Marani CLP-260 User Manual page 10

In order to verify the Input/Output Max Levels of the CLP260, need first to
make sure that NO process is active.
Max Analog Input: in order to understand what can be the maximum
Analog Input level to the unit, which is the one before the clipping of the
Op-Amps in front of the A/D converters, need to make sure that no Digital
clip (DSP process) is occurring.
The output will never clip unless the clip is coming from the digital
process.
This means that if the D/A output isn't clipped, then no clipping will come
from the Analog Op-Amp output section.
From this point of view, any position of the Output potentiometer for
evaluating the Max Input level, can be set.
Let's consider to set the output potentiometer to the position 5 of the grid
in Fig B.
Now, to define what is the Max Analog Input level, need to set the Input
Level potentiometer to a position granting enough attenuation of the
signal before the A/D, so to make sure no clip is occurring on the A/D side.
Let's set the Input potentiometer to the position 3 of the grid of Fig. A.
Done this, we can increase progressively the Input signal level until the
output will start to clip or the Input Level displayed on the LCD will not
show the ">" symbol.
In this way, can be found that the Max Input level, before to get the Input
Op amps clipping is +15dBu.
Max Analog Output: once set the Max Input Level to +15dBu, in order to
identify the Maximum Output Level, need to move the Input Level
Potentiometer from the position 3, up to the position that is clipping the
A/D converter.
With +15dBu Input, the position of the Input Level Potentiometer at the
limit of the Input Clipping, is the position 6 of the Input Level grid of Fig A.
Once set, then, the Input Level Potentiometer to the position 6, in order to
find out the Max Output Level achievable with the CLP260, need to set
the Output Level Potentiometer to the position Max
The Max output Level that can be found is +10dBu, if measured with an
Audio Precision or similar measurement tools.
CLP260 Signal to Noise Ratio (S/N): from the condition got for the Max
Analog Output verification, can be go the S/N of the CLP260.
If, with the Max Output Level of +10dBu, the Input Signal Is removed,
measuring the output can be seen that the residual Ground Floor Noise
drops to -92.7dBu, which let us say that the S/N=(Max Output) – (GND
Floor Noise) = 10dBu - (-92.7dBu) = 102.7dBu
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