SMc Audio Virtual Reality Engine Preamplifier VRE-1 - Manual (Page 13)

12
Grounding Options
Your VRE-1 provides several options for matching earth ground arrangements
for best results with your system. A binding post connected to circuit ground is
provided on the rear panel to facilitate external connections to other equipment
chassis grounds if need be, and an adjustable ground jumper is provided inside
the power supply. This jumper provides 3 options for the connection between
earth ground and circuit ground: A) isolated connection via an RC network
consisting of a 100 Ohm resistor in parallel with a .01uF capacitor, B) direct
(zero-ohm) connection, and C) no connection. (Please note that the use of a 3-
wire grounded AC cord assumes that an appropriate earth ground connection is
provided by your house AC wiring.)
The VRE-1 is shipped with this ground jumper set in the (A) isolated position.
This seems to work well in most circumstances, but you should experiment with
the jumper setting if you are experiencing any hum and/or buzz issues.
Locate the jumper by unplugging your power supply first for safety, then
removing the top 2 screws on either side of the cover (4 screws total). Remove
the cover by lifting it straight up. The ground jumper is located near the front
edge of the main circuit board, near the LED wire (see the photo below). Change
the jumper position by pulling it straight up (use your fingers or some small pliers)
and moving it to the alternate setting. The header has 3 pins, and the jumper
covers 2 at a time (the center pin is always used). The left side (as seen in the
photo) is position “A” and the right side is position “B”. The jumper may be
removed completely for setting “C” (no connection).
Note: You will see several other jumpers in the power supply, but do NOT move
them. These are factory-set for proper operation of your VRE-1.