Speaker Stands and Clean Sand / Lead Shot Questions

Discussion in 'Audio Hardware' started by mds, Sep 18, 2017.

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  1. Helom

    Helom Forum member

    Location:
    U.S.
    There will be energy transfer between any two masses that are connected - no matter how small the movement - whether it's by rubber, Sorbothane, silicon, foam, cork or any other worldly material. That's basic physics. Decoupling is a misnomer. The more appropriate term is damping.
     
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  2. Davey

    Davey NP: Hania Rani/Dobrawa Czocher ~ Inner Symphonies

    Location:
    SF Bay Area, USA
    Besides, in most cases you want to directly couple the speakers to the stands for best sound, either via screws in dedicated stands, or blu-tack in generic stands, especially when combined with mass loading the stands and coupling to the floor. Anything you can do to fix the speakers in one place, through high mass or via struts to the back wall or floor will benefit the sound, at least in my experience.
     
  3. murphythecat

    murphythecat https://www.last.fm/user/murphythecat

    Location:
    Canada
    cork, foam, not comparable to syromer of sorbothane
    with sorbothane, the residual amount of vibration (which is basically only in very LF) cannot have any effect on the sound. the stand under the speakers, when the speakers are well "damped" dont matter

    is there something you dont understand?
     
  4. Helom

    Helom Forum member

    Location:
    U.S.
    No, but apparently there's something about basic mechanical physics that you don't understand. No worries, I'm not going to waste my proverbial breath. Enjoy your magically decoupled speakers.
     
  5. murphythecat

    murphythecat https://www.last.fm/user/murphythecat

    Location:
    Canada
    First, there is such a thing decoupling speakers, not just "damping" like you say

    Foam do not decouple, nor cork. dont compare sorbothane (properly loaded) to foam.

    decoupling speakers from the stands is not magical. what would be magical is to not decouple the speakers effectively to the stand and pretend that the material inside the stand would decouple the speakers.

    so ill repeat, when you use proper stands (ie that doesnt resonate) and you decouple the speakers from the stands, what is in the stand cannot affect SQ. IF, only IF, its well decoupled. not easy to decouple, but with the right material very doable (sylomer or sorbathane, shouldnt cost more then 100$ to effectively decouple the speakers to the stands.)

    An inexpensive speaker tweak that works! - Page 2 - Gearslutz Pro Audio Community

    Not sure if your familiar with Northward Acoustics, he is world reknown for his acoustic work in various studios.

    Northward Acoustics had some interesting things to say here on Gearslutz february 2016:

    "ISO stands are pretty inefficient - as are the Auralex foam pads or "Recoil Stabilizers". In particular in the low frequencies. They do some very marginal work in the mids. ISO have a very high natural frequency with barely any deflection, so basically no decoupling characteristics, just basic damping. Pads and Recoil stabilizers are purely damping and have the disadvantage to allow too much speaker cabinet movement. So create a lot more issues than they solve.
    Standards stands are plain okay as long as they don't resonate (metal ones in particular are no good in that area) are structurally sound (multiple legs) and some form of damping is added to them: leg cavities filled with rockwool.
    Adding 5 to 6 balls of blu-tack in-between the speakers and stands has proven to be just as effective at damping the plate resonance as anything from ISO or any type of pad.
    In all cases, biggest and often only differences measured with ISO, Recoil etc are because height of the speakers is modified by inserting the products in-between the speaker and the stand. Keeping the same sweet-spot height, Early Reflections on desks and nearby equipment are shifting in frequency which creates an audible difference in the midrange.
    But it is a difference, not an improvement.

    Foam: no decoupling, just surface damping in the higher midrange and too much cabinet oscillations.
    Blu-Tack: no decoupling, only some limited surface damping in the higher midrange.
    Iso Acoustics: no decoupling, only some limited surface damping in the higher midrange.

    If you look at the ISO website, you'll see there is not once the mention of a natural frequency for the system (decoupling) or simple damping performance. The data they posted is:

    "Laser Vibrometer Testing

    Conducted by the National Research Council in Ottawa, Canada

    Illustrated and quantified the attenuation of vibrations down through the speaker stand structure.

