USB-to-S/PDIF Convertors - KingRex UC192

KingRex UC192 £159

USP: Optional battery power supply, entry level 32/192 capable converter with proprietary USB drivers. Adaptive.

Kingrex say “the UC192 can transfer from PC or Mac at 16bit, 44.1kHz to 32bit, 192kHz through S/PDIF and 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 TXCO unit with proprietary low-jitter drivers for Windows and Mac. Direct Sound, ASIO4ALL, and WASAPI are all supported and run smoothly”. The UC192 ships with a Windows driver (ASIO4ALL) that needs to be installed on your computer and the Kingrex manual explains how, in a procedure that will have Mac users rolling around the floor laughing.

The unit is not USB powered like many, so a USB power supply upgrade will not help. It has its own small wall wart supply, delivering 7.5V at 200mA.  A battery version is available however.

The UC192 works right up to 24/192 so will handle top resolution digital audio. Balanced and unbalanced S/PDIF outputs are fitted, electrical only; there is no optical output. However, the electrical outputs are isolated by pulse transformers to break hum loops and reduce electrical noise. Transformers need correct termination to minimise jitter; the mini-XLR output must see 110 Ohm termination and unbalanced 75 Ohm.

Very unusual is provision of an I2S output via an RJ45 socket. This is an internal link, where clock and data are carried separately (there is no agreed socketry for it). It is preferable to S/PDIF but few downstream DACs have a suitable input – and none from Kingrex, which is peculiar.

Kingrex advise manual driver installation before connection to a computer to prevent Windows automatically installing an unsuitable driver. Kingrex recommend Windows 7 and Mac OS-X 10.6 (Snow Leopard) or later, but older OSes will work, including XP.

SOUND QUALITY

Listening to the 'Dance of the Tumblers' shows a good presentation, up there with the others. There seems to be a touch more sheen to the sound, not unpleasant, just a bit ‘varnished’. The bass is a tad slower than the Halide Bridge and there is just a fraction less air to the sound. I have to mention at this point, that using JPlay in JRiver yielded the blue screen of death to my Windows 7 laptop, and I had to use the fallback of Foobar, which coped well. Not a level playing field, but JPlay doesn’t integrate with every convertor at present. When I try and listen to the Mozart on Foobar, there seems to be a problem with the awkward sample rate of 88.2, and Foobar doesn’t pick this up, so an exact comparison, like-with-like is impossible.

In the Mozart Prague opening, I’m aware of an issue in the Snow Maiden dance, of a looser bass operating – a bit splashy.

The convertor (top) has a mini XLR balanced output at left, plus I2S through an RJ45 socket at right.

MEASURED PERFORMANCE

The Kingrex result was dominated by appalling clock drift, no less than 7nS, seen at left in our jitter analysis. This is at least x20 more than expected from any digital source, including CD. Using the external battery supply and / or the AES/EBU balanced connection made no difference. Otherwise, signal related and random jitter figures were reasonably low, the balanced connection showing slight improvement over unbalanced.

Recording sample rate 44.1/Output sample rate 48k

clock drift 7nS

signal related 40pS

random 5pS

KingRex UC192  £159

Kingrex

www.kingrex.com