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Thread: Active versus Passive Isolation Platforms for turntables

  1. #1
    Addicted to Best! PeterA's Avatar
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    Active versus Passive Isolation Platforms for turntables

    I have read through most of the WBF threads about isolation platforms. There is now a fairly active discussion about the Herzan active platform. Rather than take that thread off topic, I would like to start another thread specifically about the differences between active and passive isolation platforms and their effectiveness under turntables. One observation has been that many of these platforms were designed specifically for scientific instruments likes microscopes and not designed for audio devices which may have internally generated vibrations created by movement within the component. I have read claims that active devices can attenuate such component generated vibrations, but I have not read an explanation about how this is achieved.

    Could users and designers experienced with both active and passive devices discuss the different approaches to isolation and how or why one approach may be more effective than another when used under audio components? I am particularly interested in the potentially different requirements needed to isolate turntables and those that generate internal vibrations and how they may be different for suspended and non suspended turntables.
    My system link on WBF: http://www.whatsbestforum.com/showth...-Sublime-Sound
    Analog: SME 30/12, SME V-12, My Sonic Labs Signature Gold, AirTight Supreme, VDH Colibri Platinum, MINT LP protractor
    Electronics: Pass Labs XA160.5 amp, XP-20 preamp, XP-25 phono, Cables: Transparent REF XL MM2,
    Speakers: Magico Mini II, Essentials: Jim Smith RoomPlay, 3 Vibraplanes, Dedicated circuits

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    Addicted to Best! PeterA's Avatar
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    Here is a photograph of my suspended SME turntable on a pre loaded Vibraplane and an explanation of how I think the various different types of vibrations within the system are addressed:

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    Floor-borne vibrations: There are two steel lolli-columns directly under the front legs of my source component rack in compression between the floor joists and bedrock floor in the basement. There is little if any floor bounce. The rack is a very stiff, rigid DIY birch ply and cherry wood structure supporting 450 lbs of steel on the top shelf. The 150 lbs Vibraplane is preloaded with a 150 lbs steel ballast plate plus the 115 lbs of turntable to approach its design load of 275 lbs.

    Air-borne vibrations: The SME has two thick steel frames separated by four suspension towers. This thin profile lessons the surface area for air borne vibrations from the speakers to effect the system. The mass of the turntable absorbs some of these air borne vibrations.

    Internally generated vibrations: The motor sits on the lower shelf separated from the platter by the drive belt and four suspension towers. Motor vibrations are drained down and away from the structure through four steel ball bearings at each foot below the suspension towers. The mass of the platter, the record clamp and soft platter surface work as a system to absorb energy generated by the stylus and record contact while cartridge vibrations travel along the arm tube through the bearing into the massive arm board and upper shelf.

    The overall approach is one of energy drainage paths, absorption by compact, minimal surface area mass, and air isolation. I don't know how active or passive isolation could address the internal vibrations, or air borne vibrations, so those are handled by the design of the turntable itself. For floor borne vibrations, I added an external passive device. I don't know if or how an active device would be more effective. Note that the motor controller is also up on the Vibraplane to avoid floor borne vibrations.
    My system link on WBF: http://www.whatsbestforum.com/showth...-Sublime-Sound
    Analog: SME 30/12, SME V-12, My Sonic Labs Signature Gold, AirTight Supreme, VDH Colibri Platinum, MINT LP protractor
    Electronics: Pass Labs XA160.5 amp, XP-20 preamp, XP-25 phono, Cables: Transparent REF XL MM2,
    Speakers: Magico Mini II, Essentials: Jim Smith RoomPlay, 3 Vibraplanes, Dedicated circuits

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    Peter, I'm in a bit of comms w Jarek of Stacore, and they're providing an interesting approach of isolating pretty far down but a lot higher as well
    His argument is active isoln does not address these broadband full spectrum vibns
    The product combines a modern take on Vibraplane pneumatics/springs so isolating low down and higher up, slate chassis which as a mixed natural product breaks up vibns further, and ball bearings which aid isoln further
    This is in comparison to a purely air based passive shelf from Speirs and full active electronic from Speirs w the Stacore priced exactly midway btwn the two

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    [Industry Expert] ddk's Avatar
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    Quote Originally Posted by PeterA View Post
    I don't know how active or passive isolation could address the internal vibrations, or air borne vibrations, so those are handled by the design of the turntable itself.
    I tend to agree with you on the turntable design, that's where many of the issues need to be addressed. I use heavy 1" or thicker plate on top of very heavy solid steel table so my experience is relative to that and not a standard audio rack. What one is used to and the design of the actual tt are things that need to be considered in this discussion if trying to figure out effectiveness. If the vibrations are airborne I don't see how any type platform or rack does anything, you need to encase the tt.

    david
    Audio Industry Affiliate:Lamm, Ortofon, ZYX, Keith Monks, Audio Desk, Jensen Transformers, Pheonix Engineering.
    Specialty & Unique Offerings: Vintage horn speakers, Vintage and Modern Turntables, Analog Accessories.

