Mark Levinson N40 User Manual download pdf (Page 101)

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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 also probably save this 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.

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