how can I make the back wall transparent?


If this is the wrong place for this topic please move it

My listening room is 11.5 x 15 and my speakers are 3.5 ft from the back wall.

I have spent considerable effort tweaking stuff, to the point where the system sounds very spacious and deep, BUT it still does not sound as spacious as systems with 6-8 ft of free space behind the speakers.

Is there any aesthetically pleasing wall treatment available that would give me that depth without moving the speakers

Taking the wall down is not an option:-)
williewonka

Showing 16 responses by williewonka

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?

Many thanks
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
WALL GONE!

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:-)
Charmin! and for best effect hang them on a rope - multi coloured will be high on WAF scale - you can even hang some on the wife/girlfriend and tell them its the latest fashion :-)
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
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 :-)

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 :-)

Cheers
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.

Cheers
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

http://www.allnoisecontrol.com/products/Acoustic-Curtains.cfm

http://www.amazon.com/Loaded-Vinyl-Square-Acoustic-Barrier/dp/B008JHE1P6/ref=sr_1_11?ie=UTF8&qid...

http://www.noisehelp.com/mass-loaded-vinyl.html

http://www.acousticalsurfaces.com/acoustical_drapery/acoustical_curtains.htm

http://www.soundproofingtips.com/soundproof-curtains/


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

Regards...


LR57 - RE:

"I was also wondering if I could use vinyl as a type of crown moulding behind me."

Do you mean the hard vinyl crown moulding?

I think Hard vinyl will probably scatter sound waves - a type of dispersion - but that could also be beneficial. Wood may be better though.

I also wondered if crown moulding could be effective - if you try it let us all know please

I have seen polystyrene crown moulding, which may react similar to vinyl given it's elastic properties? After all, polystyrene is used for soundproofing also.

I also looked up some acoustic specialist sites and one recommend "treating"  the ceiling corners of the room first, then move down the vertical corners of the room and lastly, if there was still an issue, look at wall panels - but they were using acoustic foam to treat  a home recording studio.

They did caution about using too much treatment, which can deaden the entire room and make the presentation quite dull.

I guess the profile of the crown moulding (concave vs convex) also plays a role ?

  • concave - would that cause the sound to be focussed close to the ceiling?  So that may not be desirable - standing waves?
  • Convex - that would probably disperse the sound - but I do not know if that would cause any issues somewhere else in the room

Another material - I just remembered a wall treatment my father used (in the UK) primarily for heating/insulation purposes - Polystyrene wall insulation (similar to wall paper). You use a paste to bond it to the wall just like wall paper - it's available on the web - e.g.

http://www.homebase.co.uk/en/homebaseuk/warmaline-wall-veneer---914-x-500mm-072492

You could then paper over it with a textured wall paper - like...

https://www.grahambrown.com/uk/product/18500/brush

And then paint to match the rest of the room - practically invisible!

And you've treated the entire wall, but it's more work than one piece of crown moulding.

A little crazy I know, but then - what about this hobby is NOT crazy :-)

Regards...

OK - the roller blind is now installed!

There are two kinds of vinyl that can be selected for the blind I purchased...

  1. Single colour - which is just a single sheet of very thin vinyl
  2. Dual colour - This type of vinyl is made from two different coloured layers of vinyl welded onto a cotton middle layer.

I purchased the dual colour and the size was 92" x 78".

The original sheet I tried was 72" x 24 and was at least twice the thickness of the vinyl on the roller blind I purchased.

Both were mounted about 1" from the ceiling.

Since I was pretty familiar with the sound of the room with the  72 x 24 sheet in position, I set the roller blind to drop down around the 24" mark
  1. as far as I could remember, the sound was pretty much identical
  2. I then dropped the blind to around 4 feet and noticed a slight change - improved imaging.
  3. Finally I dropped the blind to cover the window completely, at which point I really noticed significantly more depth to the image and a little more width with improved clarity and a more even bass reproduction

Perhaps the extra width of the roller blind provided some additional benefits, but it appeared that when both blinds were set to 24" the thickness of the first piece of vinyl I tried did not appear to offer any additional benefits over the thinner vinyl on the roller blind - i.e. in my room at least.

It would appear the vinyl is a pretty good material when it comes to absorbing sound waves.

The roller blind works very well  my room, since it covers the window behind my listening chair (framed with drapes on both sides) and looks very tidy when rolled up - very high on the WAF !

So that's it! - no plans for a remote controlled motorized option ;-)

Hope you find it useful

Regards...



LR57 - As stated in an earlier post - selecting the right material is key - vinyl is definitely best for this purpose 

But I think I know where you are going with this :-)

Take a look at my  DIY Vinyl Crown Moulding - last component entry on my "System"

https://systems.audiogon.com/systems/3760

I have not tried this, but I think it might work very well - especially with 1/8" MLV

If MLV is too heavy you could used vinyl upholstery material - the ends may be an issue, but...

  • you could cut a Styrofoam form at each end to glue it to and then caulk to finish

Let me  know how it turns out.

 Regards... :-)))

LR57 - not a problem - I'm in the process of helping a friend with his 12ft high ceiling and irregular shaped concrete walled condo - what a nightmare :-(((

Keep me posted with your developments and what you end up with - I would be most interested to hear how it improves things for you.

Cheers