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Anti Vibration Devices

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

  1. Purité Audio

    Purité Audio Trade: Purite Audio

    Inner tube is really a spring, rolling air diaphragm is what you need.
  2. sq225917

    sq225917 Bit of this, bit of that

    It's a big tube, it's low pressure it's removed the howl round feedback I could measure at high volume. It cost nothing. No point spending more.
  3. flutteringwow

    flutteringwow I am a sound quality evaluation device

    Didn't you just respond? See, you get it now!
  4. Ayya Khema

    Ayya Khema pfm Member

    Why not you use google and answer your own questions?

    professionals use well loaded hemisphere sorbothane for reasons they already discussed ten years ago. They also used springs loaded system if they want to go all out.

    Google coupling
    Google decoupling
    Understand the concept
    Figure out what you want
    Then look at solutions : sorbothane, springs, foam.
    Whats the best solution? Whats used in the studio industry?
  5. NickofWimbledon

    NickofWimbledon pfm Member

    I did use Google when my list of things to wonder about was getting long - it led me to join PFM.

    It's a long time since I studied any of this stuff (and even then we spent more time on stress concentration factors and transmission paths), but even I know that quite a lot of what I can see on the internet about this varies from the 'simple and incomplete' to downright weird.

    I am also aware of what goes under te speakers in some recording studios because musician friends tell me about it while laughing hysterically at what hi-f nerds like me think works and what we'll pay for it.

    I just asked a professional guitarist with 30+ years recording experience whatever happened to the Sorbothane sheets and half-balls that we saw in some studios when we were younger. His comments can be summarised as - you still see them but there never was a consensus, most people still stick their near-field monitors on the desk, and the 'big stuff at the back' may be on concrete, inserted into concrete or bolted onto the XXXXXX wall, but most of the time it's just on the floor. He's been in studios where they have 'things on springs', but it's far from standard. He has however never been in a studio that has bouncy wooden floorboards, no room treatment and lots of soft furnishings.

    The fact that studios don't all use (say) Isoacoustics Gaias or the Townshend equivalents or even spikes under speakers does not mean that they don't work well in the home.

    Some of the articles linked to on this forum have been more informative, factual and free of twaddle than the items I have found myself on the internet.
  6. Purité Audio

    Purité Audio Trade: Purite Audio

    Rolling air diaphragms, visco elastic material, spring in a gasket all ‘work’ they will isolate with varying amounts of efficiency at various frequencies, the question is will they make an audible difference?
    Under turntables perhaps, but you still have to consider airborne transmission under loudspeakers only if the loudspeaker is particularly poorly designed and the floor liable to produce audible resonance, and again we still have to consider airborne transmission.
  7. Chris

    Chris pfm Member

    Just to be different. I would confirm that some Maglev feet (Wills Sound Spikes) that I was given as a present by a mate who visited Korea, did make an audible difference for the better when I placed 3 of them (they come in sets of 4) under my Sugden A21SE in a rough isosceles triangle under where the rather large Toroidal lies, letting the amp wobble like a flan without being in contact at all with its shelf. However, being much higher than the Sugden feet which ended up dangling in thin air, they also raised the height of the Class A amp leaving much more air to circulate and presumably be sucked up through the vents in the amp base so who knows what caused the improvement I heard. Moreover I wasn´t expecting any change at all so I wasn´t auditioning or listening out for it. It just dawned on me after an hour or so of non-critical listening.
  8. Alex S

