Benchmark DAC3 DX, DAC2 DX, DAC1 digital to analog converter Instruction Manual
Below you will find brief information for digital to analog converter DAC3 DX. The DAC3 DX is a reference-grade digital to analog converter with Benchmark's HPA2™ headphone amplifier. Key features include 24-bit D/A conversion of PCM at sample rates up to 192 kHz, direct conversion of 1-bit DSD at a 2.8224 MHz sample rate, UltraLock3™ Jitter Attenuation System, high headroom DSP, dual-mode asynchronous USB Audio 2.0, and a headphone amplifier with dual high-current outputs. The DAC3 DX is well-suited for critical monitoring in studio control rooms and mastering rooms, and for high-end hi-fi environments. An optional remote control and 12V trigger provide the features needed in a home environment.
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Benchmark DAC3 DX
Instruction Manual
Reference Stereo D/A Converter
Native PCM and DSD D/A Conversion
Headphone Amplifier
Asynchronous USB
Dual Output Buses
ESS9028PRO Conversion System
(Version 1.0 Firmware)
Safety Information
Fuses
CAUTION: FOR CONTINUED FIRE
HAZARD PROTECTION ALWAYS REPLACE
THE FUSES WITH THE CORRECT SIZE
AND TYPE (0.5A 250 V SLO-BLO ® 5 X 20
MM – LITTELFUSE® HXP218.500 OR
EQUIVALENT). THE FUSE DRAWER
INCLUDES TWO FUSES. ALWAYS
REPLACE BOTH FUSES AT THE SAME
TIME.
AC Input Voltage Range
NOTE: THE DAC3 IS EQUIPPED WITH A
UNIVERSAL POWER SUPPLY. THERE IS
NO VOLTAGE SELECTION SWITCH. AC
VOLTAGE RANGE IS 88-264 VAC, 50-60
HZ. THE PRODUCT MAY ALSO BE
OPERATED FROM DC POWER OVER A
VOLTAGE RANGE OF 125-373 VDC.
Power Cord
CAUTION: ALWAYS USE A GROUNDED
POWER CORD. THE PRODUCT IS
EQUIPPED WITH A STANDARD IEC
POWER ENTRY MODULE. USE AN IEC
POWER CORD THAT IS EQUIPPED WITH
THE APPROPRIATE CONNECTOR FOR
YOUR LOCATION. CORDS ARE AVAILABLE
FROM YOUR DEALER.
Modifications
CAUTION: DO NOT SUBSTITUTE PARTS
OR MAKE ANY MODIFICATIONS
WITHOUT THE WRITTEN APPROVAL OF
BENCHMARK MEDIA SYSTEMS, INC.
MODIFICATION MAY CREATE SAFETY
HAZARDS AND VOID THE WARRANTY.
CAUTION: CHANGES OR MODIFICATIONS
NOT EXPRESSLY APPROVED BY
BENCHMARK MEDIA SYSTEMS COULD
VOID THE USER'S AUTHORITY TO
OPERATE THE EQUIPMENT UNDER FCC
REGULATIONS.
Repairs
CAUTION: DO NOT SERVICE OR REPAIR
THIS PRODUCT UNLESS PROPERLY
QUALIFIED. ONLY A QUALIFIED
TECHNICIAN SHOULD PERFORM
REPAIRS.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 2
Contents
Safety Information
Fuses
AC Input Voltage Range
Power Cord
Modifications
Repairs
Features
Introduction
Applications
DAC3 vs. DAC2
DAC3 vs. DAC1
DAC3 Technologies
Front Panel
Rear Panel
Quick Start Guide
Audio Inputs
Remote Control
Front Panel Controls
Front Panel Displays
Headphone Jacks
Operational Details
DIM and MUTE Functions
Bi-directional 12V Trigger
CALIBRATED Mode
USB MODE Selection
Driving Power Amplifiers
HPA2™ Headphone Amplifier
Digital Pass-Through
Firmware Version Identification
Rear Panel
Inputs
Outputs
AC Power-Entry and Fuse Module
Internal Settings
Jumper-Configured Options
Removing Top Cover
XLR Output Pads
Headphone Switch Configuration
Headphone Amplifier Gain
Digital PASS-THROUGH Function
9
10
10
10
11
12
15
16
16
17
19
20
20
21
22
22
23
23
26
27
28
28
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28
29
30
31
4
5
5
5
5
5
9
1
2
2
2
2
2
Rackmounting Options
Rackmount Version of the DAC3 DX
Connector Block
Premium ½-Wide Blank Rack Panel
Black ½-Wide Rack Panel
Universal Rack Adapter Tray
Rackmounting Example
32
32
32
33
33
33
34
DAC1, DAC2 and DAC3 Family History 35
DAC1 Series
DAC2 Series
DAC3 Series
35
35
36
Benchmark Technologies 37
Hybrid Gain Control™
Native DSD Conversion
High Headroom DSP
32-bit SABRE-PRO D/A System
Diagnostic Displays
Bi-Directional 12 Volt Trigger
Distributed Power Regulation
HPA2™ Headphone Amplifier
Differential Amplifiers
Jitter-Immune UltraLock3™
40
40
Multi-Mode Asynchronous USB Audio 43
37
37
37
39
39
39
39
39
USB Driver Installation
Performance Graphs
45
50
Specifications 67
Audio Performance - Balanced Outputs 67
Group Delay (Latency)
Digital Audio Inputs
Jitter Tolerance
Balanced Analog Outputs
Unbalanced Analog Outputs
HPA2 TM
Headphone Outputs
Status Display
AC Power Requirements
Dimensions
Weight
68
68
68
69
69
69
70
70
70
70
Regulatory Compliance 71
FCC and RoHS Compliance Statements 71
FCC Notice (U.S. Only)
RoHS Compliant Information
CE Certificate of Conformity
71
71
72
Warranty Information 73
Benchmark 1-Year Warranty 73
Benchmark Extended Warranty Options 74
Notes on Warranty Repairs 74
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 3
Features
HGC™ (Hybrid Gain Control) – combines motor-driven active analog potentiometers, 32-bit digital attenuators, and passive analog attenuators, to achieve state-of-the-art performance
SABRE PRO - 32-bit PCM D/A conversion system, four 32-bit D/A converters per channel
SABRE PRO – Native DSD D/A conversion system, four 1-bit DSD D/A converters per channel
Benchmark UltraLock3™ Jitter Attenuation System – eliminates jitter-induced distortion
High Headroom DSP - provides 4 dB of analog and digital headroom above 0 dBFS at an output level of 24 dBu to completely eliminate the clipping of intersample peaks
Multi-Mode Asynchronous USB Audio 2.0 – 24 bit/192 kHz, DSD (DoP 1.1)
Driverless Asynchronous USB Audio 1.1 – 24-bit/96 kHz
Sample Rate Display – displays the measured sample rate, and format (PCM or DSD)
Word Length Display – displays the measured word length
HPA2™ reference-grade "0-Ohm" headphone power amplifier with dual high-current outputs
HPA2™ gain jumpers for customizing headphone output gain for headphone sensitivities (Page
2 Headphone Output Jacks – one jack automatically mutes the main outputs, mute feature
can be programmed to mute either output bus and may be disabled (Page 29 )
1 AES XLR Digital Input – 24-bit/192 kHz PCM, DSD (DoP 1.1)
2 Coaxial Digital Inputs – 24-bit/192 kHz PCM, DSD (DoP 1.1)
2 Optical Digital Inputs – 24-bit/96 kHz PCM
1 Coaxial Digital Output – digital pass through from USB, Coax, and optical inputs when
function is enabled (Page 31 )
3 Stereo Analog Outputs – 1 pair balanced (XLR) plus 2 pairs unbalanced (RCA)
2 Stereo Analog Output Buses – either or both buses can be set to fixed gain
Low-Impedance Passive Output Pads – 0, 10, and 20 dB – optimize balanced output level
to power amplifiers and other downstream devices to maximize system SNR (Page 29 )
IR Remote with metal housing provides control of all functions (optional on some models)
Volume-Control Bypass – places one or both analog output buses in a calibrated fixed-gain
Mute – accessible from remote or front panel
Dim – Reduces output level by 20 dB, accessible from remote or front panel
Automatic De-Emphasis – automatically responds to consumer pre-emphasis bit (44.1, 48 kHz)
12V Trigger I/O – bi-directional 12V trigger can act as input, output, or both (Page 17 )
Power Switch – very low standby power , <0.5 W at 120 VAC
High-Efficiency Low-Noise Power Supplies – only 12-15 W, 88-264 VAC, 50-60 Hz
Meets FCC Class B and CE emissions requirements
Tested for immunity to radiated and conducted RF interference
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 4
Introduction
Applications
The DAC3 DX is a professional referencegrade audio digital to analog converter with
Benchmark's HPA2™ headphone amplifier.
The DAC3 DX supports 24-bit D/A conversion of PCM at sample rates up to 192 kHz. It also supports direct conversion of 1-bit DSD at a
2.8224 MHz sample rate. It is designed to be very transparent and this makes it well-suited for critical monitoring in studio control rooms and mastering rooms.
The DAC3 DX is also well-suited for high-end hi-fi environments. It includes a generous collection of inputs and outputs and can serve as the central component in any stereo hi-fi system where all inputs are digital. The DAC3
DX provides D/A conversion, source selection, volume control, and headphone amplification.
A remote control, 12V trigger, and volume control bypass function provide the features needed in a home environment.
The DAC3 DX is designed to directly drive a wide variety of power amplifiers and powered monitors. The balanced outputs include lowimpedance passive pads that can be adjusted to optimize the gain staging between the
DAC3 DX and the power amplifier. This gain optimization can provide very substantial improvements in the system-level SNR and
THD+N performance.
DAC3 vs. DAC2
The DAC3 product family builds upon
Benchmark’s highly successful DAC2 family.
The DAC3 maintains the familiar DAC2 form factor, but adds the higher performance available from the new ES9028PRO D/A converter. The DAC3 DX offers the following improvements over the DAC2 DX:
•
Active 2nd Harmonic Compensation
•
Active 3rd Harmonic Compensation
•
Lower THD
• Lower passband ripple
•
Improved frequency response
•
Increased Dynamic Range
•
Faster PLL lock times
•
Faster switching between inputs
DAC3 vs. DAC1
The DAC3 and DAC2 add these features that are not found on the DAC1:
• Asynchronous 192kHz USB Audio 2.0
•
32-bit D/A conversion system
•
Word Length Display
• Sample Rate Display
• Polarity Control
•
Direct DSD D/A Conversion
•
-20 dB DIM
•
Bi-Directional 12V Trigger
• Power Switch
• Volume Control Bypass
•
Digital Pass-Through
•
High-Headroom DSP
• Dual-Domain Hybrid Gain Control
• Additional I/O
DAC3 Technologies
Parallel Conversion Structure
The conversion system in the DAC3 DX achieves a 4.8 dB signal to noise improvement through the use of 3:1 summing on the main outputs. The
ES9028PRO D/A is an 8-channel 32-bit converter. In the DAC3 DX, three channels are summed in the analog domain to form the main outputs. The remaining two channels provide the auxiliary outputs.
The 3:1 summing also improves the THD. The non-linearities in individual conversion channels are averaged across the four summed channels and incoherent nonlinearities are attenuated by almost 4.8 dB.
Harmonic Compensation
The ES9028PRO has two distortion compensation systems that independently remove most of the 2nd and 3rd harmonic distortion in the D/A converter. Benchmark's ultra-clean analog output stages allow these systems to be fully leveraged in the DAC3
DX.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 5
High-Headroom Digital and Analog
Processing
The DAC3 DX has generous amounts of analog and digital headroom. The analog clip point is above 29 dBu. The digital clip point is
28 dBu. When operating at a typical -20 dB at
+4 dBu studio calibration, the DAC3 DX has
4 dB of digital headroom above 0 dBFS. This digital headroom prevents the clipping of intersample overs.
No Clipping of Intersample Overs
The DAC3 is one of very few D/A converters that can accurately reproduce intersample overs without clipping. Intersample peaks can reach +3.01 dBFS and commonly occur many times per second in most 44.1 kHz and 48 kHz recordings. When recordings are ripped using lossy compression systems (such as
MP3), additional intersample overs are often created. Most converters (including the
DAC1) produce bursts of distortion at every occurrence of an intersample over. In contrast, the DAC2 and DAC3 converters cleanly reproduce all intersample overs.
Low-Noise Power Supplies
The DAC3 DX uses high-efficiency low-noise power supplies. Each critical subsystem also has at least one dedicated low-noise regulator. The high-efficiency supplies deliver the substantial power required by the lowimpedance circuits, the headphone amplifier, and the output line drivers. A power switch is included. The standby power consumption is less than 0.5 W when the unit is off.
Low Magnetic Emissions
The magnetic components in the DAC3 DX power supplies operate at over 800 kHz. This allows the use of very small magnetic components that emit correspondingly small magnetic fields. This virtually eliminates all traces of line-frequency components in the output spectrum of the DAC3 DX. This also means that the DAC3 DX can be placed in close proximity to any audio component without causing interference with the other component.
UltraLock3™ Clock System
UltraLock3™ provides the outstanding jitter attenuation of Benchmark's UltraLock2™ system while providing virtually instantaneous
(6 ms) lock times.
Dual-Mode USB Input
The DAC3 DX has a USB input that can be operated in two modes; driverless USB
Audio 1.1, and a high sample rate USB
Audio 2.0. Both use asynchronous clocking to eliminate the USB interface as a source of clock jitter.
Note: To provide full backward and forward compatibility, the DAC3 DX uses the DAC2
USB drivers. This prevents the need to install two different sets of drivers. Please note that the DAC3 DX USB input will be identified as
"Benchmark DAC2" in your computer control panels. This is intentional.
Asynchronous USB Audio 2.0
The USB Audio 2.0 interface supports DSD and 192 kHz, 24-bit PCM. No drivers are required for Apple operating systems. Drivers are provided for Windows operating systems at: BenchmarkMedia.com/drivers
Native Asynchronous USB 1.1
The DAC3 DX has a driverless USB Audio 1.1 mode that supports 96 kHz, 24-bit PCM with all operating systems. This mode provides a quick and easy connection to a wide variety of computers and tablets without installing a driver.
32-bit Digital Gain Control
The DAC3 DX uses the digital section of
Benchmark's dual-domain HGC™ system
(used in the DAC3 HGC).
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 6
Benchmark’s unique motor-driven volume control sets the gain of a 32-bit dithered digital gain control. The 32-bit digital output feeds the 32-bit D/A conversion system.
The DSD signal is then routed directly to a bank of 1-bit DSD D/A converters. Three balanced 1-bit converters are summed together for each of the MAIN outputs.
The 32-bit digital gain control delivers low distortion, accuracy, and precise left-right gain matching. The noise-free 32-bit dithered system preserves musical details over a very wide range of output levels.
Digital Pass-Through
The second coaxial input (D5) can be reconfigured as a digital output. (Page
Error!
Bookmark not defined.
)
The XLR outputs leverage the low-impedance passive analog attenuation system. When properly configured, the entire dynamic range of the DAC3 DX can be lined up with the dynamic range of the power amplifier. This matching can provide a dramatic improvement in the system-level signal to noise ratio.
When D5 is configured as an output, any selected digital input is passed through to D5 without any processing. Optical, XLR, coaxial, and USB inputs can be passed through to the
D5 connector. PCM and DoP formatted DSD can both be passed through the D5 connector while also being sent to the D/A converter.
The pass-through function even works with special signals such as DTS, Dolby Digital, even though these signals cannot be decoded by the DAC3 DX.
The volume control is a servo-driven analog potentiometer. This control rotates in response to commands from the remote control while providing the convenience of manual adjustments with a physical knob.
The potentiometer produces a DC voltage that controls the gain of a dithered 32-bit multiplier. The outputs of the multiplier drive the 32-bit D/A converters.
Volume Control Bypass
The CALIBRATED mode can be activated for either or both output buses. (Page
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Bookmark not defined.
)
Low-Impedance Passive Attenuators
Like the DAC1 and DAC2, the DAC3 includes low-impedance passive attenuators on the
XLR outputs. (Page
Error! Bookmark not defined.