    (3 photos)

    These graphics illustrate 75hz tests on 3 separate stand configurations, with an amplitude of up to 314ยต m/s on the front plane of the speaker enclosure."

    This is absolutely meaningless. They don't actually provide the slightest clue as to actual performance of the system.

    I spoke to them at an AES convention, and they had no idea what I meant by Natural Frequency.

    The Auralex and Primacoustics stuff falls in the same category, but at least there is much less pretention in how they present their products.

    Sorbothane: can be very efficient if the right type for the load is used. Best is to add a dummy load (heavy blue stone) under the speaker to add mass to the system that needs decoupling and to be able to use stiffer Sorbothane pads to avoid unwanted cabinet movements at higher SPL. You also must pay attention to loading of the Sorbothane since speakers are usually front heavy. Calculating load spreading is a must, unless the weight of the added dummy load is many times fold the one of the speakers at which point the difference becomes negligible.

    A key to having all this work well is to also make sure the surface the speakers decouplers are resting on is as stiff as possible - otherwise it will disrupt the behaviour of the system: for example the spring will 'push' downward on a flexible surface when excited, hence the surface will start to bounce too instead of only the spring flexing as intended.

    Sylomer and springs + dampers remain by far the best products to use but need fairly heavy loads. With properly implemented systems, you can have a natural frequency as low as 8Hz with Sylomer and 4Hz with springs + dampers, decoupling effectively way below 20Hz."
    __________________

    you were saying?
     
    Last edited: Sep 18, 2018
  6. Helom

    Helom Forum member

    Location:
    U.S.
    Nice back peddling. Earlier you state that the fill material doesn't matter, whether "fruitie loops or lead," which infers that the stand mass does not matter.

    I suppose that's why Sound Anchor supplies Sorbothane pucks with their stands, so that the mass of the stands is of no consequence.

    And Yes, my last statement you quoted is in fact correct. Whether that has an audible effect on sound quality is endlessly debatable, but true decoupling is just that - zero mechanical connection.
     
  7. murphythecat

    murphythecat https://www.last.fm/user/murphythecat

    Location:
    Canada
    ???
    the added mass is not in the stand, but between the speakers and the decoupling material.
    not me who states whats quoted, its Northward acoustics

    so its: speakers/ heavy stone/ sorbothane/ stands. the added mass is the heavy stone to increase the decoupling material performance... not the stands

    whats in the stand, if proper stands are use (IE dont resonate) will not matter one bit. im not back peddling, ive said that on my very first post and thats precisely what I did in my system (minus the heavy stone)
     
  8. Helom

    Helom Forum member

    Location:
    U.S.
    Maybe you misunderstood my initial point. The individual masses have a direct effect on energy transfer between the two objects. It doesnt matter which side of the mechanical connection it's placed, the mass of either object will effect the nature of energy transfer to the other - that was my initial point. You're claiming it's inaudible, fair enough. Having myself experimented with different stands and coupling materials, I do find that I hear a obvious difference, even when keeping the Sorbothane pucks a constant, which happens to be my favorite coupling material for a clear midband. IME, it's a bit detrimental to bass quality, especially when used with a lightweight stand, but a worthy tradeoff.
     
  9. Wired4Fun

    Wired4Fun Forum Resident

    Location:
    Cary, NC
    I use lead shot, and it works fine for me :) Follow ALL safety precautions.
     
  10. murphythecat

    murphythecat https://www.last.fm/user/murphythecat

    Location:
    Canada
    sorbothane pucks... do you use proper loading? sorbothane to work at all need adequate loading and its best to use hemisphere. not enough loading of the hemisphere or too little make sorbothane innefective. (compression or too much compression)
    Yet another Sorbothane loading thread - Gearslutz Pro Audio Community

    not properly decoupled speaker, so coupled, might give the effect of "more bass"

    The individual masses have a direct effect on energy transfer between the two objects. It doesnt matter which side of the mechanical connection it's placed, the mass of either object will effect the nature of energy transfer to the other - that was my initial point.

    im not sure I follow. the masses of the speakers and stands should not matter since, with the right decoupling method, the energy do not transfer between either. what do effect the amount of energy transfer is indeed what is placed between the speakers and the stands.
     
  11. Helom

    Helom Forum member

    Location:
    U.S.
    I give up.
     
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