Spectrum
™
RS-232 Control and Anti-Hum Feature
14
Anti-Hum Feature
The rear panel input port labeled “Computer” has a switchable
feature to eliminate or reduce hum sounds often present when
computers are connected to external amplifiers. The hum is
known as a ground loop hum and may be present if the
computer and amplifier have electrical grounding differences.
The telltale characteristic is that it is 60 hertz (a somewhat low
tone.) Inside the amplifier is a ground isolating balun that may
reduce or eliminate the hum when switched ON. If not needed,
it is getter the leave switched OFF as the sound quality for the
connected device will be slightly better in this case.
RS-232 Control Feature
The RS-232 control feature allows the user to remotely adjust
the volume (or gain) of all the audio sources connected to the
amplifier. Such control may be exercised from a separate wall
panel controller or other device. The third-party RS-232 device
is connected via three wires to the back panel connector shown
to the right: TX/Gnd/RX.
This allows the receiver/amplifier to be placed in an area or
compartment that is not easily accessed by the user.
Codes that are required for this setup are available on the
page under “Application Notes” or
https://TeachLogic.com/TeachLogic-app-notes-rs-
Audio levels very often need to be adjusted when switching
from computer audio to DVD players and other audio sources.
Such operations as level UP, DOWN and MUTE are easily
accomplished via a typical eight button controller. Shown here
is a
Cables To Go
controller.
Connecting the control panel:
1. Connect the control panel wires to the provided 3-pin
Phoenix connector.
2.
Turn RS232 SWITCH to ON position. This will disable
the function of the input volume/gain control knobs on
the front of the amplifier.
IMPORTANT
When any remote panel is connected, RS-232 switch must be in "ON" position.
When panel is not connected, RS-232 switch must be in "OFF" position for amplifier controls to function.
