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Thread: Placement options – Impacts of location, orientation and treatments

  1. #16
    Super User JonFo's Avatar
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    Rich thanks for the feedback.

    Which diffusors did you test in your setup?

    Based on my tests, I'd agree a HF MiniTrap is a better rear wave absorber than the regular miniTrap for the ML's.
     
    Jonathan

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    Super User JonFo's Avatar
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    Quote Originally Posted by edwinr View Post
    Thanks for posting that info. Very interesting. I am lucky to have a brick wall behind my Summits. I think this wall offers a nice balance between diffsion and reflection of the rear sound wave.

    Speaker setup is tricky. I recently moved my Summits a few inches to accomodate a new pull down HT screen. I lost the sparkle I was getting before. I moved my speakers another few inches in another direction and changed the toe in slightly. I had the sparkle back...

    Ed, you are so right. The slightest placement changes can have quite substantial effects.

    I should measure a few inches of toe-in change and show what it does.
    It can be startling to see that it's easy to be 'in the zone' or out with a slight tilt or rotation.

    This reminds me, I need to measure the effects of tilt as a distinct element. I’ve always had the theory that perfectly vertical panels are best, but have yet to show objectively what the effect is.
    Jonathan

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    Would the stone shapes on my fire place act as a diffusor ? I would think so as they are all different sizes and shapes with crevices and crannies. I think I may try some treatments still, but overall Im real happy with the room.
    Martin Logan... Odyssey...Krell KSA 100s...Krell KRC3 Pre Amp...Krell Connect Media server/DAC
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    Super User JonFo's Avatar
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    Quote Originally Posted by C.A.P View Post
    Would the stone shapes on my fire place act as a diffusor ? I would think so as they are all different sizes and shapes with crevices and crannies. I think I may try some treatments still, but overall Im real happy with the room.
    C.A.P., yes they will to some extent, especially the more 'offset' they are from one another in terms of depth. However, because they are not scientifically placed, their diffusion characteristics could be either beneficial or quite detrimental depending on the layout.

    An easy test is to put some solid panel (like a sheet of plywood) behind the speakers and see what the diff is. Whether it's better or not, you'll need to see, but I guarantee it will sound quite different.

    With a Dipole speaker, not only is the placement into the room critical, but what’s behind (and to the sides) is almost as important to the sound you get at the listening position.

    So even if you are limited as to where in the room the speakers can go, you can effect substantial changes to the sound by treating the surfaces behind and to the sides of the speakers.
    Jonathan

    System #45 (Monolith IIIx, Sequell IIb, SL3XC)

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    Super User Kruppy's Avatar
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    Jonfo,
    I'm glad you are posting all of this information, nothing like a free lesson in acoustics from the resident expert. I hope to post some of my own thoughts/observations very soon from the suggestions you gave me in my room response thread.

    One question: I noticed that your mic is pointing down. Is this the typical postion for mic measurements? I questioned some of the guys on HomeTheaterShack about my Radio Shack SPL meter and got the response that the accepted position is at a 45 deg angle (understanding that the SPL meter is probably much more directional than a mic). I'm comtemplating purchasing a Behringer ECM8000 mic and a Xenyx 502 or 802 mixer/mic pre amp to get better high frequecy measurements.
    Been Thinkin bout nothing and doin nothin but thinkin...

  6. #21
    Super User Rich's Avatar
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    Quote Originally Posted by JonFo View Post
    Which diffusors did you test in your setup?
    They were the RPG Hemiffusers. Here is a link:

    http://www.rpginc.com/products/hemiffusor/index.htm

    I actually bought these for placement behind the rear speakers for surround field diffusion, but figured I would test them behind the front speakers just to see the different effects of diffusion vs. flat wall vs. absorption. I was expecting an improvement with diffusion and was surprised to find it as bad or worse than flat wall.

    Probably RPG's abfuser would be better for placement behind the panels, because it provides absorption and diffusion. I think the Real Traps diffusors will probably work great as well for the same reason.
    Rich

    This comment is intended solely for educational purposes and should not be construed as conveying any express or implied warranty of fitness for any other purpose. Said comment constitutes merely the humble opinion of its maker and does not reflect the views of the MLOC or of ML, Ltd. YMMV. Trust your own ears.

