I have used a 2" slab of Starboard, which is an acrylic type of board. I can't say it was an improvement though. the Cosmos IV is pretty good the way it is.
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The best Isolation stand is to mount a platform through a stud on your wall. I had Sound Anchors of Florida make me a thick metal piece that can be mounted on the wall. On the metal piece they welded a cross member like a T on it. You then place a 2 or 3 inch piece of maplewood block to match the dimensions of your turntable. Place the table on top of this. You can bring an armored tank into your room and your table will be stable.
I had a serious vibration and acoustical problem, because my TT platform rested on a suspended floor (i.e.-not concrete, but joists) I tried mounting a platform on the wall, but still had problems. I finally suspended my table platform out from the wall using heavy duty springs in 4 places. The platform doesn't touch the wall or floor and the cables that do touch the floor and wall are isolated by springs. The platform is bubble level, yet it is suspended. I have a friend who hung his platform from the ceiling accomplishing the same end.
People who have slab floors are fortunate indeed. Ya have to work with what ya have.
THE SOTA FLOATING SEISMIC PLATFORM http://www.sotaturntables.com/engineering.htm
The lofty goal of Environmental Isolation resulted in the development of SOTAs unique sub-chassis system, the Seismic Platform. Environmental Isolation means isolating the moving platter from all the physical and mechanical threats (footfalls, room resonance, air-borne waves, etc.) that will ultimately disrupt the retrieval of the information contained in the record grooves.
Key to the SOTA floating seismic platform is the theory of basic mechanics that tells us that the motion of a moving mass will be most constant when supported by the inertia of a greater mass. In the SOTA turntables, the 12 pound platter is successfully isolated from the environment because of the enormous mass of the 22-pound sub-assembly. To further enhance isolation, the sub-chassis is constructed of self-damping materials (again, constrained-mode construction techniques), with lead providing mass and energy sinking. Each sub-chassis is individually balanced at the factory, complete with its matching platter attached.
The unique SOTA turntable sub-chassis is then hung from a four-point spring suspension (spring utilized on the Sapphire, Star, Nova and Cosmos), giving it all the stability of four pendulums at rest. The four springs are damped to absorb high frequencies and decoupled from the sub-chassis to minimize energy transfer, fixing the suspension frequency at 2.5 Hz. By "hanging" the sub-chassis on springs, gravity stabilizes all external energies due to the centering tendency of the pendulum motion, rather than pulling the mass off center as is the case in the typical "compressed" spring suspension. With a four point suspension (made of four springs placed equi-distant from the center of gravity) and four equal masses (one of which is the adjusted mass* of the tonearm), the SOTA turntables offer a level of stability that can only be achieved with a constantly-balanced- mass system. No matter the tonearm, mass is constant, motion is predictable, and the end result is once again a system that achieves our goal of Dynamic Stability.
Hi All. Thanks for your feedback. Co-incidentally i also received this back from SOTA themselves. Thought i would email them to see what might work for a SOTA and got this response;
Yes, you are correct in that the Cosmos has environmental isolation with the spring suspension. But, if you're looking for an isolation platform, maybe we can help. SOTA, or more specifically Kirk, designed an isolation platform for our entry level models. This platform can now be used for any of our models. It features characteristics similar to the Cosmos armboard in that it is multiple layers of acrylic coupled with hard and soft metals. We've added weight ratio polymer feet to finish it off. It's high gloss black finish makes it look sexy too. The platform sized for the Cosmos will sell for $750.
I wouldn't have thought that isolation would be a big deal with a Sota tt since it is suspended; but I was pleasantly suprised last night with a tweak that I made to my system. Years ago I had my tt sitting directly on a granite slab. After reading some threads I placed a wood board between my tt and the granite and heard a nice improvement in sound. So I knew then that there is some interaction between the base and the plinth. Well, my tech at work has a few blocks of black, dense open celled foam sitting around that was used as packing material for something that we received a while back. This stuff is very dense. It occurred to me last night that this might make for some good isolation material. These blocks are 1.75" thick and two blocks wide is just a bit larger than my granite base. I placed these foam blocks on the granite and then the wood board and tt on top of that. The foam is dense enough that it barely deflected under the load. In fact, my tt was still perfectly level. No adjustment was needed.
Right away, I could hear the difference. Images are more focused and the base is tighter; tighter like a CD. I'd even swear that the surface noise got quieter. It is a remarkable improvement. Much more than I expected to hear being a suspended table. Luckily, this dense, black foam looks good sandwiched between the granite and the wood. With so little deflection in the foam; there is no bulging of the sides. Good thing because I am not taking it out.
I have a suspended turntable and recently bought a self-leveling Vibraplane to place underneath it. The improvement was clear. I then ordered a custom steel ballast plate which weights 136lbs. This is large enough to also place my motor controller on it. This increased the performance even more. I have a very solid, rigid DIY rack with lolli columns in the basement supporting the floor under the rack, so there is no bounce to my suspended wood frame floor.
Proper, serious isolation solutions are a very effective way to improve turntable performance, even if the turntable is a suspended design. Photos can be viewed on my system page.
