The State of Digital Audio Cables

 

AQUSB

Audioquest USB cables for digital audio, Coffee in focus

After recently writing about solid core audio cable designs, I began listening to various digital audio cables.  To dig in, I started by examining the transmission from computer to DAC (digital-to-analog converter) via the Audioquest USB cable line. For this listening test I employed the Antelope Audio Zodiac Platinum DAC with 10m Clock – simply connected to amp and speakers (Lipinski, and Green Mountain Audio).

The basis for the Audioquest designs start with solid core copper, then they add silver in varying amounts, a noise dissipation system, and finally a DBS or dielectric bias system.

Starting with a generic USB cable I familiarized myself with the sound. To be fair, I listened to several generic type USB cables…not all are created equal, and yes some sound decent too. After establishing the best sounding generic USB cable, I began exploring the Audioquest designs.

The Pearl, a basic LGC (long grain copper) USB cable was implemented from computer to DAC. Compared to the generic USB cable, the Pearl provided a modest but noticeable step up in clarity to the music files. The Forest, with its mere 0.5% silver over copper was easy to distinguish from the sound of the Pearl USB. A distinct and greater clarity came upon first listen, and continued use proved it more detailed indeed. A layer of background vocals was now more apparent. Moving past the Forest, one encounters the Cinnamon USB. At 1.25% silver over copper, this is still in the range of affordable USB cables (ok, for music lovers). The Cinnamon is yet again, more resolute. Not just more resolute, but better controlled and more balanced than the Forest. Next up, the AQ Carbon USB employs a whopping 5% silver over copper. This is also where Audioquest begins adding a 3 layer noise-dissipation system around the USB cable. If the Cinnamon was better balanced, the Carbon adds a more relaxed presentation – possibly due to less noise riding on the conductors. The Carbon also provided a greater sense of depth.

The last two USB cables in the Audioquest line include a 72v DBS (Dielectric Bias System). First up is the 10% silver over copper Coffee USB cable. After noticing the obvious clarity, balance, and extreme quietness (no background hash), another characteristic to the stereo field becomes apparent. Stereo height and depth information becomes easily distinguished. The arc of sound in the stereo field becomes less congested. Low, Middle, and High frequencies have a specific horizontal plain they reside in. Using the Lipinski Speaker system with subs (in addition to my 2way speakers) made this very obvious.

What comes after 10% silver, well 100% PSS (Perfect Surface Silver) of course. The Diamond USB is the most expensive offering from Audioquest. This USB cable spotlights ultra clear transmission while still being hash-free. Like Coffee USB, the Diamond possesses quiet backgrounds, great dimensionality, and rendering distortion free audio signals. Where it differs in sonic presentation is in the stereo height or arc. Compared to Coffee USB, I found the Diamond to create even greater distinctions between low, middle, and high frequencies. Specifically, center vocals were presented physically higher above the speaker than with the Coffee. While some stereo system might benefit from the Diamond, we found the Coffee USB to have the best overall balance in our systems.

Coffee

Audioquest Coffee AES/EBU

To test out the Audioquest AES/EBU cables, I used my trusty Yellowtec PUC2. The PUC2 is a USB to AES converter. This allowed me to listen with basic Canare AES/EBU cables and compare them to the Audioquest designs. Note: I used the same AQ USB cable as AES/EBU cable being tested, for the Canare AES/EBU I used a generic USB cable to connect the PUC2 to computer. Canare AES and the AQ Coffee/Diamond were compared using the Crane Song Avocet (with Quantum DAC update).

Starting with the Canare AES cable, I connected the the AES out of the PUC2 to my Crane Song Avocet DAC. From the the Crane Song Avocet, I went into Lipinski Sound speakers with amps. Using the same track (Paul Simon, Proof), I began listening. After familiarizing myself with the sound, I quickly swapped the Canare AES/EBU for the AQ Coffee AES/EBU.