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    Quote Originally Posted by JonFo View Post
    With a Dipole speaker, not only is the placement into the room critical, but what’s behind (and to the sides) is almost as important to the sound you get at the listening position.

    So even if you are limited as to where in the room the speakers can go, you can effect substantial changes to the sound by treating the surfaces behind and to the sides of the speakers.
    This is exactly my problem in my room. VERY limited in regards to placement of speakers and equipment. So with much experimentation using tilt, toe-in, bass trap and first reflection treatments, I have been able to get some really good results. So for some of you where placement is an issue, do not get discouraged, as you can still get some great improvements.

    BTW, Great post Jon
    .............

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    Jon,

    Thanks for the very interesting and informative lecture. Just wondering what the situation would be like with an absorbtive rear wall, like a heavy curtain or something.
    Ben
    System # 165 : Summit/Descent i/Stage/Passage

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    Super User Bernard's Avatar
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    Quote Originally Posted by JonFo View Post
    .............With a Dipole speaker, not only is the placement into the room critical, but what’s behind (and to the sides) is almost as important to the sound you get at the listening position............
    I thought that with a dipole the sides were not quite as important as the back; note: I am not saying the sides have negligible effect.

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    Quote Originally Posted by benleeys View Post
    Thanks for the very interesting and informative lecture. Just wondering what the situation would be like with an absorptive rear wall, like a heavy curtain or something.
    I have bookcases sitting 4ft behind my seating position. Using GIK 244 panels (3 of them) in front of the bookcases really helped my room response and overall sound. Each room is different and each person has different tastes, so trying out absorption and diffusion behind should be done to see which is the best solution.

    I had thought I read that diffusion behind the seated position is only beneficial when seated further away from the rear boundary.
    .............

  11. #26
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    Quote Originally Posted by JonFo View Post
    I have some RealTraps diffusers (which also do absorption) on their way. I will update this thread when I get them..
    JonFo, thanks for posting this great information - the charts speak for themselves. Just out of curiosity, why did you settle on Real Traps? Are they significantly better than their competitors - ASC, echobusters, etc.? Also, how many did you order, and where are your placement priorities? Stereophile seems to think highly of their new product, Mondotraps. Are there any objective tests comparing the products from the different companies?

    Also, have you heard anything about golden acoustics? http://www.goldenacoustics.com/index.html

    They are supposed to be a "revolutionary" product that uses gypsum. One guy even made the claim to me that by using their product, the limited sweet spot of the Logans can be greatly increased, and one could have more uniform sound throughout the entire room. A high end store in Chicago just bought $40k of their "deluxe" panels, and it does sound good! (The rest of their system is also very expensive - Vivid driven by Luxman).

    Here's their claim:

    Our Tuning Panel Systems(tm) work by preventing both modal and reflective distortion in any space, and by creating linear decay across the entire audible frequency spectrum. They accomplish this by naturally redirecting and scattering the sound waves which hit them without distorting those waves (unlike the distortions created by conventional room surfaces, absorption, and so-called diffusion products). Each panel is made from ultra-high density polymerized gypsum with a working mass density greater than 4 pounds per square foot so that virtually all of the sonic wave energy to 100dB that hits them is redirected back into the room (we have an elite series at 6 pounds per square foot which redirects to pressure levels to 120dB).

    Our Tuning Panels do not distort because of the unique conically-based shapes which populate them. Unlike all other shapes, a cone's radius is constantly changing with respect to its height so the cone reflects sound waves in a non-distorting way (i.e., a non-linear and non-uniform way). Picture water waves on a beach hitting flat rocks, hemispherical rocks, and conical rocks: in the first two cases, the energy undergoes far more compression, acceleration, and chaos than in the case of the cone.