I had better isolation under my tt years ago and drifted away from that. Somehow, years ago I thought a granite base would be advantageous. I then learned some time ago that the tt sitting directly on granite was not a good thing. Now I have learned over again that the more isolated my tt is from the granite the better. I have listened exclusively only to vinyl the past few weeks having a rediscovery how good analog sounds. The bass is once again crisp and deep; as good as or better than digital. Imaging is tack sharp. This past Sunday night I was listening to Dark Side of the Moon. I was delighted to experience the holigraphic sound stage of this album again after several years. The oval pattern of the sounds moving left to right and back at the beginning of the record was very apparent; as well as the oval pattern in the footsteps on the next track.
Tonywinsc, As my system has improved, those sounds swooshing around in an oval patter have moved from above the plane of the speakers to now where they are circling above my head. I have not gotten the oval to go completely behind me yet, but it is indeed an amazing effect. A bit like helicopters in a big Summer Blockbuster movie. This is an LP that continues to sound different as the system changes.
Peterayer, that is way cool. Your turntable and platform look very good. I'm sure the sound is fantastic. I have an ARC preamp and it throws a deep/wide sound stage but never forward of the front plane of the speakers. It goes deep instead. My analog soundstage goes beyond the speakers and almost to the side walls (24ft across). My digital soundstage is just as deep but not nearly as wide. I also think that the better isolation reduced surface noise on my records. I can't really prove that however.
The fly in the ointment when using suspended turntables on isolation devices such as Vibraplane is that if the resonant frequency of the turntable's suspension is close to that of the isolating system the two systems can interfere with each other. Like a car going down the street with two shock absorbers for each wheel, linked in series. The passengers in the car will have a very bumpy ride. One way to test this theory is to disengage the turntable suspension and see wa' happen.
If you want to go on the cheap, a good home-made isolation platform that I have used for years is to buy several wheelbarrow inner tubes at your local hardware store and a large cement paver block. Place the block on the inflated inner tubes and your turntable on that. Sounds silly, but I learned this trick in graduate school where we needed to isolate a monolayer trough from building vibrations and my graduate advisor had me do the same thing (he was cheap). I tried a lot of other solutions but nothing worked as well as the massive block on the tubes. I think there are some commercial products such as the Townsend Audio Seismic Sink and others that use this principle but will cost you a lot more. Good luck.
Geoffkait, that is an interesting post. I never really considered that. I may try to lock down my SME suspension and listen to the result. The other alternative is to tune either the Vibraplane or the SME towers to different frequencies. They are adjustable, but I don't know how to measure the respective resonant frequencies. Thanks. One more thing to play with.
Peterayer, the suspension Fn on your tt is likely in the 1-3 Hz range. At least my Sota is around that. So you can maybe measure it with a stopwatch since it is slow enough. Just excite your plinth and try to count as many cycles as you can while running a stopwatch. Then just divide the no. of cycles you counted by the time on the stopwatch. What Geoffkait says is possible. If the Fn's of both the tt and the platform are the same, then they can excite each other and if they get 180 degrees out of phase, then be ready to catch your tt. :) When you excite your plinth by pushing down on it, just watch to see what the platform does. Maybe it is dampened so that it does not respond to the tt mass moving up and down.
The Vibraplane and the VPI towers are almost certainly not tuned to the same resonant freq. The Vibraplane is most likely around 2.5 Hz in vertical, I suspect the VPI towers' resonant frequency is around 4 or 5 Hz, possibly higher. Even though the resonant frequencies are not equal the two systems can still interfere, when you consider the mass on spring device acts as low pass filter with attenuation characteristics analogous to electronic filter, E.g., 6 dB per octave. So they can still interfere.
The SME suspension towers are heavily damped, so pushing down on the plinth does not get it to oscillate. Likewise, the Vibraplane is fed by a compressor, so as soon as one corner is pushed down, the air bladders immediately fill up and so it does not oscillate either.
I have not tried to defeat the suspension of the SME and listened to it on the Vibraplane. I only compared the table with and without the Vibraplane, and it is better with the Vibraplane inflated. The motor controller isolated on the Vibraplane also makes quite a difference.
Thanks for your suggestions. BTW, I thought that if they are 180 degrees out of phase, they would cancel, and it is only when they are in phase that the cycles amplify to cause problems.
I suspect all is fine, because I have never seen either move and the sound has never been better. But I wonder if the isolation is redundant. I'm going to try to defeat the isolation on my the SME towers this weekend and give it a listen.
Hi All. Been awhile since i have visited this topic. And it has been for an interesting read. I should share with you all however an email i received back from Sota themselves regarding this topic. I thought at the time i may as well send them an email as they would perhaps know best what type of isolation works with their turntables and this is what i received in reply. I received the reply on 17th March of this year;
Thank you for your message and patience as we attended to show preparations and attendance.
Yes, you are correct in that the Cosmos has environmental isolation with the spring suspension. But, if you're looking for an isolation platform, maybe we can help. SOTA, or more specifically Kirk, designed an isolation platform for our entry level models. This platform can now be used for any of our models. It features characteristics similar to the Cosmos armboard in that it is multiple layers of acrylic coupled with hard and soft metals. We've added weight ratio polymer feet to finish it off. It's high gloss black finish makes it look sexy too. The platform sized for the Cosmos will sell for $750. I can't send a photo at this time ('cause my computer is too full to take anything more or it might blow up). If interest, just let us know.
SOTA Sales & Service
800-772-SOTA - (608) 538-3500
I just sent them another follow up email as Donna did promise to send me some pics. But i have yet to receive them and other priorities have intervened in the meantime.