    Alex S carbon based lifeform

    It’s the cost of this stuff! Maybe get a few squash balls, a couple of inner tubes and a pack of blutac. Or, like fancy fuses and the like, just bring yourself to ignore the ‘I saw you coming’ sections of the market.
    stevec67 likes this.
  9. westsea

    westsea Retirement present

    I don't have particularly strong views, and my approach has mostly been conditioned by DIY, particularly for speakers. I have always had a soft spot for ATC, their engineering approach over the years is impressive, although not so much their affordability, especially in recent years. Back in 87 I bought from Wilmslow Audio a set of ATC 100 drivers and crossovers, the speakers in the avatar took three hard weeks to build. Excluding the cabinets, which were custom made in Pakistan. The rear panels are dished 6mm thick steel all lined with damping material. Amps were remote with 4 metres of speaker cable The following year I chanced on a pair of active amps (the seller had replaced them with £12,000 of Naim custom made actives). Goodness knows why.
    To get to the point, the passive crossovers were mounted on the back of speakers, the idea of the steel back panels being to isolate the electronics from the speakers magnetic field. the added mass, I thought, would reduce any vibrations from the drivers themselves. Not too happy with the doors, the unavoidable hinges may produce some HF reflections, however the then 'family listening panel' passed them as being exceptional.
    On to the active amps, these were mounted on the sides of the chimney breast isolated from the speakers, and of course had to be wired with six core short cables. Preamp was also changed.
    How much the resultant improvement can be attributed to the removal of the electronics from the speaker case is a hard call, too many changes at once, but we did feel good about the new set up.
    As an aside, I thought I saw some years later that ATC and marketed a version of ATC 100 actives with the amps mounted independently of the case, but if so it does not seem to have 'caught on'. It was, I suspect, not a commercial proposition, the amps are quite large and mounting and wiring them was a PITA. They are not pretty. Nor an approach that is repeatable.
    So, although ATC may have considered that separate boxes for their amps & crossovers beneficial, the cost and practical application possibly override what is probably a small benefit
    I have tried various isolation approaches on amps, CD players and pre's without noticeable differences or improvement, that's not to say they don't work for some people or applications, the problem is the range of variables make it quite difficult to assess changes objectively
    NickofWimbledon likes this.
  10. IanW

    IanW pfm Member

    I have experimented with a few approaches after quite a bit of reading around the subject.

    The core problem that I have is that the loudspeakers sit on a suspended floor which has a large air volume beneath them which gets excited with a significant bass content in the music.

    I am in the process of building some loudspeaker stands that are very similar to @awkwardbydesign and have most of the parts but due to health reasons I have not put them all together. As an intermediate experiment I tried inserting the following:

    Between the pucks that the loudspeaker spikes go into and the laminate floor. As I would ideally like to use this approach (constrained layer damping (CLD) absorbs energy across a wide frequency range and does not re transmit the energy in a delayed form as the motion in the visco elastic glue dissipates it as heat) as the main sheet under the loudspeakers in my stands.

    I measured (with the internal iPad accelerometer) and felt the vibration in the laminate floor (which acts as a big surface area to add bass distortion to the room) by the loudspeakers and at the listening position. With the CLD sheets in place the amount of energy transferred into the floor was reduced (both on the iPad accelerometer app and felt through my fingers). And it sounded clearer in the bass and had a clearer soundstage.


    1. The iPad accelerometers are going to be narrow band (0 to 50 Hz, +/- 7.5g) and the display of the data is limited and it is difficult to say much from this other than the levels decreased.
    2. I do not yet have a microphone to use to measure the sound at the listening position before and after the constrained layer damping squares were added. Also as it is a dynamic situation (vibration in the floor (distortion) takes time to build) I would need to think about the best way to compare and display the before and after measurements.
  11. Ayya Khema

    Ayya Khema pfm Member

    Agree for the most part

    decoupling speakers is the start. The best methods are elaborate springs system.
    Sorbothane is almost as effective when properly loaded but cost next to nothing.
    But really, coupling or decoupling, it doesnt matter when you get real big ass speakers. ill eventually get sorbothane for my big speakers that weight 200lbs, but i doubt ill here much of a difference.
  12. NickofWimbledon

    NickofWimbledon pfm Member

    The comments here and on other threads on PFM and the Naim site persuaded me to try Isoacounstics Gaia II's under my B&W 804 D3s. The different tonal balance meant experiments repositioning the speakers. The short way summary of what followed is - you were right.

    In my room and system, and in particular on my bouncy wooden floor, the B&W rubbery feet sound perhaps a touch better than the spikes, but it is so close that I could pick differently on another album and another day.

