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Anti Vibration Devices

Discussion in 'audio' started by Whizzy, Dec 14, 2021.

  1. awkwardbydesign

    awkwardbydesign Officially Awesome

    Bear in mind that some studios use Van Damme cables (cheap and tough) and some use expensive cables. Not all professionals are equal.
     
    NickofWimbledon likes this.
  2. NickofWimbledon

    NickofWimbledon pfm Member


    It's a fair point from @Purité Audio of course. Fortunately, I have a spine, so can sit a bit taller in my armchair and then hunch a bit for the 'Back as it was' mandatory test. I can't be sure I kept my head still and at exactly the same height without some rather excessive restraints, but I doubt that any of us keep absolutely still when listening anyway - whatever happened to foot-tapping and headbanging and all that?

    I did also try sitting on an extra cushion to see if the SQ uplift was affected in any audible way (it wasn't), but cannot prove that the compressed thickness of the cushion was a close approximation of the net height of the Gaias.

    Fortunately, my girlfriend is about 5 inches shorter than me and hasn't quibbled with any of the above. 2 is a small sample size of course, but a couple of other listeners (one a good deal taller than me) will opine next week.

    TBH, I was (like @nobeone I suspect) a bit disappointed that it had been several hours and no-one had mentioned expectation bias. After all, if I had not 'expected' a benefit to some degree or other, I would not have tried them. In addition, having spent some time fitting them (and removing and fitting them again) and looking at them while playing music, I could hardly forget their presence. My girlfriend also didn't go for a blindfold - it was only mid-afternoon - so anyone with a strong desire to reject what we think we heard as evidence of anything is welcome to take that alone as a reason.

    Keith, the best I can do thusfar on bass grip is to defer to the explanation given by a saxophone player (girlfriend again). She says that bass notes start and stop more suddenly or decay more realistically, and that it is easier to distinguish between 2 instruments both playing very low (e.g. organ and double bass) when playing quietly.

    As for how rubbery feet can possibly do this, I don't mind too much, as mentioned. My best guess is that it has a lot to do with my floor - bouncy floorboards on bouncy cross-supports with a few inches of air underneath sounds to me as if I sit on a large bass drum. We may well be hearing the floor as well as the speakers, and the movements of the floor (with just a little delay) from one speaker presumably have an effect on the other other too. Am I missing something obvious?

    Finally, the issue of whether the B&Ws 'store energy' also seems confusing to me. Surely, the issue is where the energy goes?
     
    Last edited: Sep 23, 2022 at 4:00 PM
    Sue Pertwee-Tyr, nobeone and ToTo Man like this.
  3. Purité Audio

    Purité Audio Trade: Purite Audio

    The most difficult problem is the time taken between listening with and then without the feet, the brain only remembers a presentation for a few seconds, hence Harman’s ‘shuffler’ replacing one pair of loudspeakers with another playing at exactly the same volume within four seconds , that is impossible to replicate at home.
    There would have to be enough structural vibration transmitted to audibly excite the floorboards, when we measured here ( suspended wooden floor) that was simply not the case.
    If you placed a naked driver directly on the floor perhaps but that is one of the reasons loudspeakers have enclosures.
    Re air under the speaker bass just doesn’t work like that you have to consider the rooms total dimensions the amount of bass returned to the room.
    An audible resonance can only occur if the loudspeaker’s enclosure is storing energy at that frequency, it needs to be excited long enough and with enough amplitude to create the resonance, if the speaker were improperly designed that would be evident in the spectral decay plot.
    But hey they are not that expensive and if you believe they make a difference…
    Keith
     
  4. nobeone

    nobeone Total Member

    Fortunately it isn't impossible to do, and IsoAcoustics go round doing exactly this at shows. Worth a moment of your time. I doubt you will leave thinking there is no difference. Naturally you will not accept my word and will want to point out all the impossibilities of a fair test, but you really should try to have an open mind on this area. It might help you appreciate a spectrum is just that, and not the be all and end all
     
  5. awkwardbydesign

    awkwardbydesign Officially Awesome

    So you couldn't measure it? Have you considered that it's your measuring that is unreliable, rather then what we hear? No, of course not.
     
  6. NickofWimbledon

    NickofWimbledon pfm Member

    Some speakers are designed with walls that really buzz to the fingers, and others are very inert indeed. I find it difficult to believe that those who make thin-walled speakers, and also think that bits of wood vibrating in very particular ways is a reason why people rate (say) a Stradivarius.

    The key is surely all of the frequencies involved, including relevant resonant frequencies and harmonics. Measuring (with appropriate focus on transients) and modelling it properly is extremely complicated, even if we agree exactly what to measure and how and how accurately, but fortunately ears do a decent job.

