[anilveena]

What's the recommended approach here?  I have bass traps in the corner and absorbers at the first reflection points on the sides and was wondering if there's any advantage to adding some treatment right behind the speakers.  If so, should I use diffusion or absorption for these maggies?

Thanks!
Anil

[Nyal Mellor]

My recommendation would be to first ensure the Maggies are as far away from the back wall as practical. Then use a curved element between the speakers to redirect the sound towards the side walls. This approach needs quite a lot of space to work. If you are short on space a combination absorber / diffusor is probably the way to go, like a BAD ARC or similar.

[anilveena]

Thanks Nyal.  I have a lot of space behind the speakers, but not a whole lot of space on the sides.  Can you tell me more about the curved element?  I had not heard of this.  Is the idea that this is along the front wall behind (and between) the speakers?

Anil

[bpape]

The curved arc in the center helps with mid/high frequency reflections front to back.  IMO, something more like a QRD type of design directly behind the Maggies gives a more even scattering in time and space and helps a ton with comb filtering from the rear wave.  This combination can throw a huge soundstage which is very helpful especially when you have to be relatively close to the side walls.

Bryan

[Nyal Mellor]

Thanks Nyal.  I have a lot of space behind the speakers, but not a whole lot of space on the sides.  Can you tell me more about the curved element?  I had not heard of this.  Is the idea that this is along the front wall behind (and between) the speakers?

Anil

To reduce the level of the reflection from the back wall to high end standards (-15dB relative to the direct sound) you need to position the speakers 7-8ft from the rear wall**. Distance and the inverse square law take care of things from there. If space is tighter then a curved element with say a 2ft radius applied between the speakers to cover the first reflection point does the job nicely.

** this calculation holds true only for a point source. A Magnepan is kind of inbetween a line source and a point source. A true line source would extend floor to ceiling and exhibit a -3dB loss in SPL per doubling of distance compared to -6dB for a point source.

[anilveena]

Thanks Bryan and Nyal.  This is very helpful.

[dm]

To reduce the level of the reflection from the back wall to high end standards (-15dB relative to the direct sound) you need to position the speakers 7-8ft from the rear wall**. Distance and the inverse square law take care of things from there. If space is tighter then a curved element with say a 2ft radius applied between the speakers to cover the first reflection point does the job nicely.

** this calculation holds true only for a point source. A Magnepan is kind of inbetween a line source and a point source. A true line source would extend floor to ceiling and exhibit a -3dB loss in SPL per doubling of distance compared to -6dB for a point source.

I have GIK Acoustics QRD diffusers behind my Magnepan 1.6QR's.  (Seen in black on the wall behind my speakers)  I also tried sheets of OC703 absorbers but preferred the diffusers instead.  The diffusers broadened the sweet spot and evened out the depth of the sound.

[audioblazer]

I removed my curve , so called passive resonator at my front wall , 7.5' x 12" depth. It smeared my imaging. Some use it successfully , 1 eventually add RPG skyline at the centre of the resonator. I believe a diffuser may work better. That's why I took it done to e replace with a PRD diffuser soon.

[tasar]

I'm using QRD between OB speakers 8' apart and 6' from front wall w corner absorbers. Moving the QRDs off the front wall closer to OB's rear plane, allows me to control the the musical stage especially height. By moving them out onto the floor, it can be reduced in overall width apparently because you intercept the waveforms sooner. What was 6' wide at front wall surface is now 4' wide about 4' out. In this position adding more QRD surface does little. Overall harmonics are far more focused with depth to orchestral type recordings, never before achievable. Voice is centered with a believable height and presence.

[jimdgoulding]

Excellent responses.  Glad you guys are here.   What do you recommend for front firing box speakers?  My speakers are 54" off the wall behind and 42" off the sidewalls to the centerpoint of the baffle.  My room is 15x12x8'.  I sit at the apex of an equilateral triangle.  Thanks. 

[jimdgoulding]

Anilveena, I certainly don't mean to try and pirate your thread.  Carry on, gents, but I would like to hear back from you chaps somehow.  Thanks.

[Elizabeth]

I have heavy drawn curtains in back to corner. With tall shelving on side walls tight into corners.
Shelves of which are ful of DVDs.
My 3.6 Maggies are 42 inches from rear wall.
I have a huge picture window in between, with an air conditioner built in under window in my apt..
So I dampen the corners.
I have no stuff at first reflection.
My amp is on floor in middle, with a lowslung open frame leather chair in front of amp
(the chair is low enough that the back is below the airconditioning vents)