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  • Damping panel vibrations with a viscous membrane

    From Anton Shepelev@21:1/5 to All on Tue Jan 10 22:00:41 2017
    XPost: alt.sci.physics

    Hello, all

    I am considering employment of the Tecsound mem-
    brane:

    http://www.texsa.com/en/pl39/productos/id62/tecsound.htm

    to the internal surface of my loudspeaker cabinets
    to reduce panel resonances. Whereas the membrane is
    expensive and a whole roll is too much for my pur-
    poses, I think of buying the Tecsound tape, which is
    the same material but supplied in the form of 5 cm
    (2") tape:

    http://www.texsa.com/en/pl39/productos/id67/tecsound-s50-band-50.htm

    so I shall have to apply several parallel stripes of
    tape to each panel to cover it. Do you think that
    will provide the same level of vibration damping as
    a solid rectangular piece of the same membrane:

    +---------------+ +---------------+
    | | | |
    | | +---------------+
    | | | |
    | | vs. +---------------+
    | | | |
    | | +---------------+
    | | | |
    | | +---------------+
    | | | |
    +---------------+ +---------------+

    I have chosen the transversal orientation because
    the curvature of a panel with a fixed perimeter will
    be higher in this direction.

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  • From Scott Dorsey@21:1/5 to [email protected] on Wed Jan 11 14:00:07 2017
    XPost: alt.sci.physics

    Anton Shepelev <[email protected]> wrote:
    Hello, all

    I am considering employment of the Tecsound mem-
    brane:

    http://www.texsa.com/en/pl39/productos/id62/tecsound.htm

    to the internal surface of my loudspeaker cabinets
    to reduce panel resonances. Whereas the membrane is
    expensive and a whole roll is too much for my pur-
    poses, I think of buying the Tecsound tape, which is
    the same material but supplied in the form of 5 cm
    (2") tape:

    http://www.texsa.com/en/pl39/productos/id67/tecsound-s50-band-50.htm

    My suspicion is that this stuff mostly works by adding mass, and that the
    less mass you add, the less it works. It may also provide some reduction
    in radiation because of the impedance discontinuity but I suspect that isn't much.

    There would seem plenty of less expensive ways to add mass, some of which
    might also add rigidity too.
    --scott

    --
    "C'est un Nagra. C'est suisse, et tres, tres precis."

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  • From Anton Shepelev@21:1/5 to All on Thu Jan 12 19:21:28 2017
    XPost: alt.sci.physics

    Scott Dorsey to Anton Shepelev:

    I am considering employment of the Tecsound
    membrane:

    http://www.texsa.com/en/pl39/productos/id62/tecsound.htm

    to the internal surface of my loudspeaker cabi-
    nets to reduce panel resonances.

    My suspicion is that this stuff mostly works by
    adding mass, and that the less mass you add, the
    less it works. It may also provide some reduction
    in radiation because of the impedance discontinu-
    ity but I suspect that isn't much.

    In that case it is a rather weak solution to my
    problem. I thought it added a good deal viscosity,
    and therefore dissipative energy losses as well, be-
    cause this membrane is said to be as effective as a
    layer of lead of identical surface density, and I
    think it is mainly due to its viscosity that lead is
    a very effective damper:

    http://www.bonavolta.ch/hobby/en/audio/lo_damp.htm

    There would seem plenty of less expensive ways to
    add mass, some of which might also add rigidity
    too.

    My primiary objective is damping via energy losses.
    Sand-filled sandwiches are excellent but a su-
    pererogation for my small cabinets.

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