PS Engineering
PAC45A Audio Selector Panel and Intercom System
Installation and Operator’s Manual
200-045-0100
Page 3-2
January 2020
3.3 Communications Transmit (XMT) Selection
The PAC45D has two rotary control knobs to select communications transceiver functions for
pilot and copilot. To select a transceiver for transmit; turn the knob to select the desired radio
from the five available.
The radio is automatically selected to receive incoming radio calls when the XMT is selected.
With a PAC45D, you will never transmit on a radio that you are not receiving. The selected audio
is indicated by both knob position and the green LED indicator.
3.4 COM Audio Selector
The communications receiver audio sources are controlled by toggle switches on the pilot and
copilot side of the CTL45D. These are shared with the navigational receiver audio (up position).
Communication audio from another radio, not selected for transmit, can be heard by flipping
the associated RCV switch, which will place it in the down position. The selected audio is indi-
cated by both knob position and the green nomenclature text.
You will always hear the audio from the selected transceiver, even if the selected comm audio is
turned all the way down on the audio controller because it cannot turn the selected receive au-
dio all the way off.
The volume of all receivers is adjusted by rotating the RAD (inner) knob for pilot or copilot. PS
Engineering recommends a higher volume
at the radio and lower audio panel setting
to mini-
mize noise.
3.4.1 MultiTalker® Head Related Transfer Function (HRTF)
Communication receiver
audio signals are presented to the DSP and processed to “appear” in a
different location to the crew
. “
MultiTalker
” (US Patent #7,391,877) specifies up to nine loca-
tions. This helps the crew to better comprehend speech by locating it in a manner more easily
differentiated by the human brain.
Intercom and other audio is not spatially processed, only the six communications transceivers.
NOTE: YOU MUST USE STEREO HEADSETS, IN STEREO MODE FOR THIS FEATURE.
This adjustment allows the five
Spatial Audio inputs to be “relocated” on any of nine (9)
pre-de-
fined “Head Related Transfer Function” (HTRF) locations.
MultiTalker places the communications receiver audio in one of nine apparent locations in the
crew’s headset. This has been scientifically shown to allow the brain to focus on multiple con-
versations and improve comprehension for the listener.
3.4.2 HRTF On /Off
Placing the the HRTF switch
in the “up” position
acti-
vates the PAC45D MultiTalker® spatial function in ste-
reo headset, (receiver sources distributed) or off (re-
ceiver audio sources neutral).
HRTF
REQUIRES
Stereo
Headsets. If monaural head-
sets are used, the received au-
dio will sound “distant” or
somewhat distorted.
PRELIMINARY
