Audio Control EQS Owner's Manual page 9

UNDER THE COVERS
1. Input Grounding: For most systems you can leave
this jumper set in the BALANCED position. In some systems,
the source unit may look for a ground through the RCA
connection to the amplifier and create a ground loop, which
in turn can cause a whine (we are not talking about Merlot)
in your system. In that event, you should go ahead and
change the four jumpers to the UNBALANCED position.
2. Ground Isolation Selector: Occasionally alterna-
tor noise may appear in a system because the source unit and
amplifier are using different grounding schemes. To help in
this situation, we have provided alternative grounding
connections. Make sure your system is turned OFF before you
move these jumpers.
3. PFM Subsonic Filter: The EQS utilizes the world
famous AudioControl, PFM (Programmable Frequency
Match) filter to help with speaker control and amplifier
power management. To change the PFM frequency, it is as
simple as removing the cover and changing the module,
which you will want to do when the power is disconnected.
Your authorized AudioControl dealer carries an assortment
of these modules.
Figure 3: Cut away of inside of EQS
(not to scale)
Owner's Enjoyment Manual
3
2
1
Balanced
Unbalanced
Ground
Isolated
200
7