Audio Developments AD114 - Manual (Page 20)

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Main-output limiters - calibration involves two presets per output.
Using the 'L' output as the example …
Biasing and threshold are adjusted as follows: VR5 biases the limiter circuit to the
point of correct operation and VR4 sets the threshold. (Labelled SET 0 and THR
respectively.)
With no signal present, VR5 should be adjusted to give a reading in the
range -1.5V to -2.5V at PIN 14 of IC 2. VR4 should be adjusted to give a reading in
the range -2.5V to -3.5V at PIN 10 of IC2.
Apply a signal at 1kHz to the mixer to give a level of 0dBu at 'L' output. Then select
the limiter function and adjust VR5 until the output signal starts to fall (typically
0.2dB). The DC voltage at PIN 14 of IC 2 should be approximately -2.0V.
After setting VR5, adjust the output signal to just greater than +8dBu with the limiter
deselected. Introduce the limiter and adjust VR4 until the output signal falls to
+8dBu. This is the THRESHOLD setting. (If a different threshold setting is required,
alter the signal levels accordingly.) The DC voltage at PIN 10 of IC 2 should be
approximately 0.6V different from that at PIN 14.
The right output can be set using the above procedure, but the preset and IC
numbers change to correspond with the output being calibrated.
The link function has no individual setting of its own. To ensure this works within
specification it is important that L and R outputs are set up as a pair. After following
the above procedure, the DC voltages at PINS 14 and PINS 10 of the ICs
should be identical. (Tolerance ±0.1V with typical figures at PIN 10 of -2.6V and
PIN 14 of -2.0V)