|Posted by Amine Slimani on February 16, 2011 at 2:45 PM|
These past 2 years, we have seen an increasing number of USB to SPDIF devices hit the market. While the first devices were seriously limited in both connectivity and raw performance, they were mainly intended to provide a means to connect our computers to external DACs. The newest generation of usb to spdif converters raised the performance bar, and some USB converters can now sonically outperform the slowly dying CD Transport breed. Today, audiophiles can shop for USB converters not only for their usefulness but also for their sonic performance.
When do you need a USB to SPDIF converter? What should you look for?
To answer the first question, there are two possibilities: either you have a DAC with no USB input or you have a DAC with a subpar USB implementation. There are very few (and usually costly) DACs on the market that have a good USB implementation. Most of the DACs with USB inputs use subpar implementations in order to have a “USB ready” label. Most of the time, the SPDIF or AES input will outperform the USB input in the same DAC.
To answer the second question, when you look for a usb to spdif converter, one of the first things to look for is if the device is able to pass bit perfect data at all the available rates: 44.1, 48, 88.2, 96, 176.4 and 192. While that might sound obvious, most of the USB converters that use the Tenor chip are limited to the following sample rates: 44.1, 48 and 96. The performance side is a little bit tricky to check for as even if you can find jitter numbers about USB converters, they don’t tell much because how and what is measured can vary much from one set of specifications to the other.
Adaptive vs. Async: does it matter?
While I personally fell into the marketing propaganda for a while, believing that async (or asynchronous usb) is the only way to go, I have learned through experience that a better built adaptive converter can actually outperform sonically an asynchronous converter: Teralink X2 vs. Musiland, Digital Interface vs. Hiface.
Reviewing the Kingrex UC192
Given that I reviewed a number of usb converters these past few months, Kingrex offered me to review their newly released UC192, which is their first USB to SPDIF converter (or Digital to Digital converter as they call it).
I accepted the task for 2 main reasons: Kingrex is a company that is generally known as offering good price/quality ratio products, and contrary to many converters out there, Kingrex is not using the Tenor chip but rather had worked on an implementation of its own.
Part 1 - Description of the UC192 and the test system
Description of the Kingrex UC192:
KingRex UC192 is a high-quality computer audio transport interface for those wishing to stream high-resolution files to an existing DAC. The UC192 can transfer from PC or Mac at 16but/44.1KHz to 32bit/192KHz through S/PDIF & I2S outputs. The UC192 runs isochronous with an adaptive clock generator to auto sync with the host. The master clock generator is a classy 1ppm TCXO unit with proprietary low-jitter drivers for Windows & Mac. Direct Sound, ASIO4ALL and WASAPI are all supported and run smoothly. The UC192 is housed in an oval cross-section aluminum case with black hairbrush polish. It measures 88 x 82 x 24mm."The UC192 ships with Windows and Mac drivers that need to be installed on your computer. An external 7.5V power supply is provided.
Some more specs...
Item: UC192 USB to SPDIF digital to digital converter
USB interface :
-USB 2.0 High/Full Speed compliant
- Adaptive Clock Generator for Audio Streaming Synchronization
- Supports CRC Error Correction for Playback Data.
-Supports Wait -status
- Up to 400 kb/s Data Transfer Rate
IIS audio interface:
- Sample Rates Supported: 8Khz, 16Khz, 32Khz, 44.1Khz, 48Khz, 88.2Khz, 96Khz, 176.4Khz, &192Khz
-Bit Rates Supported: 16bit, 20bit, 24bit, 32bit
-1 Stereo SPDIF output through Integrated IEC958 Line Driver
-16,20, 24bit Mono/2 Channel
-Sample rates support : 32Khz, 44.1Khz, 48Khz, 88.2Khz, 96Khz. & 192K.
- 1ppm TCXO
Note 1: while the UC192 can output I2S and AES/EBU, I only tested the rca spdif output in my review.