)
The factory default calibration at 0 dBFS is
+24 dBu on the XLR outputs (pads at 0 dB) and 2 Vrms on the RCA outputs. If your studio calibration is different, the calibration can be adjusted in 1 dB increments from +20 dBu to +28 dBu using the removable jumpers on connector P6.
These attenuators can be adjusted in 10 dB steps to optimize the interface with the power amplifier or powered monitors. This optimization places the volume control in its best operating range. This exclusive
Benchmark feature can provide substantial improvements in the overall performance of the playback signal chain.
The M and/or A lights will be on when the
MAIN and/or AUXILIARY outputs are in the
CALIBRATED mode. A slow flashing light indicates that a calibrated output is muted or dimmed. When the CALIBRATED mode is off, the M and/or A lights will flash rapidly when the volume of the MAIN and/or
AUXILIARY outputs are being adjusted.
Native DSD Conversion
The DAC3 DX supports native DSD conversion. This feature was not available on the DAC1. DSD signals can be delivered to the USB or Coaxial inputs in DoP 1.1 format.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 7
The CALIBRATED mode is similar to the
CALIBRATED switch setting on the DAC1 except that the DAC3 DX system is much more flexible. The DAC3 DX has two independent output buses that can be programmed differently. In addition the settings for these buses are individually programmable for each digital input on the
DAC3 DX. This flexibility has many applications in studio and home environments.
Relay-Muted Analog Outputs
The XLR and RCA analog outputs are equipped with mute relays that keep the outputs muted while powering on or off.
These relays eliminate pops and clicks at the unit power up or down.
Bi-directional 12V Trigger
The 12 Volt trigger can be connected to other audio components so that an entire audio system can turn on and off in a sequenced fashion. (Page
Error! Bookmark not defined.
)
The DAC3 DX trigger I/O can be connected to a preamplifier, power amplifier, or both.
The DAC3 DX will pull the trigger I/O to 12 volts DC while the DAC3 DX is on. If the
DAC3 DX is off and an external device pulls the trigger I/O to 12 volts, the DAC3 DX will turn on.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 8
Front Panel
Rear Panel
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 9
Quick Start Guide
Audio Inputs
The DAC3 DX features six stereo digital inputs (1 AES XLR, 2 coaxial, 2 optical, and 1
USB). The XLR, coaxial and optical inputs accept professional (AES), consumer (S/PDIF) and DoP DSD data formats.
Tip:
We recommend using the coaxial or USB inputs for DSD and for PCM sample rates above 96 kHz. Optical interfaces are rated for
96 kHz data rates and may not be reliable for
DSD or sample rates above 96 kHz.
Remote Control
OFF
Turns the unit off. Any devices slaved to the 12V TRIGGER will also turn off in a controlled sequence.
Press and hold the OFF button for 3 seconds to force the 12V
TRIGGER off (only necessary when another device is acting as a TRIGGER BUS MASTER).
ON
Turns the unit on. Any devices slaved to the 12V TRIGGER will also turn on in a controlled sequence.
VOLUME Turns the volume up or down.
MUTE
DIM
Toggles the MUTE function.
Press and hold the MUTE button for 10 seconds to toggle the CALIBRATED mode on the
MAIN outputs.
Toggles the -20 dB DIM function.
Press and hold the DIM button for 10 seconds to toggle the
CALIBRATED mode on the
AUX outputs.
Selects the inputs.
INPUT
D1
D2
Selects optical digital input D1.
Selects optical digital input D2.
The remote control is designed to have a long operating range. In most applications it is not necessary to point the remote directly at the
DAC3 DX.
D3
D4
D4
Selects XLR digital input D3.
Selects coaxial digital input D4.
Selects coaxial digital input D4
USB
Selects USB input.
The chart at the right summarizes the functions of the IR remote control.
Press and hold the USB button for 10 seconds to toggle between the USB 1.1 and USB
2.0 modes.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 10
Front Panel Controls
The front panel controls duplicate all of the functions that are available from the remote control.
The chart at the right summarizes the functions of the front-panel controls.
POWER
MUTE
DIM
INPUT
VOLUME
(knob)
Turns the unit on or off. Any devices slaved to the 12V
TRIGGER will also turn on or off in a controlled sequence.
Press and hold the POWER button for 3 seconds to force the 12V TRIGGER off (only necessary when another device is acting as a TRIGGER BUS
MASTER).
Press once to toggle the -20 dB
DIM function.
Press and hold the MUTE button for 10 seconds to toggle the CALIBRATED mode on the
MAIN outputs.
Press once to toggle the -20 dB
DIM function.
Press and hold the DIM button for 10 seconds to toggle the
CALIBRATED mode on the
AUX outputs.
Selects the inputs.
Select USB and press lower button for 10 seconds to toggle between the USB 1.1 and USB
2.0 modes.
Sets the volume of all outputs that are not in CALIBRATED mode.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 11
Front Panel Displays
There are sixteen status indicator lights on the front panel. At least one light will be illuminated whenever power is on.
Calibration and Input Indicators
The M and A indicators show that the
CALIBRATED mode is active for the MAIN and/or AUX outputs.
The input indicators (U and D1-D5) show which input is selected.
A
This light will flash rapidly when the volume of the AUX bus is being adjusted.
A solid light indicates that the AUX bus is in CALIBRATED mode.
A slow-blinking light indicates that the
AUX bus is in CALIBRATED mode but the output is muted or dimmed.
M
This light will flash rapidly when the volume of the MAIN bus is being adjusted.
A solid light indicates that the MAIN bus is in CALIBRATED mode.
A slow-blinking light indicates that the
MAIN bus is in CALIBRATED mode but the output is muted or dimmed.
U
A solid light indicates that the USB input is selected and operating normally.
A blinking light indicates that the input is selected but a connection to a computer has not been established.
D1 A solid light indicates that optical input D1 is selected and operating normally.
A blinking light indicates that the input is selected but audio data is not being received.
D2 A solid light indicates that optical input D2 is selected and operating normally.
A blinking light indicates that the input is selected but audio data is not being received.
D3 A solid light indicates that XLR input
D3 is selected and operating normally.
A blinking light indicates that the input is selected but audio data is not being received.
D4 A solid light indicates that coaxial input D4 is selected and operating normally.
A blinking light indicates that the input is selected but audio data is not being received.
D5 A solid light indicates that coaxial input D5 is selected and operating normally.
A blinking light indicates that the input is selected but audio data is not being received.
Note:
D5 cannot be selected if the Digital
Pass Through function is enabled.
Instructions for configuring this jumper-
selected function can be found in the Internal
section of this manual (Page 28).
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 12
Input Error Codes
An input indicator (U or D1-D5) flash when an error is present on the selected digital input. Use the following table to diagnose the problem:
Slow Flash
(2Hz)
Med. Flash
(7Hz)
Rapid flashes
(14Hz)
Intermittent flashes
No digital signal (output muted)
Data transmission errors or Non-PCM (output muted)
Non-audio data is being received (output muted)
Some data corruption is occurring, converter may be interpolating to replace invalid samples, check the cable.
Tip:
Common causes of input errors:
•
Disconnected or faulty cable
• Use of excessively long digital cables
• Use of analog cables for digital signals
•
Use of optical cables for sample rates exceeding 96 kHz
• Incompatible data type (AC3, ADAT, etc.)
• Non-audio data is being received
MUTE and DIM Indicators
Digital Format Indicators
Two lights indicate the measured word length of the selected digital input.
Four lights indicate the measured sample rate and format of the selected digital input.
Tip:
Computers, disk players and streaming devices often subject the digital signal to sample rate conversion, changes in word length, PCM to DSD conversions, and other forms of digital processing that may degrade the quality of the audio. This display makes it easy to detect these processes.
Word Length Indicators
The 16 and 24 lights indicate the measured word length of the selected digital input. The
DAC3 DX detects active data bits and displays the results as follows:
16 Only Measured input word length is
16 bits.
16 and
24
Measured input word length is
17 to 23 bits.
24 Only Measured input word length is
24 bits.
Both Off Measured input word length is less than 16 bits.
MUTE
DIM
Indicates that all outputs are muted.
Indicates that all outputs are dimmed by 20 dB.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 13
Format indicators
The 44, 48, 2X, 4X and DSD lights indicate the sample rate and format of the selected digital input as follows:
44 Only
48 Only
The input format is PCM at a sample rate of 44.1 kHz (CD sample rate).
The input format is PCM at a sample rate of 48 kHz (often used with video).
44 and 2X The input format is PCM at a sample rate of 88.2 kHz
(high-resolution audio format).
48 and 2X The input format is PCM at a sample rate of 96 kHz (highresolution audio format).
44 and 4X The input format is PCM at a sample rate of 176.4 kHz
(high-resolution audio format).
48 and 4X The input format is PCM at a sample rate of 192 kHz
(high-resolution audio
DSD
(4x and 2X)
format).
The input format is 1-bit DSD at a sample rate of 2.8224
MHz (high-resolution audio
All Off
format). Note: DSD must be streamed in DoP format.
Digital signal is not present or is not in a supported format.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 14
Headphone Jacks
Tip:
The Volume Control simultaneously adjusts the level for both jacks. If two listeners will be simultaneously using the headphone outputs, we recommend using headphones with identical or similar voltage sensitivities.
By default, the lefthand jack mutes the
MAIN outputs.
By default, the right-hand jack keeps all outputs active.
Headphone Mute Switches
Both headphone jacks includes include switches that can be programmed to mute the MAIN outputs. When enabled, the MAIN analog outputs (XLR and RCA) are muted when a headphone plug is inserted. This feature allows the listener to switch from loudspeaker to headphone playback seamlessly. This Auto-Mute feature can be disabled or enabled on one or both jacks using internal jumpers.
Note:
Instructions for setting the Auto-Mute
jumpers can be found in the Internal Settings
section of this manual (Page 28).
HPA2 TM Headphone Power Amplifier
The headphone jacks are driven by
Benchmark's HPA2™ headphone power amplifier. This very clean power amplifier can deliver the current and voltage required by some of the most demanding headphones.
The output impedance of the HPA2™ is very close to 0 Ohms. This low output impedance delivers a high damping factor so that the amplifier can maintain precise control over the headphone transducers.
Headphone voltage sensitivities vary substantially, so we have equipped the
HPA2™ with Gain-Range jumpers that can be used to customize the headphone amplifier to your favorite headphones. If you find that you have too much output (volume control set below 11 o'clock), there are internal jumpers that can be adjusted to decrease the output level by 10 dB or 20 dB relative to the factory default setting.
Note:
Instructions for setting the headphone
Gain-Range jumpers can be found in the
Internal Settings section of this manual (Page
Tip:
For optimal performance, the headphone
Gain-Range jumpers should be set so that comfortable listening levels occur when the volume control is set above the 11 o'clock position.
Tip:
Use the left-hand jack to mute your loudspeaker system. Use the right-hand jack to keep all outputs active.
Driving Two Sets of Headphones
The HPA2™ is specifically designed with enough power to drive two sets of headphones.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 15
Operational Details
DIM and MUTE Functions
Definition:
If the DIM and MUTE modes are all off, the DAC3 DX is in NORMAL mode.
DIM Function
The DIM function reduces the output level by
20 dB. To toggle between NORMAL and DIM volume, press the DIM button on the remote or the DIM button on the front panel.
The DIM light will turn on whenever DIM is active.
The DIM function makes it convenient to fade back and forth between normal and background playback volume levels.
If the volume is adjusted while DIM is active, the NORMAL volume setting will change by the same amount.
TIP:
In the studio, the DIM function allows a temporary reduction in level without losing the volume setting that was being used for monitoring.
Tip:
In home applications the DIM function allows temporary reductions in volume during
TV commercial breaks, phone calls, or other interruptions, without losing the volume setting that was being used for normal listening.
MUTE Function
The MUTE function immediately mutes all outputs. To toggle this function, press the
MUTE button on the remote or press the
MUTE button on the front panel.
The MUTE light will turn on whenever MUTE is active.
Tip:
If the unit is in MUTE, press the DIM key to immediately enter the DIM mode.
Tip:
If the unit is in MUTE and/or DIM press the ON key (on the remote) to enter the
NORMAL mode.
Tip:
if the unit is in DIM, press the MUTE key to toggle between DIM and MUTE.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 16
Bi-directional 12V Trigger
Benchmark has reinvented the 12 volt trigger by adding bi-directional signaling. The trigger connection on the DAC3 DX can be used as an input, an output, or both. It is compatible with any common 12 volt trigger input or output. The 12V TRIGGER I/O can be used to turn other audio components on when the
DAC3 DX turns on. The DAC3 DX can also turn on and off in response to other connected components. The Benchmark bidirectional 12V Trigger is compatible with virtually all trigger systems.
The 12V TRIGGER I/O can be connected to the trigger input or output ports on a preamplifier, power amplifier, or both.
The DAC3 DX can send a 12 Volt DC trigger signal to start other components in the system, or it can wake up in response to an externally generated trigger signal. The DAC3
DX automatically configures its trigger I/O port as an input (slave) or output (master).
Trigger Output (DAC3 DX is Master)
When the DAC3 DX is turned on using the
POWER button (on the front panel), or the
ON button (on the remote), the DAC3 DX configures itself as a trigger master and will drive the 12V TRIGGER I/O to 12 volts DC and hold it there while the DAC3 DX is on.
The trigger output signal generated by the
DAC3 DX is delayed so that the DAC3 DX can stabilize before downstream devices
(such as power amplifiers) turn on. When powering down, the DAC3 DX will mute before allowing the trigger line to drop low.
The DAC3 DX keeps the internal power supplies running for 10 seconds after dropping the trigger. This delay gives other triggered components ample time to mute and shut down.
Trigger Input - (DAC3 DX is Slave)
If the DAC3 DX is off and an external device pulls the trigger I/O to 12 volts, the DAC3
DX will configure itself as a trigger slave and will follow the actions of the trigger input. The
DAC3 DX will then turn off when the external device stops sending the 12 V trigger.
Typical Trigger Applications
In most systems, the 12V TRIGGER will be used to connect the DAC3 DX to one other device. The DAC3 DX can be connected to the first trigger input at the beginning of a trigger chain, or it can be connected to the last trigger output at the end of the chain
(less common).
Typical trigger applications:
• DAC3 DX → Amplifier
•
DAC3 DX → Amplifier → Amplifier
•
DAC3 DX → Preamplifier → Amplifier
Trigger Bus Applications
The Benchmark bi-directional trigger system also supports multiple trigger ports wired together on a bus.
A group of Benchmark trigger ports can be connected to a group of non-Benchmark trigger input ports to form a single trigger bus. A bus should never be connected to more than one non-Benchmark trigger output port. If an output port is connected to the bus, this device should be used to start the audio system.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 17
A 3.5 mm (1/8") TRS "Y" cable can be used to split the trigger output of the DAC3 DX to feed more than one trigger input.
Benchmark AHB2 power amplifiers have two trigger I/O ports that are wired in parallel.
This makes it easy to connect more than one power amplifier to a trigger bus (without the use of a "Y" cord). Connect a trigger cable between the DAC3 DX and the first amplifier.
Use another trigger cable to connect this amplifier to the next amplifier. Any number of
Benchmark amplifiers can be added to the trigger bus. The DAC3 DX will turn on first, and after a delay, all of the amplifiers will turn on together.
Bi-Directional Trigger Applications
Benchmark products support bi-directional communications over a trigger bus. Any
Benchmark product connected to the bus can turn the entire system on or off. Because of the bi-directional design, any power button on a Benchmark DAC3 DX or AHB2 can be used to start or stop the system.
The Benchmark device that starts the system will become the trigger master. If the trigger master is turned off, all slave devices will follow. If a slave device is turned off, all other devices will stay on.
If the DAC3 DX is used to turn the system on, any connected AHB2 amplifiers will become slave devices and they can be turned off without shutting down the DAC3 DX. This feature makes it easy to turn the AHB2 amplifier(s) off when listening to headphones.
Slave devices can force the entire trigger bus to shut down if the POWER button or OFF button is pressed and held for 3 seconds.
Tip:
Press and hold the POWER button on any Benchmark device for 3 seconds to force a shutdown of the entire trigger-connected system.
Trigger Specifications
The Benchmark 12V TRIGGER I/O has a wide operating range to allow interfacing with most other DC trigger systems. It should only be used with trigger inputs that are designed to tolerate 12 VDC.
