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!

 

Benchmark’s ADC-1 Still Going Strong

Benchmark ADC 1 analog to digital converter

Benchmark ADC 1 analog to digital converter

I’ve been encountering Benchmark Media systems for years. From the earlier days of the modular System 1000 (distributed audio, mic preamps and AD/DA converters) to more recent products like the ADC 1 and DAC1/DAC 2. The DAC 1 made huge impact on the Pro Audio and computer audiophile scene, and now the DAC 2 is providing DSD conversion over USB for even greater file compatibility.

Not quite as popular, but equally impressive is the ADC 1 analog-to-digital converter. And Guess what? The editor over at Stereophile recently revisited the Benchmark unit and sang its praise. He compared it to an Ayre QA-9, and you can read the details here. I’m unsure why he did not compare the two units with the same sample rate, but overall you get the impression that he has appreciated the ADC-1’s  clarity and accuracy.

In my experience, the ADC 1 provided a solid and clear image of my stereo ORTF mics and Omni Flank mics. When paired with a clean mic preamp (Grace, Crane Song Flamingo) you can rest assured that what you hear is what you get.  From Orchestral Recording to Sound Effects, the Benchmark Media ADC 1 provides a sure fire way to get a jitter-free recording, not to mention a great dynamic range.

-HIFIQC

Sony Portable PHA-2 Headphone Amp/DAC with DSD

Coming March 2014, Sony releases the PHA-2 – a portable rechargeable headphone DAC and Amp. Sporting features like PCM files up to 24 bit 192 Khz and even decodes DSD audio files.  Portable DSD from the company that brought it to you!

Sony PHA-2 coming March 2014

Sony PHA-2 coming March 2014

  • Hi-Res audio: PCM 192kHz/24 bit, DSD 2.8/5.6MHz
  • Direct Digital Connection for PC and Apple® devices
  • Enhances non hi-res music sources (via analog input)
  • Asynchronous, precision USB clock for superior sound
  • Premium DAC with separate operational and headphone amps
  • Durable aluminum enclosure with protective alloy bumper
  • Selectable gain supports impedances from 8 to 600 Ohm
  • Lithium-ion battery for up to 17 hours battery life
  • Line-out to connect external amp or active speaker
  • Mounting straps, protection sheet and cables included

Also released (October 24, 2013) is this new app for playing those Hi-Res files:

Onkyo HF Player App Offers Precision Equalizer, 192/24 Playback on iOS Devices

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.

Your Computer Turned HiFi – Channel Islands Transient MK II USB Converter

Channel Islands Audio Transient MK II photo by Vahan Baladouni

Channel Islands Audio has been producing high quality audiophile products for over 15 years. Situated along the Pacific coast and near wine country, this small audio firm builds some unique stereo gear with clean modern case work. While always being interested in these tight industrial designs, I never had a chance to actually hear one. That all changed after I spent several days at T.H.E. Show Newport. Listening to CI Audio amps, passive preamps, and DACs was a treat and had me asking for more. Fortunately, I was able to take a closer look at one of their latest designs.

Under development for 2 years, the Transient MK II represents CI Audio’s research into USB to digital audio conversion.

Removing the hood of this converter reveals a XMOS based asynchronous USB input with low jitter clocks. This asynchronous method allows the Transient to act as the master audio (sample rate) clock for your computer audio. By using two sample rate clocks all the usual suspects are available; 44.1, 48, 88.2, 96, 176.4, & 192Khz. Combined with a galvanically isolated S/PDIF on 75 ohm BNC, this USB converter provides a clean way to interface with your favorite DAC (Digital to Analog converter). It even goes further, to provide I2S outputs via 5 pin DIN and HDMI. These I2S outputs separate word clock from data stream, and a handful of Hi Fi companies have begun using this interface*. Even if you don’t use the advanced I2S outputs, the true 75 ohm BNC S/PDIF allows for correct impedance when connecting to a DAC of your choice.

A look inside. Constucted from double sided glass/epoxy circuit boards w/ 2oz copper traces. Note: XMOS board, carefully selected parts/high-speed ribbon cable – Photo by Vahan Baladouni

With a clean modern faceplate, this unit has an industrial refinement about it. The sample rate is easily seen by one of six blue LEDs that indicate a lock. Steel hardware against the aluminium chassis provides a tasteful contrast, and the tactile feel of the precision machined volume buttons exemplify build quality. It is evident that a keen eye laid out the chassis design, for even the rubber feet and front logo have a machined inlet for their precise placement. Powering is simple – the Transient pulls direct current from your USB port, making it truly portable. Taking it a step further, the VDC-5 MK II power supply can be purchased for those wanting to squeeze out every last bit of resolution.