    System 1: Horns+Tubes+Vinyl and digital too- Listening Room 1
    System 2: Horns+Tubes+Vinyl and digital too- Listening Room 2- Near field setup

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    Dave, and Mike Lavigne, thanks for pushing me away from active isoln for my tt on a flexy suspended wooden flr
    My flr is pretty rigid, but it cannot match the inertness of my prev concrete flr, esp at a span of 18x50
    I'm minded to go the Stacore Pl Advanced route, 230lb (!) of modern interpretation Vibraplane pneumatics/springs w slate shelf and ball bearing lateral plane isolation
    At a price point between Speirs air/MinusK and Speirs active price points, a great looking design, and plenty of interesting tech and thoughtful engineering, it could be the go to choice esp for those like me in situations where flr not eminently suitable for active isoln

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    [Industry Expert] ddk's Avatar
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    I moved a lot in my life and getting things right took a while every time but you end up learning a lot. Good luck!

    david
    Audio Industry Affiliate:Lamm, Ortofon, ZYX, Keith Monks, Audio Desk, Jensen Transformers, Pheonix Engineering.
    Specialty & Unique Offerings: Vintage horn speakers, Vintage and Modern Turntables, Analog Accessories.

    System 1: Horns+Tubes+Vinyl and digital too- Listening Room 1
    System 2: Horns+Tubes+Vinyl and digital too- Listening Room 2- Near field setup

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    Addicted to Best! PeterA's Avatar
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    Quote Originally Posted by spiritofmusic View Post
    Dave, and Mike Lavigne, thanks for pushing me away from active isoln for my tt on a flexy suspended wooden flr
    My flr is pretty rigid, but it cannot match the inertness of my prev concrete flr, esp at a span of 18x50
    I'm minded to go the Stacore Pl Advanced route, 230lb (!) of modern interpretation Vibraplane pneumatics/springs w slate shelf and ball bearing lateral plane isolation
    At a price point between Speirs air/MinusK and Speirs active price points, a great looking design, and plenty of interesting tech and thoughtful engineering, it could be the go to choice esp for those like me in situations where flr not eminently suitable for active isoln
    Marc, have you seen measurements for the effectiveness (which frequencies are attenuated and by how much) of the Stacore products? I agree, these devices seem promising, but I would like to know more. Do they need a compressor, at what pressure are they inflated, what are the dimensions, etc? Those are heavy units and would need strong support underneath, especially if supporting a heavy turntable.
    My system link on WBF: http://www.whatsbestforum.com/showth...-Sublime-Sound
    Analog: SME 30/12, SME V-12, My Sonic Labs Signature Gold, AirTight Supreme, VDH Colibri Platinum, MINT LP protractor
    Electronics: Pass Labs XA160.5 amp, XP-20 preamp, XP-25 phono, Cables: Transparent REF XL MM2,
    Speakers: Magico Mini II, Essentials: Jim Smith RoomPlay, 3 Vibraplanes, Dedicated circuits

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    [Industry Expert] Stacore's Avatar
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    Quote Originally Posted by PeterA View Post
    One observation has been that many of these platforms were designed specifically for scientific instruments likes microscopes and not designed for audio devices which may have internally generated vibrations created by movement within the component. I have read claims that active devices can attenuate such component generated vibrations, but I have not read an explanation about how this is achieved..
    Yes this is right, in the lab you have much narrower bandwith requirements for the operation. Who cares what happens past some 100-200Hz? Microscopes do not
    You seem to be attach to an idea that an external device will help with internally generated vibrations. Well sorry to say it but it won't. The only thing it can reliably do is to prevent the vibrations from spreading around by breaking its path. One example I've been trying to promote here is to suspend loudspeakers. Try it guys and observe the results

    Quote Originally Posted by PeterA View Post
    I am particularly interested in the potentially different requirements needed to isolate turntables and those that generate internal vibrations and how they may be different for suspended and non suspended turntables.
    I strongly discourage to stack similar stiffness suspensions working in the same direction (e.g. vertical). The suspensions may go into beat oscillations (if their resonant points are close), with actually increased ULF vibrations instead of decreased.
    Jarek Korbicz
    STACORE
    Manufacturer of Advanced
    Anti-vibration Solutions

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    No specs or measurements yet, I'm in the early stages of comms w the guys at Stacore and will ask them to post
    They are happy to allow the platform to be placed direct on the floor to situate the tt at low level
    Fwiw, when I auditioned the active Accurion i4 some yrs back, the sales manager was happy to pop that on the flr in my apartment
    The way I see it is if these devices are overengineered to isolate comprehensively, there should be no reason they shouldn't be able to be used on the flr

  10. #10
    [Industry Expert] Stacore's Avatar
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    Quote Originally Posted by PeterA View Post
    Marc, have you seen measurements for the effectiveness (which frequencies are attenuated and by how much) of the Stacore products? I agree, these devices seem promising, but I would like to know more. Do they need a compressor, at what pressure are they inflated, what are the dimensions, etc? Those are heavy units and would need strong support underneath, especially if supporting a heavy turntable.
    Peter, thank you! There is no need for a compressor, you pump it with automotive pump and correct the pressure once in 2-3 months, which takes a bout a minute to do.
    The pressure depends on the load and is usually in the 2-5(max) bar region.
    Yes, we are heavy mass, Basic @ 62kg, Advanced @94kg Dimensions: 580 (L) x 480 (W) x 108 (H) [ mm ] and 580 (L) x 480 (W) x 140 (H) [ mm ] We can also do custom dims.

    Hope this helps
    Jarek Korbicz
    STACORE
    Manufacturer of Advanced
    Anti-vibration Solutions

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