The professional dCS 904 ADC sells for $12,000 U.S., and will operate at sampling frequencies from 32 (?) to 192 kHz with 24-bit resolution, while the 954 digital-to-analog converter also operates at up to 192 kHz and sells for $12,000, too. Of course, you need at least one Nagra D digital recorder (2 for 192) to make or play tapes at a cool $25,000 or so. Perhaps the Alpha 9 represents better value.
The dCS Ring DAC uses initial oversampling at 64X and other digital processing to convert the incoming 16-bit/44.1-kHz CD signal to 24 bits. According to an Arcam white paper, "The most innovative part of the design is the dCS proprietary algorithm, which continuously varies the number and positions of the selected current sources from sample to sample, as though around a circle - hence the name "Ring DAC". This ensures that the inevitable slight variations in the values of the current sources are randomly distributed throughout the quantising range. This effectively turns any tolerance errors into a random white noise signal, which is far more benign than the distortion products that would otherwise have occurred. Finally, fourth-order noise shaping is used to remove the bulk of the random noise up into the high frequency spectrum above 100 kHz, where it is easily removed with analog filtering."
The Ring DAC technology is said to deliver a very low noise floor, with typical linearity to -115 dB where it becomes masked by noise. This equates to about 19-bit performance, but a discrete cost-no-object version of this DAC was said to comfortably exceed 24 bits in averaged long-term testing. The DAC is followed by Analog Devices AD792 op amps as analog output stages surrounded by "surface mount resistors and and close tolerance PPS (polystyrene sulphide) film capacitors". The Pacific Microsonics PMD 100 digital filter is used, "set to 24-bit output word length", with "HDCD gain change in the analog domain."
The transport, as has been Arcam's recent practice, is a Sony mechanism, and it performed very well in our tests. On the Verany dropout disc, it managed track 30 (.75mm) in the single dropouts, ticking above, and locking up on 35 (2.4mm). It skipped backwards on 40 (1mm) in the narrow gauge dropouts, and locked up on 41 (1.5mm). On the CD-CHECK disc, the Alpha 9 played the first 4 levels without incident, the 4th being an error of 1.125mm (see the review of this disc elsewhere in this issue). Track 5 (1.5mm) had a constant chatter of noise, with the DED's error light also flashing continually.
In our random error test, the Arcam really shone, playing the 2:38-minute track with no skipping or hiccups, something few players in our experience have managed. The DED error light flashed often, but all of these dropouts were corrected by interpolation and were inaudible as a result. The player also sounded good in the process; many players involved in constant error correction can take on a somewhat garbled sonic character, but not the Alpha 9. This player could care less about dropouts up to about 1mm, and in almost any quantity. It did, however, have some trouble on the first two tracks of our see-through CD, ticking loudly, but managed to conceal all errors on 3 and 4, though the DED red light flashed often in the process. Even on track 4, 5-to-10 errors per second could be observed, but the music sounded fine. Though it might have some trouble with poorly aluminized CDs, the Alpha 9 will play through all but the very worst scratches and dirt, and is one of the best tracking players in our experience.
It's also one of the best sounding, scoring very highly in comparison with several other single-box players, including the remarkable Pioneer Elite DV-09 DVD player and with our reference Pioneer PDR-05/Meridian 518/Monarchy M-33 digital system. There was a rightness about its sound, with articulate, tuneful bass, clean assertive mids, and a sweet, silky treble unusual from CD playback. There's a kind of sturdy, robust quality about the Alpha 9's sound that makes it seem more like live music.
I never did get around to assessing the Alpha 9's HDCD performance because I was listening to our own CDs, as well as other favourites. However, in my heretical view, HDCD is grossly overrated, the use of emphasis in recording offering as great an increase in resolution without requiring additional decoding. Owners of many HDCD discs, however, will want to listen to this player. In fact, I think anyone seeking a single-box solution for CD should audition the Arcam Alpha 9 at length.
http://www.audio-ideas.com/reviews/digital-sources/arcam-alpha9.html
