Turntable isolation platforms


Need some reco's on turntable isolation platforms.  Currently I'm considering the isoacoustics delos.  This is another step in the battle to reduce acoustic feedback (see previous posts of mine).  I currently have TT  on a  Pangea audio rack with a rumble filter with iso feet but want to remove rumble filter and use XLR input and not RCA. All ideas are welcome for a solid platform.  GO!
polkalover
I think if looks are important, Adona gives a lot of bang for buck.  Otherwise, I would not spend big bucks.
Are you sure it's acoustic feedback, i.e., sonic degradation from the volume of the music?  Or do you mean isolation from footfalls and the like?  If it's the latter, a wall shelf makes a huge difference IMO. 
It's definitely acoustic feedback.  If I rest needle on record and turn up volume I get rumble.  I then had a friend apply pressure to rack and the rumble stopped.  I need to isolate TT better
Perhaps look at the Townshend audio spring isolation platforms? All of those type of affordable "audiophile racks" - Pangea in your case, Lovan Sovereign and VTI (ugh) in my past - are gonna make you have a bad time when you place a turntable without a spring suspension (maybe OK if you have concrete slab floor, though), especially if you like to crank the volume up. SOTA Star/Nova, with its excellent 4-point suspended subchassis, worked just fine on the Lovan rack. But a Clearaudio Innovation - not so much. A really expensive rack (Critical Mass Maxxum) also completely solved the issue for the Clearaudio deck, but at exorbitant cost compared to simple & effective springs.
A Ginko Cloud platform solved my problem when I moved my table from a sand-filled platform to a new cabinet.
 I then had a friend apply pressure to rack and the rumble stopped.


The gross sort of vibration you have, so bad a person pressing with their hand is an improvement, is gross both in frequency and amplitude. All the so-called 'isolation' stuff is tuned to work within a very narrow range. That's why one person gets great results, another so-so, another says it might even be worse. Nobody knows ahead of time what amplitude and frequency is their main problem. No manufacturer publishes that info either. So all you can do is shot-gun it. Which as usual everyone else here is happy to do. Buy! Spend! He who dies with the most discarded toys wins!

Sorry. But the answer has been there so long I built mine more than 15 years ago. Its called a sand box. Shallow little box, filled with sand (mixed with a little oil to hold it together and eliminate dust) and with a little shelf on top. The size of the box, depth of sand, and type of shelf you play around with and by trial and error are able to tune to your particular situation.

Seriously. Don't take my word for it. Don't guess- test! If I'm right then you should notice improvement from something as simple as placing a 10 lb bag of sugar on the rack next to the turntable. Then if that works you could set the turntable on two 10 lb bags laid sideways. Point is you can figure out for yourself what is going on, and what will work to fix it, and all without spending any money or even going out of the house. You could do it tonight.

Go and see.
Miller has a right idea, IMO.
hell of an idea.  thank you.  gonna go get some sand and sugar
If you like sand and sugar and things of that nature you might give some consideration to glass micro beads, perfectly round teeny tiny hard glass spheres, the ones sold for use in airport runways, much more suitable to use in isolation stands since they are more easily moved by external forces which is the hallmark of effective isolation - ease of motion. You can put the micro bead box up on cones or springs for an additional stage of isolation. Throw caution to the wind!
Do not want to insult you but I owned aPangea rack and it is nothing great. I moved up to a Solid Steel and it made a big difference. A 4 inch thick solid maple platform with some kind of isolation footers for it to sit on may help. I have 3 platforms, one made from Bubinga wood, one from maple and one granite I am giving away FREE to anyone here.

The caveat is it is pick up ONLY. I live in Rhode Island if there are any takers. The bubinga platform And Granite Platform are large enough for a VPI Prime and the maple platform will fit a Scout.

If anyone is interested in picking one up, send me a PM. I want nothing in return. I want to repeate, I will not ship, local pick up only.
I look at vibration control through an RF impedance matching background. Spiking heavy speakers or platforms improves sound by rejecting high energy bass frequency vibrations in a suspended wood floor moving up into the component or speaker.

Varying pressures in the floor and around supporting beams due to concentrated weight on spikes causes diffraction or reflection of sound, stopping travelling waves in the wood medium moving up the speaker or component. An abrupt change in density is a fraction of bass frequency wavelengths, rejecting sonic conductance which minimizes cross talk between woofers from left to right speaker or speaker to component. Bass frequencies have the most energy and can morph into higher frequency resonance in cabinets and audio racks. 

