Benchmark DAC1 2-Channel 192K/24-bit D-to-A Converter

by | May 10, 2008 | Component Reviews | 0 comments

Benchmark DAC1 2-Channel
192K/24-bit D-to-A Converter
SRP: $975

 
 
 
 
 
 

Features:
Inputs: Balanced XLR, BNC coax, TOSLINK optical digital – selectable with front-panel switch
Analog outputs: high level +4 dBu balanced, +29 dB maximum output level
Jumper-selected 10/20/30 dB pads on balanced outputs
Unbalanced outputs -10 dBV, +13.5 dB maximum output level
Two HPA2 high-current, high-output 1/4” headphone jacks
Front-panel knobs for all analog outputs or just headphone outputs
Analog output mute via rear-panel switch
Preset output levels with multi-turn trimmers – 20 dB range, 2 dB/turn
Phase-accurate UltraLock technology assures jitter immunity
Two Error LEDs, red & blue
Power indicator LED
THD+N = 107 dB, 0.00045% @ -3 dBFS input
Supports 44.1, 48, 88.2 or 96K (not 192K) with automatic de-emphasis (when pre-emphasis bit is set)
Reliable performance under all operating conditions
115V, 230V, 50/60 Hz power supply with very wide operating range
Low radiation toroidal power transformer reduces hum and line-related interference
Low power consumption (8W typical, 16W peak)
Meets FCC Class B & CE emissions requirements
Dimensions: 9.33” depth, 9.5” width, 1.725” height
Weight without power cord: 3.5 lb.
Comes in Silver or Black


Benchmark Media Systems Inc.
5925 Court St. Rd.
Syracuse, NY 13206-1707
315-437-6300
www.benchmarkmedia.com


Intro

I’ve had different D-to-A processors in the past, but when I moved up into SACD and universal disc players of the $2000-$3000 level I felt they were doing as good a job with standard CDs as a separate processor, required less cables, and couldn’t be used with SACDs or DVD-Audio anyway.  The really effective ones were outrageously expensive as well. 

 
Well, I was wrong, at least in reference to Benchmark’s DAC1.  The results are immediately hearable, and it mattered little whether I was using either of my Oppo players as the transport feeding the DAC1, or my old Sony 775 CD/SACD changer.  Nor did it matter which input to the DAC1 I used – the coaxial or the Toslink.  And by today’s standards the price of the unit is considered very reasonable.

Front and Rear Panels

There is no on/off switch on the DAC1, and neither is there a bypass switch to compare the processing with the signal direct from the CD player.  The latter is unfortunate but I found a workaround to do some A/B comparisons. There is a vertical row of three LEDs on the front: a blue to indicate power to the unit, a red to indicate no digital input signal or out of the proper sampling range, and a second red LED under that to indicate when the DAC1 is being fed an undecodable signal, such as Dolby AC3.  The LEDs are extremely bright, and without an on/off switch the top two will be on whenever you are playing a video DVD or SACD.  If close to your video display they might be annoying. I finally taped some grey plastic filter material over them.

There is a single large knob on the front panel which has two options controlled by an Output Level switch on the rear panel: either Calibrated or Variable, with an Off position in between. In Calibrated the output levels are set by as desired by trim controls on the rear panel. In Off, the outputs are muted except for the headphone jacks. In Variable, the output levels are controlled by the gain knob on the front.

 

Before leaving the front panel, the two stereo-phone-plug headphone jacks should be pointed out. They are identical and rated at 60 ohms stereo.  The headphone amp delivers high current at high output levels and is one of the better headphone amps I have ever tried.  It doesn’t quite match my AKG K-1000 headphone amp using my Grado phones, but that amp was twice the cost and is no longer being made.  Since there is just the one level control, Benchmark suggests if you plug in a two headphones that they be identical to avoid differences in level between them.

There are no digital outputs on the DAC1.  The two analog RCA jacks for the main output are on the far left of the rear panel.  The two small holes which require a small screwdriver to adjust the calibration pots are located on either side of the Output Level switch. Next are the Balanced XLR left and right output jacks. Continuing to the right we have the coax output – a BNC jack – and under it is the Toslink optical jack.  Next is a single digital XLR input jack for pro use.  It is balanced with a 110 ohm input impedance.  Last on the right is the standard IEC male jack for the separate AC power cable, and a small drawer for the two fuses.

Pro Use of the DAC1

The DAC1 is designed for both general consumer use and for professional studios.  It has rack mount halls on the front to fit half of a standard 19” rack.  The calibrated output option is designed to match the unit perfectly with studio gear. There are jumper settings inside the DAC1 to fit special applications. A schematic is in the owner’s manual identifying the various jumpers and their settings for various uses. The specs of the DAC1 take up three pages in the manual and are highly detailed.

