D.W. FEARN
VT-12 Microphone Preamplifer
23
4 .
O P E R AT I O N
Input
Since the input cable will be carrying very low level audio, it is important that a well-shield-
ed cable is used. There should be no additional connectors, patch jacks, switches, etc.
between the microphone and the VT-12 input. This can be achieved with a dedicated line
from an XLR connector in the studio to each VT-12 in the control room. Although long input
cable runs have little effect on the performance of the VT-12, it is preferable to keep the input
Figure 2. VT-12 front panel controls and indicators
line as short as possible. One successful method is to place the VT-12 in the studio with only
a short cable to the microphone. Line level from the VT-12 output is then fed back to the con-
trol room. Avoid locating the VT-12 where it will be subjected to high sound levels or exces-
sive vibration (such as on a drum riser).
Output
The output of the VT-12 is line level, transformer balanced. Note that vacuum tube equip-
ment is more sensitive to load impedance than solid state units. The VT-12 design was opti-
mized for feeding a balanced bridging input (20k ohms or greater). When feeding a 600 ohm
load, there may be a slight degradation of some
of the specifications. In modern studio
equipment, bridging line inputs are universal. If the device being fed by the VT-12 has
an input termination switch, that switch should be in the “off” position.
Summary of Contents for VT-12
Page 1: ...VT 12 Vacuum Tube 70dB Microphone Preamplifier Operating Instructions D W FEARN...
Page 4: ...4...
Page 15: ......
Page 19: ...D W FEARN VT 12 Microphone Preamplifer 22...
Page 27: ...D W FEARN VT 12 Microphone Preamplifer 30...
Page 35: ...D W FEARN VT 12 Microphone Preamplifer 38...
Page 37: ......