•
12 VDC 200 mA current-limited output
•
Input responds to 3.3 V logic and higher
• Maximum input voltage = 30 VDC
• Maximum reverse input voltage = -0.3
VDC
•
Input Impedance = 20 k Ohms
• 1/8" (3.5 mm) TRS jack
• Tip = 12 Volt Trigger I/O
•
Ring = no connection
•
Sleeve = chassis ground
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 18
CALIBRATED Mode
The CALIBRATED mode sets the MAIN and/or AUX output buses to factory calibrated levels. The two output buses are individually programmable for each digital input.
The factory preset calibration is +24 dBu at 0 dBFS on the XLR outputs, and 2 Vrms at 0 dBFS on the RCA outputs. The calibration is adjustable up or down by up to 4 dB in 1 dB steps using internal jumpers. On the XLR outputs the calibration range is +20 dBu to
+28 dBu. On the RCA outputs the calibration range is 1.26 to 3.17 Vrms.
The CALIBRATED mode is similar to the
CALIBRATED switch setting on the DAC1 except that the CALIBRATED mode can be programmable separately for each input.
The CALIBRATED mode has two distinct applications:
• Volume Control Bypass - useful when the system has an upstream digital volume control or a downstream analog volume control
• Calibrated Output - useful in studio applications where calibrated levels are needed
The M light indicates that the MAIN bus is in
CALIBRATED mode.
The A light indicates that the AUX bus is in
CALIBRATED mode.
Enabling the CALIBRATED Mode
1. Select the input channel that you wish to program
2. Press and hold the MUTE button for
10 seconds to toggle CALIBRATED mode on the MAIN outputs
3. Press and hold the DIM button for 10 seconds to toggle CALIBRATED mode on the AUX outputs.
CALIBRATED Mode - Volume Control
Bypass
The CALIBRATED mode is useful whenever the system volume will be controlled before or after the DAC3 DX. It is usually best to avoid having two cascaded volume controls in a playback system. Dual controls will usually degrade the noise performance of the system and they can lead to confusion.
If the DAC3 DX feeds a preamplifier, the preamplifier will provide a downstream analog volume control for the system and the DAC3
DX should be placed in CALIBRATED mode for all inputs.
If the DAC3 DX is directly feeding an amplifier, but one or more sources have volume controls, the sources with volume controls can be set to CALIBRATED mode.
Example 1: The USB input is fed from a computer that has an internal digital volume control. If you wish to use the volume control in the computer exclusively, you will want to enable the CALIBRATED mode on the USB input. If you do not wish to use the computer volume control, leave the CALIBRATED mode off and disable the computer volume control (or set it to maximum).
Example 2: Digital input D3 is fed from a digital audio workstation and the workstation will be controlling the playback level in the control room. The volume control on the
DAC3 DX will be controlling the playback level in another room. The MAIN outputs will be driving the control room monitors and the
AUX outputs will be driving the monitors in the other room. Select D3 and enable the
CALIBRATED mode on the MAIN outputs only.
Example 3: Input D4 is being driven by a music server. A power amplifier in the same room is driven from the MAIN outputs.
Another room needs a fixed line-level feed to an integrated amplifier (with volume control).
Select D4 and enable the CALIBRATED mode on the AUX output only.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 19
USB MODE Selection Driving Power Amplifiers
The DAC3 DX supports two USB MODES:
• USB Audio 1.1 mode - up to 24 bits at 96 kHz
•
USB Audio 2.0 mode - up to 24 bits at 192 kHz plus DSD in DoP 1.1 format
Caution:
Close all USB audio playback applications before changing the USB MODE.
If an audio application is playing while the
USB MODE is changed, the audio application may freeze.
The DAC3 DX is designed to directly drive virtually any audio power amplifier or powered monitor. This direct connection provides the cleanest and shortest path from the digital source to the monitor output.
Tip:
Benchmark does not recommend placing audio devices between the DAC3 DX and the power amplifier unless these devices are providing an indispensible system function. A direct connection between the DAC3 DX and the power amplifier will always provide the best system-level performance (SNR and
THD+N).
To change the USB MODE, select the USB
(U) input on DAC3 DX and then press and hold the USB button on the remote control for 10 seconds. If a remote control is not available, select the USB input, and then press and hold the bottom INPUT button on the front panel for 10 seconds.
The RCA and XLR outputs on the DAC3 DX are equipped with low-impedance highcurrent drivers. These robust outputs are well equipped to drive a wide variety of input impedances. The DAC3 DX outputs remain clean when driving amplifiers that present difficult loads (high input capacitance and/or low input impedance).
After holding the button for 10 seconds, either the 4X lamp or the 2X lamp will flash once indicating the new USB MODE. A flash of the 4X lamp indicates that the unit is now in USB Audio 2.0 mode. A flash of the 2X lamp indicates that the unit is now in USB
Audio 1.1 mode.
Tip:
The 4X or 2X lamp will flash once every time the USB input is selected. This flash provides a convenient indication of the current USB MODE.
The XLR outputs on the DAC3 DX are equipped with jumper-configured passive lowimpedance output pads. These pads can be set to an attenuation of 0 dB (pad off), 10
dB, or 20 dB. The pads should be used to match the output level of the DAC3 DX to the input sensitivity of the power amplifier. Most power amplifiers and powered monitors will require the use of the 10 dB or 20 dB pads.
Use the high-output 0 dB setting when driving a Benchmark AHB2 power amplifier.
Tip:
Avoid any unnecessary switching between USB MODES. Rapid switching between modes can confuse some operating systems.
Tip:
USB Audio 1.1 and USB Audio 2.0 are industry standard protocols for the transmission of digital audio over USB interfaces. Mac operating systems support both modes. To date, Windows operating systems only support USB Audio 1.1. For this reason, we provide a Windows driver for USB
Audio 2.0. No drivers are required for Mac computers.
Tip:
The Benchmark AHB2 power amplifier has a unique low-gain topology that allows it to accept full studio-level input signals. This high-level interconnection provides a very low-noise connection between the DAC3 DX and the AHB2. Set the input SENSITIVITY switch on the AHB2 to 22 dBu (all the way down). This places the AHB2 full-power output point at an input level of 22 dBu. This level is exactly 2 dB lower than the calibrated
CALIBRATED output level of the DAC3 DX
(when the pads are set to 0 dB). This configuration optimizes the gain-staging between the DAC3 DX and the AHB2 while
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 20
placing the DAC3 DX volume control in the proper range.
Tip:
If you are using a DAC3 DX with non-
Benchmark power amplifiers, the XLR pads should be set so that comfortable listening levels occur when the VOLUME control is set above 11 o’clock. This will optimize the gainstaging between the DAC3 DX and your power amplifier.
Tip:
Increase the pad setting if a comfortable listening level is reached at a VOLUME control setting below the 11 o'clock position.
Tip:
Decrease the pad setting if a comfortable listening level cannot be reached when the
VOLUME control is fully clockwise.
Instructions for setting the XLR pad jumpers
are detailed in the Internal Settings section of
this manual (Page 28).The DAC3 DX is
shipped with the XLR pads disabled (set to 0
dB). No adjustments will be necessary if you will be using a Benchmark AHB2 power amplifier.
HPA2™ Headphone Amplifier
The DAC3 DX is equipped with two 1/4" stereo headphone jacks. The audio output on both jacks is wired in parallel and is driven by
Benchmark's HPA2™ headphone power amplifier. The HPA2™ is an ultra-clean power amplifier that is capable of delivering 1.25 W into 30 Ohms. It easily drives a pair of headphones.
Both headphone jacks are equipped with mute switches that can be programmed to mute the analog outputs on the back of the DAC3 DX.
By default, the switch on the left-hand headphone jack is enabled and the switch on the right-hand headphone jack is disabled.
Instructions for setting the headphone
switches are detailed in the Internal Settings
section of this manual (Page 28).
The HPA2™ is one of the most transparent headphone amplifiers available. It also is able to deliver high current and/or high signal levels making it well suited for a wide variety of headphones. The near 0-Ohm output impedance provides outstanding damping of headphone drivers. This damping reduces distortion while maintaining precise control of the frequency response at the output of the amplifier.
The HPA2™ has a set of 3-position gainrange jumpers that can be used to increase or decrease the gain by 10 dB relative to the factory calibrated setting.
The jumpers change the gain of the HPA2™ headphone amplifier without changing the output impedance. This keeps the output impedance of the HPA2™ constant and very near 0 Ohms. External attenuators should never be inserted after a headphone amplifier as this would change the output impedance and alter the frequency response of the headphones.
Proper gain settings are important for maximizing the SNR of the headphone monitoring system. With proper settings, the full performance of the DAC3 DX can be delivered to the headphones for critical monitoring tasks and for maximum musical enjoyment.
Tip:
When the headphone gain jumpers are set properly, a normal listening level will be achieved at a VOLUME control setting above the 11 o'clock position.
Tip:
If a normal listening level is achieved below an 11 o’clock VOLUME setting, the headphone gain is too high, and the gain should be decreased.
Tip:
If the level is too low at the maximum
VOLUME setting, the headphone gain is too low, and the gain should be increased.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 21
Digital Pass-Through
The second coaxial input (D5) can be reconfigured as a digital output. When operating as an output, any selected digital input is passed through to D5 without any processing.
Optical, coaxial, and USB inputs (U, D1, D2,
D3 and D4) can be passed through to the D5 connector. The signals are buffered but are not processed in any way. For this reason, any data format can be passed through to the
D5 connector, even when these formats cannot be decoded by the DAC3 DX.
Surround formats, such as DTS, Dolby Digital, cannot be decoded by the DAC3 DX, but they can be passed to a surround system using the digital pass-through function.
The digital pass-through can also be used to provide the following digital signal conversions:
• Optical to Coaxial
•
USB to Coaxial
•
AES XLR Digital to Coaxial
•
Coaxial to Coaxial (buffering)
DoP encapsulated DSD can also be passed through D5. For example, DSD files on a computer can be sent in DoP to the USB input on the DAC3 DX. The USB input can be routed to coaxial output D5. This output can be recorded by any 24-bit, 176.4 kHz digital recorder with a coaxial input. The PCM digital recorder can then be used to play the DSD recordings in DoP format.
Firmware Version Identification
The firmware version is displayed during the lamp test while the DAC3 DX is turning on.
At least one lamp in the INPUT INDICATOR will flash rapidly while the remaining lamps will be on. The flashing lamps identify the firmware version. The values of each lamp are shown in this chart. Add the values
Digit 1 Digit 2
8 D1 D2 .8
4 U D3 .4
2 M D4 .2
1 A D5 .1 of all flashing lamps to determine the version number. If no lamp flashes in the second column, the second digit is a 0.
Example 1:
The A lamp is the only lamp that flashes. The firmware version is 1.0.
Example 2:
The A and D5 lamps flash. The firmware version is 1.1.
Example 3:
The M, A, D5, D4 and D3 lamps flash. The firmware version is 3.7.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 22
Rear Panel
Inputs
There are six stereo digital inputs on the
DAC3 DX:
•
USB - USB Audio 1.1 or 2.0 Input
•
D1 - Optical Digital Input
•
D2 - Optical Digital Input
• D3 - XLR Digital Input
• D4 - Coaxial Digital Input
• D5 - Coaxial Digital Input or Output*
These inputs are selected using the INPUT buttons on the front-panel or on the remotecontrol.
Tip:
There is no D5 button on the remote control. Use the INPUT up-down buttons or press D4 twice to select input D5. Pressing
D4 again to return to input D4.
* D5 can be jumper-configured as a digital
PASS-THROUGH output. When enabled, the selected digital input will be routed to the internal D/A converter and to output D5. The selected input will be buffered and sent to output D5 even if the format cannot be decoded by the DAC3 DX.
The digital inputs support PCM stereo
AES/EBU and SPDIF digital formats. Maximum word length is 24-bits. Maximum sample rate is 192kHz. The digital inputs also support
DSD stereo at a sample rate of 2.8224 MHz using DoP 1.1 encapsulation.
The USB input has two operating modes:
•
USB Audio 1.1 - PCM up to 24-bits at
96 kHz
• USB Audio 2.0 - PCM up to 24-bits at
192 kHz and DSD (DoP 1.1 format)
Caution:
The optical inputs (D1 and D2) are not recommended for DSD or for sample rates above 96 kHz. Optical connections may be unreliable at sample rates above 96 kHz.
Tip:
The DAC3 DX will not decode multichannel digital formats such as AC3, and
Dolby Digital. The audio will mute and the
INPUT INDICATORS will flash whenever an incompatible format is connected to the selected digital input. If the PASS-THROUGH mode is enabled, these multichannel formats can be sent to a surround processor using connector D5 as a digital output.
Caution:
The 12V TRIGGER I/O is not an audio connection! This is a 12V DC connection for synchronizing the on and off sequencing of an entire audio system.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 23
Digital Inputs - Details
All of the digital inputs on the DAC3 DX use
Benchmark's UltraLock3™ system to remove virtually all of the interface jitter. The result is that all digital inputs deliver identical audio performance. The USB, optical, XLR and coaxial digital inputs will all sound identical if they receive identical data.
The USB Audio 2.0 mode was tested for compatibility with Windows XP, Vista, 7, 8 and 10 (driver installation is required for all
Windows versions). It was also tested for compatibility with Mac OS X starting with version 10.6 (operation is driverless for all OS
X versions).
Optical Digital Inputs - D1 and D2
Computer Input – USB
The USB input accepts a Type-B male USB connector. A Type-A to Type-B USB cable is provided with the DAC3 DX. The USB cable connects the DAC3 DX directly to a computer’s USB output.
The optical input connectors (D1 and D2) are commonly known as TOSLINK connectors.
The TOSLINK optical connectors used on the
DAC3 DX are designed to work well at sample rates up to 96 kHz. Maximum word length is 24-bits. All sample rates between 28 and 96 kHz are supported. The optical inputs may be unreliable at sample rates above 96 kHz. The optical inputs will accept professional AES/EBU data formats or consumer S/PDIF data formats.
The USB input supports 44.1, 48, 88.2, 96,
176.4, and 192 kHz PCM sample rates at word lengths up to 24-bits. The USB input also accepts DSD in DoP 1.1 format.
The DAC3 DX can be configured as a USB
Audio 1.1 or USB Audio 2.0 device. Press and hold the USB button on the REMOTE for
10 seconds to toggle the USB MODE. If a remote is not available, select the USB input and then press and hold the bottom INPUT button on the front panel for 10 seconds.
Tip:
The optical inputs include dust caps.
Keep these in place if the input is not being used.
XLR Digital Input - D3
The USB AUDIO 1.1 mode does not require the installation of a driver. It allows a quick driverless connection to Windows machines when playing sample rates of 96 kHz or less.
In this mode, Windows machines can begin streaming audio within seconds after the
DAC3 DX is connected for the first time. No software or hardware configuration is usually required.
USB Audio 2.0 is required for DSD and for all PCM sample rates exceeding 96 kHz.
Windows computers require a driver to support the USB Audio 2.0 mode.
The XLR digital inputs (D3) uses a female XLR connector. The input impedance is 110 Ohms.
Maximum word length is 24-bits. All sample rates between 28 and 195 kHz are supported.
The XLR digital input will accept professional
AES/EBU data formats or consumer S/PDIF data formats. The XLR input also accepts DSD in DoP 1.1 format.
The XLR digital input is transformer coupled.
The transformer provides galvanic isolation of the signal pins (2 and 3). A capacitor protects the transformer from DC currents.
Diodes at the transformer outputs protect the digital audio receiver. Pin 1 (ground) and the
XLR shell are tied directly to the chassis to prevent currents in the internal ground system. This direct bonding also maximizes
RF shielding.
The USB Audio 1.1 mode was tested for compatibility with Windows XP, Vista, 7, 8 and 10, Mac OS X, and iPads using the 30-pin to USB Camera Kit. No driver installation is required for any of these systems when operating in USB Audio 1.1 mode.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 24
Caution:
Use 110-Ohm digital audio cables for digital XLR audio connections. Do not use analog XLR cables. Digital interfaces require the use of matched impedances. The digital input may not function, or may be unreliable if the incorrect cable is used.
Coaxial Digital Inputs - D4 and D5
The coaxial digital inputs (D4 and D5) use female RCA connectors. The input impedance is 75 Ohms. Maximum word length is 24-bits.
