
D.W. FEARN
VT-1 & VT-2 Microphone Preamplifers
20
if necessary. (Call the factory for detailed instructions). The ground pin of the power cord is
inter
nally connected to t
he chassis. This configuration is st
andard in professional equipment
and is required by most electrical codes. A grounding screw is provided on the back panel for
inst
allations t
hat use separate chassis gr
ounding. If gr
ound loop hum is detected, a careful
check of the studio grounding scheme is needed. The VT-2 is less susceptible to grounding
pr
oblems than many studio devices.
Connections
(see Figure 1)
The INPUT connectors are XLR-3 females wired with pin 1 ground, pin 2 “+” or “high,” and
pin 3 “-” or “lo
w.” The input matches 150 ohm (nominal) microphones and is transformer
balanced.
The OUTPUT connectors are XLR-3 male wired with pin 1 ground, pin 2 “+” or “high,” and
pin 3 “-” or “low.” The VT-2 is optimized for feeding balanced bridging inputs. (Virtually all
moder
n audio equipment has bridging in
puts.) The output is transformer-balanced.
The “GND” ter
minal is for use when an external grounding scheme is utilized.
The Fuse is a 3AG-type 1 amp for 100 or 120 VAC operation, and 0.5 amp for 220-240 volts.
The AC input connector is used with the mating line cord (supplied). For 120 VAC operation,
t
his cord is a Belden 17250 or equivalent.
The unit does not utilize any RFI filtering, and no RFI has been experienced, even when the
VT
-2 is operated in close proximity to AM, FM, and TV broadcast transmitters.
Input and Output Connections
See Figur
e 1
. Gold-plated XLR connectors are used for inputs and outputs. The input connec-
tors are female and the outputs male.
Figure 1. The VT-2 rear panel connectors
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