The VDC-5 MKII power supply and Transient II USB converter – 2V RMS and mute setting are quickly engaged by pressing/holding one volume button and pressing the other – photo by Vahan Baladouni

While the USB to Digital Audio conversion is the primary purpose, CI Audio has also included a built-in DAC (Wolfson) with RCA outputs and digital volume control**. Those neatly machined volume buttons also allow quick-setting of 2V RMS output for a proper analog level to feed your preamp. Even without a pre-amp,utilizing the built-in volume allows you to plug directly into an amplifier. This type of digital volume maintains excellent L/R channel separation, but for listening at lower levels a separate pre amp may be prefered.

Transient MK II and VDC-5 MK II rear. Connections include true 75 ohm BNC and i2s over DIN and HDMI, and DC input for optional power supply…don’t forget the DAC RCA outputs! photo by Vahan Baladouni

Transient MK II/Listening to the USB to S/PDIF conversion

  • Speakers: Green Mountain Audio Eos HX
  • Source: Macbook Pro w/ Pure Music
  • DAC: Crane Song Avocet
  • Amp: Anthem MCA-2
  • Cables: Audio Magic, Shunyata, DH Labs custom BNC to RCA

With a Macbook Pro running Itunes and Pure Music, I tried the Transient MK II as powered with DC from the USB connection. For this trial, my Crane Song Avocet was the DAC and I fed it from the Transient’s S/PDIF output. Audio MIDI setup quickly recognized the attached USB Audio device, and so did Pure Music.

Now I was ready to dive into some tunes. I decided to try the standard red book CD sample rate of 44.1. Without a hiccup, all the audio files played back. I found the CI Audio unit to present a solid digital signal that my DAC could easily decode. Listening to Beethoven symphonies conducted by Karajan was simple and musically involving. The width and depth of the concert hall was spacious and localization was very clear. Not only were these some fantastic recordings, but the Transient II transmitted the data without error. With more obvious resolution, I began recognizing the superior image stability and reverb tails with the Transient’s USB to S/PDIF conversion. Having used a variety of computer audio interfaces, the Transient MK II’s ability to transmit all the digital data started to become evident. This brings me to another point; even though some DACs can do jitter reduction (i.e. Crane Song Avocet), feeding a DAC a lower jitter signal will always result in cleaner audio reproduction – the Transient MK II uses custom sample rate clocks with less than 1 psec of Jitter.

Moving on to hi-resolution audio files (24 bit/ 88.2 and above) was a cinch. A quick change of the sample rate in Pure Music had me listening to Stevie Wonder at 96khz. The Transient MK II obediently changed sample rates with LED indication, and the music commenced. 24/96 transmitted without any issues and sounded great. Stevie Wonder’s multitracked clavinets smacked some funk with clean articulation and all the harmonic content. I even cued up some stereo 24/96 SFX I recorded and was impressed at the image stability, and clarity. The clean resolving presentation of the Transient became very obvious even when low-level SFX were played. Using the Transient for my professional audio needs was certainly a no-brainer.

But, what about upsampling standard 44.1 files? By allowing your computer/Pure Music to do the upsampling in 64 bit mode, the math can be done very accurately. This allows the Transient MK II to act as master clock for your upsampling requests. Upsampling an old Count Basie recording (Japanese transfer) proved to be quite worthwhile. Moving from 44.1 to 176.4 was a fun experiment. I for one enjoyed the sound presented this way, and felt that a smoothness was brought to the presentation. If you consider digital recordings harsh, this may be the way our ears respond to different degrees of filters present at different sample rates. With the solid master clock of the Transient MK II, you can experiment with upsampling and choose what sounds best to you.

VDC-5 MK II Power Supply

Channel Islands also offers an optional power supply that provides high current and low noise for the Transient MK II. This unit cosmetically matches the Transient, and eliminates the use of DC from your computer’s USB port. Since the Transient smoothly switches between computer power or the VDC-5 MKII, it was easy to hear the differences with and without it. Bass definition, extension, and stereo image stability were noticeably improved when using the seperate power supply. While these differences were heard by several friends, it was most impressive how well the Transient operated on USB bus power alone. Those with highly resolving stereo systems may want to consider the upgraded power supply.

Transient MK II provides DAC conversion for vintage Marantz 1090 stereo receiver – photo by Vahan Baladouni

As an additional feature, the Transient MK II has a built-in DAC. My friend Jin was interested, so we decided to test it out on his vintage Marantz system with Wharfedale speakers. After speaking with the designer (Dusty Vawter), I was told the Wolfson DAC has been carefully implemented to extract the best possible sound. Regardless of the DAC being a secondary feature, I thought the sound was indeed musical. Using the analog 2V RMS output into the Marantz 1090 proved to be quite lovely. More so, the presentation was clean, smooth, and involving. The tonality of instruments were natural and voices sounded equally organic. While arguments can be made for the various differences in a DAC’s sound, the one thing that stood out was that nothing stood out. No exaggeration of the audio band, just clean audio that was easy to engage and listen to for hours.

