[oneinthepipe]

The acoustic panels (24"X48") behind my speakers and at the 1st and 2nd side wall reflection points sit on the floor.  The speakers are an MTM design and are 48" tall with plinths and spikes.  Is it necessary or beneficial to raise the acoustic panels off the floor, and if so, how much should I raise them?

As always, thank you for your comments.

[richidoo]

My .02...
Center the sidewall reflection absorbers on the tweeter/ear height reflection point. Try turned sideways if you want a larger sweetspot. Placing absorbtion on the front wall helps with SBIR, but can detract from the soundstage, imo. Less of a problem if the rest of the room is soft too.

Try placing your front wall absorbers against the wall right beside the speakers, leaning against the sidewall at 45 degree angle, with one end at the baffle the rest extending toward you into the room. That has worked well for me as a bass trap.

I do like the whole front wall absorbed better than small portion of it. Then you get the SBIR fix and less soundstage confusion.

[Wayner]

I would think that the panels should be at the speaker level. If the center of the speakers is at...say 28 inches, then the panels need to be centered at that point too. Doesn't that make sense?

Wayner

[mhconley]

I am interested in the answer to this question as well.  Mine are currently sitting on the floor but I planned on hanging them.  Centering on the midrange axis seems like a good idea since this is where most the speaker's sound originates but centering on the speaker's height makes equal sense.  Is it a matter of taste or are there any guiding principles?

Martin

[oneinthepipe]

I would think that the panels should be at the speaker level. If the center of the speakers is at...say 28 inches, then the panels need to be centered at that point too. Doesn't that make sense?

Wayner

Yes, it makes sense, but my ears don't have the dispersion of the drivers, I don't believe, and I started thinking that the most important reflective area to cover would be in line with my ears.  The particular issue, however, with regard to the panels behind the speakers, is that the speakers are a transmission line design, and there is an opening in the rear of the speaker near the floor, and air comes out of this opening.  Thus, would the panel be better placed at the same height as the speakers to absorb some of this air? 

BTW, Wayner knows me too well, and he probably guessed that I don't want to have to devise a method to raise the panels off the floor if unnecessary.     I don't have Wayners' creative mind or his woodworking and fabrication skills.  Before I replaced the previous panels with 6" thick panels, it was easy to hang them by 14 gauge wire from the ceiling, but the 6" thick panels are much heavier, and I don't want to hang them as close as they are to my beautiful pal dao speakers in case the mounting hardware pulls out from the ceiling sending the panels into my speakers. 

[bpape]

In the corners, there MAY be a benefit in covering the tri-corners.  On the side walls, I recommend starting them 18-24" off the floor - especially if the speakers are very close to the side walls.

Bryan

[Carlman]

Instead of trying to hang them, make a base, like a little stool/step thing.  Attach the base to the wall using a couple of little L-brackets and just lean the panel on your little base.
-C

[oneinthepipe]

In the corners, there MAY be a benefit in covering the tri-corners.  On the side walls, I recommend starting them 18-24" off the floor - especially if the speakers are very close to the side walls.

Bryan

I have floor-to-ceiling panels in the corners.  I will raise the panels on the side walls and behind the speakers 18" above the floor, which would center them with the tweeters. (However, I might build two more panels and stack them floor-to-ceiling behind the speakers.  The more rigid fiberglass panels that I build and install, the more panels that I want to build and install because, from my listening, the better the sound. Maybe I need AA, i.e., Acoustic [panel] Anonymous.)

[oneinthepipe]

Instead of trying to hang them, make a base, like a little stool/step thing.  Attach the base to the wall using a couple of little L-brackets and just lean the panel on your little base.
-C

That is a good idea.

[bpape]

Good deal.  Forgot you were floor to ceiling in the corners.

The panels behind the speakers are more for SBIR control.  Going up to the ceiling won't significantly improve that aspece - though it will certainly impact overall decay time in the room.

Bryan

[face]

What is SBIR control?

[JLM]

Wouldn't the ideal be to keep the centerline of the panels in line with the first reflection between each speaker and the listening position?  (As many tweeters are near to seated ear height, the panel centerline would be at that same height.)

[TF1216]

What is SBIR control?

http://www.gikacoustics.com/education_sbir.html

[face]

Thank you.

[G E]

I hung my panels with the same technique one would use when hanging a picture with a heavy frame or large mirror.  Go to your favorite hardware store and you will several different types of picture hanging tackle.  I went with the traditional hook and wire rated for 30 pounds.  My panels are 24 x 48 and are glued to 1 x 2 stock and covered in lightweight muslin.  They weigh less than 30 pounds.  I attached eyelet screws to the inner frame equadistant from the top of the frame.  If you mount two or more panels adjacent to each other, the challenge is setting them up to hang evenly.  Vertical midpoint of the panels approximate the midpoint between midrange/tweeter of front speakers

My panels are set off 3.5 inches away from the wall.  I used door stops attached to the back of the frame to set off the panel from the wall.  There are lots of models to pick from, I used the chepest I could find, around $1 each.  If you use three per frame - two at the top, one at the bottom - they will hang perfectly even on walls that are nonlinear.   Works well and the sound of the room opened up compared to having the panels mounted flush to the walls.

BTW, my room is 12.5 x 15 x 9 floor to ceiling traps in the corners (4" thick) and two absorption panels on each of the 4 walls.  Next steps will be to add some panels to address ceiling reflection points and perhaps traps for wall-floor intersection

ge

[oneinthepipe]

Next steps will be to add some panels to address ceiling reflection points and perhaps traps for wall-floor intersection

ge

Bryan believes that dispersion on the ceiling might be better than absorption, in many situations.

[bpape]

It all depends on the situation.  My personal preference is for diffusion on the ceiling at reflection points given enough height.

Over your head, absorption may be a better solution if you're having height related modal issues.

Bryan

[srlaudio]

I like ceiling diffusion as well.  I agree with the need to properly mount diffusors, here a link to some useful instructions  http://www.srlaudio.com/panel_mnting_instructionsb.pdf