Selecting Balanced or Unbalanced Output Connections
The balanced outputs for 70.7 volts and 25 volts are for speakers designed
for constant-voltage lines. Each speaker must have a line-matching transform-
er, and the speakers must be connected in parallel.
The impedance taps on the
primaries of the line-matching transformers indicate how much power will be
taken from the line. Speakers can be added as required until the total wattage
absorbed by all of the transformers is equal to the rated power output of the
amplifier. However, it is good practice to allow an amplifier a headroom of
10% to 20%. For a 60-watt amplifier,
the maximum speaker load should be ap-
proximately 50 watts; for a 120-watt amplifier,
the maximum speaker load should
be approximately 100 watts.
For unbalanced operation, place a jumper between one of the speaker termi-
nals you are using and "GND."
Do not ground the center tap when you use unbal-
anced operation.
Grounding the Center Tap
If required by the installation,
the center-tap terminals may be jumpered
to the "GND" terminal when the BALANCED speaker output is used. The "GND"
terminal is next to the negative "AUX POWER" terminal on the DAX60; on the
DAX120, the "GND" terminal is next to the "COM" input terminal. When the two
center-tap terminals are linked together,
either one of them may be connected
to the "GND" terminal.
DO NOT INSTALL A JUMPER BETWEEN "GROUND" AND "CT" WITH THE UNBALANCED
SPEAKER CONNECTION: CONNECTING BOTH POINTS TO "GROUND" WOULD CREATE A
SHORT CIRCUIT ACROSS THE OUTPUT TRANSFORMER.
Split-Center-Tap Operation
The amplifier output transformer can be configured for split-center-tap
operation with symmetrical output voltages on both sides of the center tap.
This is intended for special applications with Rauland systems such as the
Telecenter 5000 and the Responder 3000. When a DAX amplifier is used with the
TC5000 or the NCS3000, (a) no more than 50 watts of power may be drawn through
the system, and (b) a TC5007 Transformer Module is required (see KI-1486).
If the installation requires an isolated, split-center-tapped output,
remove the supplied link from the two "CT" terminals: this will separate the
two halves of the output windings (see "OUTPUT CONNECTIONS," above,. and the
attached KMO780).
Note: There is a large capacitor inside the TC5000 and the NCS3000 that
provides a low AC impedance across the center taps. The split windings
are not designed to be used independently.
Auxiliary DC Power Supply
The 28-VDC terminals (on the right side of the DAX60, below the output
transformer of the DAX120) can provide up to 1.2 Amperes to preamplifiers,
Director Series control panels, and other auxiliary devices requiring DC power.
Since this supply is floating,
it can also be used for devices requiring an
7/87
Page 5
