Thoughts On Turntable Clamps And Weights

@lewm 1++ 

For turntables that are not supplied with a reflex clamp the Sota is the best. It must be used with a firm mat and a thin rubber washer over the spindle. It the mat is too soft the edges of the record will curl up. 
 

The issue here is keeping the record flat and dampened. Even small variations in pitch will ruin the effect of feeling you are at a live performance. As record elevation changes the pitch changes. Very few records are perfectly flat.

@lewm , @terry9 

Wow, hold on now. Lew, there is supposed to be a firm rubber washer about 0.5 to 1mm thick and 1/2 to 3/4" in diameter over the spindle, under the record. The Sota REFEX clamp contacts the label only at its very edge. When you tighten the clamp down the edge of the label is forced down into the label rebate flexing the record into the platter/mat. This will remove small warps and flatten dished records. It is way better than just a record weight. SME, Avid, Oracle, Kuzma and Dohmann use this method. It is not as good as vacuum clamping but a bunch less complicated and it will work everytime. Vacuum clamping will fail if the record is badly dished or too warped. 

@stringreen , IMHO periphery clamps are a Pita and an accident waiting to happen. They are totally unnecessary if you get a reflex clamp like the SOTA. 

@dwette 

In order for a suspension to isolate a turntable from environmental noise it has to have a resonance frequency between 1.5 and 3 Hz. This is a mechanical filter in which you have a mass and a set of springs with a given rate to produce the correct resonance frequency. If the springs are not tuned to the mass you have an ineffective method of isolation. In other words all that other stuff does not work. Turntables that have such suspensions include Basis, SME, Sota, Avid, some Kuzmas, The LP12, Dohmann and I am sure I am missing a few. There are platforms that you can order or adjust for the mass of your turntable such as the MinusK and Vibraplane. 

@dwette ,

Get a seismograph app on your phone, place the phone on the surface your turntable is sitting on and lightly tap the surface. Now put the phone on your platter and lightly tap the same surface. Play another source loudly with a lot of bass and check out the vibration you can measure in different locations. Your phonograph cartridge is more sensitive than the seismograph. I can not qualify the difference you will hear when you put your turntable on an isolation platform but you will hear a difference and wonder why you had not done this years ago. What you are listening to now might best be related to mud. This is why the AR XA made such a splash in the 60s.  

@dwette 

Get the app and check out how your situation is doing now. I think the app is free. When placed on the platter should be able to jump and bang around without anything registering on the platter. Wall shelfs may help with severe problems like foot fall issues but they are poor isolation otherwise. You can prove that to yourself. Get the app. it will tell you everything.

@dwette ,

That app is referring to earthquakes! The one I use is labeled Seismometer. I also use an iPhone. It looks like a real seismometer. There is a needle that paints squiggles on a graph when you disturb it. If you put it down on any surface and tap you will see a sgiggle. I have it open right now and it is registering me typing. if you go to the app store and type in seismometer, "Vibration meter, seismometer" comes up. "measure all vibrations." that is the one.  

@dwette 

Go to yellowagents.com/seismometer

@dwette,

It is not all that bad but you have to remember, your cartridge is more sensitive than your phone. Ideally you should be able to tap around the turntable and jump up and down in front of it and see nothing but a straight line on the phone. Sweetnighter (one of my favorite Weather Report records) does not have very low bass in it. Play a Billy Cobham drum solo loud. Do you have subwoofers? Systems without subwoofers generally will not project much below 40 Hz. That is a full octave they are missing.