1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Does a single sound absorber/diffuser make a difference?

Discussion in 'Speakers' started by marcus263, Sep 30, 2009.

  1. marcus263

    marcus263 Member

    Joined:
    Nov 29, 2008
    Messages:
    144
    Trophy Points:
    18
    Ratings:
    +6
    Doing a search on Google I came across several setups with people placing a single diffuser/absorber panel behind their speakers on the wall, but how much of a difference does this actually make?

    E.g.

    [​IMG]

    [​IMG]

    [​IMG]
  2. AndyST

    AndyST Member

    Joined:
    Dec 17, 2005
    Messages:
    407
    Trophy Points:
    31
    Ratings:
    +61
    A single panel of moderate size won't make a whole lot of difference. In terms of diffusion though, research shows that less than 20% of the surface area needs diffusers applied before decent results are obtained.

    The first image looks more like a space coupler than a diffuser, which does provide diffusion but also has other effects on the acoustics of the room.

    Diffusion placed behind the listening position helps give a more spacious sound and can make the room feel bigger than it is. Behind the actual speakers though I'd question how useful they would be. A typical diffuser works from around 800 - 4000Hz, much higher than the frequencies that are being sent backwards from your usual speaker.

    I'd be wary of placing too many foam panels around too. Whilst these will do a good job absorbing and diffusing the mids and highs, they will have minimal effect on bass frequencies. So you could end up with a very 'muddy' sounding room.

    Until you hear a properly treated room you won't be aware of just how much difference acoustic treatments can make. Spending money correctly in this area will yield much greater improvements than upgrading your equipment (to a point).

    My advice would be to research recording / mastering studios (the 3rd image appears to be one). These are designed to offer a completely flat frequency response that won't colour their recordings in any way. Hence the extensive use of acoustic treatments. The same design philosophies can be carried over into home cinemas.
    • Thanks Thanks x 1
  3. j0hn

    j0hn New Member

    Joined:
    May 26, 2005
    Messages:
    1,944
    Trophy Points:
    0
    Ratings:
    +74
    first picture, two thoughts, first thought...anyone for darts. second thought...they speakers look like flashers!
    • Thanks Thanks x 1
  4. BlueWizard

    BlueWizard Well-Known Member

    Joined:
    Jun 19, 2007
    Messages:
    14,963
    Trophy Points:
    166
    Ratings:
    +2,682
    First I don't think there is a single, meaning one and only one, diffuser in any of these rooms.

    Note in the first photo, there is a large square wooden device, that is separated into sections, and upon a closer look, those sections seem to be filled to different depths. So, yes that is a diffuser.

    But also notice the entire wall behind the speakers is covered with curtains which, within limits, both absorb and diffuse. Also, carpeted floor and soft furnishings.

    In the second photo, the person is using acoustic foam panels, which again
    both absorb and diffuse, and the foam panels are on the side and back walls. Again, notice the soft furnishing and curtains.

    In the third room, we are obviously in a recording studio, though whether home or professional is hard to tell. Plus we can't clearly see every surface. On the back wall, above the sofa, is a diffuser, but the wall the diffuser is mounted on could be carpeted.

    Also, notice the dark ceiling on the top right, that could be carpet or a large wedge of acoustic foam.

    My point is, all these room do a lot more than simply place a diffuser behind the speakers.

    It is actually quite common to place acoustical treatments behind the speakers. One of the most common is large triangle wedges of sound absorption in the room corners behind the speakers.

    As someone else pointed out, the entire room does not have to be covered head to toe in room treatments.

    I personally think the back wall, that is, the wall furtherest from the speakers, is the most important. Next, I would say the ceiling and floors. Then the side walls, and the wall directly behind the speakers.

    Next time you are in the local movie theater, take a closer look at the walls. In my theater, the lower walls are carpeted, and the bulk of the upper walls are covered with padding with is in turn covered with folded/pleated curtains.

    Just a few thoughts.

