Studio Technologies 55 2002 - Manual (Page 30)

Issue 4, June 2002 Model 55/56 User Guide
Page 30 Studio Technologies, Inc.
the result out the left and right outputs. In
our application we drop the level by 6dB.
This is what many recording consoles
implement, and is what the StudioComm
does too!
Talent Amplifier Mono Function
The Model 35 and Model 38 Talent Ampli-
fiers each contain a monaural switch. The
mono function sums the left and right input
signals, drops the level of the sum by 6dB,
and sends the sum to both the left and
right outputs.
Input Level and the Talent Amplifiers
Optimal performance of the Model 35 and
Model 38 Talent Amplifiers depend on the
headphone source signal levels being at
approximately the nominal input level,
either –10dBV or +4dBu, depending on
the configuration. The headphone volume
is adjusted only by the level controls on
the talent amplifiers. If the selected head-
phone source signal level is significantly
less than nominal, the talent amplifier will
simply not be able to create the maximum
volume in the headphones. While there is
some gain in the talent amplifiers, optimal
performance still requires an input close
to nominal.
The Model 38 Talent Amplifier can also
exhibit reduced performance if the level
of the headphone source is significantly
“hotter” than nominal. The entire system
has plenty of headroom, but maintaining
proper signal levels, as usual, is impor-
tant. If the source selected for head-
phones has an average level that is
excessive, a small amount of bleed-
through can be heard with the Model 38’s
cue mix level control set fully counter-
clockwise. Instead of having no sound in
the phones, a bit of sound can be heard.
This is not a design problem; the Model 38
has a sensitive preamplifier section which
doesn’t like excessive excursions in the left
channel modulation of the +23Vdc signal.
The Model 38’s power supply can reject
the left channel modulation within the
design parameters, creating a clean refer-
ence voltage for the stereo preamplifier.
Modulation levels outside the design
parameters show up in the reference
voltage!
Communication Switch Noise
During field trials of the StudioComm
components one item came up for discus-
sion concerning “thumps” in the communi-
cations functions. A brief discussion may
be useful. Electrically the Model 55 and
Model 56 electronics that support the
communications functions are quite quiet,
not adding appreciable “clicks, pops, or
thumps.” Software time delays are even
added to minimize noise when a button is
pressed. Mechanical noise being picked
up by the Model 56’s microphone can be
an issue. If the talk to phones or slate
buttons are pushed using a relatively light
touch no objectionable noise will be gener-
ated; pressing the switches with “gusto”
will cause mechanical noise to be trans-
ferred into the microphone. While the
Model 56’s microphone is of good quality,
shock mounting it was not possible using
a cost-effective method. The fact that the
Model 56 is physically small and the but-
tons must be relatively close to the micro-
phone adds to the difficulty. (Note that
most all recording consoles, both small
and large, share this condition.) So in
conclusion, use a light touch on the but-
tons and everyone should stay reasonably
happy!