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Thread: Room Dynamics and the Effect of Hard Surfaces

  1. #11
    Join Date: Feb 2010

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    I'm Dave.

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    Quote Originally Posted by Macca View Post
    My understanding is that the reflected high frequency sounds need to arrive at your ears shortly after the direct sound, too much of a delay and you get smearing and muddle. But if there are no reflected HF sounds at all it will sound dead with very little soundstage. So treating a room is a complex undertaking as you need to get into the goldilocks zone.
    Indeed. Also there have over the years (from around 1925 onwards) been different approaches to spatial recording. Early experiments with multi-channel systems suggested that for a sound stage in front of the listener that four speakers (4 channels) were the best compromise - without increasing the costs of more channels - microphones, amps and speakers, that three speakers were quite good, and that the stereo which we now accept as the norm was satisfactory - but not as good as 3 channel systems. Different recording techniques also have an impact - some attempting to remove phase information (Blumlein style), while others using spaced microphones of varying degrees. Some recordings really mess with this.

    It will also depend what kinds of music one wants to listen to. Recordings of live orchestras, soloists, bands in a "real" live environment may, or should, use different techniques from those of synthesised or artificially balanced music. Much material nowadays is effectively electronically processed - and I don't really know how recordings do manage the "ambience" - which is very likely to be "artificial" in any case.

    Should end users rely on the ambience within recordings, or shape their own environments, either by furnishing, hard/soft surfaces, distance between transducers etc., or even control it using speakers and extra ambience systems - such as has been used in large concert halls - though to varying degrees of success?
    Dave

  2. #12
    Join Date: Aug 2009

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    I'm Martin.

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    There are too many variables to establish a 'One True Way' approach, I think. As you say we can't get beyond the variety of recording techniques, let alone the room. And then we are all looking for a slightly different end result from a subjective point of view.
    Current Lash Up:

    TEAC VRDS 701T > Sony TAE1000ESD > Krell KSA50S > JM Labs Focal Electra 926.

  3. #13
    Join Date: Jul 2017

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    I'm Paul.

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    Theres alot of ifs and maybes for sure. If my head is near a flat wall and that wall is directly opposite my speakers will putting something on that wall stop or reduce sound bouncing back to my ears from behind? The sofa has to stay where it is.

    If it would would i may mock up some panels of similar dimensions to my painting. I would even consider covering the whole wall if i can find something that doesnt look naff.

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  4. #14
    Join Date: May 2016

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    Quote Originally Posted by Pepperamip View Post
    Theres alot of ifs and maybes for sure. If my head is near a flat wall and that wall is directly opposite my speakers will putting something on that wall stop or reduce sound bouncing back to my ears from behind? The sofa has to stay where it is.

    If it would would i may mock up some panels of similar dimensions to my painting. I would even consider covering the whole wall if i can find something that doesnt look naff.

    Sent from my SM-G930F using Tapatalk

    Yes, an acoustic panel or panels will reduce the rear wall reflections. I find that such reflections can "smear" the music and make it more difficult to follow detail.

    I made a couple of panels for behind my listening position. I bought a couple of naff canvas prints and covered the front surface with 100mm acoustic Rockwool. I then covered the whole thing with an old cotton sheet which I affixed with a staple gun. The cosmetic appearance was tidied up with some simple stenciling and stipple brushing with black fabric paint.

    It works well acoustically and doesn't look too bad either.

    Geoff
    Attached Images Attached Images

  5. #15
    Join Date: Jun 2018

    Location: Mildenhall, Suffolk

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    I'm John.

