the seating positions a view. Any closer and it blocks the screen. The further back we go the further apart the speakers need to be for the tv.

If you want me to try each and see what I get from REW, just for informations sake, that I can do.


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## scot (Dec 26, 2006)

Position moved 6" away from the wall behind the speakers. Both listening position and speakers. 

No major change on left. Right is more affected by nulls in fairly critical regions.


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## bpape (Sep 14, 2006)

Which plot is what? I just wanted you to move the seat forward - you moved it back. Also, didn't want to change distance to the wall you face, just the spacing between the speakers.


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## scot (Dec 26, 2006)

I went back to the original setup, then moved the speakers out 6". No major change. 

Then I accidentally re-ran the scan at a higher volume and heard a buzz. Grabbed my flashlight and discovered some of the wires had barely come loose from the mylar, bass wires only and mostly at the upper tips, one section in the middle. I spent the past week resolving that (77 to hold and 3m 30nf for perm bonding) and patched two very small rips (1/4") in one speaker. 

After resolution there was no change in the frequency response, but the volume output was enhanced. Figured it was best to cover my bases, just in case there was a mechanical cause for the issue but no such luck  

With that I replaced the speakers in the original spots and did more testing, and after a few (hundred) runs this is the best I've been able to find. 

Both speakers are 4ft from the wall, right is directly 1' back from original position and out about 3-4". Spacing between the inner side of each speaker is 100". Left speaker is slightly skewed to the left as compared to the right by 1', bringing it to being equidistant from the center drops the midrange. Distance from listening position is 12.9ft for left and 12.2ft for the right as measured by audessey.


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## nickwin (Dec 10, 2007)

This is really interesting, I get an almost identical suckout with my 1.6's but they are in a much smaller room. I've wasn't sure it it was real or a measurements artifact. I'll be curious to hear what you find. Good luck!


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## scot (Dec 26, 2006)

Wish I had better news. I've tried hundreds of positions in many different configurations, but am limited by the overall layout of the room.

In the end I pushed the speakers back, much closer to the wall behind them. They are now at about 20" away from the wall and the seating position is also moved up closer to the television, with an absorber directly behind each speaker on the wall. Closer than that causes the sound to become unnatural and have large disturbances in the response curve, further away (until 4-5+') the rear reflections are near impossible to tame without a wall full of absorbers (which I can't do) and causes the soundstage to be affected negatively. At the current distance from the rear wall, the absorber behind is able to effectively reduce the initial couple ms worth of reflections down quite a bit, while leaving me with a fairly large soundstage.

I still have a big variance in my response curve though, but this placement also maximizes the midrange's flatness, which of course effects voice heavily.

I'm not really happy with it unfortunately and may have to give up on maggies in the basement if I find the right next step. I love the sound, but the room is not right.


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## JohnUSA (Feb 19, 2019)

Interesting to hear that you use absorbers help manage reflections. I ran them back in the 80's, no absorber. 

I was running MG-II's. I don't know how the 3.5's are made. MG-II's were supposed to use the back wall to help create the bass, and absorbers would seem counter-productive. As I recall, the sweet spot was 20-24 inches from drywall wall, no angle. I seem to recall my chair was about six or seven feet away, and there was an awesome sound field. 

As per recommendation, I even had the requisite piece of yarn tied to a carpet fiber to know where to move my chair to when I wanted some solo listening time. Well before the idea of the "man-cave", where I could have left the chair in one spot. Kids, wife and friends kinda dictated the general placement of furniture.

Anyway, more of a commentary from down memory lane. Wish I could be of help to you.


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## RTS100x5 (Sep 12, 2009)

It sounds like a phase problem in the xover design... A Dirac live processor will greatly reduce phase and time alignment issues - Audessy does very little to correct phase issues.. The results in my system were very dramatic though I dont have Maggies - I have a planar magnetic / woofer combo design

https://www.minidsp.com/products/dirac-series/ddrc-24


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## bpape (Sep 14, 2006)

Agreed on Audyssey. IN my experience diffusion pretty much always trumps absorption behind the Maggies.


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