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After corresponding with a couple of acoustic treatment purveyors, I have despaired of finding any aesthetically acceptable rear wall treatment. Everything recommended is always some four inch or greater thickness monstrosity that looks like someone's hung a cloth covered shipping box on the wall. I have the same situation you do and would love to find some aesthetically acceptable way of reducing the rear wall's audible presence. Closest thing I've found that looks like it might have merit is the ASC Matrix panel. I've not found any feedback or reviews on it however.
If you want transparent I'd go for a window :-)
Joking aside, In my room I treated the wall behind the speakers with RPG diffusers works like a charm. There are several other options available at lesser cost, if your handy you could even make your own.
Asmuck has a system page built here on Audiogon, where he utilize some of the same ideas- his room is among the best I've heard.
Best of luck
Peter, the acoustic designers I consulted seemed to feel that unless one uses massive amounts of bass trapping behind the listening position, one can't effectively ameliorate the total adverse influence of the rear wall. Out of curiosity, how close is your listening position to the rear wall? I've wondered how much of the problem can be ameliorated by diffusion, but I keep getting told there needs to be more distance between the diffusers and my listening position for them to be effective (my head's probably 18-24 inches or so from the rear wall.)
I think you are making matters worse by confusing what wall the OP is addressing. He really means the front wall (which is the wall behind his front speakers) People on this forum often call the walls by the wrong name. The front wall faces the listener and the rear wall or back wall is behind the listener.
If I am mistaken, I apologize. Maybe the OP can clarify, that way you are all on the same page.
I agree, Tom, I think the op is talking about the front wall.
I'd recommend treating the room with bass traps / absorption panels and diffusors. I'm new to room treatments as I just hung my first four panels (gik 244 broad band traps) but I'm totally sold on room treatment now. I think you can gain what your looking for by treating the first reflection points and going from there!
I'm about 5 feet from the wall behind me when seated, behind me is a row of cabinets and a counter. The space above the top row of cabinets have been stuffed with insulation then the space have been sealed of with cloth creating a very nice bass trap. Its about 12" deep 24" tall and about 20 feet long.
I read the OP was wanting to treat the wall behind the speakers with something to create depth in his soundstage my reason for suggesting the RPG or similar
As alway, Good Listening
Have u looked thru the virtual systems for ideas?
In my case; room is 12 x 16 feet, speakers are 3' from wall; toe-in made a great increase in soundstage plus I'm using an equilateral triangle method. As in many of the virtual systems, I used bass traps in corners and 2 vertical DIY vertical panels on wall behind speakers; that wall then disappeared and became like a concert hall.
BUT, the panels are ugly...2 inch foam, mounted on boards that I can stow away when I have visitors. Obviously I'm not married.
"the acoustic designers I consulted seemed to feel that unless one uses massive amounts of bass trapping behind the listening position, one can't effectively ameliorate the total adverse influence of the rear wall."
I am using bass trapping panels and it works for me; in a small room you don't need massive amounts.
Williewonka, sorry to have misinterpreted your post and hijacked your thread. Needfreestuff, GIK was one of the firms I consulted and they did indeed recommend fat bass traps on the wall immediately behind my heaad. Problem is, they are visually intrusive and incompatible in a well designed domestic environment IMO. I have bass trapping in the upper room boundaries in the "plant shelving" recesses of my room and it helps a great deal. It works basically like the bass trapping Peter describes. At least I don't have nasty room response problems, the space measures pretty good. I have a medium size 18.5' x 14'room with 11' ceilings.
Bass reflections off the wall behind the speakers does not affect perceived image depth. It's the critical midrange where you want to get rid of some reflections.
It all depends on what you call "pleasing" as far as looks.
A few panels of strategically placed Sonex will help immensely.
Some companies make some fabric covered shallow boxes filled with sound absorbent material (fiberglass....) that would do the trick.
Nice Persian carpets, that you so often see in pics of listening rooms, help.
I had that issue once and physically moved the speakers out when listening and back when done. It kinda sucked but preferable to hanging weird things on the wall since it was in our living room. So it was worth the effort to me given the huge sonic benefits but maybe not for you. Or maybe there's some product that makes speakers easy to slide without adversely affecting sound?
Other thought was if you may have the flexibility to try the speakers in the corner where the corner itself is the midpoint between the speakers. I've seen manufacturers do this at shows where the room was otherwise too small and seemed to work pretty well. Just a different thought. Best of luck.
Thank for all the feedback - seems I got a few things to try :-)
The speakers are Gershman Acoustic Sonograms - which are very forgiving and very transparent.