The CI Audio Transient MK II brings Hi-Res music & Internet Radio to your HiFi! photo by Vahan Baladouni

As my friend and I were trying out the Transient MK II, we decided to check out some internet radio stations. I quickly found WWOZ, my local radio station in New Orleans. Soon, we were listening to Jazz and Funk from the Crescent City! USB converter, DAC, Hi-Res audio, and discovering internet radio through my HiFi…This little device brings a world of music into your home. You’d be surprised how good some of these stations can sound when converted through the Transient MK II. Sure, these weren’t Hi-Res audio streams, but the content was never-ending – that could now play through my stereo! This was certainly icing on the cake, and hours later we were still listening to various radio stations from around the world.

With modern sleek looks and smooth operation, the Transient MK II excels at getting the most from your computer audio. The build quality and value truly makes this product stand out. Without reservation, I highly recommend looking into this superb USB converter!

The Transient MK II includes a USB cable, one BNC to RCA adapter, and a 5 year warranty. Click here for information on Channel Islands Audio.

Transient MK II – $699.00

VDC-5 MK II – $329.00

Follow-up:

DAC section

My overall impressions with the Transient MK II were very good. While I have heard DAC sections that resolve more absolute detail (and twice the price), the analog output provides even sonics with no exagerations in the audio spectrum. The quality of the analog output made it enjoyable in all the systems I tried; Luxman L-550AX, Marantz 1090, & the NAD C 725 BEE. The Transient as a pre amp into my Anthem MCA 2 was a clean & imidiate sound. My biggest impression – this device has quality and portability that I have never experienced in a compact USB converter. This device makes it easy to share your quality recordings on friends stereo systems.

Digital conversion:

The USB to S/PDIF conversion works much better, and more reliably than my Yellowtek Puc2 USB asynchronous converter. I suspect several things that are contributing to this; understanding high-speed USB 2.0 and how to fully implement it for all sample rates, XMOS, custom word clocks, galvanic isolation, and proper s/pdif impedance.  All the sample rates work with no fuss!

*I2S is a digital audio connection being adopted by several audiophile manufacturers including Audio Alchemy,Perpetual Tech,Camelot, PS Audio…some Future CI Audio products will include this input connection.

**Connecting the DAC output directly to my Anthem MCA amp and Eos HX speakers was very worthwhile. The sound was quick, clean and without any added color or tone. This feature is great to compare your own line stage/pre amp to.

Hegel Music Systems

On my last day at T.H.E. Show Newport I walked toward the light.  Literally, the only audio exhibitor who had the beautiful California sun filling the room was Hegel Music Systems of Norway. Hegel electronics paired with Amphion speakers produced a clean modern aesthetic that made me feel welcome. I soon learned that the technology behind Hegel amplifiers was truly unique.

Eileen of Hegel really took her time to demonstrate and explain the technologies contained within their product line. The demonstration focused around using a Hegel CD player, 2 different DACs (digital-to-analog converters), and the H70 integrated amp to power the Amphion speakers. The idea was for a listener to become familiar with a CD music track (converted by the CD player’s onboard DAC) then hear the same track converted through the two different outboard DACs made by Hegel (the HD11 and the HD20). The sonic benefits in jitter reduction and power supply design were readily noticeable. Well Done.

Hegel H70 Integrated Amplifier

The amplifier technology from Hegel was impressive in that it is able to maintain a high damping factor *(greater than 1000) while using a class A/B design. I was told that by eliminating feedback loops associated with other amp designs, the Hegel amps are able to have less distortion. They use what they call a “feed forward” design. I can certainly attest that this little H70 integrated amp (70 watts a channel into 8ohms) was truly a beast! I can imagine that speakers with decent sensitivity will love the H70’s control and articulation. Most importantly though was the fact that the Hegel amplification seemed to get out-of-the-way. It amplified music effortlessly and seemed to sonically disapear. The H70 also provides analog rca inputs and even a balanced pair of inputs. Hegel even gets you set up to receive digital inputs like coaxial/spdif, optical, and even a USB input for computer audio.

While I have not had a chance to fully review these amps with speaker I am familiar with, I have a good sense of the sonic picture since the Amphion speakers were used  – A Finnish company that has ties to Genelec from the professional speaker world.

Below please find some pictures of the Hegel designs:

Hegel H20 amplifier

Hegel H100 integrated amp

*See my post on Green Amplifier Technology

Hegel amps are GREENER *It should also be noted that the Hegel Class A/B amplifier designs use 60-70% less power than traditional Class A/B amplifiers. This is due to Hegel using a lower bias current on the amp’s transistors.

Here is a video about the Hegel design.