    Steve/bluewizard
    • Thanks Thanks x 1
    Last edited: Sep 30, 2009
  5. marcus263

    marcus263 Member

    Joined:
    Nov 29, 2008
    Messages:
    144
    Trophy Points:
    18
    Ratings:
    +6
    I understand that inanimate objects like curtains and bookshelves with books (for example) can diffuse and absorb sound, but would it be efficient or an improvement to place a single panel on a wall? Understanding that these panels can cost up to £300 p/p. I've seen some setups, where people have built diffusers and just set it up on a wall as a single panel.

    [​IMG]

    I have a large empty room, and I've noticed that music in the room seems to be louder and flatter, without anything in that room, but as soon as my long heavy curtains are draw, the sound feels like it is staying within the room (absorbing) not diffusing. So, I'm essentially wondering whether it's more viable to place solid objects that can diffuse sound rather than fork out the money to buy a few panels.
  6. coldmachine

    coldmachine Member

    Joined:
    Jan 10, 2006
    Messages:
    585
    Trophy Points:
    43
    Ratings:
    +180
    The biggest single improvement, including RT60, will actually be yielded by attending to he first reflection points, rather than a notion of one surface being intrinsically more important than another.

    Are you possibly trying to describe bass traps? They are not usually simply used behind the speakers, they are usually installed in all trihedral corners. There are other room dependant location too.

    If you, or the OP, wish further info in this area, feel free to PM me.

    Diffusion and absorption are best dealt with holistically. Bass trapping is, as a subject, easily dealt with on its own. The actual implementation being rather more difficult.

    Hope this help
    • Thanks Thanks x 1
    Last edited: Oct 1, 2009
  7. marcus263

    marcus263 Member

    Joined:
    Nov 29, 2008
    Messages:
    144
    Trophy Points:
    18
    Ratings:
    +6
    That's what I was wondering, acoustics treatment in my opinion needs to be treated holistically. I'm not sure if you can slap a panel on the wall and notice any improvement or in the case of absorption notice any real difference.

    For instance, this seems like a good idea though I'm not sure if it will yield the desired results:

    [​IMG]
  8. coldmachine

    coldmachine Member

    Joined:
    Jan 10, 2006
    Messages:
    585
    Trophy Points:
    43
    Ratings:
    +180
    Firstly, that wall will drop the room reverb, but it has been installed with aesthetic consideration as well.

    You most certainly will notice a major difference with a small number of suitable absorptive panels, placed correctly.

    Dealing with the first reflection points should yield a very substantial improvement. In an average domestic room this can be more significant than any upgrade of ones electronics. Intelligibility, imaging and localization will see major improvements.

    Bass trapping will also yield good results, depending on the nature of the treatments. Simple foam traps will help down to around 100hz. even then the adsorption will be dropping like a stone well before that. 20%-120% absorption from 100hz to 1khz is fairly typical. Lower frequency trapping will require much larger traps or the use of resonator based traps.

    Broadband trapping will also reduce flutter echo as well as evening out peaks and nulls.

    The difference between an untreated room and a professionally treated room can be absolutely staggering.

    hope this helps.
    • Thanks Thanks x 1
    Last edited: Oct 1, 2009
  9. marcus263

    marcus263 Member

    Joined:
    Nov 29, 2008
    Messages:
    144
    Trophy Points:
    18
    Ratings:
    +6
    I'm trying to make some sense out of this but I still can't visualise how a single panel placed on a wall can make much difference. If we talk on scale, let’s say an empty room is 10 x 10 x 10 foot, and you have a panel that is 1 x 1 foot and is placed on the opposite wall from where the speakers are, how can this make any difference? Surely the panel has to be at least half that size (5 x 5) to yield any significant results?

    Looking through members home gallery, I've also seen pictures where people have placed a single sound absorber panel behind the speakers with the intent to absorb sound. The panels were at best twice as large as the speakers themselves. I'm guilty of the same, but I can see how it's effective other than looking aesthetically pleasing.
  10. coldmachine

    coldmachine Member

    Joined:
    Jan 10, 2006
    Messages:
    585
    Trophy Points:
    43
    Ratings:
    +180
    I'll try and be a bit clearer.

    Larger areas of absorption will bring down the reverb time, and ringing, in your room. Depending on their position they may also deal with first reflections, as i explained above. A well thought out treatment would cover both bases.

