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Product Review - Musical Fidelity X-DAC Outboard Digital-to-Analog Converter - July, 1997

Daniel Long

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X-DAC Click here for larger image

Musical Fidelity X-DAC HDCD Digital-to-Analogue Converter THD: <0.02% 20Hz-20kHz Unweighted, <0.008% 20Hz-20kHz "A" weighted; Frequency Response: 0.2dB 20Hz-20kHz; S/N ratio: better than 90dB Unweighted, better than 100dB "A" weighted; Conversion type: 18-bit Co-phase 8x oversampled; Power Requirement: 12V AC 500mA (via mains adapter supplied); Dimensions (mm): 110 x 110 x 220 (W x H x D), width and height include feet; S$799, US$499.

Introduction

Are you happy with your CD player? Chances are you are but you keep hearing about this new HDCD thing. High Density Compact Disk? Don't laugh! In our corner of the woods, that's the translation that comes to mind when you mention HDCD, not High Definition Compatible Digital. What a mouth-full! It's a wonder it's caught on, much less taken off.

So that is the question, isn't it. Has it taken off? Well, when you can find HDCD processing in players anyone can just pick up off the shelf at an audio store without having to stop by and rob a bank on the way, then I guess it has.

X-DAC

The X-DAC is another of Musical Fidelity's X-Series of budget performance components to be introduced. The first was the (insert drum-roll here) X-10D Tube Line Stage. I first saw the X-DAC at one of my usual Friday evening hangouts, Margil Hi-Fi (you see them in a photo accompanying Robert Harley's coverage of the Singapore HEX show an issue of Stereophile last year). Just sitting there. Couldn't believe my eyes when I saw HDCD on the round front face. I had to take it home.

The X-DAC is a DAC (Duh), designed to be added to existing CD players with digital outputs (if you have a dedicated transport, you probably haven't considered a DAC that costs less to build than your transport's front panel). It sports two digital inputs, a coax on RCA and Toslink. Output is via two sets of RCA. Unfortunately, because of how much it costs (or, rather, how much it doesn't cost), it won't pass digital signals on (to drive DAT/MD/CD-R decks etc.)

If you read other audio magazines, you probably know how the X-DAC looks (other than like the X-10D). It's certainly not like a conventional audio component. The cylinder is black, and the front panels are brushed aluminum, with 6 LEDs mounted on the latter. The X-DAC will lock on to 48kHz, 44.1kHz and 32kHz, so there's one LED for each of these as well as "lock", plus one each for "power" and "HDCD". The LEDs are BIG and BRIGHT! So BIG and BRIGHT that if I turned off all the lights in my living room in the evenings, I can read CD labels from about 2' away! By the way, the LEDs are not the same colour; one's green, four are red, and the last one's yellow. First time I powered it up, Bernadette (my 2.5 year-old) immediately went round wishing everyone "Merry Chhhhhhristmas!".

Innards

Since I actually paid money for the X-DAC, I really didn't want to open the cylinder up for a look inside. This nice person at Margil's actually offered to show me what the X-DAC looked like inside and he opened a showroom piece.

The input receiver is a Yamaha, then the input (whether through the coax or the Toslink via an opto-coupler) is cleaned up some before processing by the PMD-100 HDCD chip. What this does is dig out the information hidden in the LSB (least significant bit) of the 16-bit PCM sampled word and use it to precisely decode the high-resolution signal, and output this in a form appropriate to the DAC used. In this case, an 18-bit Burr-Brown Co-phase DAC, which uses bitstream conversion for the lower bits and R-2R multibit conversion for the higher bits. This is to take advantage of both the low-level detail and resolution of bitstream and the solid bass response and timing of multibit.

How it sounds

I connected the X-DAC to both my LD players (a Pioneer CLD-D770 and CLD-D780; the 770 is the same model as the US Pioneer CLD-703D) using the coax and the Toslink connections respectively. It in turn fed my Audio Alchemy DLC which drives a NAD 218THX. Speakers are the trusty Mirage M1090Is, driven full range.

