Benchmark DAC1 PRE Instruction Manual
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Benchmark DAC1 PRE Instruction Manual

2-channel 24-bit 192-khz digital-to-analog audio converter with preamp functions and usb input
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Benchmark DAC1 PRE
Instruction Manual
2-Channel 24-bit 192-kHz
Digital-to-Analog Audio Converter
with Preamp Functions and USB Input

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Summary of Contents for Benchmark DAC1 PRE

  • Page 1 Benchmark DAC1 PRE Instruction Manual 2-Channel 24-bit 192-kHz Digital-to-Analog Audio Converter with Preamp Functions and USB Input...

  • Page 2: Safety Information

    REPAIRS. 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). DAC1 PRE Instruction Manual Rev J Page 2...

  • Page 3: Table Of Contents

    Digital Inputs 2, 3, and 4 - Coaxial Benchmark 1 Year Warranty Output Level Switch Benchmark Extended Warranty Balanced XLR Analog Line Outputs Unbalanced RCA Analog Outputs Low-Impedance Passive Pads Calibration Trimmers DAC1 PRE Instruction Manual Rev J Page 3...

  • Page 4: Features

    Optical digital inputs support professional (AES) and consumer (S/PDIF) data formats at up to  96-kHz, 24-bits Benchmark’s UltraLock™ technology eliminates jitter on all digital inputs (including USB)  Jumper-selected low-impedance 10, 20, or 30 dB pads on balanced outputs ...

  • Page 5: Overview

    DAC1 has made it the ‘Benchmark’ of stand- alone D/A converters. The DAC1 USB and AdvancedUSB Audio™ Technology DAC1 PRE preserve the exact topology of the DAC1 audio path while adding some of the most frequently requested features. The USB input is compatible with Windows...

  • Page 6: Hpa2™ Headphone Amplifier

    D/A converters omit de-emphasis. The DAC1 The DAC1 PRE is designed to avoid all PRE will correctly apply precise digital de- unnecessary mute scenarios. Muting is only emphasis when and if it is needed. The de- enabled upon loss of power, or when digital emphasis circuit supports 44.1, 48, 88.2 and...

  • Page 7: Quick Start Guide

    A rotary Source Selector control selects any input (RCA) and five stereo digital inputs (3 x of the 6 inputs to the DAC1 PRE. Pressing coaxial, 1 x optical, and 1 x USB). The coaxial the Source Selector toggles the DAC1 PRE and optical digital inputs accept professional on and off.

  • Page 8: Front Panel

    The Input Status Display will flash when an equipped with an on/off switch. Press the error occurs on the selected digital input. The control knob to turn the DAC1 PRE on or off. type of error is indicated by the number of flashes before standby engages.

  • Page 9: Standby Mode

    ‘Internal Settings’ section of sensitivities differ significantly. The Volume this manual. The DAC1 PRE is shipped with Control adjusts the level for both jacks. the XLR attenuation set to -20 dB. The original gain-range of the HPA2™ (such as in the original DAC1) is often too high for the headphones of many users.

  • Page 10: Rear Panel

    The USB input accepts a ‘B-type’ male USB 1.1 or USB 2.0 connector. An ‘A-B type’ USB The optical and coaxial can decode AES/EBU cable is provided with the DAC1 PRE. The and S/PDIF input signals in either professional USB cable connects the DAC1 PRE directly to or consumer formats.

  • Page 11: Digital Input 1 - Optical

    TIP – Visit our computer audio (commonly known as S/PDIF). The coaxial application pages for the latest inputs on the DAC1 PRE are designed to information on media players, media accept either type of signal. servers, operating systems, and audio-...

  • Page 12: Output Level Switch

    Volume Control). TIP: If the DAC1 PRE is being used in a critical signal chain (such as a broadcast facility or theater) the headphone mute switch should be defeated using the internal jumpers.

  • Page 13: Unbalanced Rca Analog Outputs

    The ground connections reduce the output levels while preserving the are bonded to chassis ground full dynamic range of the DAC1 PRE. The at the location where analog DAC1 PRE ships with the 20 dB pads enabled.

  • Page 14: Calibration Trimmers

    The factory-preset levels may be increased by range of 50 to 60 Hz. At 110, the DAC1 PRE 5 dB or decreased by 15 dB in order to will operate normally over a range of 90 to conform to other studio reference levels.

  • Page 15: Internal Settings

    Internal Settings Removing Top Cover XLR Output Pad Selection (P5, P6, The DAC1 PRE cover must be removed to P7, and P8): gain access to the jumpers. Do not attempt to remove the faceplate or rear panel. Four 8-pin headers (P5, P6, P7, and P8) allow selection of the output level at the XLR jacks.
  • Page 16 Headphone Switch Disable (JP2 and JP4): The DAC1 PRE is configured so that the analog outputs will mute when a headphone plug is inserted into the left-hand jack. This is convenient when the user wishes to switch between headphones and speakers. This feature can be defeated by adding jumpers at JP1 and JP2.