    Lets assume your room has a load of furnishings and you don't need large areas of absorption to bring your reverberation time down. In this case huge improvement can still be gained by placement of absorbent panels at the first reflection points. In a room of the size you scribe, and subject to mid and high driver arrangement, they will not need to large. By definition, first reflection points are relatively small.

    A first reflection point is where the sound reflects from a wall, floor or ceiling directly to your ear. It is the most significant, and most problematic reflection. When they are dealt with, the difference is not subtle. When not dealt with, your listening experience is severely hampered. They are easily determined by having someone hold a mirror against the relevant walls. The point, from your listening position, at which you see your speaker drivers id the point from which the first reflection originates.

    The judicious use of just a few suitable, and correctly placed, panels can yield very significant results. Ive seem many rooms enjoy major improvements simply using a few 2'x2' panels.

    I hope that answers your question.
    • Thanks Thanks x 1
    Last edited: Oct 1, 2009
  11. AndyST

    AndyST Member

    Joined:
    Dec 17, 2005
    Messages:
    407
    Trophy Points:
    31
    Ratings:
    +61
    Bear in mind that the design and proper implementation of acoustic treatments can involve some quite complex maths and physics. Many people may simply buy a panel or 2 from a company such as Auralex and slap it on the wall, without any understanding of the optimal way to use the product. So just because you see pictures like that, doesn't necessarily mean it's the correct way to do it.

    The treatments your room will require is very much down to it's existing furnishings & layout. Unless it's a dedicated room there's always going to be aesthetic compromises as well.
    • Thanks Thanks x 1
  12. marcus263

    marcus263 Member

    Joined:
    Nov 29, 2008
    Messages:
    144
    Trophy Points:
    18
    Ratings:
    +6
    Now it makes sense. I've just done a bit of reading on what you guys stated, so assuming that you have speakers a foot away from the wall, is it worth placing absorbers behind a speaker to dampen the sound so it doesn't go into the other room? Quite a few articles suggest doing this.

    For example:

    [__] = absorbers

    [xxx] = speakers

    ---- = wall

    Code:
    -----------------------------------------------------------------
      [ ____]              [______________]              [_____]
    
      [xxxx]                                              [xxxx]
  13. AndyST

    AndyST Member

    Joined:
    Dec 17, 2005
    Messages:
    407
    Trophy Points:
    31
    Ratings:
    +61
    Most of the sound coming from the back of the speakers will be in the lower frequency range. High frequencies are extremely directional and are fired like a ray from the tweeter. As the frequency gets lower the spread of sound increases, and once you reach around 125Hz the speaker is radiating the sound equally in every direction (including behind the speaker).

    Now, bass waves are very long, and to absorb them you need either some very deep porous absorption (fibreglass, rockwool) or specially tuned membrane traps. The reason most bass traps are placed in corners is the distance from the panel to the wall is greatest there, giving you maximum effectiveness without using loads of space in the room.

    So a thin panel placed behind the speakers is going to do very little. One, because the frequencies they deal with aren't being fired in that direction, and two, because they are ineffective at dealing with the omni-directional bass waves.

    In terms of soundproofing your room, sticking panels on the wall will do very little. This will require some major structural work. These are purely to treat acoustics within the room, not stop the sound leaving.
    • Thanks Thanks x 1
  14. Zorba_8

    Zorba_8 Member

    Joined:
    Jan 8, 2009
    Messages:
    1,866
    Trophy Points:
    66
    Ratings:
    +150
    For a good guide and very user friendly video (there's two of them) go to "AVForums.tv" and scroll down to the bottom where there's a drop down bar. Under here you will see two videos entitled "Room Acoustics Examined Part 1" dated 27 July 2009 and "Room Acoustics Part 2" dated 10 August 2009.

    Here Rob Sinden from Geko talks about room acoustics (more tailored to lower frequency issues) but covers other issues too. Definitely worth a look. :smashin:
    • Thanks Thanks x 1
  15. coldmachine

    coldmachine Member

    Joined:
    Jan 10, 2006
    Messages:
    585
    Trophy Points:
    43
    Ratings:
    +180
    No.....Absorption panels will do very little to soundproof a room. That is a whole different subject.

