Friday, February 18, 2011

Removing bad vibes

There I was feeling all feverish again with my neurotic mind working non-stop thinking about the limitations of the Rega Planar 3 turntable's design.

Suddenly, it struck me that almost all turntable designers had never bothered to solve the problem of vibrations caused by the bearing. Not just Rega, but almost every other manufacturer out there.

The bearing makes some noise and vibrations because the spindle revolves in the bearing housing and sits on a ball bearing if the spindle has a flat bottom or if its end is spiked, the sharp end spins on the bearing housing base.

Turntable designers just use oil to lubricate the bearing and also to dampen the vibrations.

What happens to the vibrations? The thin film of oil may absorb some of it, but the rest will just travel up the bearing housing to the plinth and then to the tone arm and stylus.

Some vibrations will also travel up the spindle to the sub-platter and then the platter and pass through the mat (which will absorb some) and to the LP to the stylus.

Two strips of Dynamat wrapped around the bearing
housing at the bottom of the Rega Planar 3.

Some designers use heavy plinths or platters to dampen the vibrations from the bearing and the motor.

I decided to absorb the vibrations at the source - the bearing housing itself. Since I had a sheet of Dynamat Extreme - a dampening material comprising a black sticky compound with aluminium sheet backing which is widely used in the car industry - at home, it was just a matter of cutting a strip to wrap around the bearing housing jutting out at the bottom of the Rega's plinth. I used two pieces of Dynamat.

Then I played an LP and noted a lower noise floor.

Since I was already in a tweaking mood, I decided to go one step further - I unscrewed the plastic cover of the motor to see what else I could mess around with.

The Premotec motor. Note the
square piece of double-sided tape.

Dynamat strips were pasted on the motor and plinth.

The Premotec motor (I had upgraded the motor many years ago when Trikay was still in business) was simply stuck to the top veneer of the plinth with double-sided tape.

So I pasted Dynamat on the motor, the plinth and the veneer. I also pasted some on the small plastic cup that houses the spring-loaded thrust bearing of the motor.

I listened to the LP again - the noise floor was lowered some more.

It appears that the performance of a turntable will improve progressively when increasingly more vibrations are removed from the equation.

So if you have some spare dampening sheets lying around, you can improve the performance of your turntable simply by pasting them at strategic spots.