DIY sand filled turntable feet

JimmyNeutron

Super Member
I got a Yamaha PX-3 last month and it was in terrible condition - missing feet, dust cover, hinges, headshell, and cart. Very dirty, grimy, and filled with dust balls. I cleaned it up ( it came to be a mint condition PX-3, just unbelievable ) and I ordered a new cover and hinges, Sumiko headshell, and Denon DL-160 cart. The feet, however, were just unobtainium. So starts my search for the "perfect" turntable feet. A little bit of research was needed, and this research took me 180 degrees from current "law". Turntable feet should isolate the table from waves induced by walking, vibration, etc.

Lesson 1: steel is NOT a good isolator of vibrations.

Why then do most all turntables have a steel spring as a foot? It does'nt matter how many twists there are to steel it will still transmit vibration. Actually, the tighter the twist the higher the frequency the spring will pass, and at a faster velocity. So for my new turntable feet springs were out!

Lesson 2: Not all rubber is our freind.

Many people use a rubber ball like a tennis ball, a handball, and even ( EEEK! ) a super bouncy rubber ball cut in half. But think about it for a moment. What do ALL rubber balls have in common? They ALL transmit and AMPLIFY whatever force is applied to them! That's the whole point of most ANY ball. Hit it and it will bounce higher and farther. So a rubber ball cut in half and used as a turntable foot will only amplify and pass thru whatever vibration it recieves.

Lesson 3: "He ain't heavy, he's my sand-filled iso feet"

For a turntable to absorb vibration we need to think outside the box. We will not be using any springs or balls. We will, however, be using a dense rubber. Plumbing rubber is very dense. It has to be. It has to retain itself under tremendous pressure from water. So at Home Depot I found a perfect foot cap. It comes with a aluminum screw retainer, so we'll remove that retainer completely. This will be the bottom base. Next I found some rubber caps - the kind that slip onto the bottom of a walking cane for absorption - yeah...now we're almost there. This rubber cap will be the top of the foot, and it fits snuggly into the bottom rubber cap ( after we cut 1/2" from the top cap ). These only came in white at my local Home Depot, maybe you can find them in black. I painted them a flat textured black with some Krylon paint. I drilled a small hole in the center of the top cap and pushed thru a 5-8 mm screw ( this is what the PX-3 foot screws onto on the base ). We now have 2 pieces of dense rubber with low vibration properties that will fit snuggly together and form a foot which will screw onto the turntable. But hold on, we ain't done yet. Even though these 2 pieces of rubber will not transmit much vibration to the turntable base, there is still an air pocket inside the foot. Air DOES transmit vibrations, and since we want to stop all vibrations from reaching the turntable base we need to deal with this as well. The foot will be completely filled with sand. Sand is extremely dense when packed, will dissipate vibrations, and will add weight to the foot.

Once the feet are packed with sand and fitted snuggly, and screwed onto the PX-3 I have to say that they look very, very nice - and stock! Lastly I applied some felt padding to the bottom of the feet. The feet are still adjustable because of the threaded screw. The test was next. I played a few records and walked around the room, even lightly knocked on the table that the PX-3 is playing on. Dead quiet - no transmission of vibrations made it theu the feet and into the turntable.

For under $25.00 we have made a near dead isolation sand-filled foot with remarkable vibration absorbing qualities. Check it out for yourself.

Jimmy

The walking cane rubber feet.
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The rubber plumbing cap. Just remove the screw down strap.
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Black plastic textured paint for top cap.
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Felt padding for feet.
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Walking cane cap ( top of foot ) painted black and cut down 1/2 ", and in second photo with the screw fitted thru.
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Cap filled with sand and then fitted onto bottom cap. It seals tightly.
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For comparison against original PX-3 foot.
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Mounted on the PX-3 and playing sweet music.
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Nice work on those TT feet!

Thats a great way to make feet for you TTs that are missing their feet.
 