    If your room is not bare, and over reverberant, the first reflection points are where you should start. My previous post explains that.
    • Thanks Thanks x 1
    Last edited: Oct 1, 2009
  16. BlueWizard

    BlueWizard Well-Known Member

    Joined:
    Jun 19, 2007
    Messages:
    14,963
    Trophy Points:
    166
    Ratings:
    +2,682
    I think this is where you keep making your mistake, just as in your first post, you are assuming, people have done one and only one thing to their room. In this case, you suggest they have placed a single Absorber on the same wall as the speaker, and stopped there.

    As I pointed out in your original post, that is wrong. Likely all these rooms have many other factors that come into play; acoustical ceiling tile, carpets, etc....

    A room that 'rings' or has reverb can sound very alive on first listen, but both muddy and muddle the music, and it eventually becomes fatiguing.

    But 'ring' and 'reverb' are only one problem, you must also prevent standing waves. You must prevent large sound wave faces from being reflected off distant surfaces, and bouncing back to collide with on-coming waves. Then these waves collide, depending on phase, they produce both nulls and peaks in the room. This can happen between the side walls, though less so, mostly between the front and back wall, and it can occur between the floor and ceiling.

    To some extent general absorption can help, but it is very difficult to absorb a 35 foot long 30 hz wave. But if that long wave hits an uneven irregular surface, it is not going to bounce back in a solid wave front. It is going to be broken up into many smaller waves moving off in all direction. That prevents the massive null and peak points in the room. They may still be there, but they are small and diverse.

    Full professional acoustic room treatments can cost a king's ransom, but any thing you do with the acoustical problems of a room in mind helps. For those who don't have a king's ransom available, simple more cost effective things can improve the room.

    You seem to be concentrating on the speaker side of the room, and while that is important, I think the far side of the room is more important. Some basic absorption and diffusion there will go a long way to stopping problems cause by large and small wave front reflections.

    Now of course, that assume you have dealt with other aspects; carpets or rugs on the floors, acoustical tile on the ceiling, curtains on the windows, etc....

    It seems that most today in the UK favor the very minimalist ultra-modern room designs, and they certainly do look good, but they are an acoustical disaster. Old fashioned clutter softly furnished heavily curtained rooms are much better acoustically.

    Here we see a huge contrast in how two very different rooms can sound, even though neither has true acoustical treatments.

    With a little common sense, most room can be brought to an acceptable level with very little effort or cost.

    Dedicated AV rooms, I think require a little more since they don't have a lot of clutter. They basically have screen, speakers, and seating. A room like this need more effort to make it work, and that effort is best spend when building the room, rather than as an after thought.

    Again, while it can certainly cost a king's ransom, there are basic things that can be done on the cheap that will noticeably improve a listening room.

    But, you can't concentrate on one surface to the exclusion of all others. You need to look at every flat surface in your room and consider how it is going to effect the overall sound.

    You need to look at reflections that are going to cause timing issue; in short, reverb.

    You need to look at reflections that are going to cause standing waves, and nulls and peaks.

    If you've done a modest job of dealing with these issue, then you've gone a long way to controlling your room. How far beyond this you want to or need to go can only be determined by the owner's will and wallet, and the room itself.

    Instead of looking at it as, what if I place this here; you need to look at it as, what needs to be done and where.

    Steve/bluewizard
    • Thanks Thanks x 1
    Last edited: Oct 1, 2009
  17. marcus263

    marcus263 Member

    Joined:
    Nov 29, 2008
    Messages:
    144
    Trophy Points:
    18
    Ratings:
    +6
    Yeah I totally agree. My mistake is that I'm listening to people who don't really seem to know much about it themselves. The whole thing started when I was trying to sculpt an artistic diffuser out of wood... I got a lot of advise and critique from other people on how to go about building it.

    So curious, do people with 7.1 surround need to consider acoustics treatment if they really care about their sound quality? I presume not since sound is coming from all directions and they don't need to worry about reverb or that 'ring' you mentioned?