    Each of our conically-based shapes is called a Tricon(tm) because it's a cone that's been halved, then one of the halves has again been halved into quarters of the original cone, and the two quarter pieces are then rotated and restored to the first half. This creates a cone with an edge that assists in controlling the redirection by preventing vortexing of the wave. The heights and spacing of the various cones are derived mathematically as fractals using the golden ratio and Fibbonacci series that are prevalent in nature (e.g., pine cones, pineapples, nautilus shells, etc.). Our technlolgy is the result of 8 years of work, following over two decades of work in high definition recording and development of high definition microphone technology by our founder.

    Although a single panel will begin clarifying any area, multiple panels strategically placed will work systemically to balance and clarify large regions and entire rooms. The result is unprecedented clarity without deadness, or liveliness without distortion. There is no adverse affect to a few panels, and after approximately 20% of the total area of the room's walls plus ceiling are covered, the acoustics are so beautifully rich and pristine, and there is no discernable further improvement. Our 20% rooms are the finest sounding and most viscerally comfortable in the world. Depending on the room, beginnning around 12% coverage, spatiality and uniformity throughout the room are greatly improved (the entire room approaches becoming a "sweet spot"), and a perceived immersion in a rich, smooth sonic field takes place. Because our science is true and repeatable, we offer a money-back guarantee depending on the room and the Tuning level.


    Just curious what your thoughts are.

    Thanks,
    David

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    Super User Joey_V's Avatar
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    Quote Originally Posted by David Matz View Post
    They are supposed to be a "revolutionary" product that uses gypsum. One guy even made the claim to me that by using their product, the limited sweet spot of the Logans can be greatly increased, and one could have more uniform sound throughout the entire room. A high end store in Chicago just bought $40k of their "deluxe" panels, and it does sound good! (The rest of their system is also very expensive - Vivid driven by Luxman).

    Thanks,
    David
    David,

    This is OT, but I can guess what store you're describing there. Glenn Poor. I listened to their Vivid speakers and the Luxman, it's a real good combination. Not much gripe about them. I think they were actually a little more resolute than my Summits, albeit not as coherent.
    Joey "kid with grey hair" V
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    I have tried both absorption and diffusion behind the speakers just yesterday. Absorption killed a little bit of joy to the music, it sounded 'more informal', but diffusion helped too since the sound reflected was a bit harsh. That is logical, since curved panel is projecting wider image onto the narrow space on the wall which is reflected as it is. I guess 'abfusors' work well, but since we don't have that products over here, I will probably make some kind of diffuser out of heavy foam and maybe paint over it. I think the combination of the two is the thing we need for our panels
    Last edited by Sasha; 12-11-2007 at 02:53 AM.

  14. #29
    Senior Member Tj Bassi's Avatar
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    Great thread, Jon! I hope it keeps going....

    Tj

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    Super User JonFo's Avatar
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    Quote Originally Posted by Kruppy View Post
    Jonfo,
    I'm glad you are posting all of this information, nothing like a free lesson in acoustics from the resident expert. I hope to post some of my own thoughts/observations very soon from the suggestions you gave me in my room response thread.

    One question: I noticed that your mic is pointing down. Is this the typical postion for mic measurements? I questioned some of the guys on HomeTheaterShack about my Radio Shack SPL meter and got the response that the accepted position is at a 45 deg angle (understanding that the SPL meter is probably much more directional than a mic). I'm comtemplating purchasing a Behringer ECM8000 mic and a Xenyx 502 or 802 mixer/mic pre amp to get better high frequecy measurements.

    Kruppy, glad you are benefiting, with your pursuit, I figured this would help. I look forward to your results.

    The mic is actually pointing straight up (cable is coming out the bottom). As this is the accepted configuration for using calibrated mics to measure acoustics.

    For the SPL meters, the 45 degree hand-held variant is the right way to measure SPL.

    The ECM8K and the pre you mention will do fine with REW.

    I just got an M-Audio FireWire 410, which does everything I need for mesurements (including phanthom power for the mic), as well as being a great 8channel analog audio output card, and it has bit accurate (ASIO drivers) SPDIF I/O as well. So it's a really nice all-in one, and can be used with laptops as many of them have a IEEE-1394 (firewire/iLink) interface on them these days.
    Jonathan

    System #45 (Monolith IIIx, Sequell IIb, SL3XC)

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