Yeah, it seems to be that one of the first serious tweaks anyone does for their turntable is to build a sandbox platform. I built one a few years ago. They're very standard and only cosmetics would differ. Mine has gold spikes, and a glass top platform. I have 2 of them actually - one for my Denon DP-62L and now for my Yamaha PX-3. That's actually the inpiration behind my sand-filled iso feet. If a sandbox can have such a vast vibration absorption quality, then sand-filled feet would only benefit even more. Couple the 2 together and you basically get double the isolating power as just with one.

This project is just so simple and so effective it's a great replacement of any turntables feet. You can color the feet to match any equipment, and the rubber caps both come in various sizes - from smaller to larger. I'll be making a few more for various equipment like my CD players. But I think realistically a turntable benefits the most. I mean the absorption quality is just crazy-freaky! No amount of realistic rapping on the table will pass onto the turntable!! It's a wonder manufactures are still using steel springs to isolate their bases - it just goes against all common knowledge.

Anyway, here's my sandbox iso-platter.

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sounds like your feet probably mitigate most of the effects from it, but aren't you're taking a step backward by placing the turntable on a glass-topped table (assuming that is the final resting place)? i thought that glass was one of the worst materials on which to set vibration-sensitive equipment.

Mounted on the PX-3 and playing sweet music.
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This particular table is not where the turntable normally goes. We just moved into our new home and a lot of our furniture is still in the garage waiting to be moved in, so this table is serving as a temp.
 
Lesson #2:

In physics, what I learned was that if you throw a rubber ball into a wall, it will release energy into that wall. That is a fact. If the rubber ball was to bounce between 2 parallel walls, eventually the pendulum movement would die (slowing down with frequency change) as the energy released is transferred into the walls. As loss of energy occurs at every collision, you cannot maintain an accelerating pendulum movement. If a ball was to gather speed with every bounce (and amplify), a ball dropped by a toddler would reach incredible amounts of speed within a short lapse of time and if that were the case, we wouldn't be here (we'd all be dead) writing about their shortcomings. So it gathers no speed nor does a rubber ball amplify a signal, basic high school physics.

When you say they amplify the signal because the bounce is higher and faster, I believe you are mistaken. You can measure the loss of speed at each bounce.

You may be saying that rubber balls don't dissipate the energy as quickly as they should, I agree on that principle. To my knowledge, everything that collides with other matter cannot be accelerated nor amplified. It's simply energy transfer.

I'm not saying you don't make a good point, there may be better options to dissipate energy.
 
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Lesson #2:


You may be saying that rubber balls don't dissipate the energy as quickly as they should, I agree on that principle. To my knowledge, everything that collides with other matter cannot be accelerated nor amplified. It's simply energy transfer.

I'm not saying you don't make a good point, there may be better options to dissipate energy.

You are most certainly correct. I'm no physics major, just a good ole boy with a lot of stuff rattlin' around in the back of my head. But, some rubber does "bounce" more - like those atomic balls at the 25 cent machine. I don't think I'd like to put any kind of "live" rubber as an isolator, hence my search for a "dead" rubber - like plumbing rubber.

But yeah, you're right. :thmbsp:

Jimmy
 
You are most certainly correct. I'm no physics major, just a good ole boy with a lot of stuff rattlin' around in the back of my head. But, some rubber does "bounce" more - like those atomic balls at the 25 cent machine. I don't think I'd like to put any kind of "live" rubber as an isolator, hence my search for a "dead" rubber - like plumbing rubber.

But yeah, you're right. :thmbsp:

Jimmy

I believe this thread is more about sharing knowledge and experience. We may both have differing views and to word any idea correctly is a PITA, trust me. I have been taken to task too many times ;)!

There are still so many unknowns that concern "massive sinking" techniques and down to which part of the frequency spectrum it is effective/vulnerable. These are problems I have no solutions for but as you have stated, thinking outside of the box can lead to a whole new set of problems that make us learn a whole hell of a lot.