All sample rates between 28 and 195 kHz are supported. The coaxial digital inputs will accept professional AES/EBU data formats or consumer S/PDIF data formats. The coaxial inputs also accept DSD in DoP 1.1 format.
The coaxial digital inputs are DC isolated, current limited, and diode protected. The RCA body is bonded directly to the chassis to prevent currents in the internal ground system. This direct bonding also maximizes
RF shielding.
Caution:
Use 75-Ohm coaxial cables for digital audio connections D4 and D5. Digital interfaces require the use of matched impedances. Do not use 50-Ohm coaxial cables, twisted pair cables, or any non-coaxial cables for digital audio. The digital inputs may not function, or may be unreliable if the incorrect cable is used.
Note:
The Coaxial inputs (D4 and D5) accept professional or consumer digital audio formats. The AES3-id and SMPTE 276M standards specify a 75-Ohm, 1 Vpp, professional format which is also known as
AES/EBU and is commonly used in video production facilities. The IEC 609588-3 standard specifies a 75-Ohm, 0.5 Vpp, consumer format which is also known as
S/PDIF, and is commonly used in hi-fi equipment. The coaxial inputs are designed to accept either type of signal.
12V TRIGGER I/O
The Benchmark bi-directional 12V TRIGGER is compatible with virtually all trigger systems. The 12V TRIGGER I/O connection on the DAC3 DX can be used as an input, an output, or both. It is compatible with most 12 volt trigger inputs and outputs. The 12V
TRIGGER can be used to turn other audio components on when the DAC3 DX turns on.
The DAC3 DX can also turn on and off in response to trigger signals sent from other components.
The 12V TRIGGER I/O can be connected to the trigger input or output ports on a preamplifier, power amplifier, or both.
The DAC3 DX can send a 12 Volt trigger signal to start other components in the system, or it can wake up in response to an externally generated trigger signal. The DAC3
DX automatically configures the 12V
TRIGGER I/O port as an input (slave) or
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 25
Bi-directional 12V Trigger section for more
information.
The Benchmark 12V TRIGGER I/O has a wide operating range to allow interfacing with most other DC trigger systems. It should only be used with trigger inputs that are designed to tolerate 12 VDC.
•
12 VDC 200 mA current-limited output
•
Input responds to 3.3 V logic and higher
• Maximum input voltage = 30 VDC
•
Maximum reverse input voltage = -0.3
VDC
•
Input Impedance = 20 k Ohms
• 1/8" (3.5 mm) TRS jack
•
Tip = 12 Volt Trigger I/O
•
Ring = no connection
•
Sleeve = chassis ground uses three conversion channels wired in parallel for each XLR connector. The main bus uses 6 of the 8 channels in the ES9028PRO
D/A conversion chip. The remaining two channels in the ES9028PRO drive the AUX bus.
AUX Bus
The AUX bus drives the second pair of RCA outputs.
Output Drivers
The DAC3 DX features high-current output drivers that are capable of driving 300-Ohm loads without an increase in distortion. They are also well suited for driving long cables or high-capacitance loads.
Balanced XLR Analog Line Outputs
Caution:
The 12V TRIGGER I/O is not an audio connection! This is a 12V DC connection for synchronizing the on and off sequencing of an entire audio system.
Outputs
Analog Outputs
The Left and Right balanced outputs use
Neutrik™ gold-pin male XLR jacks. The XLR shell and pin 1 (ground) are both directly bonded to the chassis to prevent currents in the internal ground system. This direct bonding also maximizes RF shielding.
The DAC3 DX has two analog output buses
(MAIN and AUX). By default, both buses are controlled by the volume control. Either or both buses can be programmed to bypass the volume control. The CALIBRATED mode bypasses the volume control and sets the output(s) to a preset level.
MAIN Bus
The MAIN bus drives the XLR outputs and one pair of RCA outputs. The MAIN bus delivers the highest performance because it
The XLR outputs have passive attenuators that allow direct connections to a wide variety of audio devices without a loss of dynamic range. The 10 or 20 dB pads are usually required for direct interfacing to power amplifiers and powered speakers. The DAC3
DX ships with the pads disabled (0 dB setting). Use the 0 dB setting with the
Benchmark AHB2 power amplifier. A full description of the output attenuators and instructions for configuration is located in the
Internal Settings section of this manual (Page
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 26
Industry-Standard XLR Wiring
•
XLR pin 2 = + Audio Out
•
XLR pin 3 = - Audio Out
•
XLR pin 1 = Cable Shield
Caution:
If the balanced XLR outputs are wired to an unbalanced input (using a special adapter cable), pin 3 must be left floating.
Shorting pin 3 to ground will increase the temperature of the output drivers, will increase power consumption, may cause distortion, and may shorten the life of the output drivers.
Unbalanced RCA Analog Outputs
AC Power-Entry and Fuse Module
The Left and Right unbalanced outputs use female RCA jacks. The ground connections are bonded to chassis ground at the location where analog ground is bonded to the chassis. This minimizes the effects of ground loops caused by AC currents in the cable shield. The RCA output impedance is very low
(30 Ohms). This makes these outputs well suited for driving high-capacitance loads and/or high-capacitance cables.
Caution:
Mono summing with an RCA ‘Y’ cable is not recommended as this can cause high amounts of distortion. Mono summing with a ‘Y’ cable can be accomplished with the use of a modified cable by implementing a 1k
Ohm series resistor in each leg of the ‘Y’.
Note:
The XLR pads do not have any effect on the level of the RCA outputs.
Input Voltage Range
Note:
The DAC3 DX is equipped with a universal power supply. There is no voltage selection switch. AC voltage range is 88-264
VAC, 50-60 Hz.
Power Cord
Note:
The AC power input uses a standard
IEC type connector. One USA-compatible power cord is included with DAC3 DX converters. IEC style power cords in countryspecific configurations are available in your locality.
Caution: Always use a grounded power cord. The DAC3 DX is equipped with a standard IEC power entry module. Use an IEC power cord that is equipped with the appropriate connector for your location. Cords are available from your dealer.
Fuses
Caution: For continued fire hazard protection always replace the fuses with the correct size and type (0.5A 250 V
Slo-Blo
®
5 x 20 mm – Littelfuse®
HXP218.500 or equivalent). The fuse drawer includes two fuses. Always replace both fuses at the same time.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 27
Internal Settings
Jumper-Configured Options
The following functions are jumper configured:
•
XLR Output Pads
• Headphone Mute Switches
• Headphone Gain
•
Digital Pass-Through
•
Calibration Level
Removing Top Cover
The DAC3 DX cover must be removed to gain access to the jumpers. Do not attempt to remove the faceplate or rear panel.
Caution:
The DAC3 DX contains static sensitive components. Static discharge may cause component failures, may affect the long-term reliability, or may degrade the audio performance. Use a static control wrist strap when changing jumper settings.
•
Disconnect AC power by unplugging the power cord at the back of the
DAC3 DX.
•
Remove the 8 screws holding the cover (4 on each side).
• Do not remove any screws on the front, rear, or bottom panels!
•
Never remove the power entry safety cover in the rear corner of the DAC3
DX.
• Always connect a static-control wrist strap to the chassis before touching any internal component.
XLR Output Pads
The XLR outputs are equipped with lowimpedance passive pads that may be used to reduce the output levels while preserving the full dynamic range of the DAC3 DX. The
DAC3 DX ships with the pads disabled (0 dB setting).
Tip:
The XLR outputs are factory-preset to deliver professional studio levels. Most power amplifiers and powered monitors will require the use of the 10 dB or 20 dB pads.
Tip:
Use the factory-default 0 dB setting with
Benchmark's AHB2 power amplifier. When directly driving most other power amplifiers
(or powered speakers), start with the 10 dB pad setting. If necessary, change the pads so that normal listening levels are achieved when the VOLUME control is between the 11 o’clock and 3 o'clock positions.
When the output pads are enabled, the output impedance changes slightly, and the maximum recommended XLR cable length is
reduced as shown in Table 1. The table
assumes a cable capacitance of 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
10
20
60
425
135
680
96
302
0.1
0.1
0.1
Unbalanced Output Drive Capability:
Output Maximum Loss in dB
Impedance Cable (ft) at 20 kHz
30 1360 0.1
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 28
XLR Output Pad Jumpers
Four jumpers on four 6-pin headers (P8, P9,
P10, and P11) allow selection of the output level at the XLR jacks. The jumpers are properly configured if a normal playback level is achieved when the VOLUME control is set above the 11 o'clock position.
One pair of 6-pin headers control the attenuation at each XLR jack as follows:
•
0 dB - (Attenuator disabled) – (Jumper plug between pins 1 and 2 of each header) - Factory Default
•
-10 dB – (Jumper plug between pins 3 and 4 of each header)
• -20 dB – (Jumper plug between pins 5 and 6 of each header) automatically mutes the MAIN outputs. In most cases it is convenient to have one jack that mutes the outputs and one that does not mute the outputs. If your requirements are different the HEADPHONE SWITCHES can be enabled or defeated.
Headphone Switch Configuration
The HEADPHONE SWITCH on the left-hand headphone jack is enabled by placing a jumper across the bottom two pins of P1 (on the back of the faceplate circuit board), as
The HEADPHONE SWITCH on the righthand headphone jack can be enabled by adding a jumper across the top two pins of
P1. A spare jumper is supplied with the
DAC3 DX for use at this location.
•
No Jumpers - Both switches disabled
• Top Jumper Only - Right-hand switch enabled
•
Bottom Jumper Only - Left-hand switch enabled (factory default)
• Top and Bottom Jumpers - Both switches enabled
•
Jumper(s) rotated vertically - Storage of unused jumper(s)
Unused jumper(s) may be stored vertically on either pair of pins.
Figure 1 - Attenuators set to -0 dB
Headphone Switch Configuration
Both headphone jacks are equipped with switches that can mute the MAIN outputs.
The AUX outputs are not muted by the headphone switches. The switches can be enabled by placing jumpers on header P1 (on the back side of the faceplate). By default, the mute switch is enabled on the left-hand jack and disabled on the right-hand jack. In this default configuration the left-hand jack
Figure 2 - Left-Hand Headphone Switch
Enabled (Factory Default)
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 29
Headphone Amplifier Gain
The gain range of the HPA2™ can be set using jumpers JP3 and JP4:
•
•
(Factory Default)
•
The jumpers change the gain of the HPA2™ headphone amplifier without changing the output impedance. This keeps the output impedance of the HPA2™ constant and very near 0 Ohms. External attenuators should never be inserted after a headphone amplifier as this would change the output impedance and alter the frequency response of the headphones.
Proper gain settings are important for maximizing the SNR of the headphone monitoring system. With proper settings, the full performance of the DAC3 DX can be delivered to the headphones for critical monitoring tasks and for maximum musical enjoyment.
Tip:
When the headphone gain jumpers are set properly, a normal listening level will be achieved at a VOLUME control setting above the 11 o'clock position.
Tip:
If a normal listening level is achieved below an 11 o’clock VOLUME setting, the headphone gain is too high, and the gain should be decreased.
Tip:
If the level is too low at the maximum
VOLUME setting, the headphone gain is too low, and the gain should be increased.
Figure 3 - HPA2™ Gain is 0 dB
Figure 4 - HPA2™ Gain is -10 dB
(Default)
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 30
By default, D5 functions as a digital input and
the jumpers are set according to Figure 7.
Figure 6 – Digital PASS-THROUGH
Enabled
Figure 5 - HPA2™ Gain is -20 dB
Digital PASS-THROUGH Function
The digital PASS-THROUGH function can be enabled by moving both P14 jumpers toward
the faceplate shown in Figure 6. Once the
jumpers are moved into the position shown in
Figure 6, D5 is configured as a digital audio
output. When the PASS-THROUGH function is enabled, D5 cannot be selected as an input. Any other selected digital input will be routed to both the internal D/A converter and to output D5. The digital output at D5 is buffered, but is not processed. Many digital audio formats can be passed through to D5
(even when these formats cannot be decoded by the DAC3 DX).
Figure 7 - Digital PASS-THROUGH
Disabled (Factory Default)
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 31
Rackmounting Options
The DAC3 DX is available with or without rackmount ears. Either version can be rackmounted with the appropriate accessories. There are several accessories available for rackmounting a DAC3 DX:
•
Connector Block - Joins two ½-wide Benchmark products when both have rackmount-type faceplates. It can also join a rackmount DAC3 DX directly to a blank plate (no tray required).
•
Premium ½-Wide Blank Panel - Fills one side of the rack tray, or mounts directly to a rackmount DAC3 DX. Panel is 1/4" brushed aluminum with a durable clear-anodized finish.
This premium panel is styled to match the silver rackmount DAC3 DX, and includes a large engraved Benchmark logo.
•
Black ½-Wide Blank Panel - Fills one side of the rack tray, or mounts directly to a rackmount DAC3 DX. Panel is 1/8" brushed aluminum with a durable black-anodized finish.
•
Universal Rack Adapter Tray - Mounts two ½-wide Benchmark products with any combination of rackmount and non-rackmount faceplates.
Call us, contact your dealer, or visit http://BenchmarkMedia.com
to purchase accessories for your DAC3 DX.
Rackmount Version of the DAC3 DX
Connector Block
The connector block joins two ½-wide Benchmark products with rackmount type faceplates. The joined units fill a standard 19 inch wide 1-RU rack space. The connector block can also join a single ½-wide Benchmark product to a Benchmark ½-wide blank panel.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 32
Premium ½-Wide Blank Rack Panel
This premium ¼" thick blank panel matches the finish on the silver rackmount version of the DAC3
DX and features an engraved Benchmark logo. It can also be used to cover an unused slot in the
Universal Rack Adapter Tray.
Black ½-Wide Rack Panel
This ⅛" thick blank panel matches the finish on the black non-rackmount version of the DAC3 DX.
This panel can be used to cover an unused slot in the Universal Rack Adapter Tray. It can also be mounted directly to a rackmount version of the DAC3 DX.
Universal Rack Adapter Tray
The Universal Rack Adapter Tray is a tray that mounts up to two ½-wide Benchmark products in a standard 19 inch wide 1-RU rack space. The tray accepts any combination of ½-wide Benchmark products (with or without rack-mount type faceplates). The tray is not necessary if both units are equipped with rack ears.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 33
Rackmounting Example
Blank Plate and Connector Block:
The Connector Block creates a rigid connection:
Ready to mount in a standard 19" rack:
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 34
DAC1, DAC2 and DAC3 Family
History
The pristine audio performance of the awardwinning DAC1 made it the ‘Benchmark’ of stand-alone D/A converters. The DAC1 USB,
DAC1 PRE , and DAC1 HDR added many features to the basic DAC1 platform.
Benchmark converters are in use in many of the world's top studios.
The following is a brief overview of the various
Benchmark DAC1, DAC2 and DAC3 models:
DAC1 Series
DAC1
Benchmark's original DAC1 converter.
The DAC1 features included:
•
Three digital inputs
•
XLR outputs with passive pads
• RCA outputs
• Analog volume control
•
HPA2™ headphone amplifier
•
UltraLock™ jitter-attenuation system
DAC1 USB
The DAC1 USB introduced these improvements:
•
AdvancedUSB™ computer input
•
Mute switch on the left headphone jack
• Two headphone gain ranges
•
High-current LM4562/LME49860 output stages - designed to drive difficult loads
•
Lower output impedances
Benchmark's AdvancedUSB™ computer input was the first USB audio interface to support 96 kHz audio without the need to install special drivers.
DAC1 PRE
The DAC1 PRE added these improvements:
•
Three coaxial digital inputs
• Three Headphone Gain Ranges
•
LM4562/LME49860 opamps throughout
•
Premium bulkhead-mounted RCA connectors
In order to provide room for the analog inputs, we removed the XLR digital input and replaced it with two additional coaxial digital inputs.
DAC1 HDR
The DAC1 HDR added:
• IR Remote Control
•
HDR-VC™ (high dynamic range volume control).
The HDR-VC™ features a custom-made, motor-driven Alps potentiometer. The motordriven control provides the audio performance of a manual control while adding the convenience of remote control.
DAC2 Series
DAC2 HGC
The DAC2 HGC maintains the familiar ½-wide
DAC1 form factor, but the entire product was redesigned from the ground up.
