Instruction manual

DAC1 PRE Instruction Manual Rev I Page 9
No analog or digital audio signals are routed
through the Source Selector switch. Source
selection is transparent and free from
crosstalk.
If the DAC1 PRE is off or in Standby Mode
it will resume normal operation when the
Source Selector is rotated or pressed.
Standby Mode
The DAC1 PRE features an automatic
standby mode that eliminates the need to
turn the converter on and off. Standby
Mode starts 15 seconds after the selected
digital source device is turned off,
disconnected, or contains errors that prevent
D/A conversion. All status LED’s are off while
in Standby Mode.
While in Standby Mode, the DAC1 PRE
continues to monitor the selected digital input
and will immediately resume normal
operation when an error-free signal is
restored.
HPA2
TM
Headphone Jacks
The DAC1 PRE features two headphone jacks.
The left-hand jack is equipped with a switch
that automatically mutes the XLR and RCA
analog outputs when a headphone plug is
inserted. The right-hand jack has no switch.
This feature enables seamless muting of the
main outputs when headphones are being
used. This auto-mute feature can be enabled
or disabled via an internal jumper.
Instructions for setting the auto-mute jumper
are detailed in the ‘Internal Settings’
section of this manual.
TIP: Use the left-hand jack when you
want to listen to headphones and mute
your playback system. Use the right-
hand jack when you need to keep all
outputs active.
The dual jacks also allow two listeners to
monitor and compare notes on what is heard.
When comparing, we recommend using
identical headphones because headphone
sensitivities differ significantly. The Volume
Control adjusts the level for both jacks.
The original gain-range of the HPA2™ (such
as in the original DAC1) is often too high for
the headphones of many users. The DAC1
PRE features three gain ranges for the
HPA2™ to suit the sensitivity of any
particular headphones. These gain ranges
are set using internal jumpers. The jumpers
reduce the input to the HPA2™ by 0, 10, or
20 dB. These jumpers are factory-installed at
10 dB below full gain. Instructions for setting
the headphone gain range are detailed in the
‘Internal Settings’ section of this manual.
TIP: For optimal performance, the
headphone gain jumpers should be set
so that comfortable listening levels occur
when the ‘Volume Control’ is set above
the 10
th
detent.
Volume Control
The front-panel Volume Control is a 41-
detent potentiometer (see ‘Volume Control
Curve’ in the ‘Performance Graphs’ section of
this manual).
The Volume Control always controls the
output level of the headphone jacks. It can
also be used to control the output levels of
the balanced XLR and unbalanced RCA analog
outputs when the rear-panel Output Level
Switch is set to Variable.
The XLR outputs have jumper-enabled
passive attenuators that can be used to
optimize the gain structure of the playback
system.
TIP: For optimal performance and
minimal noise, the XLR gain jumpers
should be set so that comfortable
listening levels occur when the ‘Volume
Control’ is set above the 10
th
detent.
Instructions for setting the XLR pads are
detailed in the ‘Internal Settings’ section of
this manual. The DAC1 PRE is shipped with
the XLR attenuation set to -20 dB.