I was stunned by the differences, and so was my colleague (a seasoned mastering engineer). Just as I heard when using the Coffee USB, the AES cable provided a clarity and distinction to the many layered tracks of this Paul Simon mix. Bass was tighter, better defined, more robust. Middle and high frequencies also benefited from greater clarity while still being balanced yet distinct. The stereo arc allowed height information to be easily perceived and not exaggerated. Swapping back the Canare AES cable made it apparent that the sound was now congested, or squeezed sounding.

Diamond

Audioquest Diamond AES/EBU

When replacing the Coffee AES/EBU for the 100% Perfect Surface Silver Diamond, the height information became even more distinct. That arc (in the stereo field) I spoke of earlier was even more pronounced than on the Coffee AES/EBU. Extreme clarity and low background noise was obvious, but Paul Simon’s voice appears to be physically higher in the center image. When testing this AES/EBU cable in my home system I noticed the same phenomena.

The Audioquest USB and AES/EBU cables offered a clear improvement that was easily heard. While the Carbon and Coffee were my favorite designs, even the entry level USB cables from AQ provided a clear balanced presentation without any harshness.

-Happy Listening!

 

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Listening to the Hegel HD20 DAC…and Beyond

Hegel HD20 DAC from Norway

Hegel HD20 DAC from Norway

Digital-to-analog converters have come a long way, and it seems like there is no end in sight. Precise timing of the samples in a digital stream of audio can make the difference between music being reproduced naturally or with some haze and artifacts. And like many DACs the Hegel HD 20 reclocks the incoming signal for the lowest possible jitter. In addition to this reclocking, Hegel also uses a special imepedance correcting input (coax 1) to ensure the best sound from a standard RCA terminated digital cable.

At first glance this unassuming black box simply has digital inputs and analog outputs on the rear with a simple blue LCD display on front. The power supply is built-in, and a supplied remote controls the input selection and digital volume. The remote may also be used to control your computer if the DAC is connected through USB (which is limited to 96kHz SR). 2 coaxial digital inputs on RCA, one optical input, and one USB input are supplied. Analog outputs come in 2 flavors; single-ended RCA and balanced XLR.

Rear of the Hegel HD20

Rear of the Hegel HD20

In Use: The Hegel’s balanced outputs connected directly into my amplifier as well as my monitor controller for two setups. 1)The direct-to-amp scenario requires using the built-in digital volume, which can leave something to be desired when played at low volume settings. 2)When connected through my class A monitor controller via XLR the sound was tight, smooth and detailed. The space of the stereo image was well-defined and localization of instruments was clear. Funny enough, we found that coax 2 provided this tighter larger stereo image compared to coax 1 (with the impedance correction).

Playing acoustic music through my Green Mountain Audio Eos HX was natural and defined with the HD20. If it has any sound signature, I would say it is relaxed and detailed. Nothing in the mixes I listened to sounded hyped or overly detailed. The beauty of this DAC was its ability to stay organic and 3 dimensional in the home environment.

Using the HD20 with a dedicated headphone amp was may favorite. The sound is spacious, natural….just plain listenable. Many of my favorite Jazz recordings came through my HD-600 headphones with a smoothness that made music listening a treat. Combined with the CI Audio headphone amp, the Hegel truly shined.

Opting for the USB input allowed me access to internet radio and computer audio files. This USB input  is limited to 96kHz SR. While this is certainly a convenient feature, it lacks the full sample rate handling for high-definition downloads..

Other than the coaxial 1 input issues, I was impressed with the large natural sound stage and the organic timbre that the Hegel HD20 was capable of delivering. Now with the introduction of the Hegel HD25, the company has harnessed current 32 bit DAC chipsets, and allowed the full 192Khz SR over the USB input. In addition, the NEW HD25 also allows you to choose between two different digital filters to suit your tastes. While I have not auditioned this new DAC offering, I can certainly say that if the HD20 is any sonic indication, an audition of the new HD25 from Hegel is a must.