I'm very fortunate in that I have not experienced many of the problems others have re: traps and reflected sound - I did have an echo behind the speakers, but a couple of tall panels fixed that.
I tried hanging some material behind the speakers, which helped a little with reflected sound, so maybe something thicker like a rug might be more effective ?
The speakers are of the standard forward firing drivers type, so I assume that if there is some reflected sound coming from the wall behind them, then it would be first be coming from the wall behind the listener?
The speakers do have quite a wide dispersion angle, but not enough to reflect off of the wall behind them.
If I were to look into some kind of deflection panel, which direction should I aim the deflected sound?- up, down, outwards, inwards ?
Would the deflectors need to be the height of the room?
In one hi-fi store I visit, they have "scatter reflection panels" which are long strips of wood at 45 degrees to the wall - can anyone vouch for the effectiveness of something like this?
The only way really is to use speakers that are bi-directional, like Magnepan planars for example, or omnidirectional. Front ported or acoustic suspension speaker designs, ie those where most or all sound is emitted from the front, will be most problematic.
Then it is a matter of getting enough distance between speakers and rear wall for proper timing of spatial queues (usually a few feet minimum) along with a good balance level between the direct and reflected sound that reaches your ears. That is determined mainly by distance from wall and db level of rear emitted sound, ie that reflected off rear wall. More distance to rear wall will require higher db of reflected sound to produce illusion of extending past rear wall. That is why bidirectional or omni speakers tend to do this best.
Again, I think Mapman means "front" wall. I'm in the "room sound" camp (although perhaps alone) where the furniture, rugs, bookcases, me, etc., provide plenty of ambience control. I do have my listening "sweet spot" 4 feet or so from the back wall (behind me...in case we're still not clear on that), and the main speakers about 3 feet from the front wall with a sub tucked behind one of them. Done. The side walls/glass doors are well away from all this and besides, I like some "room sound"...there are bumpy standing waves here and there but not in my listening spot so I don't care. I have a glass coffee table in front of that spot and put a couple of throw pillows on it when doing "active listening" (love that concept), so I'm not a complete philistine.
YEs, I mean wall behind speakers opposite from listening position, which is the one in front of you when listening facing speakers.
You can use room acoustics or fight them. Both are valid approaches. Each might have a better chance of success depending on magnitude and nature of room acoustics. All rooms have a unique sound and best to first assess it then use it and tweak accordingly as needed IMHO.
So, If I understand you all correctly...
Other than the placement of furniture, rugs and the two screens that I have in place to dampen an echo behind the speakers and careful placement of the speakers to attain the best sound (to remove standing waves etc) and to derive the best imaging...
Additional and very precise adjustment of the speakers either further from or closer to the wall behind them, may result in the sound waves from the speakers becoming aligned in some way with the reflected sound waves resulting in a more cohesive image that appears to make the rear wall less apparent - correct ?
One thing I have noticed is that albums recorded in the studio is more prone to "the wall effect" whereas the venue acoustics of live performances tend to make the wall much less apparent.
If I only had a bigger room :-)
I'll give it a whirl and let you know how it pans out - many thanks
I think you've got it covered.
One thing worth adding is that you might have to adjust distance between speakers as well when you play with distance from front wall in order to maintain good imaging, including a strong center image in particular. Mono recordings are particularly useful for testing to see how well center imaging is doing. If center imaging works well for a mono recording, stereo recordings should benefit as well.
Its also worth noting that what works best for sound stage size and imaging may not be exactly the same setup that works best for flat frequency response top to bottom. I like to get the soundstage and imaging right first, then tweak from there as needed to get tonality right as needed. That might include wall treatments, or any of the usual suspects used to tweak sound quality from there.
Wow - I was expecting much more trouble than this - I'm beginning to love these speakers. Talk about forgiving!
I only had to move them a few inches back and the sound stage front to back became much more pronounced. Previously everything was behind the speakers. With the new placement the main artist is further forward but not in front of them. The rest of the sound stage is nicely spaced backwards.
Fortunately, those nasty standing waves seemed to have stayed away, so no need for any traps.
Toe-in is best at about one inch over the depth of the speaker (15 inches). More than that and the sound stage starts to close in :-)
The clarity also has improved a lot - even outside the room the sound is amazing and crystal clear
Thanks for all the input - this was the last part of the puzzle that had eluded me.
