The Well-Tempered Computer, an introduction to computer audio

Tuesday, March 27, 2012

Trigon Chronolog

Networked CD/DVD player/ripper

wav, mp3, flac, cdda, nsv, m4a, aac, strm, pls, rm, mpa, wma, ogg, mp2, m3u, mod, amf, 669, dmf, dsm, far, gdm, imf, it, m15, med, okt, s3m, stm, sfx, ult, uni, xm, sid, ac3, dts, cue, aif, aiff, wpl, ape, mac, mpc, mp+, mpp, shn, zip, rar, wv, nsf, spc, gym, adplug, adx, dsp, adp, ymf, ast, afc, hps, xsp

OS: Linux
Protocol: UPnP
Networking: 1GB LAN Ethernet/WLAN-WiFi interface

Graphical user interface using touch-WEB portal
Bit rate and frequency display
Automatic updates via the Internet

Output: RCA/XLR and HDMI/DVI

Website: Trigon
Price: $9,495

Monday, March 26, 2012

The best optical drive

A typical audiophile worry is “Is my rip bit perfect?”
There a couple of things to say about this subject and I do it here.

Another typical question is “What is the best optical drive to rip my CDs”
The answer is often Plextor.
They do have an excellent reputation but years ago they stopped making their own drives.
Today a Plextor is simple a rebadges OEM.

Little is known about the accuracy of optical drives from different brands.
But there is some empirical data.
The AccurateRip database tells you if your rip is accurate or not.
It can be used the other way around too, how many rips are accurate given a certain brand/model.
A list can be found here: CD/DVD Drive Accuracy List 2012

Review: Kingrex UD-384 and U-Power

We came across Kingrex's product while searching for a power supply upgrade for another manufacturer's DAC.  Kingrex's PSU MKII proved to be one of the most cost effective upgrade we can recommend to a USB or wall wart powered DACs.  We weren't the only one, but also numerous favorable feedback from various internet forums.

At the time Kingrex also makes a very nifty USB to SPDIF converter (they prefer to call it DDCs - digital to digital converters) called the UC192 (still in the line up, firmware upgraded to 32/384 conversion through i2s).  We were so impressed with the power supply that we contacted Kingrex for a review unit.  Kingrex informed us that they were about to launch a new model, which is not only a DDC, but also a high resolution 32/384 capable DAC/DDC plus a dedicated power battery supply designed for it.  So we decided to wait for the UD-384 and U-Power which are the subjects of our review here.

Dynamic Duo

The combo arrived and we are quite surprised to see how small they are.  They are light (less than 200g each) and compact, each about eleven cm long, and made of anodized extruded aluminum.  They are quite well made but rather light and 'casual' looking.  The U-Power is optional ($179) and in such case the UD384 would be powered by a supplied generic 7.5v wall wart.  You can then choose from two upgrade path - the U-Power, or the more expensive AC-powered PSU MkII, please do note that you will have to specified a 7.5v version for the latter.  For those of you who are suspicious of  how good clean power can do to the sound, you'll be surprised that for hifi equipment, a significant percentage of the overall sound quality depends on that.  Basically you are what you eat.

The unique thing about the UD-384 (US$479) is that it is both a DAC and a USB to SPDIF converter.  We think this is such a nifty idea since you may, in the future, want to upgrade to a more extravagant DAC which you can still use the unit's asynchronous USB conversion that works up to 24bit/192kHz (SPDIF's technical limitations prevents the UD-384 to output higher than 192kHz).  There are however no other digital inputs except USB.  Drivers are supplied for Windows, there are no drivers necessary for Mac users.

Internal digital engineering is quite unorthodox.  For instance, there is a single 'anonymous' chip handling USB receiving, and digital to analog conversion.  There is also a single high precision thermally stabilized TCXO 1ppm super low jitter clock giving beat to all of the sampling rates covering 44kHz to 384kHz.  High quality resistors and capacitors are used through out with nice attention to details on where these components would have effects on the sound.  The other peculiar thing about the UD-384 is that when used in DAC mode, with the current firmware, it can decode the highest specified 384kHz but not 352.8khz.  We believe this is due to its minimalist sigle-chip/single-clock configurations.  However, Kingrex's engineer probably has reasons to go minimalistic as proven by its sound quality - read on. 

The U-Power internals are also well thought-out.  There are  two 3.7v Li-ion batteries supplying 2600mAh of power. Charging is done through the supplied wall wart, and a circuit disconnects noisy A/C supply during battery playback. There's also a USB power port on the U-Power, I was hoping this is a power input but it actually is an output which can feed 5v power to a USB device.

