Behind the Glass
A look at the inner workings of the standby button on a Mark Levinson No5302 Amplifier.
By Matt Waterman
Principal Mechanical Engineer, Global Engineering
HARMAN Luxury Audio Group
The Mark Levinson No5302 amplifier has only one front panel user interface control: the standby button. This article describes what makes this button special, besides that it toggles power on one of the best audio amplifiers available today.
First, as the only user control on the front of the No5302, it deserved special attention. Like all Mark Levinson touch points it is solid metal; in this case 6000 series aluminum. No plated plastic shell here. The aluminum is machined to tight tolerances, then bead-blasted and black-anodized for a beautiful satin finish matching the left and right outer front panels.
Second, this standby button sits flush with and is surrounded by a polycarbonate light ring sleeve, which glows with a warm red light when in operation, and which is in turn surrounded by the smooth glass of the center front panel.
Third is the special little injection-molded bit that makes it all work. This part sits inside the light ring behind the button and has three very important jobs to do:
• It has feet with locating pins to center the PC board on the button assembly and position it at the correct height.
• It has spring-loaded hooks to hold the light ring lightly against the inside of the glass front panel.
• It has an array of eight spring arms with ball ends which provide a suspension for the button to give it a firm positive action whether it is pushed on its center or anywhere around its edge.
The ability to 3D print prototypes was a valuable tool for testing and refining this design. Adjustments for button travel and spring rate were made to get the function and feel right before committing to injection-mold tooling.
The result is a luxury user interface, functional and good looking, with a healthy dose of the attention-to-detail engineering that our customers expect from every Mark Levinson product.