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Unlike the USB input all the S/PDIF sockets are transformer coupled for galvanic isolation. In rare cases this could mandate additional decoupling of the USB socket with a specific cable or box available for a few euros from suppliers of computer accessories.
When an owner has free choice Westlake recommends the asynchronous USB input which is controlled by Audiolab’s own clock i.e. works in master mode rather than having to extract the clock from the source signal as with the S/PDIF protocol. The onboard transport of course is slaved to the same master clock as the USB input to be equally good.
The best converter chip is hamstrung if its surroundings aren’t suitably posh, particularly the power supply. John Westlake paid homage to this by even ordering custom capacitors with very low series resistance to get them closer to ideal behavior. Series resistance in power supplies is directly proportional to the extent and content of self noise. Post rectification the 8200CDQ regulates and filters the incoming power over multiple stages to apparently hit exceptional S/N figures. Those allowed Westlake to sacrifice about 20dB with output Jfet opamps which, though noisier, sounded better.
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Whilst analog signal input is limited to RCAs, an input opamp immediately converts them to balanced operation. Analog attenuation isn’t via a standard pot but FET-switched resistor network which is integrated into a chip followed by the afore-mentioned Jfet opamp buffers which condition the signal for current. The XLR sockets here are thus truly balanced and output twice the voltage from the RCAs. This is high enough to drive long cables. The manual advises that the machine gets warm during normal use. That’s putting it mildly. The various voltage regulators and output stage biased in class A get plenty toasty to hit ca. 40-45°C if I had to guess. Installation thus must be mindful of proper breathing room.
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As this would be my first review for fairaudio I asked the publishers about what they expected. "No purple prose, no unqualified raves and sonic commentary that doesn’t merely state how you liked something but which describes precisely and comprehensively what something sounded like." That was a fair but also tall demand. Whilst no outright rave, this review would nevertheless end up enthusiastically positive. To clearly capture sonics becomes quite challenging with modern digital. Any designer worth his pay will easily avoid the type of colorations and nonlinearities which continue to plague turntables and particularly loudspeakers. Pointing at crass colorations between 3.125 and 3.126Hz becomes impossible with digital.
Impedance integration between players and preamps (in this case even power amps) is no longer problematic when even modern valve preamps arrive with suitably high input impedance and any competently designed digital source sports sufficiently low output impedance to avoid the earlier capacitive HF roll-off. I find the performance delta between CD players and their digital relations smaller than in other component categories. That said our readers are quite serious about differences between quality machines even where those differences occupy far narrower margins than for example speakers. I’d concur that such audible differences are important and often decisive about whether particular gear will be satisfying to you over the long haul or not.
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A fundamental signature with the Audiolab 8200CDQ proved somewhat elusive since the choice of digital filter was quite influential. Early digital’s standard sharp rolloff was routinely quite unpleasant and sounded ‘digital’ in the manner analog devotees despise on principle. My favorite filter quickly became optimal transient XD. John Westlake concurs but advised that in certain systems the optimal transient DD was very good too and offers lower bass. The JBL speakers I used for this review couldn’t verify this. They must fade out above where these differences in bass operate.
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As the name indicates, optimal transient is about impulse fidelity without pre-ringing or squashed rise times but ‘dirt’ or noise above the audible band. Westlake didn’t want to divulge more but did add that not every amp or speaker will cotton to this filter. Here the owner’s manual is helpful about what to look for.
Fundamentally the 8200CDQ behaved like any other quality digital source – clear, open, with high bandwidth and free from irregular colorations in specific bands. The optimal transient XD filter was arguably a touch brighter than the golden mean of my acquaintances in this sector and with certain CDs could be too much of a good thing. This changed with the optimal transient DD filter. The optimal spectrum filters were softer and darker. The transient filters staged deeper, the spectrum equivalents staged wider to make it mostly a matter of taste.
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