Studio Technologies 220 2013 - Manual (Page 38)

Issue 5, February 2013 Model 220 User Guide
Page 38 Studio Technologies, Inc.
labeled P10 provides access to auxiliary
relay contact A. Header P9 provides ac-
cess to auxiliary relay contact B. With both
headers pin 1 is normally closed, pin 2
is common, and pin 3 is normally open.
For additional details on connecting to
the 3-position headers please refer to the
Additional Connectors section in the
Technical Notes area of this user guide.
Direct Microphone Output
The Model 220’s main output is intended
to be used as the on-air, stadium an-
nouncement, or other primary audio feed.
The path from the unit’s microphone input
connector to the main output connector is
by way of active circuitry. A low noise, low
distortion microphone preamplifier stage,
“clickless” audio switching, and a high-
quality transformer-coupled output circuit
work together in achieving excellent per-
formance. The nominal level of the main
output is –2 dBu, allowing interconnection
with related devices at a near-standard
“line” level. However, there may be ap-
plications where an output that directly re-
lates to the connected microphone would
be beneficial. The Model 220 has made
provision to accomplish this by using the
optional direct microphone output card.
This card, available from Studio Tech-
nologies and purchased separately (part
number 31058), is mounted in a spare
connector location available on the Model
220’s back panel. With this addition both
an “active” main output and a “passive”
direct microphone output will be available.
Of course, both outputs provide quiet
noise-free on/off (“muting”) control.
The primary application for the direct
microphone output is when the Model
220 is integrated into a system that in-
cludes a high-performance microphone
preamplifier. This preamplifier may be part
of a stand-alone voice-processor unit, or
a microphone input associated with an
audio console. Engineering personnel
may prefer the sonic characteristics of the
external microphone preamp over that of
the one integrated into the Model 220.
It’s important to note that the direct mi-
crophone output card provides a direct
“metallic” path from the microphone input
to the external preamplifier circuitry. It is
not simply an audio “pad” (attenuator) that
reduces the level of the main output from
“line” to “mic.” The Model 220’s auxiliary
relay contact, along with circuitry on the
direct microphone output card, provide
click-free muting of the signal.
The direct microphone output card
contains only passive circuitry. A 3-pin
male XLR connector is provided for the
output signal. A resistor and large electro-
lytic capacitor form the muting circuit.
This arrangement allows muting to take
place without disturbing phantom power
that may be enabled to support a con-
denser microphone. The direct micro-
phone output card also contacts two
3-position header connectors. These
interface with “headers” on the Model
220’s main printed circuit board assembly,
providing access to the microphone input
connector and auxiliary relay contact.
The direct microphone output card kit
contains a printed circuit board assembly,
two interconnecting cables, and mounting
hardware. Installing the kit is very simple.
The card’s 3-pin male XLR connector
is mounted into one of the three spare
connector locations on the Model 220’s
back panel. Specifically, the connector
location that is closest to the microphone
input connector should be used. The two
screws, with associated locking nuts,
are used to secure the connector and