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panzerholz plinth?

Discussion in 'd.i.y.' started by jamie123, Dec 19, 2016.

  1. misterdog

    misterdog Not the canine kind

  2. YNWOAN

    YNWOAN 100% Analogue

    That looks really interesting :).

    It sounds a bit like Paxolin which is a resin impregnated and bonded paper structure.
     
  3. ChrisPa

    ChrisPa pfm Member

    Which - Corian or panzerholz?
     
  4. Helen Bach

    Helen Bach if it ain't Baroque ...

    with a name like Grimm, I suggest it has to be Corian :D
     
  5. orangeart

    orangeart KJF Audio Ltd.

    Its Hi Macs
     
  6. guydarryl

    guydarryl Active Member

    Refreshing to read a post that makes scientific sense to me. thanks :)
     
  7. JemHayward

    JemHayward pfm Member

    If we want a structure to transmit vibrations, rather than dissipate them as heat, would we want a high damping factor, or a low damping factor, or, is damping factor just irrelevant in this context?
     
  8. guydarryl

    guydarryl Active Member

    I would have thought that if you want transmission then keep it simple and no damping factor!
     
  9. Helen Bach

    Helen Bach if it ain't Baroque ...

    what do you mean by 'transmit vibrations'? from where to where, and why?

    No damping factor? Every solid material has a damping factor.
     
  10. guydarryl

    guydarryl Active Member

    I guess that Jem was asking from the point of view that rather than trying to "damp" vibrations within a structure (such as a turntable plinth), would it be more sensible to try and transmit/conduct/carry the vibrations to an alternative location - "earth"?

    My (tongue in cheek) response is in that case you would want no "damping factor" in the material.

    Often in the case of trying to find a solution to a problem it is best to try and take the theoretical solution to an extreme.
     
  11. Helen Bach

    Helen Bach if it ain't Baroque ...

    I think, then, I would ask what the 'mechanical earth' was.

    Vibrations (in the structures we are discussing, at audio frequencies) can be thought of as tiny up and down movements of a panel (often called a plate in physics). These displacements cover virtually all of the panel, depending on the resonance frequencies of the modes. Internal damping of the panel material will convert the vibrations into heat by friction (although other damping will probably be present). The greater the damping, the shorter the time taken for the vibrations to diminish.

    If the panel is connected to a mechanical earth, depending on the relative masses, either the earth will vibrate, or the vibrations will not be 'earthed', and the panel continues to vibrate. If the vibrations are transferred to the 'earth', then that must have damping properties, or it will continue to vibrate, and transfer these vibrations back to the panel. I can't see that this is a good thing. Either way, the panel will still vibrate a lot.

    For a simple approach (all for that) just choose materials with very good intrinsic damping, and please, no-one mention damping sucks the life out of their music.
     
  12. nicetone

    nicetone pfm Member

    Helen - great reading in your posts here and on Suffolk Tony's thread. Much food for thought. Thanks, and more please!
     
  13. Helen Bach

    Helen Bach if it ain't Baroque ...

    thank you, kind sir. :)
     
  14. JemHayward

    JemHayward pfm Member

    I was thinking about the mechanical job of connecting two things together so they move in unison, e.g. parts of car suspension, and maybe even a subchassis of a turntable (if we think that is desirable) - or at a smaller scale, from the stylus to the coils in a cartridge. Is there an advantage / disadvantage to high/low DF in these sort of structures.
     
  15. Helen Bach

    Helen Bach if it ain't Baroque ...

    as I understand it, a car's suspension is built to be as stiff as possible, with with some riggle room in the form of bushes. The springs give the compliance, whereas the so-called 'shock absorbers' are the damping. There is no earth, unless it is floating! ;)

    In the pickup cartridge, one must aim to conduct the vibrations of the stylus to the other end of the cantilever as accurately as possible, but damp it (significantly) with an elastomer. Damping values around 0.2 to 0.6 I have measured.

    I think the essence of these designs (and many others, including loudspeakers) is that damping is used to obtain the response we desire. It seems almost essential in most situations.
     
  16. JemHayward

    JemHayward pfm Member

    But is damping desirable in the elements that we want to be stiff, e.g. the cantilever, or the suspension arm itself?
     
  17. Julf

    Julf Evil brother of Mark V Shaney

    That is true for a modern car, but you clearly haven't driven in a Morgan... :)
     
  18. PigletsDad

    PigletsDad pfm Member

    Yes. At a resonant frequency, the effective stiffness falls to roughly the static stiffness divided by the Q of the resonance. Damping, which reduces the Q, maintains the stiffness across frequency.
     
  19. Helen Bach

    Helen Bach if it ain't Baroque ...

    no, but I have driven a Triumph (passed my test (first time) in one!) which also has leaf springs, which is what I think you are alluding to, but both had/have shocks?
     
  20. ChrisPa

    ChrisPa pfm Member

    There are 2 other very important systems in a car's suspension - tyres, and upholstery

    The tyres are probably at least as significant as the suspension. They are springs and damping all in one. They have different lateral and vertical behaviour. There are different behaviours from the sidewall/air system and from the tread/road surface system
     

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