Crown OC-150A - Input Connection Procedures; Important Input Connection Cautions

Amp inputs #I, tf2 and #3 all have isolated grounds, both channel-tom
channel, and from the chassis. Amplifiers with balanced outputs may be
used without problems.
Amp #2 input is connected to the front panel headphone jacks via the
headphone selector switch. Mechanically, these stereo jacks have
cammpn grounds. To keep input #2 balanced, the ground return for
channel I has been deliberately eliminated. (Strap "c ,see schematie, MI*
264.) Thus input #2 can k usedasa balanced input for metering only; no
signal will be present on channel 1 at the headphone jacks. The e1ectra.o-
static barrier strip may be used as a balanced output.
Most present-day amplifiers have a common ground between channels.
Thus strap "X" is not needed for normal operation. If single channel
operation is desired, then strap "X' must be installed, Additionally, a
similar strap could be added to all inputs, and thespeakt3rcables could be
reduced to 3-conductor ea bles.
-. Any load connected to a balanced output must have isolated grounds! Just
because electrostatic headphone boxes have four wires does not mean the
set has isolated grounds!
Never parallel the OCm150A input terminals, except in the case of using
one amplifier for speakers and headphones. Any time an unbalanced in-
put is parallsled to another input(s), all inputs involved become un-
balanced!
$5 PY
-- With strap
X connected, you cannot use a balanced amplifier (such as
any CROWN amp operating in mono) into input #2.
For special hook-up diagram for CROWN mono amps, see INPUT
CONNECTIONS FOLDOUT. This hook-up provides full power to the
speakers and half power to the headphone jacks.
- Never adjust the mechanical zero adjust on the meter fronts.