Litature on the WEB generally indicates that a power supply for a stepper motor should be 20 (min) and 25 (max) times the voltage rating of the motor. Are these voltage multipliers also true for DC servo motors or should the poweer supply match the voltage of the motor?

Servo motors are usually rated as "not to exceed" voltage.

Fred Smith - IMService
http://www.cadcamcadcam.com/hobby

Essentially, the motor voltage rating determines the voltage rating of the power supply that you need for a servo motor. The peak current draw of the motor(s) determines how much current capacity the P/S needs to have.

Enjoy the read:

Servo amp P/S design
http://www.elecdesign.com/Articles/ArticleID/7635/7635.html

Servo motor , servo amp, powersupply sizing for CNC
http://www.rutex.com/pdf/Mystique2.pdf

Like the article mentions the PWM amp is not a piece of wire, what that means is that to go higher than the rated voltage without some form of 'energy' control such as PWM would cook the motor due to the current being uncontrolled at that point, because although the motor does in fact 'see' the higher voltage, the energy or mean current is controlled by current limit in the amplifier, reducing the energy by means of the Pulse width.
The power supply can be designed higher than the 3% they suggest, without damage to the motor as long as the mean current is controlled in this way.
Al.

Thank you for the responces. I read the electronics article, it will be a lot of help in the future..

Thanks again