That is just the start of treatment as I understand it. Performance improves if the fraction of vibration that finds it way up the feet or leaving the feet is attenuated as loss or sound absorption through the use of rubber, sand, isolation feet or platforms - whatever provides wideband absorption of vibration energy.

Basically you want to minimize reflection which is return loss in RF world by matching impedances. That is density and stiffness for maximum sonic conductance of materials. That's how cones work to pull high frequency vibrations out of components. Bass frequencies leaving speakers are best treated with loss through isolation since energy is high and will reverb through the floor. Higher frequency energy will not cause trouble in the floor, but should not be reflected off the isolation footer back into the speaker or component. 

Antenna are tuned or impedance matched for minimum return loss. If we use loss to extend bandwidth and minimize return loss , gain suffers. Fortunately, using loss in vibration control can improve performance with no downside since we are not trying to transmit vibrational energy through the floor at same time.
Miller has it right. Different shelf (atop the sand) will make a difference.

brotw69
I look at vibration control through an RF impedance matching background. Spiking heavy speakers or platforms improves sound by rejecting high energy bass frequency vibrations in a suspended wood floor moving up into the component or speaker.

Varying pressures in the floor and around supporting beams due to concentrated weight on spikes causes diffraction or reflection of sound, stopping travelling waves in the wood medium moving up the speaker or component. An abrupt change in density is a fraction of bass frequency wavelengths, rejecting sonic conductance which minimizes cross talk between woofers from left to right speaker or speaker to component. Bass frequencies have the most energy and can morph into higher frequency resonance in cabinets and audio racks.

That is just the start of treatment as I understand it. Performance improves if the fraction of vibration that finds it way up the feet or leaving the feet is attenuated as loss or sound absorption through the use of rubber, sand, isolation feet or platforms - whatever provides wideband absorption of vibration energy.

>>>>I’m not sure I agree with your detective work. What seems clear is that spikes and cones minimize contact area and reduce the contact with compliant or springy materials like carpets/pads. There are several variables just for cones and spikes, e.g. material, shape.

For traditional mass-on-spring isolation devices we know they function as 🔜 mechanical low pass filters 🔙, 6 dB per octave, preventing or at least reducing the transmission of vibration from the floor to the component. The vibration of concern is both the seismic type - traffic, Earth crust motion, etc. - and speaker mechanical feedback and footfall.
We're all talking about the same thing here. I've just provided a alternate, general way to understand what's going on, not just with turntables but speakers and components with noisy transformers as well. Mass on spring works well at low frequencies because of bass energy loss in the spring. Sand is likely needed for the high frequency isolation through absorption.

If you place a lightweight platform on spikes on a suspended wood floor without carpet, I doubt your going to get low frequency isolation.

That gets to my point, the floor is acting like a diaphram which has to have relatively even movement of soundwaves to be an effective transducer. Place a heavy weight in one spot and you have a node or lower energy zone. Sound waves traveling through the floor are reflecting off the perimeter of that weighted floor spot and travel around it or through supporting beams to other sections of the floor that allow vibration. It's like a large scale piezo-electric buzzer for bass.

Cones or vibrapods work on components because weight is concentrated under the metal chassis effectively conducting or draining vibration out of the component. Unlike the floor, the metal in the chassis doesn't change density near the cones. Cones work best with lossy plinths that dissipate energy.

The effective channeling, isolating and dissipation of vibration energy can be achieved by knowing when to minimize boundary reflections and when to incorporate loss. It's all wave energy, highly similar to RF.

brotw70

brotw70
We’re all talking about the same thing here. I’ve just provided a alternate, general way to understand what’s going on, not just with turntables but speakers and components with noisy transformers as well. Mass on spring works well at low frequencies because of bass energy loss in the spring. Sand is likely needed for the high frequency isolation through absorption.

>>>>At the risk of you thinking I’m picking on you, we’re not talking about the same thing here. In fact, mass-on-spring isolation is better (more effective) as you go up 🔝 in frequency. By the time you get to 25 Hz on the way up 🔝in frequency - even for a modest iso system - the effectiveness of isolation is more than 95%. By the time you get to 30 Hz it’s 99.5%. So, it’s more effective for high frequencies than for very low frequencies. Hel-loo! Not to rub it in too much but mass-on-spring isolation is not due to losses in the spring. It’s more complicated. That’s why it’s called mass-on-spring. It functions as a mechanical low pass filter with a 6 dB per octave characteristic.
Ok, had to look that up. Mass on spring looks effective for isolating turntables through other means. I'm more interested speaker and component vibration solutions that drain sources of vibration to the floor. Haven't seen many spring solutions for those. I think springs just solve the floor moving up and down problem rather than lateral.