    The Gaias are not like that. They do very little to low-volume female voice, at least at first, but the stereo image is cleaner. As soon as the volume goes up and a punchy bass comes in, there is a clear improvement - tighter bass means more vigorous rhythm, not less. I still have not got them exactly vertical, but will have another go tomorrow. I am already confident that the overall sound is markedly better, so thanks for the explanations and encouragement to give them a try.

    The fact that they raise the tweeters to exactly ear level may be contributing to the sound difference, but I don't mind too much what has improved technically. The usual tests (Hejira, Cowboy Junkies, DSOTM, Graceland, Rite of Spring, Bruch Violin Concerto) show all the same benefits that everyone who likes them has already mentioned. I can play a touch quieter and make out lyrics, but the most obvious change so far was Nirvana's Come as You Are at the sort of volume that would be approved of in Seattle - the improvement in bass grip is really noticeable.

    For context, I changed the olive 250 that has served for 30 years yesterday (!) with a 300DR. That is certainly a bigger upgrade of course, and I am struggling to think of one of the cliched areas to discuss that it doesn't make a bit better. The Gaias are not like that - they make bass cleaner at any volume, so it does not cover up anything else that one might have been missing and rhythms are more obvious, They have one job to do, and seem to do it well.

    I am doubtful if I could have achieved the same results with a DIY Sorbothane approach, but I really don't mind. Unless I have a sudden & remarkable change of heart tomorrow, they are staying.
    Last edited: Sep 23, 2022 at 9:46 AM
    Sue Pertwee-Tyr and nobeone like this.
  13. sls4321

    sls4321 pfm Member

    Wilson cabinets are pretty rigid, I changed spikes under my Sabrina for Iso-Puck 76 with positive results.They are the designed for use with heavy studio monitors and other studio equipment.

    I user the standard Iso-pucks under my turntable with superb results.

    I get all my hifi in one small cabinet with the turnable on top. I changed the feet for wheels (heavy duty ones with screw plates) and put sorbothane sheet between the screw plates and the unit. It works a treat and cost about £50.
    NickofWimbledon likes this.
  14. nobeone

    nobeone Total Member

    @NickofWimbledon Ah it must be because B&W don't know how to make speakers, such a poor and broken design. Terrible cheap speakers. Awful that they sound better for a few hundred of IsoAcoustic utter foo with no measurements :p

    Really pleased they work for you. Keep up the good work.
  15. Alex S

    Alex S carbon based lifeform

    Never forget to read the small print.
    nobeone likes this.
  16. NickofWimbledon

    NickofWimbledon pfm Member

    Not changing your first name to Keith I hope?
    nobeone likes this.
  17. nobeone

    nobeone Total Member

  18. Purité Audio

    Purité Audio Trade: Purite Audio

  19. ToTo Man

    ToTo Man the band not the dog

    I was wondering when Keith were going to point out this catastrophically fatal flaw in Nick's methodology....

    On a serious note, Keith does have a point here, which is why I made sure to keep the height of my speakers unchanged before and after installing the OREA pucks (I did this by adding/removing plywood shims from under the speakers) ;). FR measurements showed my methodology was robust as there was no change in the before or after FR or waterfall measurements (by 'no change' I mean a change bigger than the intersample variations you get from repeated measurements, - the room is never energised the same way twice and trying to interpret changes in spectral decay with basic tools like a UMIK-1 and REW in the presence of external noise pollution is folly IME). Yet the improvement in the dynamic attack in the midrange was so obvious after installing the pucks I had to tweak my EQ settings as I found my speaker's presentation had become too forward for my liking.
    nobeone and NickofWimbledon like this.
  20. nobeone

    nobeone Total Member

    Were you blind folded, twirled round thrice, and confused by talk about cardioid response, all competantly designed DACs (and presumably speakers) sounding the same while trying to fathom why it sounded different? No? UKAS accredited test house? No? Ah you are obviously deluded by the expectation bias having ££ to improve £££ speakers :D

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