With your turntable deck, I figure you want the feet to absorb the sound waves and funnel them away from the deck itself and into that nice big sandbox. You also need a wave sinking path that goes from the deck to the sandbox through these feet. You want to drain that energy also I guess. This is where springs or lighter materials inserted inside the feet may be of help I believe. As you know, air pressure that changes inside a listening room (sound waves) will collide with the deck itself so you need a drain path for providing the platter/tonearm/cartridge the best suited environment to do its job correctly.

There are many techniques available but little can be done for the low frequencies when the wavelengths are so much longer (bigger) than a footer is. How does a small foot absorb and drain a 40Hz signal into the sandbox? I have no idea how this can be solved because I plead ignorance. I still have a lot to learn so I'm looking forward to see how you can circumvent some issues and the solutions you will apply.

Ideas like constrained layer damping may be useful in this project but then again, I never tried it.

Good luck, this is an interesting thread that should be kept alive. Keep on plugging and hopefully, we can all benefit from your findings if you want to share them with us!
 
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Very cool idea, but I have a couple of wonders about this.. and about the whole sand movement...

First I wonder, it looks like the inside walker tips actually contact the outside rubber sand holder. So doesn't this kind of nullify the sand based on our rubber passing vibrations theory?

Secondly, is there enough sand in there that even after settling, the open ring of the inner cup won't contact the bottom, the outer cup?

Third, concerning the sand boxes... If you have a sandbox for long enough, won't all the minor vibrations settle the sand over time enough that it becomes very packed and very dense, thus passing vibrations. and you find yourself having to take it apart and loosen the sand up to get back to dampening?
 
Great comments by Dogscanskate, and Silmilost. Let me start by saying I have no clue about physics or the like. I am more of a "matter of fact" kinda guy. If I can see it, feel it, smell it, then it must be "it". Most of you guys will know me from my past projects like the ARK, the MS1P media server, and the many equipment rebuilds I've posted about. With that said I try to get the most "value" out of my projects. This one was no different. But I also try to apply what little bit of facts I know.

The sand-filled iso feet, to me, are just what TT feet should be, while steel springs, to me, should NOT be. When I imagine a spring I imagine those old spring reverberation units that would echo the sound of music, or of the trailing "twanaaannngggg" when you strike steel. So if it vibrates then it cannot isolate. So when using a steel spring as a TT foot any vibration that reaches the spring will "twaaannnngggg" rather than stop. Also, at least in my little head, the TT feet are not meant to stop airbourne waves ( like from the dust cover picking up vibrations - the rigidity of the plinth should absorb that ), but rather keep waves that try to enter the TT from the feet away ( like people walking on a wooden floor ). So I look at it as waves entering the TT should be stopped at the feet, not vice versa. Sand has been known, and proven, to be a very effective isolator of the type of waves that can enter TT's and cause that "BUMP BUMP" from the speaker. Sand is used in speaker cabinets, speaker stands, and in the form of ceramics in components ( like Kyocera's awesome series ). So it was only logical to incorporate sand into the feet to help diffuse and/or dissipate any leftover waves that the rubber itself can't absorb.

The rubber, again in my mind, has to pass Jimmy Neutron's BDB test ( Bounce, don't Bounce ). If I'm holding a piece of rubber like a tennis ball, and I drop it to the ground and it bounces then I don't want to use it for any absorption applications. But If I drop another piece of rubber and it just plops onto the floor then that's the quality I want in my feet - no transmission of energy ( or at least very little - less than a tennis ball for instance ). The plumbers rubber, for the most part, just plops when it's dropped. For a TT foot that is exactly the quality I want. Now, fill the inside pocket with an inert and acoustically dead material, like sand, and we add weight ( which is good ) and will absorb any leftover rogue waves that pass thru the rubber. The end result is a foot that meets several of the qualities for a good isolating turntable foot - mass, weight, absorption, and diffussion.

Now, again, I'm no whiz. But in my system, on my PX-3, I have ZERO BUMP, BUMP coming thru my speakers when I perform the rap test - rap on the table with your knuckles. Whether this silence has anything to do with the sand filled iso-feet, well we can only speculate because I don't have the test equipment to perform such tests. But at the very least the feet are attractive, are cheap, are easy to build, and work very, very well.
 
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