    Edit: The people I've been listening to actually put up just "one" panel and swear it makes a difference, not sure if it's just a placebo.
    Last edited: Oct 2, 2009
  18. AndyST

    AndyST Member

    Joined:
    Dec 17, 2005
    Messages:
    407
    Trophy Points:
    31
    Ratings:
    +61
    I'd say acoustic treatments are more important when you're looking at home cinemas with 5-7 speakers and a sub. The problems will still be there, but with more sound sources it will amplify their effect.

    Now you can pretty much treat the mids and highs with some basic additions such as curtains and a rug on the floor at the first reflection point for example. If the room has a lot of soft furnishings you could consider adding diffusers which will break up sound waves without taking the energy out of the room.

    The area you really need proper treatments in is at the bass end of things. EQ is good to a point, but it has limitations. The main one is it cannot fix nulls. Good EQ can adjust phase to reduce them where the microphone is placed, but move your head a bit to the side and you've got a completely different response.

    Decent bass traps on the other hand will reduce both peaks and nulls, for any position in the room. They will also reduce ringing and decay time giving you much tighter and more detailed bass (thanks to the nulls being fixed). So I'd recommend you start with these, placed in as many corners of the room as you can.

    Then, as others have said look at the first reflection points using a mirror and see what you can place there to absorb or diffuse the sound waves.

    Wood is an excellent material for building diffusers with too. The math to create optimal dispersion of the sound waves can be pretty daunting, but there are some standard templates and tools you can use if you want to build your own.
  19. marcus263

    marcus263 Member

    Joined:
    Nov 29, 2008
    Messages:
    144
    Trophy Points:
    18
    Ratings:
    +6
    Here is a report I was "basing" my trial diffuser on: http://downloads.bbc.co.uk/rd/pubs/reports/1969-16.pdf

    With a picture here:

    [​IMG]

    I'm wondering though, what effects am I looking for with a diffuser and an absorber? Different people seem to have their own subjective view on this, but there must be a universal acceptance, e.g. using an absorber reduces that echo sound you often hear in large empty rooms.
  20. AndyST

    AndyST Member

    Joined:
    Dec 17, 2005
    Messages:
    407
    Trophy Points:
    31
    Ratings:
    +61
    It can be a difficult area to research for that very reason, there's such a variety of opinion about what is best (even amongst professionals). What you're aiming for is to make the room disappear from the soundstage, and to have a roughly flat frequency response where all frequencies decay at a similar rate.

    The ideal place for this is an anechoic chamber, however it's just not practical to build one of these in a typical home. Plus if you've ever been in one it's a very creepy experience, absolute silence.

    What you should aim for is balance. You need enough absorption to keep decay times down and correct bass issues, and enough diffusion to spread the remaining sound energy around the room so it isn't localised. Few people actually use diffusers as premade ones are expensive to buy and DIY ones take a lot of effort to make. On the other hand it's very cheap to buy or simple to make an absorbant panel.
  21. BlueWizard

    BlueWizard Well-Known Member

    Joined:
    Jun 19, 2007
    Messages:
    14,963
    Trophy Points:
    166
    Ratings:
    +2,682
    For some very informative videos on acoustic treatments, check out Real Traps -

    Main Website -

    RealTraps - Home

    Videos -

    RealTraps - Videos

    There is one particular video where the owner of the company is demonstrating various types of diffusers including a bookshelf. You can hear a difference between the various types.

    Really trapping deep bass is difficult, but controlling reflections is well with in the realm of the do-it-yourselfer. There are several videos, including those from Real Traps on YouTube about building your own absorbers, and diffusers.

    Anything you do will make a difference. One diffuser will make a difference, but whether that difference is enough to solve your problems, and whether the diffuser will work best on the front wall, the back wall, or the ceiling can only be determined by trial and error combine with careful objective listening.

    For those who want general diffusers ON THE CHEAP, consider convoluted packing foam or a convoluted mattress pad. The packing foam, if I remember right can be bought pretty cheap in charcoal, white, o pink. Sadly mattress pad are only available in basic off-white.