Note 2: While a 1PPM clock might sound impressive, it doesn’t actually tell much about the actual performance of the clock. A more interesting data would have been to have the “ps” figure of the clock.
Below is a picture I found about the internals:
Transports: Jkeny’s modified Hiface MK1, Musiland Monitor 01 USD, Teralink X2, Audio-gd Digital Interface
Digital cables: Hifi Cables Sobek, Oyaide DB-510
DAC: Audio-gd DAC-19 DSP (with DSP1 V5)
Interconnects: Deep Sounds SPS ACSS, Artisan Ultimate Silver Dream RCA
Amplifiers: Audio-gd C2
Power cords : Hifi Cables & Cie PowertransPlus (x2), Hifi Cable & Cie SimpleTrans, Olflex power cords
Power filter : Bada LB-5600, Essential Audio Tools Noise Eater
Vibration Control : Aktyna ARIS decoupling feet, Maple and Acrylic Platforms, Sandbox, Various Herbie’s Audio Labs tweaks
Reference Tracks used for this review:
Rachmaninoff Dances - HD Tracks - 24/96
Mahler - Symphony n 5 - Decca - 16/44
Mozart Violin Concertos - Marianne Thorsen - 2L - 24/96
Sol Gabetta - Schostakowitsch Cellokonzert Nr. 2/Cello - 16/44
Vivaldi - Concerto for 2 violins - Carmignola/Mullova - 16/44
Natalie Dessay - Italian Opera Arias - Emi Classics - 16/44
Puccini - La Boheme - Decca - 16/44
Dunedin Consort - Messiah - Linn Records - 24/88
London Symphony Orchestra - Carmina Burana - 24/88
Keith Jarrett - Paris / London - Testament - 24/96
Glenn Gould - The Goldberg Variations 1981 - 16/44
Hans Zimmer - Gladiator Soundtrack - 16/44
Hans Zimmer - The Dark Knight OST - 16/44
The Essential James Bond - City of Prague Philharmonic orchestra - 16/44
The Dave Brubeck Quartet - Take Five - 16/44
Jazz at the Pawnshop - HD Tracks - 24/88
Ella Fitzgerald / Louis Armstrong - Ella & Louis - 24/96
Diana Krall - From this Moment on - 24/88
Diana Krall - Live in Paris - 16/44
Diana Krall - The Girl in the Other Room - 16/44
Norah Jones - Come Away With Me - 16/44
Patricia Barber - Companion - 16/44
Johnny Cash - The Essential - 16/44
The World's Greatest Audiophile Vocal Recordings - Chesky - 24/96
The Kinks - One for the Road Live - 24/96
The Eagles - Hell Freezes Over - XRCD - 16/44
Soundrama - "The Pulse" Test CD - 16/44
Head-fi/Chesky Sampler - Open Your Ears - 24/96
Part 2 - Setting up the UC192:
Drivers and firmware:
The first sample unit I receive (in December) had a faulty firmware which caused it to slow down the computer considerably in Windows XP and some older Mac OS issues. I reported the problem to Kingrex and they were very helpful in determining the problem and providing a solution. I sent back the review for a firmware update and as soon as I received it the second time (early January) everything worked without a hiccup.
The only thing that one should be aware of is that the UC192 outputs by default to the I2S output while the spdif one is muted. Hence, the UC192 can only work with ASIO4ALL (in Win XP) and by selecting the second output on ASIO4ALL control panel.
I was told by Christine from Kingrex that a future Driver/Firmware update will allow to output to both I2S and Spdif at the same time. This should allow the UC192 to be used with any media player without the need for ASIO4ALL.
I read in the manual that Kingrex products needed 200 hours of burn-in.
In my case, I allowed the UC192 to “burn-in” for 2 weeks before engaging in critical listening. Though, I have to admit that I couldn’t detect any significant change in the burn-in period.
Note: In comparison, the Teralink-X and Teralink X2 changed dramatically with burn-in during the first week of use, going from bloated and confused to a nice warm and relatively more neutral signature.