  • Page 17: Rack Mounting

    The Universal Rack Mount Adapter is a An optional rack mount adapter allows the tray that mounts up to two System1™ mounting of any two Benchmark System1™ products in a single race space. The tray products in a single rack space. A Blank accepts any combination of System1™...

  • Page 18: Benchmark Technologies

    30-Ohm headphone loads, and 600- Ohm headphone loads are virtually identical. The HPA2™ will substantially improve the The DAC1 PRE headphone output is driven sound of 30 and 60-Ohm headphones. It will by Benchmark’s signature HPA2™ headphone make very noticeable improvements with amplifier.
  • Page 19 Jitter induced sidebands can be measured using an FFT analyzer. The DAC1 PRE, DAC1, DAC-104, ADC1 and the ADC-104 employ Benchmark’s Problem #2: Jitter can severely degrade the UltraLock™ technology to eliminate jitter- anti-alias filters in an oversampling converter.
  • Page 20 D/A. The with varying jitter frequencies. The results will consistent performance delivered by the be very enlightening. Jitter related problems DAC1 PRE eliminates one major variable: have audible (and measurable) effects on A/D jitter. and D/A devices. Practitioners of Digital Audio need to understand these effects.

  • Page 21: Advancedusb Audio™ Technology

    In addition, custom drivers transparent audio streaming at 96 kHz, 24- usually consume more system resources bit, the Benchmark USB solution is a dream- (memory and CPU) than native solutions. come-true for lovers of high quality audio playback. Plus, with no drivers to install, you...
  • Page 22 16-bit material. Native device. Any audio played from the computer USB output devices have had a reputation for will then be routed to the Benchmark USB poor sound quality. This is primarily due to device immediately. There is no software to the 16-bit word-length reduction.
  • Page 23 Benchmark’s AdvancedUSB Audio™ solution offers users the convenience of simultaneous high-quality playback from more than one DAC1 PRE Instruction Manual Rev J Page 23...

  • Page 24: Performance Graphs

    Performance Graphs The following graphs apply to both DAC1 and DAC1 PRE converters: Frequency Response Tests Frequency Response at Fs = 48 kHz The above graphs show the frequency response of the DAC1 when it is operating at a 48-kHz sample rate.
  • Page 25 0.05 dB/division scale. The amplitude response is down by only 0.22 dB at 20 kHz and only –1 dB at 43 kHz. The bass response extends well below the 10-Hz limitation of the measurement equipment. DAC1 PRE Instruction Manual Rev J Page 25...

  • Page 26: Fft Analysis Of Idle Channel Noise

    The above graph demonstrates that the DAC1 is free from idle tones and clock crosstalk. The highest spurious tone measures –128 dBFS and is AC line related hum. The highest non-line related tone measures –138 dBFS. DAC1 PRE Instruction Manual Rev J Page 26...

  • Page 27: Multi-Unit Phase Response

    Multi-Unit Phase Response Any combination of DAC1, DAC1 USB, and DAC1 PRE converters may be used to create a multi- channel playback system that maintains phase accuracy across all channels at sample rates up to 110 kHz. The above graph shows the differential phase between 10 audio channels using 5 DAC1 converters operating at 96 kHz.

  • Page 28: Thd+N Tests

    DAC1). This implies that the distortion created by the DAC1 should be below the threshold of hearing unless playback levels exceed 112 dB peak SPL. Distortion should still be well masked at higher playback levels. DAC1 PRE Instruction Manual Rev J Page 28...
  • Page 29 THD+N vs. Level at 1 kHz – Balanced Outputs Below –4 dBFS, distortion is lower than the noise floor of the converter. Above –3 dBFS, distortion reaches a maximum value of only –107 dBFS. DAC1 PRE Instruction Manual Rev J Page 29...
  • Page 30 This graph shows the output of the HPA2™ headphone amp driving a 60-Ohm load at a very high level (+14 dBu). Even under these conditions, the HPA2™ delivers the full rated performance of the DAC1. Compare this to the performance of the balanced outputs (see previous graph). DAC1 PRE Instruction Manual Rev J Page 30...
  • Page 31 THD+N vs. Level at 1 kHz - Unbalanced Outputs This graph demonstrates the performance of the unbalanced outputs. Note that the performance is nearly identical to that of the balanced outputs. DAC1 PRE Instruction Manual Rev J Page 31...
  • Page 32 The above graph shows that the DAC1 provides consistent performance at all sample rates. Distortion is not a function of sample rate. The minor variations in the above plots are due to measurement limitations. DAC1 PRE Instruction Manual Rev J Page 32...