    Packing foam will not be flame retardant, but a mattress pad will be. These act as both basic diffusers and absorbers. Though the color is less than pleasing.

    Real Acoustical Foam is also available, but it is not real cheap; usually in convoluted or wedge shape. This will certainly work the best.

    Some examples, just for reference (this is a USA site, but the same can be purchased in the UK, I just don't know where.)

    Parts-Express.com: Super Wedge Acoustic Wall Tile 5" x 12" x 12" (UL 94) Each | wall tile wedge bass trap home theater acoustic control sonic impact

    Parts-Express.com: Acoustic Foam 1-1/2" 24" x 18" UL 94 | foam acoustic foam damping dampening dampening foam cabinet foam egg crate convoluted cabinet_damping

    Parts-Express.com: Cascade Pyramid Design Panel 2" Charcoal | acoustic panel sound control acoustic foam pyramid foam wall panel

    Parts-Express.com: Cascade Pyramid Design Panel 3" Blue | acoustic panel sound control acoustic foam pyramid foam wall panel

    Parts-Express.com: Acoustic Wall Tile 2" x 12" x 12" (UL 94) Box of 16 | wall tile wedge noise control acoustic control studio foam sonic impact

    Parts-Express.com: Cascade Cornertec Ceiling Corner Trap Charcoal | bass trap corner trap sound corner ceiling bass trap noise

    Here is a quick reference to some basic Packing Foam, again just for illustration -

    http://www.uline.com/BL_8002/Anti-Static-Convoluted-Foam-Sets

    http://www.uline.com/BL_863/Convoluted-Foam-Sets?keywords=foam

    Also, remember a room doesn't have to be perfect, it just needs to be reasonable.

    As another simple possibility for a AV room, would be moderately low price tapestries for various Art Print and Poster shop. If you are in a windowless room with no curtains, as a home theater might be, you could hang tapestries on the wall between the speakers and the listeners. These would help soften the room and would look very nice too. If you stood the tapestries out from the wall a bit, you could even hide additional sound absorbing material behind them.

    Examples of tapestries -

    AllPosters.com - The World's Largest Poster and Print Store!

    Again, a USA site, but I have no doubt the equivalent in available in the EU.

    EDITED: Sorry for such a long post. All Posters does have a UK website that has almost a thousand more tapestries than the USA site -

    http://www.allposters.co.uk/gallery...arch=tapestry&imageField2.x=0&imageField2.y=0

    Logic says you would choose darker muted colors.

    These aren't dirt cheap, but you probable spent a fortune on a home cinema room, what a couple hundred more to get the best from it? Plus there are a couple thousand to choose from, and they do look good.

    Really, what you can do to improve a room is only limited by your imagination, and how far you want to take it.

    Steve/bluewizard
    • Thanks Thanks x 1
    Last edited: Oct 3, 2009
  22. marcus263

    marcus263 Member

    Joined:
    Nov 29, 2008
    Messages:
    144
    Trophy Points:
    18
    Ratings:
    +6
    Blue Thanks for the links. I was beginning to think that all this diffuser/absorber thing was just marketing because I could never tell the difference. I was also starting to think that I was being "told" what good sound should sound like, but Oh my God hearing the difference between treated and untreated rooms in this video: RealTraps - Ultimate Small Mixing & Mastering Room (6 min mark) I can really tell. My room sounds exactly like it does in all the untreated sound tests so I am constantly messing with my Itunes Equaliser to get acceptable sounds, otherwise as the guy stated, it does drive you cracking mad and give you a bit of an ear ache especially listening to classical rock like Guns 'n Roses or Survivor - it drives you mad.

    What I've also just realised is that I need absorbers not diffusers as my room is too small, so I'm getting all that reflection which is making music listening a pain (RealTraps - All About Diffusion - 12:30 Mark)
  23. BlueWizard

    BlueWizard Well-Known Member

    Joined:
    Jun 19, 2007
    Messages:
    14,963
    Trophy Points:
    166
    Ratings:
    +2,682
    If you go to the Real Traps website, you see a series of photos across the top of the page. You can click on these photo and get a closer view. Most of these are extreme compared to what the average person can do. But notice that many of the wall and ceiling traps stand off from the wall or ceiling. By doing this, the absorbers and absorb from both sides.

