Specifications

4
MODIFICATIONS
To access internal modifications, first disconnect power to the unit. Then lay the unit on a flat surface with the front panel facing forward
and the top panel facing up. Remove the top panel (eight screws along the sides and rear; one screw centered behind the front panel).
Modifications are at the center of the circuit board, starting from the left side (see diagrams below). Modifications require no soldering.
MIC/LINE ASSIGN: Internal jumpers are provided to assign Mic/Line Input signal to the Main Output and the Zone Output, independently.
From the factory, Mic/Line Input signal is assigned to both the Main Output and the Zone Output. To un-assign Mic/Line Input signal from
the Main Output, move jumper P2 (‘MIC INPUT TO MAIN OUTPUT’) forward one pin to the ‘OUT’ position, using needle-nose pliers. To
un-assign Mic/Line Input signal from the Zone Output, move jumper P1 (‘MIC INPUT TO ZONE OUTPUT’) forward one pin to the ‘OUT’
position. If desired, Mic/Line Input signal may be un-assigned from both outputs. A jumper is also provided to assign Mic/Line Input signal
to the Main Output pre or post tone (Treble & Bass). From the factory, Mic/Line Input signal is assigned post-tone (not affected by Treble &
Bass). To assign Mic/Line Input signal pre-tone (affected by Treble & Bass), move jumper P3 (‘MIC INPUT TO MAIN OUTPUTS’) forward
one pin to the ‘PRE-TONE’ position, using needle-nose pliers. See also Mic Pre/Post VCA on page 5.
IN
MIC INPUT TO MAIN OUTPUTS
OUT
IN
MIC INPUT TO ZONE OUTPUT
OUT
POST-TONE (SEE VCA JUMPERS)
MIC INPUT TO MAIN OUTPUTS
PRE-TONE
P1
P2 P3
STEREO INPUT ASSIGN: Internal jumpers are provided to assign Stereo Line Input signals to the Main Output and the Zone Output,
independently. From the factory, Stereo Line Input signal is assigned to both the Main Output and the Zone Output. To un-assign Stereo
Line Input signal from the Main Output, move jumpers P4 & P6 (‘LEFT INPUT TO MAIN OUTPUT’ & ‘RIGHT INPUT TO MAIN OUTPUT’)
forward one pin to the ‘OUT’ position, using needle-nose pliers. If desired, left & right Stereo Line Input signals may be un-assigned from
the Main Output independently. To un-assign Stereo Line Input signal from the Zone Output, move jumper P8 (‘STEREO INPUTS TO
ZONE OUTPUT’) forward one pin to the ‘OUT’ position, using needle-nose pliers.
MUTE ASSIGN: Internal jumpers are provided to assign muting of Stereo Line Input signals at the Main Output and the Zone Output,
independently. From the factory, muting is assigned to both the Main Output and the Zone Output. To un-assign muting from the Main
Output, move jumpers P5 & P7 (‘LEFT INPUT MUTING’ & ‘RIGHT INPUT MUTING’) forward one pin to the ‘OFF’ position, using needle-
nose pliers. If desired, muting may be un-assigned from left & right Main Outputs independently. To un-assign muting from the Zone
Output, move jumper P9 (‘STEREO TO ZONE MUTING’) forward one pin to the ‘OFF’ position, using needle-nose pliers. If desired,
muting may be un-assigned from both the Main Output and the Zone Output.
NOTE: Mic/Line Assign, Stereo Input Assign, and Mute Assign are totally independent of each other. Therefore, Mic/Line Input signal may
be un-assigned from either output, without un-assigning the muting function from that output. Likewise, the muting function may be un-
assigned from either output, without un-assigning Mic/Line Input signal from that output. To un-assign both Mic/Line Input signal and the
muting function from a given output, both jumpers must be moved. Also, Mic/Line Input signal may be un-assigned from the Main Output
and Stereo Line Input signal may be un-assigned from the Zone Output, creating separate outputs for Stereo Line Input and mono Mic/Line
Input signals. This is useful when separate high-fidelity (music) and distributed (speech) speaker systems are desired.
MUTE ADJUST: Internal screwdriver adjustable controls are provided to adjust the amount of muting applied to Stereo Line Input signals.
From the factory, -40dB of muting is set for Stereo Line Input signals. To decrease the amount of muting at the Main Output, adjust
controls R75 & R76 (‘MUTE TRIM’) clockwise. To decrease the amount of muting at the Zone Output, adjust control R77 (‘MUTE TRIM’)
clockwise. These controls are totally independent. Therefore, different amounts of muting may be set for each output. However, muting is
usually set the same for left & right Main Outputs. The muting range is adjustable from -40dB (max.) to -4dB (min.).
IN
OUT
P4
ON
OFF
P5
MUTE TRIM
(CCW = MAX)
LEFT INPUT TO MAIN OUT
PU
LEFT INPUT MUTING
IN
OUT
P6
ON
OFF
P7
MUTE TRIM
(CCW = MAX)
RIGHT INPUT TO MAIN OUT
PU
RIGHT INPUT MUTING
IN
OUT
P8
ON
OFF
P9
MUTE TRIM
(CCW = MAX
)
STEREO INPU
TS
TO ZONE OUT
PU
STEREO TO ZO
N
MUTING
R75 R76 R77