2.4 Channel Switching Channel switching
on the LA102 selects input channel (displaying ‘L’ or ‘R’ on the screen). on
the LA101 cycles through ‘L+R’, ‘L’ and ‘R’ channels, while
mutes both
channels and displays ‘
MTD’. Pressing again will restore the selected channel
state (‘
L+R’, ‘L’ or ‘R’) which can be changed even while the output is muted in
preparation for de-muting. When an output channel is turned off, it is switched by an
internal relay and terminated with the selected output impedance.
2.5 Programmable Presets and Initial Settings Programmable presets
The five numbered keys on the LA101 give instant access to preset levels and frequencies
as labelled on the panel. If the last thing changed was frequency then they operate as
frequency presets, otherwise they give preset levels. This can be confusing at first, but
with proper use it gives very quick access. We recommend always pressing one of the
frequency
or level up-down keys, to define the mode of operation,
before using the presets.
Level presets Start up frequency Start up level Initial settings
The presets can be programmed by simply selecting the desired frequency or level in the
normal way and then pressing
followed by the preset key (1 to 5) to be re-
programmed. The LA101 will prompt for the preset number, by displaying ‘
P?’ beside
the frequency or level display. Their settings are retained in non-volatile memory, and
many users will prefer to set values like 20Hz, 3150Hz, 15kHz or +8dB permanently.
Configuration T
When the LA101 is turned on (or reset) it will generate the frequency and level of one of
the presets. By default this is preset 4 which usually gives 1kHz and 0dB. Any change to
preset 4 will therefore change the start-up frequency and level as well. However, the
LA101 can be made to select the frequency and level assigned to any preset, by setting
configuration S (for level) and T (for frequency) to any preset number (1-6). For
example, users testing sensitive microphone inputs might like to set configuration S1 to
make the LA101 generate -60dB (the level usually assigned to preset 1). Furthermore,
configuration S0 can be used to make the oscillator start up with its output muted.
Configurations S6 and T6 will force the output level and frequency to the values set when
the unit was last turned off or reset. See section 1.6 for further details of configurations.
To avoid overloading sensitive inputs, it is possible to turn the LA101 on with its output
muted, by holding the
key while switching on. Mute on start-up Test level in manual mode
2.6 Relative Levels − Test Level (TL) Setting test level Test level setting TL in manual mode
Both units cater for relative level generation and measurement. Pressing on the
LA101 stores the current output level as a test level and displays TL. The output level is
now displayed relative to this test level. Pressing
again, or resetting (by tapping
18
2. Manual Operation
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