Part name: Disc-clamp

 

Used for clamping the disc onto the turntable with the correct clamping force. Applies clamping force to the clamping area as defined by the disc manufacturers. Multipole low magnetic field is has a short circuit ring for total field enclosure. Low mechanical inertia is combined with a high clamping force.

The clamp and turntable are made to handle thick, thin, in and out of spec disc’s. As a result the fitting of the clamp is not a tight fitting but allowing some space to deal with the tolerances.  It is intentionally made this way.

Because of the non tight fitting  the clamp may “egg” around. This does not influence the performance of the system. Only the eye of the viewer is annoyed by the movement as it gives the impression of a non regular disc speed. Theoretically it does not influence the speed and cannot do so.

In combination with the offered centre hub as shown here. The “egging” is reduced and above all the disc and clamp handling is improved. Discs will glide to their rest position and the clamp will snap into its position.

Magnetic clamper recommendations

 

A magnetic clamper has to be used in order to keep the disc in position.

Such a clamper has been especially designed for the CD-PRO,  CD-PRO2 and CD-PRO2LF modules and we advise to use it in order to get the best performances out of your application (playability, disc acceptance,…).

   

However, the clamper is a visible part in your application and you may want to design it yourself, so that it matches the line of your products. In this case, the following recommendations have to be taken into account :

· The minimum clamping force is 135 gram force. (metric grams) Below 135 grf, the radial noise increases. Below 85 grf, the radial noise reaches an unacceptable level. Besides, an extra thick disc will decrease the clamping force and meanwhile consume tolerances.

· The maximum clamping force is 200 gram force.

· The maximum weight on the turntable is also 200 grams. The maximum rotational inertia will be a problem before this weight is reached.

· The original magnet is equipped with a metal ring to act as a shortcut for magnetic stray fields. In this way, the magnetic stray fields do not reach the opto-magnetic actuator system. This should also be taken into account when designing a new clamper.

· The inertia of the system should not be increased by means of a heavy disc clamp puck. Best is to keep the puck weight well below 150 grams.

· The shape of the clamper should have a low inertia profile. As low as possible

· The actual clamping area is the edge of the turn-table. The clamper should only clamp in the area close to the edge of the turntable (some discs may be “problematic” shaped). Please refer to the mechanical diagram of the turn table : CD-PRO2 

· If you design a clamper which does not fulfill the above recommendations, performances of the application may be seriously affected : it would be consequently better to use the original recommended clamp device. ( It was designed in 1982, well over 20 years ago. )

· If you want to have an idea about the amount of rotational inertia of your clamp. Then play back the first track and switch the power off. Now use a stopwatch to determine the moment it actually stops. Compare this with the original situation.

VAU1254 CD-PRO2LF  latest version 

Phone :+31 475 468060

Fax     :+31 475 468061

Email  : info@diy-high-end.com

Bare turntable of the

CD-PROx