I used a great number of CDs in my tests, including both HDCD-encoded and regular non-HDCD good and bad sounding ones (I include a full list at the end of this review). My particular reference is the Pioneer CLD-D770 which uses Pioneer's Legato Link. The Pioneer is clean sounding and can be a little lean in the low to mid-bass. It is fairly extended at the frequency extremes but not especially so; this is surprising given that Legato Link actually tries to re-create frequencies above the audible spectrum, and therefore the Pioneer should have sounded airier than it does.

The X-DAC was superior in every way to the Pioneer, save one. Let me start at the top. While the Pioneer was fairly extended, the higher treble had a grainy texture much like medium quality silk: on first inspection it impresses, but after some wearing, you start to think about having something better.

The X-DAC, on the other hand, defines silky. I have never heard treble as I have after inserting the X-DAC into the system. It wasn't up front and brash but rather smooth and understated, always pleasing, never aggressive. Cymbals were shimmery in their quality, never hissy unless it was so on the recording. There was, however, one particular recording that gave the X-DAC a hard time: this was the Mapleshade recording of Clifford Brown Live at Ethell's. The drum kit high-hats here were a little splashy and listening to track after track here was a wearing. So maybe there is a little forwardness in the mid- to extreme treble in the X-DAC. I didn't notice this on other CDs, however, if they were well recorded.

Moving down to the upper-, middle- and lower- mids, again this is where the X-DAC excelled. Vocals were presented with such presence, especially with female singers such as Rebecca Pidgeon, Janis Ian, Jennifer Warnes, and Linda Ronstadt. Each of these ladies have their very own particular style, and none was lost or obscured by the X-DAC.

So the only area where the Pioneer took the honours (and only just) was in the extreme low end. The very deepest bass on recordings such as RR's Pomp & Pipes shuddered the room to a greater extent with the Pioneer than with the X-DAC. This was really not apparent on most music recordings anyway since my Mirages roll off at about 30Hz. The X-DAC was, however, warmer sounding and fuller in the mid-bass, though only marginally so. This was not a bad thing if you have a lean sounding setup.

If I had to describe the X-DAC as a whole, rather than a sum of parts, I think I would call its presentation detailed and coherent across the entire spectrum. It sounds rather laid back, and the music comes from deep within the soundstage. As a measure of how well the X-DAC re-creates the recording venue, on CDs with ambience well recorded, the front half of my listening space (of which my speakers occupy the front edge) disappears to be replaced by wherever the CD takes me.

One last aspect of the X-DAC's performance is pace. I guess this is the least describable of any audio component's qualities. With the X-DAC, however, whenever I played an upbeat piece (would you call MJ's Black or White off his Dangerous CD upbeat?), we noticed my son would start bobbing his head in time and shaking his booty (whatever that is!). And frequently, we were worried he would get a sore neck! I guess that's pace.

Conclusion

Overall, I think the X-DAC represents an almost unbelievable bargain. I have not had the opportunity of hearing superlative converters like the Mark Levinsons or the Spectrals and though I am quite sure you get your money's worth with either of these state of the art DACs, the X-DAC is the perfect upgrade for those who've been waiting for the entry cost of HDCD to come down.
So, it is not recommended. It's mandatory.

CDs used:

HDCD

1997 CES Sampler, Stephen Stills - Manassas, Jimi Hendrix - The Ultimate Experience, Mark Knopfler - Golden Heart, Mickey Hart - Mystery Box, Reference Recordings -HDCD SAMPLER VOL II, RR-53 - MIKE GARSON: Oxnard Sessions Vol. II, RR-59 - DICK HYMAN: From the Age of Swing, RR-61 - TURTLE CREEK CHORALE: Postcards, RR-62 - DALLAS WIND SYMPHONY / FREDERICK FENNELL: Beachcomber, Arnold for Band, RR-63 - CLARK TERRY / FRANK WESS / DePAUL UNIV. BIG BAND: Big Band Basie, RR-66 - DALLAS WIND SYMPHONY / JERRY JUNKIN: Arnold for Band

Non-HDCD:

Airto Moreira and the Gods of Jazz - Killer Bees, Pat Coil - Schemes and Dreams, Janis Ian - Between the Lines, Rebecca Pidgeon - The New York Girls' Club, The Raven, Michael Ruff - Speaking in Melodies, Neil Young - Landing on Water, Clifford Brown - Live at Ethell's

Daniel Long

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Copyright 1997 Secrets of Home Theater & High Fidelity

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