The DAC2 HGC features:
• Four 32-bit converters per channel
• Native 24-bit/192kHz PCM conversion
•
Native 64X DSD conversion
•
High-headroom digital processing
• UltraLock2™ jitter attenuation
• Multi-mode asynchronous USB audio input
•
Sample rate and word length displays
•
Polarity control
• Home theater bypass
•
Digital pass-through
•
Bi-directional 12V trigger
•
Two stereo analog inputs
• Three stereo analog outputs
•
Two optical inputs
•
High-efficiency low-noise power supplies
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 35
DAC2 L
The DAC2 L is identical to the DAC2 HGC except that the DAC2 L has no headphone amplifier.
DAC2 D
The DAC2 D is identical to the DAC2 HGC except that the DAC2 D has no analog inputs and no 12V trigger.
DAC2 DX
The DAC2 DX replaced the DAC2 D. The new model added an XLR digital input and the 12V trigger. It also added a second output bus so that one set of outputs could be placed in calibrated mode while the other was controlled by the volume knob.
DAC3 Series
On the surface, the DAC3 series converters look exactly like the DAC2 converters. They have the same controls, the same connectors, and even the similar-looking circuit boards.
The difference is that many critical components and systems have been upgraded.
The new DAC3 delivers lower THD, improved digital filtering, and faster PLL lock times.
The firmware, digital signal processing, and
UltraLock™ clock system have all been upgraded in the new DAC3. Most notably, the
DAC3 series includes the new ES9028PRO D/A converter. This groundbreaking D/A converter
IC offers several significant improvements over the ES9018 converter used in the DAC2 series. Until the ESS PRO series was introduced, the ES9018 was the highest performance D/A converter IC available. The
ESS PRO series converters are now setting this benchmark. The Benchmark DAC3 is one of the first products to feature this new 32-bit
D/A converter.
Benchmark's ultra-clean analog stages, lowjitter UltraLock3™ clock system, and highheadroom DSP leverage the full capabilities of the new ESS PRO series converters.
DAC3 DX vs. DAC2 DX
The DAC3 series adds the following improvements over the DAC2 series:
•
ESS SABRE-PRO D/A Conversion
•
UltraLock3™ clock system o
Instantaneous lock o
Instantaneous input switching
•
THD reduction system o
2nd-harmonic compensation o
3rd-harmonic compensation
• Improved digital filters o
Lower passband ripple o
Flatter frequency response
• Higher maximum output level
• Increased Dynamic Range
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 36
Benchmark Technologies
Hybrid Gain Control™
HGC™ is Benchmark's unique Hybrid Gain
Control™ system. The DAC3 combines active analog gain control, passive low-impedance attenuators, a 32-bit digital gain control, and a servo-driven volume control.
All inputs are controlled by the rotary volume control. This volume control moves in response to commands from the remote control. Analog inputs (included on DAC3
HGC and DAC3 L models) are never converted to digital. On all DAC3 models, digital inputs never pass through an analog potentiometer. Digital inputs are precisely controlled in the 32-bit DSP system. The DSP system preserves precise L/R balance, and precise stereo imaging, while avoiding any source of noise and distortion.
Benchmark's unique passive output attenuators provide distortion-free gain reduction without reducing the dynamic range of the converter. The attenuators optimize the gain staging between the DAC3 and the power amplifier. This optimization is absolutely essential for maximizing the dynamic range of the entire playback system.
Much of the success of the DAC1 and DAC2 converters can be attributed to the passive output attenuators. Musical details can be obscured by system noise whenever a preamplifier and power amplifier are improperly matched. The HGC™ system in your DAC3 will make full use of your power amplifier's dynamic range. Experience newly revealed details in your favorite recordings.
The front-panel volume control is a servodriven gain control built around a custommade Alps potentiometer. The custom Alps pot is equipped with a remote-controllable motor drive.
This potentiometer is equipped with a clutch which prevents damage from overriding the motor drive. If the pot is driven beyond the end of its range, it will not damage the motor.
Also, if the pot is manually overridden, it will not damage the motor.
Native DSD Conversion
The digital coaxial inputs and the USB Audio
2.0 input on the DAC3 support native DSD conversion. DoP 1.1 DSD encapsulation is automatically detected on all digital inputs.
The system seamlessly switches to native
DSD conversion when DoP is detected. DoP
1.1 DSD encapsulation is supported by many media players. DSD downloads are now available from several sources.
High Headroom DSP
All of the digital processing in the DAC3 is designed with a headroom of 3.5 dB above 0 dBFS. A sinusoid that just reaches the maximum positive and negative digital codes has a level of 0 dBFS. If the peaks of the sinusoid occur between samples, higher signals can be captured without clipping. For a pure tone, the maximum intersample peak that can be represented by a PCM system is
Benchmark's high-headroom DSP can handle intersample peaks without overloading or clipping. Intersample peaks are cleanly rendered by the DAC3 and are delivered to the analog outputs without clipping or
distortion (see Figure 10). Very few D/A
converters can make this claim!
In most D/A conversion systems, intersample peaks cause overloading of the upsampling interpolators and digital filters that are found
in all sigma-delta converters (see Figure 9).
When overloads occur, bursts of nonharmonic distortion are produced. These bursts of high-frequency distortion may occur many times per second and may add a false brightness and harshness to the sound. This defect impacts PCM formats but does not impact 1-bit DSD formats. The absence of intersample clipping may explain some people's preference for DSD. The DAC3 delivers clean PCM conversion that meets or exceeds the clarity of DSD.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 37
Intersample Overs
(1 = Maximum Digital Code)
1.5
0.5
-0.5
Analog
Audio
Digital
Samples
-1.5
Figure 8 - Intersample Over at +3.01 dB
Intersample overs are common in low sample rate (44.1 kHz and 48 kHz) commercial releases. Due to the mathematics and the bandwidth of typical input signals, intersample overs are less of a problem in high sample rate recordings. The reason for this is that the worst-case (+3.01 dB) intersample overs occurs for pure tones that are exactly 1/4 of the sample rate (see
Figure 8). At the 44.1 kHz CD sample rate,
the worst case occurs at 11.025 kHz. It turns out that many recordings have substantial peaks near this frequency. In contrast, at a sample rate of 88.2 kHz, the worst-case intersample overs occur at a frequency of
22.1 kHz where most musical sources have insufficient energy to produce significant intersample overs. The 88.2 kHz sample rate is still susceptible to intersample overs, but the magnitude of the worst-case overs tends to be much lower. For example, at 1/8 of the sample rate (11.025 kHz), the maximum intersample peak is about +0.66 dB instead of the 3.01 dB worst case at a sample rate of
44.1 kHz.
The biggest advantage of higher sample rates may be the immunity to intersample overs. If higher sample rates sound better, this difference may be entirely due to the absence of DSP overloads caused by intersample overs. Benchmark's high-headroom DSP
(Figure 10) renders low sample rates with
the clarity and detail normally associated with high sample rates.
1.5
0.5
-0.5
-1.5
Conventional Interpolation
(Intersample Overs are Clipped)
Analog
Audio
Digital
Samples
Figure 9 - Clipped Intersample Overs
PCM systems can accurately capture peaks that exceed 0 dBFS, but these peaks will overload the oversampling interpolators in most delta-sigma D/A converters. The solution is not to eliminate the interpolation process; the solution is to build interpolators with more headroom.
High-Headroom Interpolation
(Intersample Overs are Not Clipped)
1.5
0.5
-0.5
Analog
Audio
Digital
Samples
-1.5
Figure 10 - High-Headroom Interpolation
The interpolation process is absolutely necessary to achieve 24-bit state-of-the art conversion performance. Unfortunately, most interpolators clip! This clipping produces distortion products that are non-harmonic and non-musical. We believe these broadband distortion products often add a harshness or false high-frequency brightness to digital reproduction. Benchmark DAC2 and DAC3 converters have high-headroom non-clipping interpolators. We believe these interpolators provide groundbreaking improvements to digital to analog conversion.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 38
32-bit SABRE-PRO D/A System
Eight balanced 32-bit D/A converters deliver audio to Benchmark's low-impedance current to voltage converters. Two converters drive the two AUX output channels. The remaining six converters drive the two MAIN output channels. The 4:1 redundancy on the MAIN outputs reduces noise by about 4.8 dB. This redundancy also reduces the THD. The conversion system at the core of the DAC3 is as good as it gets. The analog circuits that follow the D/A converter are carefully designed. Benchmark has leveraged its long history of building reference analog audio equipment to create an outstanding output stage.
Benchmark components can communicate bidirectionally on the trigger I/O ports. This bidirectional communication provides greater flexibility. In a given system, the power button on any Benchmark device can be used to start or stop the entire audio system in a sequenced manner.
Distributed Power Regulation
To achieve the lowest possible noise, the
DAC3 uses distributed power supply regulation. There are 20 voltage regulators in the DAC3. Each critical subsystem has at least one dedicated low-noise voltage regulator.
Diagnostic Displays
Ever wonder why that 192 kHz 24-bit download on your computer just doesn't sound right? Your media player or computer may be downsampling to 44.1 kHz and/or truncating to 16-bits. Many media players and computer operating systems apply poorquality sample rate conversion and/or truncation. Fortunately these problems can be eliminated with the selection of a good frequency-agile media player.
Many disk players also downsample all sources to 44.1/16. This processing can do significant damage to the audio quality.
The sample-rate and word-length displays on the DAC3 confirm the proper operation of your disk player, media player, and computer.
Bi-Directional 12 Volt Trigger
We have created two discrete ultra low-noise regulators for the ES9028PRO D/A converter.
We use separate regulators for the left and right channels. This Benchmark exclusive feature improves the noise and THD performance of the already-outstanding
ES9028PRO converter chip.
HPA2™ Headphone Amplifier
The DAC3 headphone output is driven by
Benchmark’s signature HPA2™ headphone power amplifier. This high-current, highoutput amplifier has an output impedance that is nearly 0 Ohms. It is designed to drive loads as low as 30 Ohms without any increase in distortion. It also has sufficient amplitude to drive low-sensitivity 600-Ohm headphones.
The HPA2™ includes current-limiting circuits that fully protect against damage from short circuits. This is important because the right channel of a headphone amplifier will experience a short whenever a mono phone plug is inserted into the stereo headphone jack. Shorts may also occur when a plug is partially inserted.
Benchmark has re-invented the 12 volt trigger. The trigger connection on the DAC3 can be used as an input or output or both, and is compatible with any common 12 volt trigger input or output. The trigger can be used to turn a power amplifier on or off automatically. The DAC3 will also respond to a 12 volt trigger and follow the actions of another audio component.
"0-Ohm" Output Impedance
Most headphone amplifiers use series resistors to maintain stability and protect against short-circuit conditions. These resistors are usually at least 30 Ohms, and have a negative impact on performance.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 39
A headphone amplifier with series resistors may measure very well on a test bench when driving resistive loads. However, the same amplifier will measure very poorly when driving a headphone load. Unfortunately, most manufacturers do not measure or specify headphone amplifier performance when loaded with real headphones. The measurements use ideal resistive loads. Our measurements show that headphones do not behave like resistive loads.
Headphone Performance
In our tests we have measured substantial distortion across resistors that are wired in series with headphones. We have conducted measurements with a variety of headphones.
In general, distortion increases as headphone impedance decreases. This distortion can be eliminated with a properly designed "0-Ohm" headphone amplifier.
The performance of the HPA2™ does not change when headphones are driven. THD+N measurements for no-load, 30-Ohm resistive loads, 30-Ohm headphone loads, and 600-
Ohm headphone loads are virtually identical.
The HPA2™ will substantially improve the sound of 30 and 60-Ohm headphones. It will make very noticeable improvements with
600-Ohm headphones.
Differential Amplifiers
Differential amplifiers remove common-mode distortion components from the D/A converter outputs. This feature is critical for achieving low-distortion in down-stream devices.
Benchmark addresses common-mode distortion so that it will not cause distortion in power amplifiers and other connected devices. Common-mode distortion can cause audible distortion while escaping the scrutiny of an audio analyzer. The balanced and unbalanced outputs on the DAC3 deliver very similar performance.
Many D/A converters omit the differential amplifiers after the converters. Specifications usually ignore common-mode distortion. A balanced signal with high common-mode distortion can measure just fine when feeding a precisely balanced input on a high-quality audio analyzer. However, any imbalance in a downstream device will expose the commonmode distortion.
Jitter-Immune UltraLock3™
UltraLock3™ is an improved version of the
UltraLock2™ clock system used in the
DAC2. The new UltraLock3™ system provides faster lock times than the older
UltraLock2™ and UltraLock™ systems. The
DSP processing is 32-bits, DSP headroom is
3.5 dB, sample rate is 211 kHz, and jitterinduced distortion and noise is at least 160 dB below the level of the music - well below the threshold of hearing. Benchmark's
UltraLock3™ system eliminates all audible jitter artifacts while achieving instantaneous locking.
The Importance of Eliminating Jitter
Accurate 24-bit audio conversion requires a very low-jitter conversion clock. Jitter can very easily turn a 24-bit converter into a 16bit converter (or worse). There is no point in buying a 24-bit converter if clock jitter has not been adequately addressed.
Jitter is present on every digital audio interface. This type of jitter is known as
‘interface jitter’ and it is present even in the most carefully designed audio systems.
Interface jitter accumulates as digital signals travel down a cable from one digital device to the next. If we measure interface jitter in a typical system we will find that it is 10 to
10,000 times higher than the maximum allowable level for accurate 24-bit conversion.
Fortunately, interface jitter has absolutely no effect on the audio unless it influences the conversion clock in an analog-to-digital converter (A/D), the conversion clock in a digital-to-analog converter (D/A), or the rate estimator in an asynchronous sample rate converter (ASRC).
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 40
Many converters use a single-stage Phase
Lock Loop (PLL) circuit to derive their conversion clocks from AES/EBU, wordclock, or superclock reference signals. Single-stage
PLL circuits provide some jitter attenuation above 5 kHz but none below 5 kHz.
Unfortunately, digital audio signals often have their strongest jitter components at 2 kHz.
Consequently, these converters can achieve their rated performance only when driven from very low jitter sources and through very short cables. It is highly unlikely that any converter with a single-stage PLL can achieve better than 16 bits of performance in a typical installation. Specified performance may be severely degraded in most installations.
Better converters often use a two-stage PLL circuit to filter out more of the interface jitter.
In theory, a two-stage PLL can remove enough of the jitter to achieve accurate 24-bit conversion (and some do). However, not all two-stage PLL circuits are created equal.
Many two-stage PLLs do not remove enough of the low-frequency jitter. In addition, twostage PLL circuits often require several seconds to lock to an incoming signal. Twostage PLL circuits may fail to lock when jitter is too high, or when the reference sample frequency has drifted.
UltraLock™ converters exceed the jitter attenuation performance of two-stage PLL converters while achieving near instantaneous lock time. They are free from the slow-lock and no-lock problems that can plague twostage PLL designs. UltraLock™ converters have extremely high immunity to interface jitter under all operating conditions.
The UltraLock™ system is so effective that no jitter-induced artifacts could be detected using an Audio Precision System 2 Cascade test set while the inputs to the DAC3 were exposed to high levels of interface jitter. The measurement limits included the ability to detect artifacts as low as –144 dBFS, but none could be detected, even while applying jitter amplitudes as high as 12.75 UI, over a frequency range of 2 Hz to 200 kHz. Any
AES/EBU signal that can be decoded by the
AES/EBU receiver in the DAC3 will be reproduced without the addition of any measurable jitter artifacts.
Benchmark’s UltraLock™ technology eliminates jitter-induced performance problems. UltraLock™ technology isolates the conversion clock from the digital audio interface clock. Jitter on a D/A digital audio input, or an A/D reference input can never have any measurable effect on the conversion clock of an UltraLock™ converter. In an
UltraLock™ converter, the conversion clock is never phase-locked to a reference clock.
Instead the converter oversampling-ratio is varied with extremely high precision to achieve the proper phase relationship to the reference clock. The clock isolation of the
UltraLock™ system ensures that interface jitter can never degrade the quality of the audio conversion. Specified performance is consistent and repeatable in any installation with cables of any quality level!
How does conversion clock jitter degrade converter performance?
