it sounds more like damping rather than isolation although it probably isolates at certain frequencies. If you want to have some fun put the stylus down on a stationary record and hook your phono stage to an oscilloscope. Then play a sine wave sweep loudly and see what gets through.@mijostyn Its both. I have tested it and the platform has proven remarkably wide band. I'd recommend the platform but the manufacturer went out a long time ago (Ultraresolution Technology).
How to isolate turntable from footstep shake or vibration
Even while the Oracle turnable that I use has a built-in springs suspension by design there is a low or even sub-low frequency boom every time someone walks in a room. This becomes really bad with the subwoofer’s volume set high as the low frequency footsteps make straight to subwoofer where they are amplified shaking everything around. It seems the cartridge is picking up the footsteps very efficiently as even a lightest foot down becomes audioable. What can be done to attempt to isolate the turntable from the low frequency vibrations? Interesting, that the lower the volume of the subwoofer, the less the footstep shake is evident and with the subwoofer turned off it is a barely a problem at all.
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Hanging with magnets would not be a viable option unless the magnetic field strength was meticulously matched to the total mass of the turntable. Even the weight of the LP itself would have to be considered, and you’d have to take care not to rest objects on the plinth surface. Otherwise you would either have the equivalent of an unsuspended state (magnets in physical contact) or the sudden equivalent of nothing holding the turntable up as it crashed to the shelf or earth. Suspending the turntable footers between opposing magnets, top and bottom, might work. |
mijostyn4,740 posts07-22-2021 8:37am"user510, there are well designed turntables suspensions and not so well designed suspensions. Suspended turntables that have their sub chassis sitting on springs like the AR XA, LP 12 and Thorens turntables are inherently unstable and they tend to oscillate laterally when aggravated. They will skip with footfalls sometimes even more readily than unsuspended turntables. Suspended turntables that have their sub chassis hanging from the springs are inherently stable and want to maintain their resting positions. This category includes SME, some Basis and Sota turntables. They will not skip with footfalls. You can put them on a collapsible card table and they will operate fine without any audible consequence. " Agree that some suspended subchassis type turntables are more stable than are others. Also agree that the lighter Thorens models are definitely prone toward footfall. And this is inherent in the design. Particularly the models such as the TD150 and TD16x/TD14x. However the AR-XA was originally quite stable and able to effectively isolate from physical disturbances such as foot fall, or being bumped into, or even have a fist hit the top of the cabinet while the thing was playing a record.....and not skip. This was one of their advertised abilities. And it was proven time after time in public demonstrations. I think I understand why the AR isolated well while the Thorens or Ariston RD-11 or LP-12 did not. It had to do with a combination of things including the mass of the suspended parts as well as stiffness of that suspended subchassis. The Thorens models, along with the LP12 models did suffer some chassis flex when being disturbed into motion. This chassis flex altered distance between platter bearing and the tonearm mounting, effectively causing the stylus to jump out of the groove. Only later, some several decades later, has Linn addressed this issue with the Sole subchassis. Thorens addressed it with their heavier TD125 and TD126 models which have cast aluminum subchassis that are stout enough not to flex while in oscillation. But they knew what they had back in their earliest versions. https://www.theanalogdept.com/td150_history.htm That said, and it is an interesting discussion, I wonder if anyone has actually solved the issue described in the OP.-Steve |
user510, I have intimate experience with both the AR XA and I have owned 2 LP 12s. They are both potentially unstable and do not handle footfalls well just as ghdprentice indicates. A Sota you can rap on the surface and dance the jig on springy floor and it will not care. It is all about the self centering stability of the suspension that count. |
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