They rock!

How does it sound? In one word - impressive.  If you do a blind test having your typical big shiny aluminum box high end DAC side by side and ask your friends to guess, they would surely have it wrong.  What we are most surprised by is its ability to handle slam and weight.  The resolution is also amazing with air and openness rivaling the best out there, both with normal 44.1k CD rips and native high resolution files.  Having said that, this is not a DAC for detail freaks.  It doesn't draw you into the minute details like some of the DACs do, but more the coherent message.  It just excels on tempo and energy and plainly "boogie".  Soundstage is spacious, precise and wide, with images being so stable you can reach out and touch them.  Although the stage is not as deep as some, but enough for you to work out the layers without feeling a wee bit of congestion.  This is not a hifi-sounding DAC, it is ever so smooth without edginess of lesser DACs.  Pace Rhythm and Timing are excellent breathing down the neck of much more expensive units.  The mid bass is tight but never bloated, which puts it on the clean and taught side of the scale as opposed to romantic and lush tendencies of  tube peers.

Most of our listening was with the supplied U-Power unit.  However, we did have on hand the dearer Kingrex PSU MkII for comparisons.  The differences were quite small.  You will have a slight better macro dynamic with music with big dynamic range swings, but the all else were excellent as it is.  The synergies of the two units are there and is highly recommended you get the UD-384 and U-Power as a combo.


Once in a while you come across a product that are so deceptive simple in appearances. These little boxes proved to be so much for the price.  If you are new to computer audio and do not want to spend a fortune on state-of-the-art converter or DAC, the UD-384 is a great future-proof USB/SPDIF converter with a superb DAC to boot.  We think the UD combo is the best sounding DAC we have heard so far in its price range.

Sunday, March 18, 2012

Monkey Banana Turbo 8

Active monitor with SPDIF input

System'2-way' active
Price € 399,- each
Digital inputS/PDIF
HF driver1-inch natural silk dome
LF Driver8-inch ceramic cone
Analogue inputXLR/TRS Combo connectors,
Amp30/80 Watt A/B
DSPBuild-in DAC

Website: Monkey Banana

NOCS NS2 Air Monitors

Active speakers with AirPlay technology $399
  • Frequency response: 20 Hz - 20 kHz
  • Woofers: 3" Kevlar with dual magnets
  • Tweeters: 3/4" silk dome
  • Digital Signal Processor: 32-bit
  • Total Harmonic Distortion: <0.15%
  • Signal-to-Noise Ratio: > 85 dB
  • Amplifier type: Class D
Website: NOCS 

Tuesday, March 6, 2012

John Kenny JKSPDIF MK3

Modified HiFace 24/192 asynchronous USB - SPDIF converter
Manufacturers description:
  • it is completely off-grid, powered from 2 internal batteries (these will last about 24 hours between charges)
  • it is portable - no need for external power supply when listening to audio
  • the SPDIF output stage is now based on the Wolfson WM8804 chip
  • SPDIF signal is now within spec
  • it comes in an aluminium enclosure
  • it now uses a USB type B socket
  • internal battery charger - requires user supplied 9V or 12V DC supply
Website: John Kenny
Price: €320

Sunday, March 4, 2012

NAD M51 Direct Digital DAC

35-bit 844kHz DAC and Digital Preamp.

Manufactures description:
Running at 108MHz, the M51 resamples the incoming pulse code modulated (PCM) signal and converts it to a pulse width modulation signal (PWM) with a sampling rate of 844kHz. Operating in a differential mode with double precision, the M51 has state-of-the-art specifications for low noise and freedom from distortion. The extreme headroom afforded by the 35-bit architecture allows for a DSP-based volume control that does not reduce resolution. Even with 24-bit high definition signals, the output can be attenuated by 66dB (very, very quiet) before bit truncation begins.

Rated Distortion (THD+N with AES 17 filter) <0.0005% (0dBFS)
IMD Distortion 0.0001%
Signal/Noise Ratio <-125dB (ref. 0dBFS 2V out)
Channel Separation >-115dB (ref. 0dBFS Volume -1dB)
Sample Rate 32kHz to 192kHz (USB and digital S/PDIF)
Frequency Response ±0.5dB (ref. 20Hz - 96kHz sample rate)
Output Level 2V (ref. input 0dBFS)


  • SPDIF Coaxial x 1
  • Optical x 1
  • HDMI x 2 (stereo only)
  • USB Audio Codec 2.0: asynchronous 24/192 support


  • HDMI Video Out (3D video pass through)
  • Analogue Unbalanced and Balanced