OTARI RADAR II, Operation Manual, Page: 30 / 261

Balanced vs. Unbalanced Signals: Balanced audio cable has three
conductors: two conductors carrying the same signal at opposite polarities and a
ground. Balancing generally results in lower susceptibility to electromagnetic
(EMI) and radio frequency (RFI) induced noise, and permits longer cable runs
without risk of interference. As well, balanced cables do not necessarily need to
be grounded at both ends and this means fewer ground loop problems.
On the other hand, unbalanced cables have two conductors only: one for signal
and one for return. The return must always be grounded in order for signal to
flow. This scheme is more susceptible to radio or electromagnetic interference
and poor quality cables can be noisy if they are handled. Many studios, however,
successfully use unbalanced lines and they should not present problems if the
equipment in the studio is properly grounded.
Wiring diagrams for balanced and
unbalanced cables appears in Appendix A.
1.5.3 Input and Output Reference Levels
Zero dB in digital audio equipment is the maximum signal level that an input
device such as a mixer, effects unit or recording machine can accept to gain
optimum signal-to-noise ratio before distorting. When a VU meter shows an
input signal level of 0 VU, +4 gear will be actually 4 dB above .775 volts RMS.
When the meter shows 0 VU on -10 gear, the signal is 10 dB below 1 volt RMS.
RADAR II will adjust its meter sensitivity to your selection.
RADAR II can accept either of the two standards for reference level; +4 and -10.
These levels may be set via RADAR II’s Setup menu. (For further information,
please refer to §4.X or Appendix A.)
1.5.4 Grounding
The analog audio circuitry in RADAR II operates with a separate ground, which
is not connected to the AC power ground. This allows the user to determine the
grounding scheme that best suits their studio’s requirements.
There are two grounding terminals on RADAR II’s back panel; CHS GND is
connected directly to the metal chassis and the ground wire of the incoming AC
power line. ANA GND is connected to the sleeve of each audio input and output
including the SMPTE In and Out.
RADAR II is shipped with the ANA GND and the CHS GND connected. If
grounding problems do occur (hum or excessive crosstalk), the ANA GND and
CHS GND may be unstrapped, and/or the analog ground may be connected to
the technical ground shared by other equipment in the studio.
W E L C O M E T O R A D A R ! 1-9
Edition 1