Quick Start Guide; Audio Inputs; Volume Control; Direct Interfacing To Power Amplifiers - Benchmark DAC1 PRE Instruction Manual

Quick Start Guide

Audio Inputs

The DAC1 PRE features one stereo analog
input (RCA) and five stereo digital inputs (3 x
coaxial, 1 x optical, and 1 x USB). The coaxial
and optical digital inputs accept professional
(AES) and consumer (S/PDIF) data formats at
word lengths up to 24-bits. The coaxial inputs
support sample rates up to 192 kHz. The
optical inputs support sample rates up to 96
kHz.

Volume Control

The front-panel Volume Control sets the
output level of the headphone jacks, and can
also be used to control the output level of the
main outputs (balanced XLR and unbalanced
RCA analog) when in Variable output mode.
A rear-panel switch selects Variable or
Calibrated output mode. In Variable output
mode, all analog outputs are controlled by the
Volume Control. In Calibrated output
mode, the volume is fixed at the level set by
the calibration trim-pots.

Direct Interfacing to Power Amplifiers

The DAC1 PRE is designed to be able to
interface directly to power amps and powered
studio monitors. This configuration provides
the cleanest and shortest path from the
digital source to the monitor output, and
often results in a substantial improvement in
sound quality.
The DAC1 PRE is equipped with 10, 20, and
30 dB output attenuators for optimal
interfacing. The pads optimize the output
signal level of the DAC1 PRE for the input
sensitivity of virtually any load (amplifier,
preamp, etc). Most power amplifiers and
powered monitors require the 20 dB pad
DAC1 PRE Instruction Manual Rev J
setting. The DAC1 PRE is factory-set with
the 20 dB pad enabled.

Source Selector and On/OFF Switch

A rotary Source Selector control selects any
of the 6 inputs to the DAC1 PRE. Pressing
the Source Selector toggles the DAC1 PRE
on and off. The on/off function features a
very fast soft mute/un-mute and doubles as a
mute control.

Input Status Display

Under normal operation, the Input Status
Display shows which of the 6 inputs is
currently selected. A steady light indicates
that a normal signal is present. Flashing
lights indicate error conditions. If the error
condition continues, the automatic-standby
mode will begin.

Automatic Standby/Resume

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 a digital source
device is turned off, disconnected, or contains
errors that prevent D/A conversion. All lights
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.

Mute on Headphone Insertion

The left-hand headphone jack includes a
switch that mutes the main analog outputs
(XLR and RCA) when a headphone plug is
inserted. This feature allows the listener to
switch from loudspeaker to headphone
playback seamlessly. This mute feature can
be disabled with internal jumpers.
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