PS Engineering PMA6000M-S - Manual (Page 10)

PS Engineering
PMA6000 Series Audio Selector Panel and Intercom System
Installation Manual
200-066-0006 Page 2-3 Rev. 6, March 2005
ference is possible. The PMA6000s were designed in a RFI hardened chassis and have internal Electro-
magnetic Interference (EMI) filters on all inputs and outputs.
Ground loop noise occurs when there are two or more ground paths for the same signal (i.e., airframe and
ground return wire). Large cyclic loads such as strobes, inverters, etc., can inject noise signals onto the
airframe that are detected by the audio system. Follow the wiring diagram very carefully to help ensure a
minimum of ground loop potential. Use only Mil Spec shielded wires (MIL-C-275000, or better). Under no
circumstances combine a microphone and headphone wiring into the same shielded bundle. Always use a
2- or 3-conductor, shield wire as shown on the installation wiring diagram.
Radiated signals can be a factor when low level microphone signals are "bundled" with current carrying
power wires. Keep these cables physically separated. It is very important that you use insulated washers to
isolate the ground return path from the airframe to all headphone and microphone jacks.
Adding a high-performance audio control system, particularly in conjunction with active noise canceling
headsets, cannot improve on older avionics that were designed for cabin-speaker use. PS Engineering
makes no claim that the audio panel will provide a noise-free audio quality under all installation conditions,
particularly with older avionics.
2.4.2 Entertainment Input
2.4.2.1 Monaural (6000, 6000M, 6000C, 6000MC)
Two entertainment devices (CD player, cassette player, etc.) can be connected to the unit. Install two 1/8-
inch stereo jacks in a convenient location so that the pilot can plug in the entertainment devices into the
system.
For a stereo input, we recommend tying the left and right channels (tip and ring) together, so both stereo
channels are provided to the monaural audio panel, and the audio amplitude available to the audio panel is
increased. Audio signal at the entertainment input must be a minimum of 500 mV P-P for optimum music
performance. We have noticed that the portable devices using 4 batteries seem to work better than the 2-
cell types. Also we have found that some cigarette-lighter adapters introduce noise into the system due to
the dropping power supply.
N O T E : T h e S o f t M u t e m u s t b e e n a b l e d i n t h e 6 0 0 0 , 6 0 0 0 M , 6 0 0 0 C , 6 0 0 0 M C
e i t h e r b y c o n n e c t i n g t o p c o n n e c t o r p i n s N a n d 1 2 t o g e t h e r i n t h e h a r n e s s , o r
t h r o u g h a n e x t e r n a l S o f t M u t e E n a b l e s w i t c h .
2.4.2.2 Stereo (6000S, 6000MS, 6000SC, 6000MSC)
Two stereo entertainment devices (CD player, cassette player, etc.) can be connected to the unit. Install two
1/8-inch stereo jacks in a convenient location so that the pilot can plug in the entertainment devices into the
system. The audio signal at the entertainment input must be a minimum of 500 mV P-P per channel for
optimum music performance. We have noticed that the portable devices using 4 batteries seem to work
better than the 2-cell types. Also we have found that some cigarette-lighter adapters introduce noise into
the system due to the dropping power supply.
2.4.2.3 Soft Mute
The PMA6000-system incorporates a "Soft Mute" system. This will mute the entertainment devices during
ICS or radio traffic. While in the ALL or ISO modes, entertainment #1 is heard by everyone (except by the
pilot in ISO mode). While in the CREW mode, pilot and copilot will hear entertainment #1 while the pas-
sengers will hear entertainment #2.
Entertainment inputs #1 and #2 can be paralleled so a single entertainment source can serve both the
passengers and the crew in "crew" mode. It is suggested however, that a switch (DPDT) be installed
between the single entertainment device and entertainment input #1. This will allow the pilot and copilot to