    Also, in the diffuser video, notice how crisp and life-like the guitar was in front of a good diffuser, and notice how dull and muddled it sounded in front of less type diffusers. Also, notice how dull it sounded in front of an absorber.

    You don't want the room to be 100% absorbing, or the life goes out of the music, but you don't want excessive reflections either, or the music steps all over itself.

    And, as I said before, few can afford acoustical perfection. Most of us do the best we can with the room and the resources we have. In most cases, good enough is...well...good enough.

    Steve/bluewizard
  24. dazzdax

    dazzdax Member

    Joined:
    Sep 6, 2010
    Messages:
    2
    Trophy Points:
    1
    Ratings:
    +0
    Hi folks, my audio system is situated in this room (see picture). Behind the left speaker (Soundlab A-1 electrostatic) and on the left side of it there are two large windows, which are covered by wood blind (Luxaflex), behind the right speaker there is a concrete wall. Although the room is quite symmetrical, acoustically speaking it is far from (acoustically) symmetrical. So I would like to ask you: what do you think of this situation? Should I get a large diffusor and place it behind the right speaker, to create a condition that resembles that of the left speaker because I believe the blinds are functioning like diffusors. Or am I wrong? Thank you in advance.

    Chris (dazzdax@xs4all.nl)

    Attached Files:

  25. Mark.Yudkin

    Mark.Yudkin Member

    Joined:
    Sep 19, 2007
    Messages:
    8,807
    Trophy Points:
    136
    Ratings:
    +1,271
    1) This thread is a year old. If you have a new question, open a new thread.

    2) Soundlabs ESLs are a very special case with their drum resonance based planar membranes, and they are very hard to find outside of the US. Since this is a European forum, you aren't going to find many people here with Soundlabs ESLs, especially at their prohibitive local price (the Audiophile-1 PX is listed by the UK Importer at £21,525, 3 times as much as the Quad ESL-2905 with which it directly competes). Those of us with Quad, Martin Logan or Kings Audio ESLs cannot apply our knowledge to your case, due to the unique properties of the Soundlabs panel design and differences to the designs of Quad, Martin Logan or Kings Audio.

    3) The SALLIE module is apparently specifically manufactured by Soundlabs as a remedy for problems such as yours, and is custom-tailored to the specific radiation patterns of their speakers (see link). I would suggest you contact your local Soundlabs dealer to source a pair for testing. I would not expect a diffusor involving only one speaker to yield much of an improvement.
    Last edited: Sep 7, 2010
  26. dazzdax

    dazzdax Member

    Joined:
    Sep 6, 2010
    Messages:
    2
    Trophy Points:
    1
    Ratings:
    +0
    Thank you for your reply Mark. Do you agree that the room is acoustically asymmetrical? I can hear some differences between the right and left speaker. It seems to me that the left speakers sounds a bit mellower and less in spl than the right speaker and I believe that is caused by the scattering of sound waves by the blinds behind the left speaker (while the backwards beam from the right speaker is reflected back by the concrete wall).

    Chris
  27. Mark.Yudkin

    Mark.Yudkin Member

    Joined:
    Sep 19, 2007
    Messages:
    8,807
    Trophy Points:
    136
    Ratings:
    +1,271
    Dipolar planars emit as much energy to the rear as to the front. This makes positioning critical, and the difference between concrete and glass could well be audible. However, given the limited positioning information, it is equally impossible to exclude other issues. For example, rear clearance (I have 1.2m) or the space / furnishing between the speakers (I have a freestanding TV).

    However:
    sounds to me more like you may need to get the ESLs (or possibly the amplifier) looked at, as an SPL difference you can actually hear is more likely to be caused by defective equipment than by differences in hard rear reflection surfaces.

    I therefore suggest first checking this. Switch the speakers to see if the problems move with the speaker or not; if so, get the speakers serviced. If not, switch the left and right speaker wires at the rear of the amp to reverse the stereo image and again check if the problems change positions; if so, get the amp serviced.

Share This Page