5-35
Nº40 Media Console Menu System
Analog Input Offset If you have an analog connection associated with the input you are
defining, you can set an analog input offset that will be imple-
mented for that connection whenever it is used. This adjustment
serves two purposes: it allows you to match the perceived volume of
all the analog sources to that of the digital sources in your system
(which are normally already matched fairly closely); it also allows
you to adjust the level of the incoming analog signal to prevent it
from overloading the analog to digital converters. Doing either of
these adjustments with any degree of accuracy will accomplish
both ends.
The Nº40 includes a state of the art analog to digital converter
(ADC). Since all processing in the Nº40 is handled in the digital
domain, analog signals must first be converted to digital form. It is
extremely important to avoid overloading or “clipping” the ADC,
since doing so results in a nasty burst of distortion that sounds
similar to a power amplifier clipping. Unlike power amplifiers, this
sort of clipping can occur at any volume level, since the ADC is
being clipped well before the volume control in the signal path.
Fortunately, the Nº40 can detect when its ADC is being clipped, and
posts a notice to that effect in its front panel display and on the on
screen display. If you see such a message, you should turn down the
input level on the Nº40 (which turns down the volume of the
signal going into the ADC). You should als o probably save thi s new
setting as the default setting for that input, which will save you
from running into this problem again—unless you later play some-
thing that is even louder. (In which case, you simply repeat the
process outlined below.)
1. Turn the master volume control on the Nº40 down.
When the analog to digital converter clips, it distorts the wave-
form much as a power amplifier does when it clips. This is both
unpleasant to hear and potentially dangerous to speakers at
high volumes. Turn the volume down to a quiet, but still
audible level just to be on the safe side, but so you can still hear
what you are doing.
2. Enter the analog input offset portion of the input menu, and
play the loudest selection you can find on the analog source in
question.
Since you are not playing this “loud section” loudly: keep it
quiet, but play the biggest musical crescendo or movie explo-
sion available on the source at hand.
3. Adjust the analog input level on Nº40 until the display on the
audio processor just reads “Clipping!”; then lower the input
level by 2-3 dB.
The goal is to give yourself just a little “headroom” in case the
next recording you play is a bit louder than the one you are
using for this adjustment.