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Old 7th May 2012, 04:34 AM   #11
andyr is offline andyr  Australia
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Originally Posted by Jozua View Post
Hi

I used mable for my CD player and it excellent in my system.

Jozua
But did you try any other substance, to compare?

Regards,

Andy
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Old 7th May 2012, 04:39 AM   #12
a.wayne is offline a.wayne  United States
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Sandbox is best IMO, or you can get a suspended table , AR, Linn for eg ......
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Old 7th May 2012, 09:30 AM   #13
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Sandbox is best IMO, or you can get a suspended table , AR, Linn for eg ......
I tried sandboxes under my valve amps, spiked to the floor. Then I went to a homemade rack system, with shelves suspended on polypropylene "wires", strung corner to corner of the rack, and that seems to sound cleaner. I have various shelves, granite, MDF, foamed vinyl, slate, but to be honest my system is not "clean" enough to tell the difference between shelves. At the moment.
As for constrained layer damping, my (admittedly limited,) understanding is that the layers need to be tightly bonded together to constrain the microscopic movements in the materials involved. Glueing with silicone adhesive is probably too soft to qualify, but that is not to say it won't work, probably just a different mechanism involved. Hopefully someone with engineering knowledge will set me (and you?) right on this.
With the inner tubes, I found cheap soft ones give a more compliant support than good strong ones. YMMV, of course. Under a preamp they were a bit stiff, but under my speakers I get about 2Hz resonance, like Seismic Sinks.
With an earlier version of my speakers, hanging the mid/treble cabinet from a frame with shoe laces (cotton? Does that matter??) above the bass cabinet, instead of spiking them together, cleaned up the BASS amazingly; active xover at 180Hz, so the mids carried a lot of bass as well.
There are a lot of different ways to isolate or damp, and I am lucky enough to be able to make and try different things. Now, if I could just remember which one was which........
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Old 7th May 2012, 09:33 AM   #14
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Originally Posted by Nanook View Post
...

Mass can help isolate a component from external vibrations (like a 40 ton highway tractor and trailer speeding down your street).
Sounds like a crash barrier might be needed there!
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Old 7th May 2012, 01:40 PM   #15
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Originally Posted by awkwardbydesign View Post
Sounds like a crash barrier might be needed there!
With enough mass - say some large boulders in the metric ton range - you might be able to isolate the house form the road vibrations too!!!

I once lived in a shaky old house built in the late 1800's and getting things stable there was a challenge - wound up using a reel to reel to play most music to avoid the TT.
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Old 8th May 2012, 08:04 PM   #16
wrankin is offline wrankin  United States
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Thanks for all the ideas, guys!

Nanook: your comments about external vs. internal vibration sources is spot on. Right now my major battle is combating external vibrations so mass is a plus. Internal vibrations will be address when I eventually get around to designing a new plinth.

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Old 9th May 2012, 09:33 AM   #17
oshifis is offline oshifis  Hungary
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I used marble sub-base for my home-made turntable, hung on springs. It was very sensitive to footsteps. Later I modified the construction so that it was supported on balsa wood blocks. That was more stable, but I did not like the sound. I think heavy subchassis is a dead end.
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Old 9th May 2012, 10:22 AM   #18
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Squash balls work well . Loricraft use them on the Garrard 501 and openly admit it . 5 are used . Worth a try . I have used big bubble wrap .

Best I came across was brass cones with maple wood support . The guy was most insistent it was the best . I never told him I liked it as he went on so much about it . Brass not bronze he said . They were big cones . No idea if it works in another situation . I imagine marble under that would be great .

Last edited by nigel pearson; 9th May 2012 at 10:26 AM.
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Old 9th May 2012, 08:11 PM   #19
Nanook is offline Nanook  Canada
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Default Jesse, pls PM me. More comments on isolation: internal vs. external

For most of us the intrusions of relatively high energy low frequency vibrations is what upsets the sound. I currently have this problem. I live in a rented house, that has very poor floors (as in springy). If I walk past my turntable while playing I can easily upset it. With the addition of the slab of granite underneath my equipment stand, the effect essentially disappears. Then the stand can do as it is suppose to do, isolate each component from one another. This does nothing to effect the actual resonance of each individual component. The only way to deal with that is to ensure that each component has enough internal dampening, or has the means to absorb and radiate any vibrations away.

One way to create an increase in internal dampening is to use a dampening material such as "Dynamat" or similar. Basically adding an elasto-polymer or rubber of some sort. Another option is to remake the component cabinets out of one of nature's best inventions: wood. It seems alot of these issues were just not considered or did not interfere with the enjoyment of music when most everything in audio was made of wood. It seems to me that as manufacturing went away from wood cabinets for audio components, the issue of internal vibrations and the smearing of sound occurred. I suspect if we made new wood cabinets for our gear, many of the internal vibrations would be "naturally" disapated.

Isolating a component from its bretheren in an audio rack or stand requires decoupling of components from each other. The use of Isolation platforms or shelves are indicated in this instance. The best isolator ? No isolator. But obviously that it is not practical. So a couple of things come to mind. Air bladders (inner tubes) and sand boxes can be used here (sandboxes can be considered as isolating from external vibration and isolating or controlling internal vibrations. and for this reason they work well in a great number of systems).

Another option is the "hung" or "strung" or "suspended" types of racking or shelves. These do require a little more of thinking prior to implementation if DIYing yourself. Hardware can get a little expensive if using these sorts of materials. Unlikely to be cost prohibitive as a commercial stand, but not cheap either.

Personally I have found combinations to work well. I have never used any sandboxes. Placing my equipment rack on my slab of granite seems to isolate the it from external rumbles. The use of inner tubes and such works well under most components as long as the tube can handle the mass (something to consider if using underneath any component approaching 50 lbs).

Regarding the suspended type, my audio partner is returning here for a month and we have a few audio projects on the go. One is an ultra light, ultra rigid rack with the potential for suspension of the shelving for isolation. Once completed I'll post some pictures and some comments regarding the sound of it. This is based on the "80 20 rack" over at Audiokarma (I think). But the suspension portion will be our take on it. I suspect I will do a write up of it for Affordable$$Audio.

One last comment: Squash balls. Me and my audio partner retrofitted a Roksan Xerxes (MkI) with squash balls used as springs intead of the "blobs" or whatever the Roksan folks call the threaded rubber/steel suspemsion pieces. They worked well therre, as the subchassis is relarively light. Trying to use squash balls under my old Alex didn't really work. The table literally "squashed" the balls.
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Old 9th May 2012, 09:03 PM   #20
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I met a professor Dolly of Harwell in Oxfordshire about 30 years ago . He was asking about this subject and got furious with me when I suggested what we are talking about here ( he stated the BBC used about 50 kg ) . I think the late boss of SME said 50 tons is about right for a turntable support .

The prof was indignant and started saying how could I be so certain . My answer was he should get an oscilloscope and measure it . 60 dB dynamic range was set ( about what a record can offer ) . Soon I get an excited phone call . I am wrong and the problem is ten times my estimate ( 500 tons ) . The stylus was placed on a stationary record . He could see his wife's footsteps going down the garden as she pegged out the washing ( he said ) . Ironically he was near the Didcot power station . Nothing from that ( I asked ) !

Remember an Ortofon pick up might need a gain of 20 000 at 20 Hz ( 100 uV type SPU ) . That will make the problem worse . Add a gain of 25 from the power amp at moderate volumes to get half a million .

On the strength of this the prof bought a B&O turntable . I didn't get that !

Some people make magnetic levitation tables . Looks easy to do and might work ( lots of small magnets ) . Will need stabilizing if so ( rubber bands ) .
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