Benchmark Media Systems, Inc.
Page 8 of 39
ANALOG OUTPUTS:
Balanced Analog Outputs:
Left and Right balanced outputs are provided on Neutrik™ gold-pin male XLR jacks. The output levels may be
controlled from the front panel, or may be set to fixed levels using the rear-panel
Calibration Potentiometers
.
The output impedance of the XLR outputs is 60 Ω when the output pads are disabled. The low output impedance
makes these outputs well suited for driving up to 680 feet of cable (assuming 32 pF/foot). If the output pads are
enabled, the output impedance will be higher, and the maximum allowable cable length must be reduced as
shown in Table 1(assuming 32 pF/foot and a maximum allowable loss of 0.1 dB at 20 kHz).
Table 1 - Cable Drive Capability
Balanced Output Drive Capability:
Attenuator
Output
Maximum Loss in dB
Setting (dB) Impedance Cable (ft)
at 20 kHz
0
60
680
0.1
10
1600
26
0.1
20
500
82
0.1
30
160
255
0.1
Unbalanced Output Drive Capability:
Output
Maximum Loss in dB
Impedance Cable (ft)
at 20 kHz
30
1360
0.1
XLR pin 2 = + Audio Out
XLR pin 3 = - Audio Out
XLR pin 1 = Cable Shield (grounded directly to the chassis to prevent internal ground loops)
Caution:
If the balanced XLR outputs are wired to an unbalanced input (using special adapter cables), pin 3 must
be left floating. Shorting pin 3 to ground will cause very high levels of distortion.
Caution:
The XLR outputs are studio-grade line-level outputs and should not be plugged into microphone inputs
without the use of the internal 20 or 30 dB pads (or a suitable external pad).
Unbalanced Analog Outputs:
The Left and Right unbalanced outputs are provided on standard RCA style jacks. The left channel output
connector is white, and right channel output connector is red. The output levels may be controlled from the front
panel, or may be set to fixed levels using the rear-panel
Calibration Potentiometers
. The XLR attenuators do
not have any effect on the level of the RCA outputs. The RCA output levels are 12 dB lower than the XLR outputs
(when the internal XLR attenuators are disabled). When the XLR outputs are calibrated to +4 dBu at –0 dBFS, the
RCA outputs will conform to the –10 dBV convention for consumer grade equipment. The output impedance at
the RCA jacks is 30 Ω and is low enough to allow for the use of high or low capacitance cable and the common
high capacitance of consumer receiver/amplifier inputs. Mono summing with a “Y” cable is not recommended as
this will cause high amounts of distortion. Mono summing with a “Y” cable can be accomplished with the use of a
modified cable by implementing a 1.25kΩ series resistor.
Note:
The RCA outputs should not be used to drive cables exceeding 1360 feet (see Table 1).
DIGITAL INPUTS:
There are three digital inputs on the DAC1. These inputs are selected from a front-panel toggle switch. All of the
inputs can decode AES/EBU and S/PDIF input signals in either professional or consumer formats. The DAC1 will
