Originally Posted by
Ammonite Acoustics
If anyone with a Jelco arm is a bit puzzled why placing a weight on top of the arm structure can possibly be a Good Thing, my advice is to try it. In the first instance, just use a spare counterweight (usually the heavy one that comes with the arm), and place it carefully on top of the damping knob. Adding mass in this way, to my ears, greatly enhances the depth of sound and musical flow. It's free to try in the first instance and you can always get Steve to make you a nice shiny one that sits more securely on top of the arm if you like the effect.
There's nothing pseudo-scientific or foo about why this works - one of the best ways of damping a resonant structure is to apply mass. That's all!
This tweak also works with my FR64S and I will get Steve to make me another weight to sit securely over the top of that arm