I would go to your local granite countertop site and ask them to cut you a 1.5 to 2 inch thick piece large enough to place your table on. all the imaging greatly improves and feedback becomes a non issue.
For most stuff millercarbon's sandbox solution will work fine. It is just a mater of making it look good. There is only one problem I can think of and that is the floor. Concrete floors are perfect for Hi Fi rooms because they are so stiff and non resonant. Wood floors however are spring boards.
More mass = lower resonance frequency = more bounce. You can really give yourself a foot fall problem this way. I have seen tonearms go airborne. With a wood floor there are only two solutions I can think of. A wall shelf which was previously mentioned which works great as long as there are not little ones crashing into the wall or a well designed suspended turntable. 
The Isoacoustics platform should isolate you from that "rumble" you have noticed. It will not isolate you from foot falls. If you are on a concrete floor the Isoacoustics platform will be all you need. 
Going back to turntables, the SOTA is a brilliant design actually more so than the Basis or SME. All three tables have properly designed and tuned suspensions. You can jump up and down in front of all three and nothing will happen even if you have crappy floors. But with the SOTA the suspended platform is internalized so you can bump up against the plinth and nothing will happen. When  placing the tonearm I can use the plinth as a steady rest. You can not do this with the other turntables. I have both a SOTA and an SME. The reason I got the SME is that I wanted to use a Kuzma 4 point 14 and SOTA does not make a turntable you can mount this arm on. If they did I would have gotten it. The SME is a great turntable but the SOTA is nicer to use and the Macassar Ebony plinth is drop dead gorgeous. The SME is...industrial. 
Having a properly isolated turntable is just as, if not more important than getting the tonearm set up dead on. If you get one of the above turntables you do not have to spend money on a special stand or shelf. You could place any of these turntables on a collapsible card table and they would work fine.  

brotw
71
Ok, had to look that up. Mass on spring looks effective for isolating turntables through other means. I’m more interested speaker and component vibration solutions that drain sources of vibration to the floor. Haven’t seen many spring solutions for those. I think springs just solve the floor moving up and down problem rather than lateral.

>>>>As I already pointed out, mass on spring iso system operate in both directions, up 🔝and down ⬇️ That’s why you have such devices as inverted pendulums, etc. That’s why everybody and his brother says go watch the Townshend YouTube video on speaker isolation. A video is worth a thousand words. The mass on spring system is used for all (rpt all) isolation applications, including tube and solid state electronics, turntables, speakers, etc. By the way, even cement slabs move up and down, 
I am using a Symposium Iso Segue under my Classic III and can't recommend it highly enough. My floor is suspended over a large crawl space and the Iso Segue really cleaned up the lower end.
@todd30312  

What is supporting the Segue?
Why do you need one? Do you really need one? 
I needed one as my TT was on a simple table that flexed. I had (20mm thick) piece of granite made, plonked it on the table and my TT onto it. Was good enough for me.
All great thoughts on this universal challenge we often have in our listening rooms.  I am on wood floors and conventional foundations so when my 20lb dog would walk through the house I could feel each step in my listening position.....crazy!  I moved to a wall shelf but now have the same issue polkalover mentions.  When I lower the arm, sometimes I get an immediate bass tone from the speakers.  I didn't think of applying downward pressure, but instead applied slight upward pressure like I was going to pick up my turntable but didn't actually lift off the shelf.  It immediately stops the rumble/tone.  There hasn't been much comment here on the Delos or any of their Orea feet.  These are somewhat reasonable in price.  I am looking at either 3 of the Bronze feet or the Delos 1.75in thick platform.  This is $150 vs $400.  I will call tomorrow and see how these feet of the platform compare to the Orea.  This isn't explained in the technical details, but I would imagine it is the same design.  I may order both and simply keep my preference.  The farther I go with improving my system the more weaknesses are revealed.  It is so much fun and challenging....god I love this hobby!!!  
I had acoustic feedback with my Kuzma Stabi R Tt sitting on a HRS R1X platform (on an Usher Audio Rack on suspended wood floors).  I called HRS and they suggested that I get low frequency replacement feet. Cost me around $500 for the feet and it did the job.  
Look at my system page, and derive an idea from that 
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