You think you have total turntable isolation?

Discussion in 'Audio Hardware' started by GuildX700, Aug 28, 2016.

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  1. GuildX700

    GuildX700 Forum Resident Thread Starter

    Location:
    USA
    I figured my new set up in the man cave basement would have 100% total floor isolation, the basement has a double thick poured concrete floor. It was my grandpas house from the 1950's, when building it the basement floor was supposed to be colored concrete, dark red. He got there as they were pouring and it was not colored, so he demanded they come with more colored the proper color and they did. Not sure how thick it ended up, but it's thicker than standard that's for sure.

    My homemade turntable stand sits close to the block wall next to a mid wall filled double block strengthening pilaster column. It has a 4" thick glued/screwed layered top now ballasted by 2 bags of lead shot, 1 on each side of the turntable. It's hollow frame is packed with lead shot, the 2 shelves are now full with records too. The adjustable feet have 1/4" thick Delrin pads on them, the turntable, an Empire 698 also has some medium stiff rubber feet on it and has a sprung suspension. Cartridge is a Shure V15VxMR with the brush stabilizer down.

    Basically this stand is rock solid and sturdy, you can pound your fist on the top and it does not bother the turntable when playing a record.

    I decided to test the floor isolation today when I was checking the tonearm height with thicker records, I had the turntable turned off and the needle placed in the middle of a nice flat 180 gram record with the record clamp on.

    I turned on the system, started out at low volume, several feet from the turntable I lightly stomped my bare foot on the concrete floor, did not hear anything, kept going, at about 3/4 volume there it was, you could clearly hear me stomp my foot on the concrete floor through the speakers via the turntable.

    I was floored, I thought no way in hell would that be able to happen.

    Ok, thankfully unlike a crappy built wood floor, it's impossible to make the table skip down here in the basement, but the fact is even with a concrete floor you don't have real great isolation.

    One thing to note was the total absence of feedback, I would've bet on getting feedback before hearing my feet on the floor.

    I guess I'll experiment with different feet on the stand and table for starters and see if that makes a difference. Having some of those expensive isolation bases or cones would make for some interesting testing too I'll bet. Too bad I can't get my hands on some as loaners for testing.

    I wonder if anything can total isolate?


    [​IMG]
     
    Last edited: Aug 28, 2016
  2. Mad shadows

    Mad shadows Forum Resident

    Location:
    Karlskrona- Sweden
    You can make your own rollerblocks with ashtrays + steel ball.
    I use it under my equipment stand to god effect.
     
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  3. GuildX700

    GuildX700 Forum Resident Thread Starter

    Location:
    USA
    I'll have to try something like that. At least I have a baseline so I can prove if anything works for an improvement.
     
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  4. triple

    triple Senior Member

    Location:
    Zagreb, Croatia
    Where is the isolation - the photo shows a rack coupled to the foor?
     
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  5. missan

    missan Forum Resident

    Location:
    Stockholm
    Sorry, but just to be clear, You are not isolating anything here. You are instead coupling the TT to the floor, thru the spikes and the rack. That means if the spikes vibrates, so will the TT and the needle. This could be a good thing, or a bad thing, depending on the floor and the TT in question. I have a concrete floor, it´s not nearly good and heavy enough for coupling.
     
    Last edited: Aug 28, 2016
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  6. chervokas

    chervokas Senior Member

    Like others have noted, the turntable stand isn't isolating, it's a sturdy, hard to move stand coupled to a a sturdy, hard to move floor. The sprung suspension on the turntable is what's providing the isolation, and it sounds like it's doing a pretty good job of that if you can pound your fist on the stand while the record is playing and have no disturbance. But if you can get to floor to move you can get the stand to move since the stand is coupled to it. And apparently you can do that with stomping on it at a frequency or in a direction where the sprung suspension isn't perfectly effective. The good news is that unless something's doing some heavy stomping on floor near the turntable, it's probably not something that comes into play when you're listening to music.
     
  7. KT88

    KT88 Senior Member

    [​IMG]
    -Bill
     
  8. Manimal

    Manimal Forum Resident

    Location:
    Southern US
    Ha! I was thinking the same thing:)
     
  9. The Pinhead

    The Pinhead KING OF BOOM AND SIZZLE IN HELL

    Not saying this totally isolates every TT bit IME nothing beats a simple wall-mounted shelf . My house is on a first floor by an avenue where all kinds of heavy buses and trucks circulate at all hours. You can feel sudden bumps on your buttocks that make you (almost) jump on the couch while watching TV or listening to music. But the TT remains immutable. I can also have a party and unless (Satan forbid:mad:) some moronic kid or drunk makes actual physical contact with the shelf, nothing, niet, zilch, nada:D
     
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  10. GuildX700

    GuildX700 Forum Resident Thread Starter

    Location:
    USA
    Yeah, I guess I was mixed up in my terminology, coupled VS isolated. So which does one strive for with a turntable, isolation or coupling?