Now for some serious listening:-)
Wow. This is a great thread. I am going to try the rolls of, sshh, tp. It will be less expensive than real traps or others and I can change the design anytime I want. Wow!! I can paint them the rainbow colors if I want to. Oh now I am getting excited!! Ok now, I have an important question before I go on this journey of no return. How high can I stack them? And does anybody have any specs or ideas on what to expect its effect on the sound will be? And what brand should I use? Yes I will be using brand new rolls if you were wondering.
Aggielaw the following dimensions apply to the centre of the front of the speaker
23.5 inches from side wall and 37.25 inches from rear wall
The speakers are toe-in 0.5 inch.
I tried several toe-in angles, but for the Sonograms in this room the angle selected gave the widest image with the greatest depth and kept standing waves to a minimum.
I had read lots of posts on speaker placement and they all talk about the image snapping in place - my experience was a little more gradual.
I must admit that this new "spaciousness" only came about after getting all my "other ducks" in a row - in my case those last ducks were my interconnects, power supply and power cords, without which I do not think the whole thing would have come together so vividly.
Not that the old ones were bad, they just didn't have the same synergy as those currently in place
It freaks me out just how good this system sounds now :-)
So exactly what did I hear during this process....
The staging from left to right was already very precise. For this I used a well recorded classical orchestral track because I know where the stringed instruments should be - e.g. left to right - violins, violas, cello, double bass, or something like that.
If your speakers are too far apart you can hear actual gaps between the many instruments - they sound disjoint.
Too close together and the instruments sound on top of each other - they should flow from left to right each having their own space with no gaps.
My specific problem was that from front to back on some tracks, it sounded as though everything was coming directly from the wall behind the speakers. Other tracks sounded as though they were coming from behind the wall, but there was never any sound coming from in front of the wall.
Selecting a track that sounded "flat to the wall" and starting with the front of the speakers about 44 inches from the wall behind, I moved the speakers back one inch at a time (to start with).
With each movement, the track started to have more depth from front to back and much clearer sounding with more details becoming apparent. I continued until the image started to loose it's clarity and the moved the speakers forward again to the point with the most clarity.
It's quite difficult the covey in words exactly what to listen for and at what point you have gone too far, but it became quite apparent when I was moving the speakers.
Once I had them in the right place I tried several toe-in angles and selected the best one. Again, when you are doing it it is readily apparent.
One thing I did notice during this process were standing waves in the bass frequencies , and positioned the speakers such that the sound had a nice balance to it from a couple of different listening locations.
Why more than one? Well, I have the sweet spot, where the sound is very good. And then there is the "wife and I" location, where we sit on those cold winter nights enjoying a glass of wine after a hard day skiing :-)
I had tried several times to find the right speaker location, but never really understood what I was doing, let alone what to look for. I tried the various formulae to no avail, because most of them call for the speakers to be in some position that required me to move furniture out of the room.
It wasn't until I read the posts in this thread, that I realized what having the speaker in the right place was actually achieving.
My thanks to all who contributed - I hope others find it as enlightening.
I guess this hobby (obsession) is a series of discoveries and this is just my latest...
Even after finding the correct speaker position (posted above), there were a few very annoying tracks that failed to impress me and always sounded very "confused".
I started thinking about my room and how sound might be bouncing around.
This brought me back to my initial room treatment - two 15" x 78" screens. I remembered that when I was experimenting with the screens, it was the height of the screens that contributed the most benefit.
Thinking about my room...
- 15 x 12 x 8 feet - audio system/speakers on a short wall
- the long wall on the left has a double open doorway
- the long wall on the right has a sofa and pictures(no glass) on the wall
- the short wall behind my listening chair(s) has a large bow window with very light drapes that do not have any effect on sound when closed
- in the corner to the right of my chair was a tall bookcase loaded with vinyl.
- floor is hardwood mostly covered with an area rug
So with all those soft furnishings in the lower half of the room it seemed logical to me that if there were any reflected sound waves bouncing around - they should be occurring in the upper half of the room.
Armed with a 2' x 6' heavyweight vinyl "curtain" and two large extendable stands I thought I'd try some different positions in upper regions of the room
1. a centralized location behind the speakers
- this offered very little relief on a couple of tracks, but not enough to make me declare it was a success.
2. a centralized location up against the wall behind the listening position
- the curtain dropped below the frame of the window by about 12"
- The resulting effect was immediately noticeable, pretty much an OMG moment!
- clarity improved beyond my expectations
- an image that now easily exceeds the boundaries of the room on most all tracks
- projection of venue acoustics forward of the speakers which now easily envelopes the listener on most tracks
- it's like surround sound with only two speakers
- the improvements can also easily be heard outside of the room also, with significantly more clarity, simply amazing.