I tried a few USB cables with the UC192 and while there were differences between different models, it was relatively small in scale, which is a good thing for a USB converter.
Converters that are too sensitive to the USB cable such as the Musiland, Teralink... are flawed in my opinion.
While my “reference” Wireworld Ultraviolet USB Cable was more detailed and open than Kingrex’ stock USB cable, the difference was rather small and Kingrex’ cable had a weightier tonal balance which complimented better the sonic signature of the UC192.
In my system, I subjectively preferred J River Media Center over Foobar v1.0. I encourage anyone trying the UC192 (or any USB converter for that matter) to try them with different media players. You will be surprised by the results.
As a general note, Kingrex recommends Foobar because it is free and also because they have tested it to be bit perfect at all sample rates with their UC192. When I asked them, they didn’t seem to have tested the UC192 with J River Media Center.
I tried the UC192 in 2 scenarios: directly into my reference DAC and also into a reclocker/upsampler.
In the first scenario, I turned the PLL off on my DAC19DSP in order to emphasize the differences between different transports. With the PLL off, the dac19dsp becomes very (perhaps too) sensitive to the quality of the transport. My favourite DAC becomes unlistenable with entry level converters such as the Musiland.
In the second scenario, I used the UC192 as a transport and inserted the Audio-gd Digital Interface (reclocker/upsampler) in between the two. That way, I was able to compare the UC192 (+digital cable) against the Digital Interface running from its USB input. While the UC192 (+SPDIF) was slightly better than straight USB, I could live with both solutions. The same cannot be said for entry level USB converters such as the Musiland which don’t perform quite as well as the straight USB input of the Digital Interface.
Given how the differences were small in scenario 2 (which should represent a DAC with excellent jitter rejection),I decided to focus my review on the worst case scenario (scenario 1).
So while reading the review, keep in mind that I tested the UC192 with a DAC that was very sensitive to jitter and against a tweaked version of the Digital Interface which I slightly prefer to Jkeny’s battery powered Hiface (which has received rave reviews by me as well as many reviewers).
Note: My reference converter these past few months has been the “tweaked” Digital Interface which I use with the following: a linear external power supply, an after market OFC power cord, an upgraded 1ps Tentlabs XO and upsampling set to 96K. I am also using Herbie’s Audio Stabilizers and Tenderfoot, as well as Acrylic sheet on top of a sandbox.
This “tweaked” Digital Interface has slightly outperformed Jkeny’s Hiface MK1 in my particular set-up to give a point of reference.
I need perhaps to add a last comment regarding my testing methodology before getting to the sound.
I rely mainly on long term listening for writing a review. I personally believe that short A/B comparisons can help in the reviewing process but are not suitable to really evaluate the intrinsic qualities of a component. Some audiophiles sometimes get lost in comparing gear to other gear and forget to compare the sound to the live representation. Recordings themselves are not neutral, and you get a great variation in quality and methods of recordings from one album to the other.
It is important to play a wide range of albums to truly understand the sonic signature of the component under review. That can’t be done solely on comparison basis on a limited set of tracks.
I try to understand the sound of the component as a whole before getting into the descriptions of the pieces. I also try to present as much as possible what I heard and how I heard it before presenting my interpretation and conclusion.
In my experience, the same two listeners can hear the exact same thing but draw different conclusions.
I believe that every listener and reviewer has their own biases and subjective preferences no matter how hard they try to be objective.
Let’s move to the sound!
Part 3 - The Sound:
Timber & tonal balance:
In my experience with USB to SPDIF converters, I can put the converters I came across in three categories: lean and bright sounding (EMU 0404 USB, Musiland, M2Tech Hiface), Warm or bloated sounding (Teralink X, Teralink X2) and relatively neutral (Jkeny’s Hiface, Digital Interface).