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    In general the methods to acoustially tune a disturbed air movement in a room are carried out using controls, through Absorbtion and Diffusion of soundwaves meeting reflective surfaces.
    The basic intention is that the ear receives much of the sound projected directly from the speakers, with the goal for the ear not to receive a excess of reflected sound from surfaces within the room.
    The control measures can be furthered if external interfereing noise,
    i.e 'Road Noise' are having a noticable impact on the quality of sound being produced.
    In general most individuals like colouration in their music replay presentation, so overkill on devices to control a rooms disturbed air movement will be unneccessary.
    Carefully placed absorption panels, so that a void of about 100mm from a wall to absortion material is present, will allow for a double absortion of sound wave.
    Diffuser panels will break up sound waves redirecting their travel away from the ear.
    The end users ear is the key to identifying the overall effect of the controls in use.
    So the applications of devices and perceived effect on the listening space are subjective to the individual, in relation to how much colouration they are willing to live with.
    Even putting trust in a computer programme, with sound pressure measuring devices, will not always produce a result that suit a individuals preferences.
    It may be a good starting point to create the desired control.
    As a example a reverberation or ring created by certain frequencies can vanish immediately with correct placement of control devices, this would be classed a positive.
    As a rule this field of learning is a DIY friendly place.
    Most of the common used control devices are relatively easy to produce and with a little investigation, materials can be sourced cheaply.
    If making a Insulation Absorption Panel, a 45Kg per cubic metre insulation is the recognised all rounder.
    There are plenty of Diffusion Panels ideas out there, even plans with scientific calculations supporting them.
    I have just seen the OP's image and seen that it looks like he is using his scatter cushions as additional absorbers.
    As a alternative the records can be stagger stacked on the rack, in 50mm batches, with one batch projecting about 50 -100 froward from the original stack line, this wll serve as a basic type of diffuser.

  6. #16
    Join Date: Jul 2017

    Location: Kent

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    I'm Paul.

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    Thanks John, i often give up listening if for example its summer, i have the windows open and theres too much noise polution. I dont want to make the entire room dead but im sure a little

    Geoff i like the idea of making my own panels so ive ordered some rockwool (120 x 60 x 5cm) which i will try naked in various positions. If i like the results i will frame and cover them and probably save myself a small fortune in the process.

    An accoustic panel / tile v bare wall round mine.....whos up for it?

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  7. #17
    Join Date: Jan 2009

    Location: Essex

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    I'm openingabottleofwine.

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    Quote Originally Posted by Macca View Post
    My understanding is that the reflected high frequency sounds need to arrive at your ears shortly after the direct sound, too much of a delay and you get smearing and muddle. But if there are no reflected HF sounds at all it will sound dead with very little soundstage. So treating a room is a complex undertaking as you need to get into the goldilocks zone.
    Yes, it's called the Haas, or precedence effect: https://en.wikipedia.org/wiki/Precedence_effect .

    I seems that the 'live end, dead end' school of thinking (that I mentioned) has now been abandoned.
    Barry

  8. #18
    Join Date: Aug 2009

    Location: Staffordshire, England

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    I'm Martin.

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    I think that predates a lot of the research done in the last ten years or so. It's still basically right though.
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    TEAC VRDS 701T > Sony TAE1000ESD > Krell KSA50S > JM Labs Focal Electra 926.

  9. #19
    Join Date: Jul 2017

    Location: Kent

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    I'm Paul.

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    I seems that the 'live end, dead end' school of thinking (that I mentioned) has now been abandoned.[/QUOTE]

    Not totally Barry as the first thing I will do is put the panels at the speaker end. My right speaker is in a corner and is causing a little boom so I'll have one on the right wall before the french door curtains and one directly behind the speaker. I'll do the same with the left speaker too (except just the one panel behind as this one is in the middle of a long wall) I'll try the additional panels on the rear wall afterwards and see if that improves things or not. Nothing will be permantly fixed until I'm happy but I appreciate the live end / dead end approach you've highlighted.
    Current system:
    RPi + Allo Digione
    Beresford Caiman Seg & Dorado powered by 15v Linear PSU
    Transcendent Sound Mini Beast OTL
    Amptastic Mini-1
    Klipsch KG4.5 Speakers with Titanium Diagphrams and Sonicap Cap upgrade
    110aH Leisure Battery powers the Mini-1 & Digione

  10. #20
    Join Date: Aug 2009

    Location: Staffordshire, England

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    I'm Martin.

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    This is worth a read - if only to get an idea of how complex it all is:

    https://www.audiosciencereview.com/f...-acoustics.75/


    'How many singers do you know that like to sing outside where there are almost no reflections? Have you tried to sing yourself there? Fact is that some of these effects are totally non-intuitive. We think a reflection is a bad thing. But clearly no singer thinks that. I know it is hard to let go of these notions but let go we must'
    Current Lash Up:

    TEAC VRDS 701T > Sony TAE1000ESD > Krell KSA50S > JM Labs Focal Electra 926.

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