Problem #1: Jitter phase-modulates the audio signal. This modulation creates sidebands (unwanted tones) above and below every tone in the audio signal. Worse yet, these sidebands are often widely separated from the tones in the original signal.
Jitter-induced sidebands are not musical in nature because they are not harmonically related to the original audio. Furthermore, these sidebands are poorly masked (easy to hear) because they can be widely separated above and below the frequencies of the original audio tones. In many ways, jitter induced distortion resembles intermodulation distortion (IMD). Like IMD, jitter induced distortion is much more audible than harmonic distortion, and more audible than
THD measurements would suggest.
Jitter creates ‘new audio’ that is not harmonically related to the original audio signal. This ‘new audio’ is unexpected and unwanted. It can cause a loss of imaging, and can add a low and mid frequency ‘muddiness’ that was not in the original audio.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 41
Jitter-induced sidebands can be measured using an FFT analyzer while the converter plays a pure high-amplitude tone. We typically use a full-scale 10 kHz test tone to test for the presence of jitter-induced side
bands (see Graph 16 Graph 16). This FFT
shows that the DAC3 is free from any jitterinduced sidebands to a measurement limit of about -144 dB relative to the level of the test tone. The graph plots the output spectrum of the DAC3 when exposed to 31 different jitter frequencies ranging from 100 Hz to 100 kHz.
All 31 output spectra are identical and are free from any signs of jitter-induced distortion. can alias down into lower (audio) frequencies.
These crosstalk problems may not become obvious until jitter is present.
Stop-band attenuation can be measured very easily by sweeping a test tone between 24 kHz and at least 200 kHz while monitoring the output of the converter.
Put UltraLock™ converters to the test:
Problem #2: Jitter can severely degrade the anti-alias filters in an oversampling converter.
This is a little known but easily measurable effect. Most audio converters operate at high oversampling ratios. This allows the use of high-performance digital anti-alias filters in place of the relatively poor performing analog anti-alias filters. In theory, digital anti-alias filters can have extremely sharp cutoff characteristics, and very few negative effects on the in-band audio signal. Digital anti-alias filters are usually designed to achieve at least
100 dB of stop-band attenuation. But, digital filters are designed using the mathematical assumption that the time interval between samples is a constant. Unfortunately, sample clock jitter in an A/D or D/A varies the effective time interval between samples. This variation alters the performance of these carefully designed filters. Small amounts of jitter can severely degrade stop-band performance, and can render these filters useless for preventing aliasing.
The obvious function of a digital anti-alias filter is the removal of audio tones that are too high in frequency to be represented at the selected sample rate. The not-so-obvious function is the removal of high-frequency signals that originate inside the converter box, or even originate inside the converter IC.
These high-frequency signals are a result of crosstalk between digital and analog signals, and may have high amplitudes in a poorly designed system. Under ideal (low jitter) conditions, the digital anti-alias filter may remove most of this unwanted noise before it
We encourage our customers to perform the above tests on UltraLock™ converters (or let your ears be the judge). There will be absolutely no change in performance as jitter is added to any digital input on an
UltraLock™ converter. Try the same tests on any converter using conventional single or two-stage PLL circuits. Tests should be performed with varying levels of jitter and with varying jitter frequencies. The results will be very enlightening. Jitter related problems have audible (and measurable) effects on A/D and D/A devices. Practitioners of Digital Audio need to understand these effects.
Is it possible to eliminate all of the effects of jitter in an entire digital audio system?
Interface jitter will accumulate throughout even the most carefully designed digital audio system. Fortunately, interface jitter can only degrade digital audio if it affects the sampling circuit in an analog-to-digital or digital-to-analog converter. Any attempt to cure jitter outside of an A/D or D/A will prove expensive and, at best, will only partially reduce jitter-induced artifacts. Dedicated clock signals (word clock, and super clock, etc.) are often distributed to A/D converters and D/A converters in an attempt to reduce jitter. Again, these are only partial solutions because jitter even accumulates in these clock distribution systems. Furthermore, a poor quality master clock generator can degrade the performance of the entire system
(if converter performance is dependent upon reference clock quality). Jitter-free A/D and
D/A converters are the only true insurance against the ill effects of jitter.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 42
UltraLock™ converters are jitter-immune under all operating conditions (they will never add audible jitter-induced artifacts to an audio signal). available, make sure that there are no other devices sharing the USB hub that services the port. When possible, connect the DAC3 to a port that supports USB 2.0 or higher.
What UltraLock™ converters cannot do:
UltraLock™ converters cannot undo damage that has already been done. If an A/D with a jitter problem was used to create a digital audio signal, then there is nothing that can be done to remove the jitter-induced distortion that happened inside the A/D converter.
Jitter-induced sidebands are extremely complex and cannot be removed with any existing audio device. Therefore, it is very important to attack jitter at both ends of the audio chain. The DAC3 is a great start, as it will allow accurate assessment of various A/D converters. It is impossible to audibly evaluate A/D performance without a good
D/A. The consistent performance delivered by the DAC3 eliminates one major variable - jitter.
Multi-Mode Asynchronous USB
Audio
Plug it in and Start Listening…
Immediately
Benchmark's Advanced USB Audio system supports the industry standard USB Audio
1.1 and USB Audio 2.0 protocols. These audio protocols should not be confused with
USB port speeds. The USB Audio 1.1 protocol requires at least a USB 1.0 (Full
Speed) port. USB Audio 2.0 requires at least a USB 2.0 (High Speed) port.
Tip:
The USB Audio 2.0 protocol is required for sample rates above 96 kHz. This protocol will not run on USB 1.0 ports. When possible, connect the DAC3 to a port that supports
USB 2.0 or higher.
Asynchronous USB
In all modes the USB communications are asynchronous. An ultra low jitter conversion clock is generated inside the DAC3. The asynchronous USB interface pulls data from the computer without using computergenerated clocks. The D/A conversion in the
DAC3 is completely isolated by the asynchronous USB interface and by the
UltraLock3™ jitter-attenuation system.
The DAC3 has a low-jitter master clock which controls the transfer of audio data from the computer to the USB sub-system. The computer asynchronously transfers audio data to a buffer in the DAC3. The contents of the buffer are then asynchronously transferred to the D/A conversion sub-system. This second asynchronous transfer eliminates any traces of jitter that accumulate as the data is transferred between the USB and conversion subsystems. No traces of jitter-induced distortion are detectable at our measurement limits (about -144 dBFS). This truly represents the state-of-the art. Enjoy the convenience of computer playback without compromise.
Benchmark's USB Audio 1.1 and USB Audio
2.0 modes are frequency agile. This means that the sample rate is controlled by the computer. The DAC3 will follow sample rate changes initiated by the computer and/or the media playback software.
The Asynchronous USB system supports USB
Audio 2.0 for high-resolution 192kHz, and
DSD playback. No drivers are required for
MAC operating systems. An easy-to-install driver adds 192 kHz and DSD capabilities to
Windows operating systems.
Tip:
The USB Audio 1.1 protocol will run on any USB port, but if it is run on a USB 1.0
(Full Speed) port, it will require all of the available bandwidth to support 96 kHz sample rates. If a USB 1.0 port is the fastest port
The asynchronous driverless USB Audio 1.1 mode supports sample rates up to 96 kHz.
This USB mode can be selected from the front panel or from the remote control.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 43
The driverless USB Audio 1.1 mode allows quick plug-and-play connections to Windows,
MAC, iOS, and Linux operating systems without installing drivers. Just plug in the
USB, and the DAC3 becomes an available audio device. In many cases, audio will automatically be routed to the newly connected device. If not, it can be selected as the current or default playback device.
The industry-standard USB Audio Mode 2.0 mode is not yet natively supported by the current Windows operating systems. For this reason, a driver is required for Windows operating systems. The driver supports
Windows XP, Vista, or 7, 8 and 10. This driver is required for DSD and sample rates above
96 kHz when using Windows.
The USB subsystem is computer powered
(through the USB cord) and it remains active when the DAC3 is powered down. This feature prevents interruptions to the computer playback operations and eliminates the need to reconfigure the computer every time the converter is turned on.
The Windows USB Audio 2.0 driver is available at:
BenchmarkMedia.com/drivers
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 44
USB Driver Installation
Windows Operating Systems
Note:
The DAC2/DAC3 driver is available for download at: BenchmarkMedia.com/drivers
Note: To provide full backward and forward compatibility, the DAC3 uses the DAC2 USB drivers.
This prevents the need to install two different sets of drivers. Please note that the DAC3 USB input will be identified as "Benchmark DAC2" in your computer control panels. This is intentional.
Before you install the driver, make sure the USB cable is unplugged.
1. In the DAC2 Driver folder, double click “setup.exe.”
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 45
2. A welcome screen will pop-up. Click “Next.”
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 46
3. When you see the following screen, turn on the DAC3, plug in the USB cable, and select the
USB input on the DAC3. By default, the DAC3 is shipped in USB Audio 1.0 mode. Do not proceed to the next step until the USB Audio 2.0 mode has been enabled. You can enable the USB Audio 2.0 mode using one of the following two methods:
•
METHOD 1 - REMOTE CONTROL: Using your remote control, press and hold USB button for 10 seconds (the 4X light should flash once). If the 2X light flashes instead of the 4X light, repeat this step.
•
METHOD 2 - FRONT PANEL: From the front panel, select the USB input and then hold the lower INPUT button for 10 seconds (the 4X light should flash once). If the
2X light flashes instead of the 4X light, repeat this step.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 47
4. You will now be prompted to select a location to install the driver. It will default to your
Program Files folder. If you wish to install it another location, you can change the location.
We suggest keeping it in the default location. Click “Install”.
5. When the installation begins you will see the following screen. Please be patient while the driver installs. Installation may require several minutes.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 48
6. When the installation finishes a message at the top will say “Installation Complete.” Click
“Next” to continue.
7. Click “Finish.” The Setup will close automatically. This completes the installation process.
You can now enjoy music over the USB Audio 2.0 connection at sample rates up to 192 kHz. DSD can also be played in DoP 1.1 format.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 49
Performance Graphs
Audio Precision DAC3 DX - FFT Idle Channel Noise at Max Gain, 0 dBr = 0 dBFS = 28 dBu
r
d
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A
+0
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-60
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0 2k 4k 6k 8k 10k 12k 14k 16k
Hz
18k 20k
Sweep Trace
1
1
1
2
Color Line Style Thick Data
Green Solid
Red Solid
4
4
Fft.Ch.1 Ampl
Fft.Ch.2 Ampl
Axis
Left
Right
Comment
DAC3 DX - FFT Idle Channel Noise.at27
22k 24k 26k 28k 30k 32k
+0
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-40
-60
-80
-100
r
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A
-120
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-160
Graph 1 – FFT Idle Channel Noise
The extraordinary performance of the DAC3 DX is demonstrated by the FFT plot shown above.
There is no sign of any AC hum, there are no idle tones, and there are no spurious tones detected at a measurement limit of -160 dBFS.
The rise at 0 Hz is normal in an FFT analysis and is not an indication of noise. This 32k point FFT analysis uses a Blackman-Harris window with 16x power averaging, and spans a frequency range of DC to 32 kHz.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 50
Audio Precision DAC3 DX - FFT Idle Channel Noise - Low Frequency, 0 dBr = 0 dBFS = 28 dBu
r
d
B
A
-60
-80
-100
-120
-140
+0 dx=121.213 Hz dy=-1.459 dB
-20
-40
-160
25 75 100 125 150 200
Hz
225 250 275 300
Sweep Trace
1
1
1
2
Color Line Style Thick Data
Green Solid
Red Solid
4
4
Fft.Ch.1 Ampl
Axis
Left
Comment Cursor1 Cursor2
Left Channel -158.415 dBr A -161.185 dBr A
Fft.Ch.2 Ampl Right Right Channel *-158.970 dBr *-160.430 dBr
DAC3 DX - FFT Idle Channel Noise - Low Frequency.at27
325 350 375 400
Graph 2 - Low Frequency FFT - AC Line-Related Hum
The DAC3 DX shows no evidence of AC line-related hum to a measurement limit of about -160 dBFS. The cursors are placed at 60 Hz and 180 Hz (frequencies where we would expect to see interference from the 60 Hz AC input. In the idle channel noise spectrum there is absolutely no sign of any AC hum! At full output, these line-related frequencies still measure better than -135 dB (see
This graph demonstrates one of the advantages of switching power supplies. The switching power supplies in the DAC3 DX operate at frequencies above the audio band and this eliminates the strong line-frequency magnetic fields that would have been created by line-frequency power transformers.
+0
-20
-40
-60
-80
-100
r
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-120
-140
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 51
Audio Precision DAC3 DX - FFT 10 kHz, 0 dBr = 0 dBFS = 24 dBu
+0 dx=10.0196 kHz dy=-14.283 dB
-20
-40
-60
d
B
r
A
-80
-100
-111.066
-120
-125.349
-140
-160
0 2k 4k 6k 8k 10k 12k 14k 16k
Hz
18k 22k
Sweep Trace
1
2
2
2
Color Line Style Thick Data
Green Solid
Red Solid
4
4
Fft.Ch.1 Ampl
Fft.Ch.1 Ampl
Axis
Left
Left
Comment Source 2
Left Channel : 1.00000 =Swr.Ch. A Input
Right Channel
Cursor1
-109.432 dBr A
*-111.066 dBr
Cursor2
-120.421 dBr A
*-125.349 dBr
DAC3 DX - FFT 10 kHz.at27
24k 26k 28k 32k
Graph 3 - FFT 10 kHz
The 10 kHz FFT analysis is an excellent test for detecting sample clock jitter. Jitter will create sidebands (unwanted tones) above and below the 10 kHz test tone. For example, a jitter frequency of 1 kHz would create two sideband tones; a lower sideband at 9 kHz, and an upper sideband at 11 kHz. Similarly, a jitter frequency of 2 kHz would produce sideband tones at 8 kHz and 12 kHz. The above plot shows no evidence of jitter-induced sidebands to a measurement limit of about -149 dB relative to the amplitude of the 10 kHz test tone.
Note the very low harmonic distortion; the 2nd harmonic (20 kHz) measured -109 to -111 dB, and the 3rd harmonic (30 kHz) measured -120 to -125 dB.
This 32k point FFT analysis uses a Blackman-Harris window with 16x power averaging. The 10 kHz fundamental has been removed by a notch filter in order to increase the resolution of the A/D converter in the AP2722 test set.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 52
Audio Precision DAC3 DX - FFT 1 kHz, 0 dBr = 0 dBFS = 24 dBu
d
B
r
A
-100
-40
-60
-80
+0 dx=1.00000 kHz dy=+3.640 dB
-20
-123.707
-140
-160
0 200 400 600 800 1k 1.2k
1.4k
1.6k
1.8k
Hz
2.2k
2.4k
Sweep Trace
1
2
2
2
Color Line Style Thick Data
Green Solid
Red Solid
4
4
Fft.Ch.1 Ampl
Fft.Ch.1 Ampl
Axis
Left
Left
Comment Source 2
Left Channel : 1.00000 =Swr.Ch. A Input
Right Channel
Cursor1
-118.332 dBr A
*-123.707 dBr
Cursor2
-120.312 dBr A
*-120.068 dBr
DAC3 DX - FFT 1 kHz.at27
2.6k
2.8k
3.2k
3.4k
Graph 4 - FFT 1 kHz
The 1 kHz FFT analysis demonstrates the very low harmonic distortion of the DAC3 DX. The second harmonic distortion (2 kHz) measured -118 to -123 dB, while the 3rd harmonic distortion measured better than -120 dB relative to the amplitude of the 1 kHz test tone.
This 32k point FFT analysis uses a Blackman-Harris window with 16x power averaging. The 1 kHz fundamental has been removed by a notch filter in order to increase the resolution of the A/D converter in the AP2722 test set.