  • Page 33: Jitter Tests

    In fact, the DAC1 can tolerate much higher levels of jitter without any measurable change in performance (see the next graph). DAC1 PRE Instruction Manual Rev J Page 33...
  • Page 34 DAC1 performance did not change when the jitter was turned off. The same test was conducted using FFT analysis to look for jitter-induced artifacts. No change was observed on a FFT analysis (see the next graph). DAC1 PRE Instruction Manual Rev J Page 34...
  • Page 35 Immunity to Cable-Induced Jitter The above FFT plots demonstrate that the performance of the DAC1 is not degraded in any way when long cables are used to transmit digital audio to the DAC1. DAC1 PRE Instruction Manual Rev J Page 35...

  • Page 36: Input Sensitivity Tests

    The above graph shows that the performance of the DAC1 is not a function of the signal level at the coaxial digital input. When the signal is too low to decode (< 120 mVpp), the converter mutes gracefully. DAC1 PRE Instruction Manual Rev J Page 36...
  • Page 37 1000 feet of Category 5 UTP cable, the DAC1 receivers have enough sensitivity to allow reliable operation. The jitter produced by this connection is removed entirely by the Benchmark UltraLock™ clock circuits and the DAC1 operates at full-specified performance.

  • Page 38: Volume Control Curve

    Volume Control Curve Volume Control 10.0 -10.0 -20.0 -30.0 -40.0 -50.0 -60.0 -70.0 -80.0 Rotation (Steps) Volume Control - Step Size Rotation (Steps) DAC1 PRE Instruction Manual Rev J Page 38...

  • Page 39: Specifications

    < -126 dB Inter-channel Differential Phase (Stereo Pair – any +/- 0.5 degrees at 20 kHz sample rate) Inter-channel Differential Phase (Between DAC1 PRE +/- 0.5 degrees at 20 kHz Units Fs<110 kHz) Inter-channel Differential Phase (Between DAC1 PRE +/- 4.1 degrees at 20 kHz Units Fs>110 kHz)

  • Page 40: Group Delay (Latency)

    Delay = 1.01 ms + (48/Fs) 1.55 ms at 88.2 kHz 1.51 ms at 96 kHz Where Fs = the sample rate in Hz. 1.28 ms at 176.4 kHz 1.26 ms at 192 kHz DAC1 PRE Instruction Manual Rev J Page 40...

  • Page 41: Analog Audio Inputs

    75 Ohms or Hi-Z (Bridging) selected) Transformer Coupled Digital Inputs Yes (Coaxial) DC Blocking Capacitors on Digital Inputs Yes (Coaxial) Transient and Over-Voltage Protection on Digital Inputs Minimum Digital Input Level 150 mVpp on Coaxial DAC1 PRE Instruction Manual Rev J Page 41...
  • Page 42 >1.2 UI sine at 40 kHz >0.4 UI sine at 80 kHz >0.29 UI sine at 90 kHz >0.25 UI sine above 160 kHz Jitter Attenuation Method Benchmark UltraLock™ - all inputs DAC1 PRE Instruction Manual Rev J Page 42...

  • Page 43: Balanced Analog Outputs

    Output Level Range (at 0 dBFS) In ‘Variable’ Mode Off to +11 dBu Calibration Adjustability 2 dB / turn Output Level Variation with Sample Rate (44.1 kHz vs. < +/- 0.006 dB 96 kHz) DAC1 PRE Instruction Manual Rev J Page 43...

  • Page 44: Hpa2 Tm Headphone Outputs

    -106 dB, 0.0005% into 30 Ohms at +18 dBu (1.26W) Status Display Indicators - Type and Location 3 Blue LED’s on Front Panel Selection/Status Indication Solid: Digital Input Selection Flashing: Signal Error None: Standby Mode DAC1 PRE Instruction Manual Rev J Page 44...

  • Page 45: Ac Power Requirements

    9.33” (237 mm) cord Width 9.5” (249 mm) Height 1.725” (44.5 mm) Weight DAC1 PRE only 3.5 lb. DAC1 PRE with power cord, extra fuses, and manual 4.5 lb. Shipping weight 7 lb. DAC1 PRE Instruction Manual Rev J Page 45...

  • Page 46: Regulatory Compliance

    (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)).

  • Page 47: Ce Certificates Of Conformity

    CE Certificates of Conformity DAC1 PRE Instruction Manual Rev J Page 47...
  • Page 48 DAC1 PRE Instruction Manual Rev J Page 48...

  • Page 49: Warranty Information

    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.

  • Page 50: Benchmark Extended Warranty

    Benchmark Extended Warranty The Benchmark Extended 5* Year Warranty Benchmark Media Systems, Inc. optionally extends the standard one (1) year warranty to a period of five (5)* 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 prepaid registration card or through the product registration section of the Benchmark Media Systems, Inc.
  • Page 51 Copyright © 2007, 2009, 2010, 2012 Benchmark Media Systems, Inc. All rights reserved. Benchmark Media Systems, Inc. Benchmark Media Systems, Inc. 203 East Hampton Place, STE 2 Syracuse, NY 13206-1633 +1-315-437-6300, FAX +1-315-437-8119 www.benchmarkmedia.com DAC1 PRE Instruction Manual Rev J...

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