The UC192 falls in the lean sounding category. While it is to some extent better balanced than a Musiland or a stock Hiface it doesn’t sound quite as neutral as Jkeny’s Hiface or an upgraded Digital Interface (wit a 1ps XO clock and 96K upsampling set to 96K).
With the UC192, there is a slight mid treble brightness, and a slight roll off at the frequency extremes in comparison with the “big boys” (Jkeny’s Hiface and DI). However, the UC192 irregularities are far smaller in scale than the mid treble brightness of the Musiland or the mid-bass bump of the Teralink X series.
So I would say that save for that slight brightness that might emphasize sibilance with some recording/gear, the UC192 has a relatively neutral tonal balance for the category.
So how about the richness of timber? In my experience, what separates an "OK" converter from an excellent is the richness and diversity of colour it uses to draw a sonic picture. With some converters, you have the impression that you only have the fundamental and that the upper harmonics are missing (giving that “digital” sound). With the better converters, the harmonics can sound as true and as diversified as life (or at least it can try to approach it).
The UC192 falls somewhere in the middle between entry level converters and the upper end I have tested. If I had to give numbers, I would say that the UC192 is operating at 20 bits, the stock Hiface is operating at 16 bits, while a battery powered Hiface or a “tweaked” Digital Interface are operating at full 24 bits.
What it means is that while in most recordings you probably won’t miss anything, with high quality and well mastered classical recordings, you will notice that a violin or a piano is slightly off or simplified. This isn’t such a big issue because you usually need something better to compare to in order to realize what you are missing.
Replacing the stock switch power supply with a linear one does improve a little bit the tonal balance and richness of timber but it remains nonetheless a little behind the “big boys”.
In this department, the UC192 performs relatively well. Because it is voiced slightly more aggressively than my reference converters, the transients can seem faster on short listening, which also has an effect on the perception of dynamics.
I doubt anyone using an entry or a (non-tweaked) mid level DAC will ever complain about the dynamics of the UC192 which are better than what you get with a Musiland or Teralink X2 for instance.
Soundstage & Imaging:
The UC192 can throw a relatively big soundstage, with relatively good pinpoint imaging. It is a step above entry level converters such as the Musiland and Teralink X2. Also, from triangulating, it is better than the stock Hiface.
However, in comparison to the best of class (Jkeny’s Hiface, Digital Interface), the UC192 is more in your face and lacks the 3D palpability of those better converters. The good thing is that you might not be aware of this limitation if you haven’t heard better or if you are using less revealing gear than the ALO recabled Beyer T1 I used for my review.
The limitation in soundstage and imaging will be most noticeable during intense passages of symphonic orchestras, where you won’t get the same separation and air around the instruments as you get with the “big boys”. On most recordings, it wasn’t an issue in my experience.
Transparency & Definition:
In my reviews, I like to make a difference between perceived resolution and real resolution.
On quick listening or with some test set-ups, the perceived resolution is affected by the actual resolution of the component under scrutiny as well as the tonal balance. The UC192, which as has a slightly forward tonal balance, can increase the perception of resolution in some systems: entry/mid level and warm systems.
When speaking about real resolution, I would say that the UC192 performs quite well and only the tiniest low level details and ambiance clues seem to be missing in comparison with the “big boys”.
Overall, I have been pretty happy with the performance of the UC192. It is a very good converter, with a relatively good tonal balance and with no big flaw to speak of.
So should you get a UC192? In my opinion, it really depends on what you are shopping for. If you were looking to buy a stock Hiface which can do 24/192 (as well as 88.2 and 176.4), look no further: from triangulating the performance of the UC192, I can say with confidence that the UC192 will do a much better job than a stock Hiface.
However, if you are looking for something that can play in the same ballpark as a battery powered Hiface, this is not the usb converter you are looking for, nor should it be given its entry level pricing. Adding a linear power supply does indeed raise the performance a notch but not to the level of a battery powered Hiface.
Overall, the UC192 is a strong performer under the $200 barrier.