how can I make the back wall transparent?

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
quite bassey
- 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 :-)

Great post !

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.