Turntable Isolation Journey

Not to detract from all of the positive feedback . . . Is not the Clearaudio Ceramic Magnetic Bearing (CMB) technically a suspension in this scenario?

@boothroyd Yes, a good observation -- I used to be optimistic the CMB itself could help provide isolation. However, my observations across the range (Innovation Compact, Wood, Master) are that it does not provide effective isolation. I think the issue is that there’s only compliance in exactly direction: straight up & down. It’s still a rigid bearing in every other sense. Even where there is compliance, it doesn’t exactly operate like a mass-on-spring.

The CMB’s function is to reduce bearing rumble and eliminate the ball & thrust plate wear, which it does brilliantly: these are exceptionally quiet tables, and they easily take on massive platters with 5+ pounds of clamping. If it were compliant in directions other than straight up & down, it would be a poor turntable bearing because this would elicit a wobbly instability (ala the MagLev turntable’s platter).

@mulveling Excellent post. Thanks for taking the time.

Good post and I see that many of you are astute and have a good understanding of vibrations and their effects on our stereo gear.  I want to add a few remarks to help everyone understand how best to isolate their gear.

Springs isolate and rubbers dampen.  A spring/mass system has a dynamic response curve that can be expressed as a ratio of input vs output across a frequency range.  Beyond the natural frequency of the spring/mass system the response ratio becomes less than one.  That means the vibrations going into the spring/mass system are reduced coming out.  I isolate my gear with spring rates that achieve a Natural Frequency of 3 Hz, or there abouts in order to isolate my gear at all higher frequencies.  It is easy enough knowing the mass of a stereo component to calculate the spring rate required to achieve a system natural frequency of 3 Hz.  I have never seen a Townsend speaker platform in person but I'm sure that is what it does.

Rubbers dampen.  I know, we often see the term "rubber isolators" but that is not entirely accurate.  Dampers reduce vibrations- especially important around the natural frequency of spring mass systems since the system can go out of control at its resonance point.  But dampers also cause phase shift.  This phase shift property of rubber is why we hear tonal variations or colorations.  Sometimes these colorations are helpful and sometimes they are undesired.  Nevertheless, all of the spring/mass systems of our stereo gear need dampening.  The problem for me is I am not smart enough to determine the best dampening materials or amounts to use beforehand with calculations.  I have to use the trial and error method or what we call experimentation.  In most cases I found that isolating each of my stereo components with springs and then utilizing the factory supplied feet for dampening is sufficient.  So I have each component on a wooden or delrin board supported by springs.  In the case of my Sota turntable, I have it standing on a carbon fiber board supported by Isoacoustics Orea feet.  After much experimentation with various materials I found this was the best solution.  Yes, I was surprised by how much even my Sota is affected by the base it stands on.  It has never been susceptible to footfalls or woofer pumping, but the tone changes based on the stand it is placed on.  Since the Sota turntable suspension has a natural frequency of 3 Hz it cannot be placed on a spring isolation platform.  A double spring/mass system would be a total disaster.

I built my own speaker isolation platforms a few years ago using springs and butcher blocks.  I got 48 lb/in springs from McMaster Carr and four per speaker got me a natural frequency of 3.1 Hz for the speakers I had back then.  I was amazed at the difference in the sound on my suspended floor that isolating the speakers made.  Eventually, I bought the Isoacoustic Gaia footers to try on my speakers.  The speakers sounded better with the Gaia footers although they did not isolate the speakers from the floor as perfectly as my spring platforms.  Why?  The Gaia footers add dampening and this made the tonal balance of my speakers more pleasant.  I moved my spring platforms to my home theater subwoofers.  They make the bass deep, clear and crisp.  

To sum up, it takes a combination of isolation and dampening to find the optimum sound.  I do it by putting each of my components on a spring loaded platform for the isolation part and then dampen the component at the base- in my case typically the feet supplied by the manufacturer.  But experimentation with other dampening materials for each component may yield a better solution.

PS.  I'm amazed at the number of expensive high end turntables that lack any sort of isolation, or just a minimal amount of isolation requiring the consumer to spend yet even more money on a highly engineered isolation platform.  If your turntable lacks a spring isolation system then build platform yourself and save yourself some money.  You can find natural frequency calculators online for spring/mass systems.

@tonywinga Another great post. Thank you.

Regarding your statement, "A double spring/mass system would be a total disaster.". Since products like Oreos are damped isolation devices as you stated, would a set of those beneath a good platform which supports a spring type suspension turntable be detrimental?

@tonywinga Another great post. Thank you.

Regarding your statement, "A double spring/mass system would be a total disaster.". Since products like Oreos are damped isolation devices as you stated, would a set of those beneath a good platform which supports a spring type suspension turntable be detrimental?

I’ll defer to @tonywinga for better explanation since he knows far more about this topic. But yes, I was aware one should never stack springs -- since their resonant frequencies can interact in very detrimental ways (huge displacement amplitudes when excited) -- I believe this has to do with the constructive & destructive interference nature of waves. My old dealer actually warned me of this when I first got into vinyl. So you should never, for example, put a SOTA turntable atop Townshend springs.

I don’t believe stacking "squishy" damping interfaces like Orea feet suffers the same problem. Or at least, not severely enough to be of concern in typical use cases. I also don’t believe combining springs with damping devices is a problem -- in fact that’s a great approach! The main issue would be loss of stability when over-stacking -- don’t risk that expensive turntable toppling over!

Technically, my turntable's full vertical support stack is:
floor => hockey pucks (damping) -> CMS rack (very rigid) w/ spikes => CMS Platinum filter (constrained layer damping) => Townshend platform
And its horizontal stack is:
wall => Auralex 2" tile (damping) => CMS rack frame => CMS Platinum filter (constrained layer damping) => Townshend platform

@tonywinga I would like to better understand the actual differences between damping devices and mass-on-spring systems. Doesn’t a spring system act "kind of" like damping above its resonant frequency? Or is there something else going on? And don’t damping interfaces also have resonant frequency? Thanks!!