|
New member Username: Matt123Post Number: 3 Registered: Nov-05 | Does anybody have any ideas on how to go some way to isolate the deck? It is on a desk, not the best place, but the only area it will fit... Thanks. |
|
Gold Member Username: Jan_b_vigneDallas, TX Post Number: 7279 Registered: May-04 | There are numerous ways to isolate a turntable. How your table responds to any particular tweak will determine what you should use. Most people have to consider the visual appeal of any isolation system also. Most isolation systems are not very attractive. You can begin with three layers of 3/4" MDF stacked on top of each other. Or, you can attach a shelf to a load bearing wall. There really are too many options to name them all. Look through the archives on the forum and you'll find several threads devoted to this topic. Whatever you decide on, it must be absloutely stable. No sponge rubber or loosey-goosey supports. The table should sit on a surface that seems to be part of the founfdation of the room. In many cases heavy materials are not the best choice unless they become ultra-heavy. Sometimes just removing the dustcover when you play a record will be sufficient. |
|
Silver Member Username: Stu_pittNew York City, New York Post Number: 853 Registered: May-05 | Jan - A while back you posted a link to a diy sandbox isolation unit. I can't find the link. If you remember what I'm referring to, could you re-post it? I googled it and couldn't find it. I think it said it could be used for TT's. Any thoughts as to why or why not? |
|
Gold Member Username: Jan_b_vigneDallas, TX Post Number: 7298 Registered: May-04 | http://www.cognitivevent.com/sandbox.html Any isolation system for a turntable should be titanically stable. "Titanic", of course, referring to Greek Gods and Olympian efforts, not what's rusting at the bottom of the ocean. Should you use a sand/air isolation system there is some risk of loosing this stability. Look at how tables are manufactured and you'll see the idea you should be aiming for. Even with a suspended sub-chassis table, the operating system is tied together to move as a unit. Because, move it will. Now we are discussing movement relative to, but not of, the platter assembly. Any amount of variation in one portion of the system relative to another will result in degraded performance from the table. Look at the motor assemblies of the top flight tables. The generally accepted way to attain stability in speed is to first lock the motor in place relative to the platter by means of substantial mass attached to the motor. Consider that it is difficult to begin moving a large mass but, once started, it is even more difficult to stop. Remember the dimensions involved in producing sound (movement/vibration relative to a fixed "center" position) when devising your turntable isolation system. If anything disrupts the stability of the pieces in relation to each other, you will be creating new sounds, masking existing sounds, simply not responding to sounds in the record groove or, worse case scenario, actually destroying the sound from the record groove. I've never been certain a sand based isolation system can provide the amount of stability required for a turntable without some extra measure of design and construction. (Consider the amount of movement possible relative to a solid earthing on three layers of MDF bolted to a structure of lead/sand filled support columns.) I have even more doubts about a springy air suspension unless lots of technolgy (read dollars) have been put into play. Different tables react to different supports. A Linn will almost always do better on something that is rigid, light and low mass in order to release energy quickly. In this case, Linn assumes the table will be affected by the mechanical and air borne resonances generated by the playback system and also by the mechanical action of the table itself. Other suspended tables, such as VPI with its stiffer suspension, perfer to be "locked down" to the most massive, stable support possible. Once again no one should assume any tweak, however logical it might seem, that works on one system will be universal in its application. |
|
New member Username: Matt123Post Number: 4 Registered: Nov-05 | Thanks! Lots of options to consider... |
|
Silver Member Username: Stu_pittNew York City, New York Post Number: 855 Registered: May-05 | Thanks Jan. |
|
Gold Member Username: Jan_b_vigneDallas, TX Post Number: 7302 Registered: May-04 | Another silver bullet left behind. |
|
Silver Member Username: Ca_convertCardiffUK Post Number: 189 Registered: Jan-05 | A Linn will almost always do better on something that is rigid, light and low mass in order to release energy quickly Jan...how does this work? I'm assuming you imply that the unwanted energy is dissipated (through the feet?) into the table/support in which is should be lost somwhere - therefore, the suppport should not be earthed (infnite mass etc) or too rigid since it needs to absorb and dissipate this energy to heat. I have tried experimenting with "plasticine" which is incredibly inert and absorbs energy well as a damping material or enrgy sink on the feet of my lightweight plinth under the Linn which seems to work well. I havent tried the "ideal" Linn support since domestic arrangments prevent this so am trying anything within the constraints of a wooden cabinet. Its possible that givcen it might act as a microphone absorbing vibration, it could also be made to work in reverse. How I havent figured yet though..... |
|
Gold Member Username: Jan_b_vigneDallas, TX Post Number: 7317 Registered: May-04 | No, but if you do, please let the world know how you did what you did. I'm not sure I can get far enough into the mysticism that surrounds the LP12 to tell you exactly what the concepts are in choosing the correct support system. Short, open, light and rigid are the keys, apparently. Some say the suggested 24" height is to have Linn owners kneel down before their tables whenever they play a record. The one thing about the Linn is it almost always does something different than any other table. It's loose suspension is taken from the old AR AB-1 design from 1957 and hasn't changed in concept since the Linn was introduced. The parts have been upgraded and the whole affair has been tightened to make the idea work better but still the Linn is the odd duck of tables today. Most everyone else has switched to a higher mass and a more rigid system. The idea of the light, open but extremely rigid support system for the Linn is to dissipate energy quickly. The opposite of what your cabinet is doing due to its mass and inherent resonance as an open box. Linn "admits" the table will have some degree of mechanical and air borne vibration that ends up in the table's structure unless you literally move earth and sky to avoid the problem. Instead of having the vibrations slowed by the mass of a heavy support system the LP12 seems to prefer getting the vibration through the system as quickly as possible and releasing the energy as quickly as possible. Normally I've seen the LP12 on top of a light wood or thin MDF top shelf that is not fastened to the support stand but just laid on top of some tabs/spikes from the support's structure. This tends to "sync" whatever vibration gets through the support with the signal from the table instead of placing it out of phase with what is happening at the record/stylus interface. But loose is not what you want in the support of the Linn. Like most tables it should feel as if it is bolted to the top plate of the support. Due to the torque of the motor, even after it has reached speed, the table will generate some "torquing" of the table's structure. The rigidity of the support should be aimed at holding the whole turntable system together as tightly as possible. Any unwanted energy from the motor or the tansformer in the power supply should be damped and drained away by the support system. It is a matter of two impossibilities being used together to create a bit more of the myth that set up and operation of the LP12 is something that is the province of a very few with very special (read expensive) talents. The Linn is still a popular table, particularly in England, so you should be able to find plenty of information about set up and support systems for your table. The Linn is very sensitive to placement and set up and virtually everything you do to a Linn will alter the sound. Should you walk into a Linn dealer to ask for help, look around at how they have their tables set up. I would be prepared with the smelling salts once you tell the dealer where you have your table sited. |
|
Silver Member Username: Ca_convertCardiffUK Post Number: 193 Registered: Jan-05 | Thanks for the advice. Bizarrely, I would probably get away with lining the woodien cabinet to make it inert than changeing it completely, such are the constraints imposed by the desire for domestic harmony. I am going to experiment with using an ideal support just to see (hear) what I am missing. It is already sat upon a wooden plinth which is basically an MDF shelf which is isolated from the cabinet beneath with plasticine. |