Note that under this full-output condition, the AC line-related hum frequencies (60 Hz, 180 Hz, and
240 Hz) measure better than - 135 dB.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 53
Audio Precision
+1
+0.5
dx=41.6509 kHz dy=+0.020 dB
DAC3 DX - FREQUENCY RESPONSE
Fs = 192 kHz
02/02/17 16:47:10
r
d
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-0.5
-1
-1.5
-2
-2.5
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-7
-7.5
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-9
-9.5
-10
10.0021
20 50 100 200 500 1k
Hz
2k
Sweep Trace Color
1 1 Red
Line Style
Solid
Thick
4
Data Axis Comment
Anlr.Level A Left
Cursor1 Cursor2
*-0.013 dBr *+0.006 dBr
DAC3 DX - Frequency Response.at27
5k 10k 20k 90k
Graph 5 - Frequency Response
This plot demonstrates the ruler-flat frequency response of the DAC3 DX. Note that the frequency response measures - 0.013 dB at 10 Hz and -0.006 dB at 40 kHz. The extreme low-frequency extension of the DAC3 DX virtually eliminates the phase shifts that often occur at low frequencies
(near 20 Hz). Bass is rendered in the proper timing relative to high-frequency content.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 54
Audio Precision DAC3 DX - Differential Phase
Fs = 96 kHz
+1 dx=19.7956 kHz dy=-0.16 deg
+0.8
+0.6
+0.4
+0.2
d
e
g
+0
-0.07
-0.2
-0.23
-0.4
-0.6
-0.8
-1
2.5k
5k 7.5k
10k 12.5k
15k 17.5k
22.5k
Hz
25k 27.5k
30k
Sweep Trace
1
2
1
1
Color Line Style Thick Data
Green Solid
Red Solid
4
4
Anlr.Phase
Anlr.Phase
Axis
Left
Left
Comment
Left to Right
Right to Left
Cursor1 Cursor2
*-0.07 deg *-0.23 deg
+0.06 deg +0.15 deg
DAC3 DX - Differential Phase.at27
32.5k
35k 37.5k
42.5k
45k
Graph 6 - Differential Phase
This plot demonstrates the inter-channel phase accuracy of the DAC3 DX. This is a highly expanded scale, spanning only +/- 1 degree at 45 kHz. From this plot, the inter-channel phase accuracy is calculated to be +/- 0.25 degrees at 20 kHz, and +/- 0.43 degrees at 40 kHz.
The phase accuracy of the DAC3 DX approaches the phase accuracy of the Audio Precision AP2722 test set. For this reason, the phase error in the AP must be subtracted from the measurement. The green trace assigns the left channel to channel 1 of the AP, and the right channel to channel 2 of the AP. The red trace reverses the inputs. The two traces must be averaged to remove the phase errors of the AP test set. The ripple in the two plots is due to the AP test set.
DAC3 converters are phase-accurate between boxes. Three DAC3 converters can be used as a group to form a phase-accurate 5.1 surround system. Four DAC3 converters can be combined to form a 7.1 system. The phase accuracy between any two channels will match the typical phase accuracy shown above.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 55
Audio Precision DAC3 DX - THD and THD+N vs. Amplitude, 1 kHz, 0 dBFS = 24 dBu
d
B
r
A
-105
-110
-115
-90
-95
-100
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-125
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-30 -28 -26 -24 -22 -20 -18 -16
dBFS
-14 -12
Sweep Trace
1
1
1
2
Color
Red
Black
Line Style
Solid
Solid
Thick
4
4
Data Axis Comment
Distortion.Ch.1 Harm Sum1 Left
Anlr.THD+N Ampl Right
THD
THD+N
DAC3 DX - THD and THD+N vs Amplitude.at27
-10 -8 -6 -4 -2 -0
-130
Graph 7 - THD and THD+N vs. Amplitude (Balanced Outputs)
These plots demonstrate the very low harmonic distortion produced by the DAC3 DX with digital input signal levels ranging from -30 dBFS to 0 dBFS. These plots show that THD should never reach the threshold of hearing in most listening environments. This is proof that the DAC3 DX is virtually uncolored by any traces of harmonic distortion.
The black curve is a plot of THD+N, band limited to 22 kHz, and was acquired using the analog analyzer in the AP2722 test set. The red curve is a plot of THD (harmonic distortion only) and was acquired using the analog notch filter, A/D converter, and digital harmonic distortion analyzer in the AP2722 test set. This THD curve includes all harmonics falling below 32 kHz. The steps near -3 dBFS and -9 dBFS are due to the auto ranging of the AP2722 test set and are an indication that the
THD performance of the DAC3 DX is very close to the measurement limits of the AP2722.
-90
-95
-100
-105
-110
-115
d
B
r
A
-120
-125
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 56
Audio Precision DAC3 DX - THD and THD+N vs. Amplitude, 1 kHz, 0 dBFS = 2Vrms
Main Unbalanced Outputs
-105
r
d
B
A
-110
-115
-120
-125
-90
-95
-100
-130
-30 -28 -26 -24 -22 -20 -18 -16
dBFS
-14 -12
Sweep Trace
1
1
1
2
Color
Red
Black
Line Style
Solid
Solid
Thick
4
4
Data Axis Comment
Distortion.Ch.1 Harm Sum1 Left
Anlr.THD+N Ampl Right
THD Only
THD+N
DAC3 DX - THD and THD+N vs Amplitude Unbalanced.at27
-10 -8 -6 -4 -2 -0
-130
Graph 8 - THD and THD+N vs. Amplitude (Unbalanced Outputs)
This plot shows the THD and THD+N performance of the unbalanced outputs.
Note that the THD performance of the unbalanced outputs approaches that of the balanced outputs. The THD+N levels are slightly higher on the unbalanced outputs. This is due to the relatively low (2 Vrms) signal levels used on unbalanced interfaces. This noise difference highlights one advantage of professional-level balanced interconnects.
-90
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Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 57
Audio Precision DAC3 DX - THD vs. Amplitude, 1 kHz, 0 dBFS = 2Vrms Unbalanced, 24 dBu Balanced
Balanced vs. Unbalanced Outputs
-115
r
d
B
A
-120
-125
-130
-100
-105
-110
-135
-140
-30 -28 -26 -24 -22 -20 -18 -16
dBFS
-14 -12
Sweep Trace
1
2
3
2
Color
Black
Red
Line Style
Solid
Solid
Thick
4
4
Data Axis Comment Source 2
Distortion.Ch.1 Harm Sum1 Right THD Balanced
Distortion.Ch.1 Harm Sum1 Left
DAC3 DX - THD vs Amplitude Balanced vs Unbalanced.at27
-10 -8 -6 -4 -2 -0
-140
Graph 9 - THD vs. Amplitude - Balanced vs. Unbalanced Outputs
This plot demonstrates that the balanced and unbalanced analog outputs on the DAC3 DX have very similar THD performance. The unbalanced outputs (red curve) closely match the performance of the balanced outputs (black curve) at high signal levels. The separation between the curves at signal levels below -10 dBFS is due to the improved SNR provided by the balanced interfaces. At 0 dBFS, the balanced interfaces were calibrated to +24 dBu (12.28 Vrms) while the unbalanced interfaces were calibrated to +8.24 dBu (2 Vrms). The higher signal levels used with the balanced interfaces make it easier to achieve high signal to noise ratios. This is just one reason why
Benchmark recommends balanced interconnects.
The DAC3 DX includes differential amplifiers that remove common-mode THD from the balanced outputs of the SABRE-PRO converters. These differential amplifiers give the unbalanced outputs the ability to approach the THD performance of the balanced outputs. Please note that the differential amplifiers also eliminate common-mode distortion on the balanced outputs.
Top-quality D/A conversion chips (such as the ES9028PRO) are equipped with balanced outputs.
These balanced outputs allow a significant reduction of THD if they are followed by precision differential amplifiers. Conversion chips tend to produce significant common-mode distortion products that should be removed by a differential amplifier. The DAC3 DX includes precision differential amplifiers following the outputs of the ES9028PRO. Many competing products omit these differential amplifiers. The omission of the differential amplifiers would make the THD much higher on the unbalanced outputs. The differential amplifiers also improve the system performance when the balanced outputs are driving balanced inputs that are not precisely trimmed.
The THD measurements shown above confirm the effectiveness of the differential amplifiers in the
DAC3 DX. Additional confirmation can be obtained by measuring the THD of either side of the balanced outputs relative to ground.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 58
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-105
-110
-115
-120
-125
r
d
B
B
-130
-135
Audio Precision DAC3 DX - Headphone Amplifier - THD+N vs Power at 1 KHZ (w/20 kHz LPF unweighted)
Headphone outputs into 300 Ohms, both channels driven dx=299.8 mW dy=-27.855 dB
+0
-10
d
B
-20
-30
-40
-50
-60
-70
-90
-100
-104.147
-110
-120
10.14u
20u 50u 100u 200u 500u 1m
W
2m 5m 10m
Sweep Trace Color
1 1 Red
Line Style
Solid
Thick
4
Data Axis Comment
Anlr.THD+N Ratio Left
Cursor1
*-76.292 dB
Cursor2
*-104.147 dB
DAC3 DX - HEADPHONE - THD+N vs Power - 300 Ohm Load.at27
20m 50m 100m
Graph 10 - Headphone Amplifier into 300 Ohms – THD+N versus Power
This plot shows the THD+N performance of the headphone outputs when driving a typical 300-Ohm load. Note that the THD+N performance of the headphone outputs approaches that of the balanced outputs (-104 dB at 20 mW). Benchmark's HPA2™ headphone amplifier can cleanly deliver 21.5 dBu (9.2 Vrms) into a 300-Ohm load.
This graph shows that the HPA2™ has the voltage required to drive high-impedance headphones.
The following graph shows that the HPA2™ has the power required to drive low-impedance headphones. In either case, the near 0-Ohm output impedance provides outstanding control and damping of the headphone drivers.
The HPA2™ includes 3 jumper-programmable gain ranges that can be configured to match the voltage sensitivity of your favorite headphones. The gain-range settings do not change the output impedance or the THD of the headphone amplifier.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 59
Audio Precision dx=1.256 W
DAC3 DX - Headphone Amplifier - THD+N vs Power at 1 KHZ (w/20 kHz LPF unweighted)
Headphone outputs into 30 Ohms, both channels driven dy=-10.605 dB
+0
-10
d
B
-20
-30
-40
-50
-60
-70
-100
-110
-120
100u 200u 500u 1m 2m 5m 10m 20m
W
50m 100m
Sweep Trace Color
1 1 Red
Line Style
Solid
Thick
4
Data Axis Comment
Anlr.THD+N Ratio Left
Cursor1
*-76.536 dB
Cursor2
*-87.141 dB
DAC3 DX - HEADPHONE - THD+N vs Power - 30 Ohm Load.at27
200m 500m 1
1.256
2 3
Graph 11 - Headphone Amplifier into 30 Ohms – THD+N versus Power
This plot shows the THD+N performance of the headphone outputs under a very heavy load (30-
Ohms). Note that the THD+N performance of the headphone outputs still approaches that of the balanced outputs (-100 dB at 50 mW).
This graph demonstrate that Benchmark's HPA2™ headphone amplifier can cleanly deliver 1.25 W into 30 Ohms, both channels driven.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 60
Audio Precision DAC3 DX - THD+N VS FREQ AT 0 dBFS, 24 dBu (w/80 kHz LPF unweighted)
Balanced Outputs
-90 dx=19.0427 kHz dy=+5.144 dB
-95
-100
d
B
-115
-120
-125
-130
20 50 100 200 500
Hz
2k
Sweep Trace
1
1
1
2
Color Line Style Thick Data
Green Solid
Red Solid
4
4
Anlr.THD+N Ratio
Axis
Left
Comment
Left Channel
Cursor1
-107.584 dB
Cursor2
-102.294 dB
Anlr.THD+N Ratio Left Right Channel *-109.025 dB *-103.880 dB
DAC3 DX - THD+N vs Frequency 80 kHz.at27
5k 10k
Graph 12 - THD+N vs. Frequency 80 kHz
The analog output stages on the DAC3 DX have high slew rates and are capable of maintaining low THD levels at high frequencies even when driven to 0 dBFS. Note that the THD+N remains very low at 20 kHz, even when operating at maximum output levels.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 61
Audio Precision DAC3 DX - THD and THD+N vs. Frequency, 1 kHz, 0 dBFS, 24 dBu
Digital In to Balanced Analog Out
-115
r
d
B
A
-120
-125
-130
-135
-100
T dx=9.02137 kHz dy=+4.944 dB
T T
-105
-110
-140
20 50 100 200 500 2k
Hz
Sweep Trace
1
1
1
2
Color
Black
Red
Line Style
Solid
Solid
Thick
4
4
Data Axis Comment Cursor1 Cursor2
Anlr.THD+N Ampl Left THD+N, 80 kHz LPF -106.644 dBr A
Distortion.Ch.1 Harm Sum1 Right THD, 48 kHz LPF *-110.245 dBr
DAC3 DX - THD and THD+N vs Frequency Digital to Analog.at27
5k
-100
-105
-120
-125
r
d
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A
-130
-135
20k
-140
Graph 13 - THD and THD+N vs. Frequency
These plots demonstrate that the harmonic distortion of the DAC3 DX is lower than the THD+N numbers would suggest. This black curve is a plot of THD+N. The red curve is a plot of THD only.
Below about 10 kHz, the THD is so low that the THD+N measurement is dominated by noise.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 62
Audio Precision DAC3 DX - THD+N vs Sample Rate, 1 kHz at 0 dBFS (w/20 kHz LPF unweighted)
-90 dx=182.000 kHz dy=-0.138 dB
-95
-100
-105
d
B
-110
-115
-120
-125
-130
28k
40k 60k 80k 100k 120k
Hz
140k
Sweep Trace
1
1
1
2
Color Line Style Thick Data
Green Solid
Red Solid
4
4
Anlr.THD+N Ratio
Axis
Left
Comment
Left Channel
Cursor1
-111.486 dB
Cursor2
-111.229 dB
Anlr.THD+N Ratio Left Right Channel *-112.023 dB *-112.161 dB
DAC3 DX - THD+N vs Sample Rate.at27
160k
Graph 14 - THD+N versus Sample Rate
The THD+N performance of the DAC3 DX is identical at all Sample Rates.
180k 200k
210k
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 63
Audio Precision DAC3 DX - INTERFACE JITTER TOLERANCE - Distortion vs Jitter
3.456 kHz Test Tone at 0 dBFS, THD+N 22 to 22 kHz BW
d
B
+0
-10
-20
-30
-40
-80
-90
-100
-50
-60
-70
-110
-120
100 200 500 1k 2k 5k
Hz
Sweep Trace Color
1
1
1
2
Red
Black
Line Style
Solid
Solid
Thick
4
4
Data Axis
Anlr.THD+N Ratio Left
Dio.Interface Jitter Right
Comment
DAC3 DX - Jitter Tolerance.at27
10k 20k 50k
20
10
5
2
1
500m U
I
200m
100m
50m
20m
90k
10m
Graph 15 - Jitter Tolerance
The Audio Engineering Society (AES) has created a jitter tolerance template for testing digital audio devices. The black curve shows the AES jitter tolerance template (see right-hand vertical axis).