    I'm still shocked that me, a 158 pound guy can lightly stomp a bare foot on what is a VERY solid concrete floor and that action can be transmitted through everything to the needle on the record.

    I'm just wondering what is being transmitted then when music is being played, the speakers are on metal stands with the center post heavily damped with memory foam with their spikes covered with the provided rubber coverings.

    I've picked up a couple of cheap items today that I'm going to experiment with that should provide isolation rather than coupling.
     
  11. thegage

    thegage Forum Currency Nerd

    My rack sits on a concrete block (used for passive solar in front of south-facing windows) that's 8 feet wide, 16 feet long, and 12 feet deep down into the basement to bedrock. Still, even with my turntable sitting on Symposium Ultra platform I can stomp on the concrete and hear a faint echo through the system. EVERYTHING vibrates, to one degree or another. The trick is to manage the vibrations. I solidly couple all of my equipment (bypassing component feet) to platforms (Symposium, Silent Running Audio) that dissipate the vibration through conversion to heat. Works for me.

    John K.
     
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  12. chervokas

    chervokas Senior Member

    The thing is, your turntable's sprung suspension probably has a resonant frequency in, I dunno, the area of maybe 4 or 5 Hz, maybe a little higher, maybe a little lower. There's no music going on there, and hopefully it's also well below the mass/compliance resonance of your arm and cart which is maybe around 10 Hz. So, when music is playing it shouldn't cause the stand to vibrate at the table suspension's resonant frequency -- so it won't excite the thing to start bouncing -- or below, where it's not effective. But maybe stomping on the concrete does create a vibration in those ultra low frequencies where they can pass right through the table's suspension or worse, at a frequency that could get the suspension oscillating. Because the stand is also relatively tall, it may be vibrating not only vertically but also horizontally when you're stomping, and the sprung suspension maybe isn't isolating from the horizontal movement as effectively. Still, if the resonance of the system is well below audio frequencies and effective isolation goes down to well below audio frequencies, and there's nothing routinely exciting the floor or stand at frequencies where the suspension is not effective, it shouldn't be a problem.
     
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  13. GuildX700

    GuildX700 Forum Resident Thread Starter

    Location:
    USA
    Interesting, thanks for the reply.
     
  14. GuildX700

    GuildX700 Forum Resident Thread Starter

    Location:
    USA
    So I'm going to try a few VERY cheap ideas along isolation first.

    Different feet on the turntable stand.

    Right now they are metal with Delrin ( a medium hard plastic like material), which must couple reasonably good to the concrete floor? I'm going to change those to some high pressure rubber ones, which are designed as isolation feet for generators.

    [​IMG]

    It may work, or it may make things worse, who knows?

    Each one can handle 125 pounds so I should be ok with a 500 lb max load on the rack with 4 of them, with the records and all. For $12 total it's worth a try.

    I'm also going to pull the 4 small semi hard plastic feet off the turntable's wood base and set it on 4 of these 2"x2" squares of rubber/cork/rubber instead, they are designed as footers to isolate noisy air conditioning compressors. Again, cheap at 12 for $10. Hell if I like them I may try them under my audio components too at that price.


    [​IMG]

    Stuff should arrive Thursday.

    I'm really interested to see if one or both of these makes matters better/worse/ or no change.
    For a total outlay of $22, well no big loss except mostly my time fooling around with this.
     
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  15. Licorice pizza

    Licorice pizza Livin’ On The Fault Line

    I rarely stomp on my floor while I'm spinning albums. If there's gonna be stomping, like a party, I bring out the iPad.
     
  16. Hockey pucks also work. Multiple threads here attesting to their effectiveness. :)

    They're particularly effective at keeping Cups on the proper side of Pennsylvania. ;)
     
  17. dividebytube

    dividebytube Forum Resident

    Location:
    Grand Rapids, MI
    My turntable is sprung and sits on an Ikea Expedit loaded with records -very heavy. That sits on padded carpeting which in turn sits on a concrete floor (I live in a bi-level where the main floor is the basement). I've jumped around on the turntable without any skipping or any noticeable feedback. Heck my B&W speakers are only a few inches away from the bookcase. I'll try the "stomp" test tonight to see if anything is picked up.
     