UltraLock

Benchmark’s DACs zero in on jitter, which they find in every digital audio interface.  Accurate conversion of digital audio to 24-bit requires a very low-jitter conversion clock, and without it you can end up with just 16-bit or worse. Their UltraLock technology is designed to eliminate all jitter-induced performance problems by isolating the conversion clock from the digital audio interface clock.  The converter’s oversampling-ratio is varied with extremely high precision to achieve the proper phase relationship to the reference clock.  There are over two pages of explanation in the Benchmark manual related to jitter and its audible effects on the audio.

Listening Comparisons

I set up my Oppo 983H for standard CD playback thru its RCA analog output jacks going into the front left and right of the 6-channel analog input of my Sunfire TGP-5 AV preamp. This input does no processing at all of the analog signal. Then I fed the 983H digital Toslink output signal to the Toslink input of the DAC1, using a cable I had with a BNC connector on one end to fit the DAC1.  I then ran the two analog output jacks of the DAC1 into the Sunfire analog input I had already labeled “Oppo,” and set it for Source Direct, which means no processing goes on at all.  This enabled me to sit back in my sweet  spot and instantly switch between the all-Oppo signal and the Oppo-as-a-transport decoded by the DAC1.

I began with some quite old CDs that I knew had sonic problems – some Bernstein recordings on Sony Classical, some CDs from Russian sources and so on. I wasn’t able to hear a huge improvement switching back and forth and was a bit disappointed.  Sometimes there was a slight enhancement in clarity, but it was quite subtle. I later read that the UltraLock converter cannot undo damage that has already been done to the signal if there were jitter problems with the A-to-D converters original used in making the recordings, and evidently such problems existed in the CDs I had picked out.

I began to discover that the better the CD, the greater the enhancement the DAC1 could provide it.  My jaw dropped at some of the comparisons using the new First Impressions Music K2 HD sampler.  All the selections gained greatly in transparency, impact, “air,” and instruments just sound more “there” than directly off the Oppo deck.  I put on a CD issued in 2000 of Antheil’s Ballet Mecanique and other percussion works.  The first track was an early work by John Cage and Lou Harrison for percussion quartet.  The playback without the DAC1 was excellent, with good spatiality and variety of percussive sounds from different instruments – some of them homemade. However, switching to the DAC1 decoding showed that the “A” example was actually dulled and opaque-sounding.  Via the Benchmark there was much more air, presence, transparency, and a feeling of the real sounds of the instruments – not just an electronic imitation. The big climaxes in the work were actually scary.

One of my standard test CDs is Opus 3’s “A Selection from Testrecords 1, 2 & 3” – a gold CD.  Track 1 is the famous female vocal (In Swedish) Tiden bara gar – which used to be a much-used test track in the all-LP era.  Thru the DAC1 this track reminded me of the way it sounded on the best analog turntable off vinyl!  The natural presence on the vocalist was uncanny. Next was a Telemann selection by the Stockholm Guitar Quartet.  The non-DAC1 playback sounded dulled vs. the guitar reproduction from the DAC1. There was a more believable recreation of the four guitarists plucking the strings in front of me. The third track is Thomas Ornberg’s Blue Five in a trad jazz number.  The DAC1 version had more presence and impact.  The piano sounds slightly distant straight out of the Oppo, but thru the DAC1 it is definitely more “there.”  As a strong SACD fan, I find many of my standard CDs now sound just about as good as the two-channel layer of most of my SACDs.

My dining area is some distance from the listening/viewing area and off to the right from it. However, even sitting at the dining table and reaching my remote way over to the left to activate the Sunfire preamp, I could still hear the enhancement of the DAC1 over the signal entirely from the CD player. As I’m auditioning various CDs for review I sometimes forget I have left the Sunfire on 6-channel after playing a multichannel SACD, and am now bypassing the DAC1.  I will mumble to myself about the recording being a bit lifeless and dulled, and then realize that I neglected to press that “Oppo” button and switch to the DAC1 processing. Then it comes alive and sounds more like real musicians at work. I don’t believe you will find many tweaks that are as identifiable in their upgrade of your sonics as this. It’s definitely not due to clever marketing or that audio feeling that it must sound better because it was so expensive.
I vote the DAC1 to be the best all around improvement you could make to your present CD reproduction without spending thousands more!  I’m wondering why I waited so long to give it a critical listen. Needless to say, I’ve purchased the DAC1 and made it a central part of my reference system used in reviewing CDs.

Other Options

The DAC1 was the first processor from Benchmark a few years ago, and other models have recently been added to the line that increase its usability for many. One is the DAC1 USB, which adds USB connectivity for those working with audio files, having a media server, or just wanting higher quality CD playback from their PC in their office.  The DAC1 PRE adds a first-rate stereo preamp to the headphone amp already a part of the unit, and the ADC1 USB – as its designation would indicate – is an analog-to-digital converter for use in pro and semipro studios and for serious recordists.  It uses some of the same high quality jitter-fighting circuitry as the DAC1 in the conversion of the analog signals from the mikes and board to digital.  There is also a four-channel mike pre-mixer. The added features takes the price of these units over the $1000 mark, but not by that much.

 — John Sunier

 

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