    Of course, the benefits of Gaias could be all in the mind - I can't prove otherwise. However, as long as I and everyone who hears my hi-fi remans just as fooled as we are this evening, we'll be happy listeners - job done.
     
  7. IanW

    IanW pfm Member

    In my case it was minutes, but yes I could be mistaken, hence taking measurements.

    All the speakers (small stand mounts up to big floor standers) that I have ever used in my lounge have set off the laminate floorboards into resonance when playing something like the Prodigy. My current loudspeakers do it the least. Feeling the cabinet at the same time exhibits no motion as the cabinets are effectively inert (a declared manufacturer design aim). So the energy that excites the floor must be either airborne or through the interface to the floor. My hypothesis and hence the experiment was to see if a constrained layer damping solution (measured in a test lab by the manufacturers to cut energy transfer by 20 dB from around 30 Hz up to 200 Hz) as part of the speaker to floor interface would reduce the energy transfer. Which as I described in an earlier post, it did. So it is possible for this to happen and maybe others have a similar problem to me.

    That is not correct, the speaker has no need to store energy in the enclosure to set something in the room off into resonance (in my case the floorboards, in part through the speaker to laminate floor board interface), it just needs to put enough energy into the room, over a time period, in the frequency range that will set the resonance off.
     
  8. ToTo Man

    ToTo Man the band not the dog

    When I was young and foolish I placed a pair of Bose 301s on top of a display cabinet with nothing underneath to keep them in place. Within minutes of bangin' out some 90's dance choons one of them got a bit over-excited and jumped six feet to its death, making a rather large dent in my newly sanded and varnished floor... I wonder if Keith's measurement would have picked that up?!
     
    Last edited: Sep 23, 2022 at 10:16 PM
  9. Tony L

    Tony L Administrator

    If you actually had even the slightest grasp of what music was and how it works you’d realise how profoundly dumb that statement was. Real music happens at least as much in the amplitude and time domains, which none of your religious cult seem to know how to measure. The rest of us can obviously hear it!
     
  10. Joe P

    Joe P Memory Alpha incarnate / mod

    It's true. All we can hear are notes, not how loudly or quietly they're played.

    OK, that was true for the harpsichord, but once the piano — short for fortepiano — was invented, musicians could vary the volume of notes, too. A good pianist can also vary the timing of notes, as illustrated here.



    Just a guess, but a hi-fi likely has to get all three right to reproduce music.

    Joe
     
  11. Purité Audio

    Purité Audio Trade: Purite Audio

    They are all related Tony perhaps a little reading?
    Keith
     
  12. Alex S

    Alex S carbon based lifeform

    Which studios use fancy cables? I’ll keep an eye out for their super recordings.
     
  13. Tony L

    Tony L Administrator

    I’ve forgotten more about this stuff than you will ever learn. You are laughably out of your depth.
     
    nobeone likes this.
  14. Purité Audio

    Purité Audio Trade: Purite Audio

    It is both of course, you can isolate to some extent the physical transmission but then there is still the airborne content, these devices are sold on the premise that they somehow ‘manage’ the internal vibration but they can’t, they can isolate the speaker from the floor, the question is does your floor vibrate enough to create an audible resonance.
    It might.
    Keith
     
  15. IanW

    IanW pfm Member

    I know that in my room it is both, that is why I treated my room years ago with Helmholtz Resonators to take resonant energy out around the resonant frequencies (the room modes). I have then added minor tweaks with some EQ, but it is the HRs that made the biggest difference for me measurement wise (noise and waterfall decay and RT60 improvements) and audibly.
     
    nobeone and NickofWimbledon like this.
  16. NickofWimbledon

    NickofWimbledon pfm Member

    You can try Abbey Road, and some with more knowledge than me can probably explain about the Emil Berliner approach to equipment - as long as you don't mind the effect of about 30 microphones.
     
  17. NickofWimbledon

    NickofWimbledon pfm Member

    I have no idea what they used at which points, but have noticed Abbey Road turning up in 2 threads as an example of extreme care and unusual-looking and/ or bulky kit. DG as I understand it discarded just about everything anyone else did for a decade or two - all in-house - but again it is clearly hearsay as I have never been in either.
     
  18. Alex S

    Alex S carbon based lifeform

    I thought they used Van Damme and the Abbey Road cables were a branding exercise. Could be wrong.
     
  19. NickofWimbledon

    NickofWimbledon pfm Member

    The last bit sounds very right, but I don’t think were hard to convince -including some professionals - the George Martin history wasn’t the only reason.

    Van Damme sounds very plausible to me, if later, but I’d just be guessing wildly - sorry.
     
  20. flutteringwow

    flutteringwow I am a sound quality evaluation device

    He is (probably facetiously as its a well repeated story) referring to Studio Connections who apparently developed a cable called Monitor for EMI. Having seen them at Abbey Road, they are still used but they are not the only cable brand there.
     

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