Control Settings - TELETRONIX LA-2A Instruction Manual

J .
(.J
(J]
[.J
[I
J
[)J
[.]
[,J
[,J
[,J
f J
['l
[:J
[I
J
[1.1
[ J
[l
J
[~J
[ ' j
I
[ ; :1
[ J
['J
[' J
away from the straight "No-Gain Reduction" line is determined by the setting of the "Peak
Reduction" control.
It
can be seen from the curve that compression Occurs and gradually in ­
creases over the first 10 DB of input level rise. The slope of the curve then becomes horizontal,
preventing an increase of output level regardless of input increase.
CONTROL SETTINGS
It is recommended that the "Peak Reduction" control be set to prevent increase in output
level beyond the 100% modulation point. This setting should be made on typical program material.
Setting of the "Gain" and "Peak Reduction" controls are independent. However, the "Gain"
control should be set to provide sufficient output after the "Peak Reduction" control has been
adj usted.
The "Peak Reduction" control should be set for the desired amount of gain reduction as
indicated by the meter . Continuous extreme reduction, such as 20 or 30 DB, does tend to reduce
the dynamic range of music. Maximum benefit is obtained by running 4 to 8 DB of compression
continuously. This will usually cause full limiting to occur when 100% modulation is approached.
For ease of control and to prevent overload of the input transformer, sufficient fixed pad
should be placed ahead of the LA-2A to allow normal output at approximately 50% setting of the
gain control.
VU METER
The VU Meter serves two functions;
it
indicates output level as well as gain reduction
directly in DB. When the meter selector switch is placed in the "output" position, the meter will
indicate output level across the 600 ohm terminals. The meter is calibrated to read 0 VU or 100%
when the amplifier output is +10 DBM or +4 DBM, depending upon the switch position.
The position marked "Gain Reduction" permits the meter to indicate the amount of gain
reduction or peak limiting directly in DB. During periods of no gain reduction the pointer will
return to 0 VU on the meter scale. The pointer is initially set to this position by means of the
screw driver adj usted control located on the left end of the front panel.
STEREO
If
two LA-2A Leveling Amplifiers are to be used in tandem for stereo, the gain reduction
of each amplifier can be made equal, regardless of which channel is instigating the limiting.
This is accomplished by interconnecting terminals 6 and 7 of the LA-2A Leveling Amplifiers.
The interconnecting wire should not be over two feet in length and should be shielded, the ends
of the shield being connected to the #7 terminals (ground).
Stereo "set-up" is as follows:
1. Connect the input terminals of the left and right channel LA-2A to an audio
oscillator. Make certain that the amplifiers are connected in phase to the generator.
LA-2A (3-66)
Page 5
~--------------------------------------------------------,