Induced jitter approaches 5 UI at 200 Hz, and is reduced to 0.125 UI above 8 kHz. The red trace shows the THD+N of the DAC3 DX (left-hand vertical axis) while being driven with the jitter shown on the black curve. Over the entire range of the AES jitter tolerance test, the THD+N performance of the DAC3 DX is unchanged. The DAC3 DX easily passes the AES jitter tolerance test, and it does so without any performance degradation.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 64
Audio Precision DAC3 DX - INTERFACE JITTER TOLERANCE FFT
10 kHz Test Tone at 0 dBFS, AES Jitter Tolerance Sweep
r
d
B
A
-80
-100
-120
-140
+0
-20
-40
-60
-160
0 2k 4k 6k 8k 10k 12k 14k 16k
Hz
18k 20k 22k
18
19
20
21
22
23
12
13
14
15
16
17
8
9
6
7
10
11
3
4
1
2
5
24
25
26
27
28
29
30
31
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
Sweep Trace Color Line Style Thick Data
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Blue
Cyan
Green
Yellow
Red
Solid
Solid
Solid
Solid
Solid
Magenta Solid
Blue Solid
Cyan
Green
Solid
Solid
Yellow
Red
Solid
Solid
Magenta Solid
Blue Solid
Cyan
Green
Solid
Solid
Yellow
Red
Solid
Solid
Magenta Solid
Blue Solid
Cyan
Green
Solid
Solid
Yellow
Red
Solid
Solid
Magenta Solid
Blue Solid
Cyan
Green
Solid
Solid
Yellow
Red
Solid
Solid
Magenta Solid
Blue Solid
Axis
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Fft.Ch.1 Ampl Left
Comment Source 2
: 100.000 Hz=Dio.Jitter Freq
: 125.893 Hz=Dio.Jitter Freq
: 158.489 Hz=Dio.Jitter Freq
: 199.526 Hz=Dio.Jitter Freq
: 251.189 Hz=Dio.Jitter Freq
: 316.228 Hz=Dio.Jitter Freq
: 398.107 Hz=Dio.Jitter Freq
: 501.187 Hz=Dio.Jitter Freq
: 630.957 Hz=Dio.Jitter Freq
: 794.328 Hz=Dio.Jitter Freq
: 1.00000 kHz=Dio.Jitter Freq
: 1.25893 kHz=Dio.Jitter Freq
: 1.58489 kHz=Dio.Jitter Freq
: 1.99526 kHz=Dio.Jitter Freq
: 2.51189 kHz=Dio.Jitter Freq
: 3.16228 kHz=Dio.Jitter Freq
: 3.98107 kHz=Dio.Jitter Freq
: 5.01187 kHz=Dio.Jitter Freq
: 6.30957 kHz=Dio.Jitter Freq
: 7.94328 kHz=Dio.Jitter Freq
: 10.0000 kHz=Dio.Jitter Freq
: 12.5893 kHz=Dio.Jitter Freq
: 15.8489 kHz=Dio.Jitter Freq
: 19.9526 kHz=Dio.Jitter Freq
: 25.1189 kHz=Dio.Jitter Freq
: 31.6228 kHz=Dio.Jitter Freq
: 39.8107 kHz=Dio.Jitter Freq
: 50.1187 kHz=Dio.Jitter Freq
: 63.0957 kHz=Dio.Jitter Freq
: 79.4328 kHz=Dio.Jitter Freq
: 100.000 kHz=Dio.Jitter Freq
DAC3 DX - Jitter Tolerance FFT.at27
24k 26k 28k 30k 32k
Graph 16 - Jitter Tolerance FFT
This figure shows a series of FFTs that were acquired while running the AES jitter tolerance test.
This is the ultimate jitter-immunity test.
Note that none of the 31 FFTs show any signs of jitter-induced sidebands. Note that the plots are
identical to the plots shown in Graph3
The DAC3 DX shows no change in performance when the AES jitter tolerance test is applied to the digital inputs. No jitter-induced sidebands are visible anywhere in this measurement.
Please note that the 10 kHz fundamental needed to be notched out in order to make this very highresolution measurement. If the fundamental was not notched out, the spurious tones, produced by the A/D converter in the AP2722 test set, would have obscured the virtually-perfect results.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 65
r
d
B
A
Audio Precision dx=9.00196 kHz dy=+1.474 dB
-50
-60
-70
-80
-90
-100
-110
-120
-130
-140
-150
+0
-10
-20
-30
-40
-160
0
1.01761k
2k 4k 6k
DAC3 DX - 11K 12K IMD
8k 12k 14k
Hz
Sweep Trace
1
1
1
2
Color Line Style Thick Data
Green Solid
Red Solid
4
4
Fft.Ch.1 Ampl
Axis
Left
Comment Cursor1 Cursor2
Left Channel -126.709 dBr A -125.744 dBr A
Fft.Ch.2 Ampl Right Right Channel *-125.636 dBr *-124.162 dBr
DAC3 DX - IMD 11K 12K.at27
16k
02/03/17 09:08:53
18k
-140
-150
20k
-160
Graph 17 - IMD 11k 12K
This plot demonstrates that the DAC3 has very low IMD distortion. The 1 kHz difference frequency measures about -126 dB, and the 10 kHz and 13 kHz products measure about -125 dB. The actual
IMD may be better. The results shown are partially limited by the performance of the AP2722 test set.
All IMD distortion products should be well below audible levels.
-50
-60
-70
-80
-90
-100
-110
-120
+0
-10
-20
-30
-40
r
d
B
A
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 66
Specifications
Audio Performance - Balanced Outputs
Fs = 44.1 to 96 kHz, 20 to 20 kHz BW, 1 kHz test tone, 0 dBFS = +24 dBu (unless noted)
SNR – A-Weighted, 0 dBFS = +27.5 dBu
SNR – Unweighted, 0 dBFS = +27.5 dBu
Dynamic Range - A-Weighted at maximum volume
Dynamic Range - Unweighted at maximum volume
THD+N, 1 kHz at 0 dBFS
THD+N, 1 kHz at -1 dBFS
THD+N, 1 kHz at –3 dBFS
THD+N, 20 to 20 kHz sweep at –3 dBFS
Frequency Response at Fs=192 kHz
Frequency Response at Fs=48 kHz
Crosstalk
127 dB
125 dB
127 dB
125 dB
-111 dBFS, -111 dB, 0.00028%
-112 dBFS, -111 dB, 0.00028%
-116 dBFS, -113 dB, 0.00022%
-108 dBFS, -105 dB, 0.00056%
+/- 0.005 dB (20 to 20 kHz)
-0.013 dB at 10 Hz
+0.005 dB at 20 kHz
+0.006 dB at 40 kHz
-0.002 dB at 80 kHz
+/- 0.006 dB (20 to 20 kHz)
-0.015 dB at 10 Hz
-0.001 dB at 20 kHz
-120 dB at 20 Hz
-120 dB at 1 kHz
-106 dB at 20 kHz
< -144 dB Maximum Amplitude of Jitter Induced Sidebands (10 kHz 0 dBFS test tone, 12.75 UI sinusoidal jitter at 1 kHz)
Maximum Amplitude of Spurious Tones with 0 dBFS test signal
Maximum Amplitude of Idle Tones
Maximum Amplitude of AC line related Hum & Noise
Inter-channel Differential Phase (Stereo Pair – any sample rate)
Inter-channel Differential Phase (Between DAC3 Units
Fs<110 kHz) Any sample rate.
Maximum Lock Time after Fs change
Soft Mute Ramp Up/Down Time
Mute on Receive Error
Mute on Lock Error
Mute on Idle Channel
50/15 us De-Emphasis Enable
De-Emphasis Method
De-Emphasis Supported at
< -138 dB
< -147 dB
< -135 dB
+/- 0.25 degrees at 20 kHz
+/- 0.25 degrees at 20 kHz
6 ms
9.6 ms
Yes
Yes
No
Automatic in Consumer Mode
Digital IIR
Fs = 32, 44.1, 48 kHz
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 67
Group Delay (Latency)
Delay – Digital Input to Analog Output (function of sample rate)
1.36 ms at 44.1 kHz
1.27 ms at 48 kHz
0.90 ms at 88.2 kHz
0.82 ms at 96 kHz
0.51 ms at 176.4 kHz
0.47 ms at 192 kHz
Digital Audio Inputs
Number of Digital Inputs (switch selected)
Number of Channels
Input Sample Frequency Range
6 (1 USB, 2 Optical, 1 XLR, 2 Coaxial)
2
28 to 210 kHz (Coaxial and XLR)
28 to 96 kHz (Optical)
Maximum Input Word Length
Digital Input Impedance
44.1, 48, 88.2, 96, 176.4, 192 (USB)
DC Blocking Capacitors on Digital Inputs
Transient and Over-Voltage Protection on Digital Inputs Yes (Coaxial and XLR Inputs)
Transformer Coupling on Digital Inputs
Minimum Digital Input Level
24 bits
75 Ohms (Coaxial), 110 Ohms (XLR)
Yes (Coaxial and XLR Inputs)
Yes (XLR Input)
250 mVpp (Coaxial and XLR Inputs)
Jitter Tolerance
(With no Measurable Change in Performance)
>12.75 UI sine, 100 Hz to 3 kHz
>1.5 UI sine at 20 kHz
>1.5 UI sine at 40 kHz
>1.5 UI sine at 80 kHz
>1.5 UI sine at 90 kHz
>0.25 UI sine above 160 kHz
Benchmark UltraLock3™ - all inputs Jitter Attenuation Method
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 68
Balanced Analog Outputs
Number of Balanced Analog Outputs
Output Connector
Output Impedance
2
Gold-Pin Neutrik™ male XLR
60 Ohms (Attenuator off)
425 Ohms (Attenuator = 10 dB)
Analog Output Clip Point
Factory Set Calibration Level (with 0 dBFS digital input) +24 dBu (Attenuator = 0 dB)
Volume Control Range (with 0 dBFS digital input)
135 Ohms (Attenuator = 20 dB)
+29 dBu
Output Level Variation with Sample Rate
Off to +28 dBu (Attenuator = 0 dB)
Off to +18 dBu (Attenuator = 10 dB)
Off to +8 dBu (Attenuator = 20 dB)
< +/- 0.006 dB
Unbalanced Analog Outputs
Number of Unbalanced Analog Outputs
Output Connector
Output Impedance
Analog Output Clip Point
Factory-Set Home Theater Bypass Output Level (with 0 dBFS digital input)
Output Level Range (with 0 dBFS digital input)
Output Level Variation with Sample Rate
4
RCA
30 Ohms
+13.5 dBu (3.7 Vrms)
+8.2 dBu (2 Vrms)
Off to +12.2 dBu (3.2 Vrms)
< +/- 0.006 dB
HPA2 TM
Headphone Outputs
Number of Headphone Outputs
Output Connectors
Output Impedance
Output Level Control
Output Level Range (with 0 dBFS digital input)
Output Power
Maximum Output Current
Overload Protection (independent per channel)
Bandwidth
THD+N at 20 mW
2
¼” TRS with switch on left-hand jack
< 0.11 Ohms
Stereo Control on Front Panel
Off to +22 dBu (9.7 Vrms)
1.25 W into 30 Ohms
250 mA
Current limited at 300 mA, Thermal
> 500 kHz, -0.35 dB at 200 kHz
-108 dB (0.0004%) into 300
Ohms, -100 dB (0.0010%) into 30
Ohms
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 69
Status Display
Indicators - Type and Location
Selection/Status Indication
AC Power Requirements
Nominal Operating Range
Min/Max Operating range
Power
Fuses (2 required)
Dimensions
Form Factor
Depth behind front panel
Overall depth including connectors
Width
Height
Weight
DAC3 only
DAC3 with accessories and manual
Shipping weight
16 LEDs on Front Panel
1 – Mute
1 - Dim
6 – Input
2 – Calibrated Output
2 – Word length
4 – Sample Rate
100 – 240 VAC, 50 - 60 Hz
90 – 260 VAC, 47 - 63 Hz
< 0.5 Watts Standby
12 Watts Typical Program
15 Watts Maximum
5x20 mm, 0.5 A 250 V Slo-Blo ® Type
½ Rack Wide, 1 RU High
8.5” (216 mm)
9.33” (237 mm)
9.5” (249 mm)
1.725” (44.5 mm)
3 lb.
4 lb.
7 lb.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 70
Regulatory Compliance
FCC and RoHS Compliance Statements
FCC Notice (U.S. Only)
NOTICE: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications.
However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:
•
Reorient or relocate receiving antenna.
•
Increase the separation between the equipment and receiver.
• Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
•
Consult the dealer or an experienced radio/TV technician for help.
This device complies with Part 15 of the FCC rules. Operation is subject to the following two conditions:
1. This device may not cause harmful interference.
2. This device must accept any interference received including interference that may cause undesired operation.
Instructions to Users: This equipment complies with the requirements of FCC (Federal
Communication Commission) equipment provided that following conditions are met:
•
RCA Digital Connections: Shielded 75-Ohm coaxial cable must be used.
NOTICE: Changes or modifications not expressly approved by the party responsible for compliance could void the user's authority to operate the equipment.
RoHS Compliant Information
This statement clarifies Benchmark Media Systems, Inc. product compliance with the EU’s
(European Union) directive 2002/95/EC, or, RoHS (Restrictions of Hazardous Substances).
As of July 01, 2006, All Benchmark Media Systems, Inc. products placed on the European Union market are compliant (containing quantity limit weight less than or equal to 0.1% (1000 ppm) of any homogeneous Lead (Pb), Mercury (Hg), Hexavalent Chromium (Cr VI), and flame retardant
Polybrominated Biphenyls (PBB) or Polybrominated Diphenyl Ethers (PBDE)).
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 71
CE Certificate of Conformity
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 72
Warranty Information
Benchmark 1-Year Warranty
The Benchmark 1-Year Warranty
Benchmark Media Systems, Inc. warrants its products to be free from defects in material and workmanship under normal use and service for a period of one year from the date of
delivery.
This warranty extends only to the original purchaser. This warranty does not apply to fuses, lamps, batteries, or any products or parts that have been subjected to misuse, neglect, accident, modification, or abnormal operating conditions.
In the event of failure of a product under this warranty, Benchmark Media Systems, Inc. will repair, at no charge, the product returned to its factory. Benchmark Media Systems, Inc. may, at its option, replace the product in lieu of repair. If the failure has been caused by misuse, neglect, accident, or, abnormal operating conditions, repairs will be billed at the normal shop rate. In such cases, an estimate will be submitted before work is started, if requested by the customer.
Attempts to deliberately deface, mutilate, or remove the product's label will render this warranty void. Benchmark will not honor warranties for any products disingenuously purchased on the US or Canadian markets for export.
The foregoing warranty is in lieu of all other warranties, expressed or implied, including but not limited to any implied warranty of merchantability, fitness or adequacy for any particular purpose or use. Benchmark Media Systems, Inc. shall not be liable for any special, incidental, or consequential damages, and reserves the right to change this information without notice.
This limited warranty gives the consumer-owner specific legal rights, and there may also be other rights that vary from state to state.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 73
Benchmark Extended Warranty Options
The Benchmark Extended 5-Year Warranty *
Benchmark Media Systems, Inc. optionally extends the standard 1-year warranty to a period of
five years from the date of delivery.
*For the extended warranty to become effective, the original purchaser must register the product at the time of purchase either by way of the enclosed registration card or through the product registration section of the Benchmark Media Systems, Inc. website. This optional warranty applies only to products purchased within the US and Canada and is extended only to the original purchaser.
Attempts to deliberately deface, mutilate, or remove the product's label will render this warranty void. Benchmark will not honor warranties for any products disingenuously purchased on the US or Canadian markets for export. The terms of the extended warranty are subject to change without notice. For products purchased outside the US and Canada, please refer to the
Extended Two 2-Year International Warranty.
The Benchmark Extended 2-Year International Warranty **
Benchmark Media Systems, Inc. optionally extends the standard 1-year warranty to a period of
two years from the date of delivery.
**For the extended warranty to become effective, the original purchaser must register the product at the time of purchase either by way of the enclosed registration card or through the product registration section of the Benchmark Media Systems, Inc. website. This optional warranty applies only to products purchased outside the US and Canada and is extended only to the original purchaser.
Attempts to deliberately deface, mutilate, or remove the product's label will render this warranty void. Benchmark will not honor warranties for any products disingenuously purchased on the US or Canadian markets for export. The terms of the extended warranty are subject to change without notice. For products purchased in within the US and Canada, please refer to the
Extended Five 5-Year Warranty.
Notes on Warranty Repairs
An RMA (return merchandise authorization) number, issued by our Customer Service
Department, is required when sending products for repair.
They must be shipped to Benchmark Media Systems prepaid and preferably in their original shipping carton with the RMA number clearly visible on the exterior of the packaging. A letter should be included giving full details of the difficulty.
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 74
Revision A - 2/01/2017
Copyright © 2007, 2008, 2009, 2012, 2013, 2014, 2015, 2016, 2017
Benchmark Media Systems, Inc.
All rights reserved.
Benchmark Media Systems, Inc.
Benchmark Media Systems, Inc.
203 East Hampton Place, STE 2
Syracuse, NY 13206
USA
PHONE: +1-315-437-6300
FAX: +1-315-437-8119 benchmarkmedia.com
Instruction Manual for DAC3 DX with 1.0 Firmware - Rev. A Page 75

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Key features
- 24-bit D/A conversion of PCM up to 192 kHz
- Direct conversion of 1-bit DSD at 2.8224 MHz
- UltraLock3™ Jitter Attenuation System
- Dual-mode asynchronous USB Audio 2.0
- HPA2™ Headphone Amplifier with dual high-current outputs
- Reference-grade headphone amplifier
- Volume control bypass
- Bi-directional 12V trigger