Basically - all walls are now transparent - yes GONE!
What really surprises me is that I have no "treatments" on the wall behind the speakers - other than the two screens that are actually more on the side walls into the corners.
I then tried a couple of variations...
- curtain right up against the ceiling
>>> provided the most benefit
- leaving a foot of space above the curtain
>>> resulted in the sound becoming a little muddled and
- shorten curtain to 15" but right up against the ceiling
>>> a little less depth in the image than the 24" deep curtain - but still excellent
Achieveing so much benefit from treatment in the upper 15"-24' of the room is what surprised me the most.
I think I am very fortunate that I do not need to cover large areas of my walls in acoustic tiles - the mere suggestion of which sent the WAF scale dipping well into the negative.
She will now be very happy if I simply replace the vinyl curtain with a purpose made roller blind to fit the entire window. :-)
And, I figure there may be more benefits to be had if I cover the glass completely :-)
I'm not saying that all rooms only require treatment of the top 15"-24", especially if your room has solid side walls.
But it is where I'll start - next time :-)
But one last question: Has anyone out there found that the installation of cove/crown mouldings improved the SQ??? - thanks
Hope you find this useful :-)
Williewonka, thats some really nice effort you have been putting in.
Give the ASI Liveline resonators a try. They essentially do exactly what you are trying to achieve, they make the room disappear! And they are extremely small in size, like a match box each. The big deal about them is, their effect is like the walls have disappeared but the musical energy which should be present in a small room remains with great open-ness. They not only improve focus and soundstaging but also greatly help in improving the immediacy, dynamics and timbral accuracy. Every wall (and for that matter every item) in the room would be adding or taking away something from the tone, the ASI makes the wall disappear in the most graceful sense, as in tonality and frequency response is also corrected. Talk to Frank Tchang and give a basic set of resonators a try if possible. Your wife wont even know you have added something to the room, they are that small.
Achieving so much benefit from treatment in the upper 15"-24' of the room is what surprised me the most.
That's the way Peter(Pbnaudio) treated his rear wall; absorption along the entire upper wall. It's even more effective in his case since he has space between his listening position and the wall.
I'd like to do that, but my setup is in a living room.
Lowrider57 - my setup is also in the living room, so the 24"× 60" piece of white vinyl currently supported by two stands is a bit of an eyesore right now.
However, I've just ordered a 92" × 78" vinyl roller blind ($215) that will fit behind the drapes and is almost invisible when retracted. High on the WAF scale :-)
Perhaps you could mount a similar blind with a white valance to "hide" it
-after all, it will be up against the ceiling (retracted) - no one looks up there :-)
If it's a plain wall you could put an outrageous work of art under it to divert peoples attention?
Possibilities are endless :-)
$215 is not the cheapest tweak I've implemented, but it has been the most effective to date.
Even my wife thinks the system now sounds amazing :-)
Pani, many thanks for the tip.
Everything you said in your post about energy, sound staging etc... - basically all the benefits you mentioned - is exactly what I am now experiencing.
However, I do have a couple of albums that seem to be a little bass heavy - so once I've determined that it is due to room acoustics and not the actual recording I'll definitely give them a try.
One album - Eric Clapton's "Unplugged" had some seriously bloated low frequency foot tapping going on in my room, which has now subsided to a more realistic level, but it could still do with some more "fine tuning" to get it perfect.
Lowrider57 - the vinyl used - being soft like material - probably absorbs more than it reflects. Otherwise, as you stated above - it would simply reflect the sound back to the speakers just as the window did.
I do have drapes for the window, but they are very light and had little to no effect when I had them closed, so I am guessing most of the sound passed right through them.
Whereas the vinyl does not allow the sound to flow through it like the drapes.
Perhaps the sound is converted into motion?
It has to change into something and I'm pretty sure it's not heat :-)
I also tried some other thin fabric a while back - same results as the drapes
I get the roller-blind next week. It is a little lighter weight than the vinyl I used.
I will post an update once it's installed
Lowrider57 - I did some digging and found a lot of info on Mass Loaded Vinyl (MLV)
Turns out the sound waves are converted to heat by the vinyl - because they cannot get through it.
The MLV is a lot heavier than the vinyl I have used, so it would offer even better sound damping qualitied. It's used by several companies that want to provide a more pleasing treatment, such as drapes
Here are some links
The roller blind I am getting is made of a lighter vinyl, so it will be interesting to see how it fairs
I will post an update once it's installed