Sound Performance Lab 9844 - Manual (Page 9)

9
Control elements
The MIC GAIN knob controls the input signal's amplification. The
range extends to 72 dB of gain. The levels should be adjusted for a
meter reading around 0 VU to get the best signal-to-noise perfor-
mance. Please note that the meters show only an rms/average
level, so keep your GoldMike from pegging the meters' needles.
When adjusting the MIC GAIN, consider the type of microphone
(dynamic, condenser or ribbon) and the microphone's sensitivity;
likewise, check sound pressure levels at the sound source, the
microphone placement and room acoustics. The sensitivity of a
dynamic microphone is approximately 2 mV/Pa, whereas a
condenser microphone may reach 20 mV/Pa, an increase of 20 dB.
Condenser Mics require a 48-volt power supply, which is sent
through the balanced audio cable on pins 2 and 3. When turning
on the supply voltage, a phantom circuit is generated by splitting
the 48-volt supply signal equally between the + and - conductors
of the audio cabling; the voltage is returned through the cable's
shield. No potential difference is present between the two
conductors (+/-); dynamic microphones may be used while
phantom power is switched on without damage.
Phantom power in effect reduces the interference from ground
loops as well as other unwanted signals picked up by the shiel-
ding. It also proves to be a very HF resilient connection.
WARNING: All balanced microphones with isolated
grounds, even tube-equipped microphones, may be used
while phantom power is switched on. All other microphones
require the phantom power to be switched off.
Connect line-level signals and unbalanced microphones
only while phantom power is off.
7
2 3 4 5 6
MIC GAIN 1
48 V 2
Phantom power specs in
accordance with
DIN 45 596/ IEC 268-15
1
The VU meters show
a rms/average signal
Check the transducer type and
sensitivity
!