SONOSAX SX-PR (by Gary J. Louie) - Manual (Page 3)

main channels.
OVD (LED) - lights when the input amplifier is 6 dB from clipping. With the 0 dB gain
setting, this occurs at inputs of +10 dBu with clipping occurring at +16 dBu.
SX-PR MASTER MODULE
Note: Sonosax 0 dB = +6 dBu (re 0.775 V) = 1.55 V
REAR PANEL
MAIN OUTPUTS - Left and right main outputs. XLR-3 male type connectors. Active
balanced, pin 2 high, pin 3 low, pin 1 ground as per IEC standard. Drives 600 Ohm
loads to +18 dBu before clipping. Outputs may be operated in unbalanced mode by
shorting either balanced audio lead to ground. CMRR adjustment is available internally.
0/-60 dB switches - selects the nominal output level for the main outputs. 0 dB is normal
line level (+6 dBu output for an indicated 0 dB on the modulometer). -60 dB is nominal
microphone level (-54 dBu output for an indicated 0 dB on the modulometer), so the
main outputs can be connected to another unit's microphone inputs.
HEADPHONE jack - standard 1/4 inch stereo headphone jack, with tip wired as left, ring
wired as right, sleeve common. Stereo or mono monitoring is controlled by the top panel
headphone monitor controls. Maximum output level is +15 dBu @200 ohms.
EXTERNAL POWER jack - standard 5.5 mm external diameter, 2.1 mm internal diameter
coaxial power jack. Accepts 6 - 12 volts AC or DC at 500 mA. (A bridge rectifier is used
for this input)
ACCESSORY connector - DB9 type computer style connector, for connection of the tape
inputs (left and right, unbalanced), and main outputs (left and right, balanced) in parallel
with the XLR-3 main outputs. The tape inputs are factory set for for +6 dBu. Pinout is as
follows:
1 - right output, low (xlr pin 3)
2 - gnd 3 - left output, low (xlr pin 3)
4 - tape input, left
5 - tape input, right
6 - right output, high (xlr pin 2)
7 - left output, high (xlr pin 2)
8 - gnd 9 - tape gnd
TOP PANEL
BATTERIES - accepts 3 size C batteries for portable operation. Please note the polarity
required for each cell. Nickel-Cadmium (Ni-Cd) cells (accumulators) may be used. They
will be charged whenever external power is applied, even when the power switch is off. If
non-rechargeable batteries are installed, remove the CHARGING JUMPER on the DC to
DC converter circuit board. Otherwise, charging current will be applied to the batteries
whenever external power is applied, and will destroy the batteries and ruin the mixer. DO
NOT attempt to remove the aluminum section between the battery wells. It is a heat sink
for components in the DC to DC converter. Note that although Ni-Cds can be recharged
many times, their useful life between charges is significantly less than a fresh set of
disposable alkaline cells.
HEADPHONE MONITOR SECTION:
(MONO)/STEREO/MONO switch - a left + right (sum) program is sent to both headphone