0 Members and 1 Guest are viewing this topic. Read 11386 times.
I've heard it said that image depth is increased when you pull the speakers out from the wall behind them. So which is more important, the distance the drivers on the front are to the wall behind or the distance the back of the speaker is to the wall behind?For reference I'm refering to closed back speakers, not open back or open baffle speakers.Thanks.
Both. The distance the drivers are from the back (and side) wall(s) will effect reflections, sounds stage width and depth and imaging. The distances the rear ports are from the wall will effect bass response.
Speakers almost always benefit from being set away from the wall or corners.There are a couple of aspects to consider here. First, the farther the speakers are away from the wall, the later reflections off of room surfaces arrive at the listening position. If the distance to the rear wall is short, human hearing cannot tell whether those are room reflections or part of the original signal. So these early reflections can serve to "smear" the image. There are two ways to deal with this issue. Acoustic panels placed at first reflection points can absorb those early reflections and keep the sound pristine at the listening position. Where are these first reflection points? It is easy to find them with the help of a mirror and an assistant.While seated in the listening position, have your assistant slide a mirror along the side walls until you see a reflection of the speaker in the mirror. This is a first reflection point. Repeat this for the rear wall and perhaps the ceiling to locate all of these first reflection points.The second way to deal with these is to position the speakers at least 4 feet from the nearest surfaces. This is not possible in most cases since the rooms are not large enough. But if it is, reflections from surfaces about 4 feet or more from the speaker will be interpreted as room reflections and not as coming directly from the speakers. So no acoustic treatments may be required.The other aspect of this question relates to the amount of midbass energy you experience. If the speaker is placed close to a wall, these frequencies will be reinforced. This will vary from room to room and from speaker to speaker. For example, we have found that ported speakers are more sensitive to this effect than transmission line speakers. But if your speakers are sounding a little on the "boomy" side, pulling them away from the rear walls and corners will likely improve bass performance.I hope this helps.- Jim
Well, the front of the speaker is the source of the sound, and it wraps around the speaker and bounces off the baffle, the sides, walls, rear wall, etc. at lower frequencies.Nuance pointed out that if the port is in the rear and is too close to a wall it can introduce aberrations to the bass you don't want to hear as they are not in synch with the driver on the front I believe. (out of phase?)It may be easier to pull the speakers toward you in a small room and go with a nearfield triangle and treat the side wall reflections first. If you still get boomy corners due to bass build-up then traps in the corners may be a next step. My room is only 13.5 wide and I trap with triangles floor to ceiling that are about 16 inches deep. They work!Also, do not set the speakers equally from each wall. I have a 6 inch offset to one side and am around the 62% back position. This helps reduce the effect of room modes we cannot escape.I go with answer A. I was typing this response while you were typing yours.
First reflections will impact the sound regardless if it is from a rear wall, side wall or ceiling. The easiest thing to do in your situation is to kill the first reflections off the rear wall (since the side walls seem far enough away).In a rear ported design, you want the speaker far enough from the rear wall so that midbass frequencies are not reinforced creating "boomy" sound. This has nothing to do with image depth, but is a consideration in all speaker set-ups.In terms of image depth, in order to create the optimum situation, you either have to kill the first reflection off the rear wall or move the speakers out from the rear wall far enough so that reflections are interpreted as reflections. The farther you move the speakers from the rear wall, the later reflections will arrive at the listening position and the deeper the "room" will sound. In that regard, image depth can be enhanced by moving the front of the speaker farther from the rear wall.- Jim
I forgot about the ceiling, but the room has a cathedral ceiling with at least 7ft or more of space directly above the top of the speakers.Do you have an idea of what distance is required to perceive the reflection as a reflection and not part of the original sound? I thought I read a post some time back that the reflected sound should have to travel at least 5 ft farther than the original sound, that would mean a minimum distance of 2.5ft from the front of the speaker. Does this sound correct?BTW, my listening position is about 8ft from the speakers.Thanks.
I am not entirely positive, but somewhere between 4 to 5 feet is probably correct.- Jim
Thanks. I'm at about 4.5 feet (about 2.25ft each way), so I'm probably right on the border. I'm might try to see if I can pull the speaker out another 3 inches (I'm hitting my limit already) to see what happens; that would put me right at the 5ft mark.
For not much money you could purchase two RPG binary diffusor panels that were 2" thick by 2' wide by 4' high, covered in fabric that coordinates with your decor. You'd place these vertically on the wall behind your speakers to absorb and scatter that reflection point.A second panel or two, mounted horizontally on the wall directly behind your head, would be nice too.http://www.silentsource.com/diffusors-rpg-bad.htmlhttp://www.silentsource.com/diffusors-rpg-bad-arc.htmlThey make a large contribution to imaging.