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  18. missan

    missan Forum Resident

    Location:
    Stockholm
    Wow!
     
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  19. chervokas

    chervokas Senior Member

    I'm not sure that decoupling the stand from the floor is the best idea. Coupling a rigid massive stand to a massive concrete floor seems to me to be a pretty good base for a sprung suspension table. Decoupling a table by using some kind of material that is designed to turn movement into heat through friction -- which is what a lot of these isolation materials are designed to do -- will just make the table more susceptible to movement I suspect, vs. what you have now which is a table that doesn't move unless you stomp on the floor.

    And you definitely don't want to apply any kind of decoupling that's going to have a resonance at the same frequency of the sprung suspension resonance (in probably the 3-6 Hz range). That could actually make things worse.

    I'd probably go the opposite direction, I'd try more tightly coupling the stand to the floor with some kind of threaded cones that fit the stand's footer holes and can handle the weight, in the hopes of transmitting any stand movement into the floor (on the assumption that significant floor movement isn't happening when you're playing music, and when it is it's at frequencies where the sprung suspension is working).

    Pneumatic isolation with air bladders -- of the sort that's used under electron microscopes and of the sort that the old Townshend Seismic Sink was designed for (not the new ones which are just damped springs) -- can, potentially, depending on the design, give you isolation at lower frequencies than probably where your sprung suspension is working, but they can be super expensive, and homebrew replicas -- like mostly deflated inner tubes and such -- while they work under things like turntables (if they're deflated enough to function at the right frequencies), can make leveling a challenge. The problem is, even with those, often their resonant frequency is in the area of around 2 - 3 Hz, and that's around the frequency of footfalls on that floor I bet. (There are lab pneumatic isolators with resonant frequencies as low as 1 Hz, that would work, but we're talking thousands of dollars here to solve a problem that I think is really not a problem in your application).

    If you really want to isolate your table from foot stomping on the concrete floor, besides not stomping on the floor, you may be better off damping the stomping -- I don't know at what frequencies those silicone gel mats work, but something like that maybe (though if you're not getting vibration with normal footfalls, or with at music frequencies, I wouldn't worry about it).

    If you believe Sorbothane's data -- http://www.sorbothane.com/Data/Sites/31/pdfs/data-sheets/102-Sorbothane-performance-curves.pdf --, it's considerably more effective at dissipating shock and movement than something like neoprene, and it looks like if you can use 30 duro Sorbothane you can really get good low frequency movement dissipation (404 - www.sorbothane.com »). As with any such material, the load is crucial -- if you put too much weight on say a Sorbothane footer and compress it, it won't work and it'll just be coupling -- but those kinds of isolators might be worth a try.

    Also worth a try might be the loose silicone cellfoam materials Steve Herblin sells as Herbie's Audio Lab. I haven't tried 'em but I've used some of his other products and they're great and he offers solutions like turntable footers AND stand footers. And he's responsive to questions you might send him.

    But I think the trick is going to be finding something that can respond fast but work at very low frequencies.
     
  20. Metralla

    Metralla Joined Jan 13, 2002

    Location:
    San Jose, CA
    I think you will find that electron microsocopes have moved to active systems like the Herzan or Minus-K.
     
  21. dividebytube

    dividebytube Forum Resident

    Location:
    Grand Rapids, MI
    whoops - around! Not on!
     
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  22. jupiterboy

    jupiterboy Forum Residue

    Location:
    Buffalo, NY
    I've thought about this, and my best guess is that you need to pour a separate foundation for the table/system with a gap between the foundation of the house and that of the system.
     
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  23. Scott222C

    Scott222C Loner, Rebel & Family Man

    Location:
    here
    And lose that butt-ugly rack .......
     
  24. Ski Bum

    Ski Bum Happy Audiophile

    Location:
    Vail, CO
    I have used a lot of isolation techniques and products, but the large air pressurized feet that VPI uses on the Vanquish (Direct Drive Avenger) turntable are simply the most effective I've ever used. I can literally bang on the shelf next to the turntable and nothing comes through the speakers, even when playing at high volume. Harry claims you can put the turntable directly on a subwoofer. Amazing products.
     
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  25. GuildX700

    GuildX700 Forum Resident Thread Starter

    Location:
    USA
    Great post, thanks.
     
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