Page 116
MAXX-1200 Owner’s Manual
Audio Level Calibration
The input and output gain of the analog audio circuits is factory calibrated to a +4 dBu
standard. Each circuit includes a trimmer with a range of approximately ±1.5 dB. The
following procedures may be used to calibrate these to unity gain. Each trimmer is located
above the XLR connector with which it is associated.
Calibration Procedure
This procedure assumes that the technician is familiar with test procedures employing the
Audio Precision® test equipment or its equivalent.
1.
Play the test clip titled zTONE present on the server disk. This is a two-channel clip
recorded at a level equivalent to a +4 dBu output level.
2.
While observing the output level of audio Channel 1 Left, adjust trimmer RV4 until a level
of e4.0 dBu is obtained.
3.
Repeat this procedure for audio Channel 1 Right, while adjusting trimmer RV3, and also for
each subsequent audio channel using its associated trim pot.
After calibrating the gain settings for all analog audio outputs as in steps 1 through 3 above,
calibrate the server’s input gain as follows:
4.
Using the graphic user interface, place server Channel 1 in the E-E mode, so an input signal
will appear at its output.
5.
While observing the output level of audio Channel 1-L, apply a 1 KHz sine wave from the
audio generator to audio Input 1-L.*
6.
Adjust input trimmer RV2 until a level of e4.0 dBu is obtained at the output of
Channel 1L.
7.
Repeat this procedure for audio Input 1-R, making the gain adjustment with input trimmer
RV1.
The preceding steps establish a gain of unity through the server.
* In the absence of a generator, use the calibrated outputs of Channel 2 playing zTONE to
feed the inputs.
