Studio Technologies 240 - Manual (Page 23)

Model 240 User Guide Issue 1, August 2013
Studio Technologies, Inc. Page 23
function is active. This is included for applica-
tions where connecting monitor loudspeak-
ers, rather than a headset or headphones, is
desired. If the headphone output level is not
functioning as designed it’s possible that the
setting of the headphone normal/dim con-
figuration DIP switch may need to be revised.
Advanced
Operation
Adjusting the Line Input
Trim Pots
As has been previously mentioned, associ-
ated with the two line inputs are trim pots
that allow the input levels to be adjusted. The
two trim pots are accessible by way of round
openings in the bottom of the Model 240’s
enclosure. By adjusting these trim pots,
signals with a nominal level of –10 to +6 dBu
can be effectively used as main output pro-
gram and headphone sources. Unfortunately,
there are no definitive rules regarding how
best to adjust the trim pots, but some sug-
gestions may prove to be valuable. Depend-
ing on how the line inputs are utilized, the
trim pots can be used to either adjust the
absolute level of each line input signal, or to
adjust the relative level of the signals when
compared to other sources. The following
examples may provide some clarification.
Let’s begin with an application that has a
stereo cue source connected to the line
inputs. The cue source selection switches
are configured to create a stereo headphone
output with line input 1 assigned to the left
channel and line input 2 assigned to the right
channel. Begin the trim pot adjustment pro-
cess by moving the user level controls
(located on the front panel) to their detent
(50% of rotation) positions. Then, with the
stereo cue source providing signal at its
normal level, adjust the trim pots to provide
a comfortable level to the connected head-
phones. The user can now, in response to
changing conditions, adjust the front-panel
level controls as desired. Returning the
controls to their detent positions will always
provide the “reference” level to the head-
phone output.
A second example has a source of audio
connected to line input 1. This audio is
assigned as program audio for one or more
of the main outputs. The input trim pot as-
sociated with line input 1 can be used to
adjust the relative level of the program audio
source as compared to the talk level from
the connected headset. The trim pot allows
the desired “mix” to be created, providing
the user with an effective signal with the
desired ratio of talk audio to program audio.
Intercom Interface Sidetone
Adjustment
Associated with the main output-to-intercom
functions are sidetone trim potentiometers
that are used to adjust the level of talk and
program signal that is returned to the head-
phone output by way of the intercom inter-
face circuitry. These two trim pots are part
of the analog hybrid circuit that separates
(nulls) audio from a main output channel
being sent to the intercom interface from
audio being received from the intercom
interface. If audio from either or both of
the intercom channels is to be used as a
headphone source, and either or both of
the main output-to-intercom functions has
been configured, the sidetone trim pots
may need to be adjusted.
One trim pot is associated with the side-
tone level for each channel of the intercom
interface. Both are accessible on the bottom
of the Model 240’s enclosure, adjacent to
the trim pots associated with the line-level