Hall Research AD-340 - Manual (Page 16)

Model AD-340
14
3.3.4 Analog Input/Output Volume Control
The analog input and output is set to Line Levels for CD, DVD and BD Players at
2
Vrms
(5.6 V-
peak-to-peak
), so if any of these sources are used the volume control
should be set to Unity Audio Gain (Default). However if the source is a weaker
signal – like a MICROPHONE input connected with RCA adapter – an adjustable
Gain Control allows the user to manually control both the gain of the analog
input (ADC Gain) and the analog (DAC Gain) output. The audio gain is controlled
from the GUI and is memorized.
WARNING: Make sure that the gain is not set too high when you manually adjust
the ADC or DAC gain, as this will distort either the input signal and/or the output
signal. Select UNITY on the GUI to get back to the fixed Line Level Setting at 2
Vrms Input/Output.
Analog Gain Range Function
ADC Gain -24 dB to +24
dB Adjustable Gain for the Analog Input
(Analog to Digital Converter)
DAC Gain -6 dB to +6 dB Adjustable Gain for the Analog Output
(Digital to Analog Converter)
 ANALOG INPUT  ANALOG OUTPUT: Both the input ADC and
output DAC gains are user controllable.
 DIGITAL INPUT  ANALOG OUTPUT: When Digital Input (for PCM
only) is converted to Analog Output; the user can control the output
DAC gain.
 DIGITAL INPUT  DIGITAL OUTPUT: There is no Gain Control for the
DIGITAL INPUT to OUTPUT (for any digital formats)
 ANALOG OVERFLOW: If the Analog Input signals are over 2 Vrms,
the Analog Overflow Indicator will start to blink.
3.3.5 Delay Function
Internal Delay: Different video processing equipment in the signal processing
chain can sometimes add a delay of several video frames (2-8 frames) relative to
the audio. Since video processing takes a much longer time than audio
processing, video tends to lag behind audio when audio/video becomes
asynchronous due to internal delay. Audio arriving early is generally considered
more annoying than audio arriving late relative to the video. Generally speaking,
the sound should not lead the video by more than 15 ms for an enjoyable user
experience. Likewise, sound should not lag behind the video by more than 45
ms. The threshold of detectability of asynchronous audio/video is around 45 ms,
while the threshold of acceptability is around 90 ms.