PS Audio C-100 Control Amplifier

Equipment report
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Integrated amplifiers
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PS Audio C-100 Control
PS Audio C-100 Control Amplifier

The C-100 control amplifier is part of PS Audio’s Trio line of small-footprint electronics, which also includes the P-200 preamplifier and the A-100, a Class D amplifier that Barry Willis praised in Issue 170. A paragon of efficient, attractive packaging, the C-100 shares the narrow width and long depth of the Rowland Research Model 201, which as it turns out is also a Class D amp. Not exactly bad company to be keeping. The look of the front panel is open and friendly with a single input button and volume-control knob and should appeal to all but the most electrophobic users. However, don’t call this amp “lifestyle.” There’s some serious engineering happening here. The dual-mono ICEpower output stage is supplied from independently regulated power supplies. On tap are 100 watts into 8 ohms and 200 watts into 4 ohms. On the back panel are three RCA inputs, and provisions for bi-amping. The C-100 is remote-controlled, but on the downside the remote’s soft pad keyboard is hard to manipulate and ultimately annoying.

Importantly, the Trio family liberally shares key aspects of PS Audio’s proprietary technology—most notably its Gain Cell technology. Not a typical volume control, the Gain Cell is an active stage whose gain is determined by the volume-control setting, rather than by adjuting the gain with a potentiometer that merely attenuates the signal. This eliminates a stage, says PS Audio, but further details are, as they say, proprietary.

Sonically, the C-100 is straightforward, honest, and tonally persuasive. It goes about its business, centering its sonics squarely in the middle range. Vocals are poised, relaxed, but not laid-back. If Norah Jones’ “Sinking Fast” (Not Too Late [Blue Note]) doesn’t sound like she’s intimate with the microphone then it’s either your amp or speakers or both. Only the big, loose barroom drum kit should soundstage well behind her vocal. Macro-dynamic information is lively, and thanks to the silence of the amp, tiny musical details emerge unescorted by comet tails of noise. On top there’s a bit of shading, due in part to a treble region that slightly rounds off upper harmonics. Images are well-grounded on the soundstage, and forcefully struck piano fundamentals are authoritative. Bass extension is solid and defined, with a trace of midbass warmth, but as so frequently is the case with smaller amps, the amount of low-end authority that the C-100 brings to bear will depend on speaker-matching. More about that later.

The C-100 reproduces music with a strong sensation of the rhythm and drive in a recording. It’s got the transient speed to light up Chris Thile’s virtuoso mandolin excursions (This Side, Nickel Creek [Rounder]), revealing his elegant touch and the hidden micro-dynamics of his bluegrass instrument. He’s a player who brings to the surface an expressive voice that the mandolin never shows with pedestrian players.

The C-100 is only mildly subtractive when it comes to hanging onto low-level harmonic information or charting every nook and cranny of a soundstage. On a typical acoustic recording the ceiling over a hall will lower a bit over the audience—an effect consonant with the softer, shaded treble of the amp. And sections of orchestral players possess a more convincing presence downstage than toward the back of the hall. You can hear this slight veiling during the spirited duels of fiddle player Mark O’Connor, cellist Yo Yo Ma, and bassist Edgar Meyer (“1A,” Appalachian Journey [Sony]). Their interplay is intricate, like a musician’s chess game, but only when some of the lowest-level machinations are consistently resolved, which wasn’t always the case with the C-100.

At its limits with a loudspeaker of stellar transparency like the Revel Gem2, the C-100 will get a little short of breath on top and will begin to generalize dynamic information. These issues recall TAS’s recent switching-amplifier survey where the subtle but persistent flattening of upper-octave micro-dynamics was the most common problem that TAS editors pointed out. With the C-100 this issue could arise during dynamic shifts in passages with multiple voices, like the chorale of Rutter’s Requiem, or during explosive brass-ensemble passages. Timbre bleaches slightly, the air around the instrumentalists grows drier, and the result is a narrower window of energy on top.

Living with the C-100 reminded me all over again that when selecting a system it’s all about context—the relationships and interdependency of the parts of the audio chain. Mating the C-100 with a speaker of low sensitivity or one with a reactive load wouldn’t maximize its strengths. In this regard, assembling a system is much more challenging at the lower-priced levels than it is when you have the freedom to throw money at a problem. Selecting “affordable” gear means you have to use a little brainpower and do your research. The C-100 can’t spark an MBL or ATC or Pioneer 2S-EX to life, nor should it be expected to. However, grab an efficiency expert like a PSB Alpha, or, better yet, a Synchrony Two B, or perhaps a Vienna Acoustics Haydn, or the new B&W 685, and suddenly a so-called budget system makes you feel as though you’ve won the lottery.

And as it turned I had on hand the raw elements for just this sort of system. At 88dB sensitivity the PSB Synchrony Two B ($1500/ pr.) seemed to fit right into the C-100’s D-power wheelhouse, delivering the punch and drive that continue to surprise first-time listeners of this modest but carefully executed two-way compact. Also, in keeping with the small footprint of this system, the nearly invisible Crystal Cable Piccolo speaker ($1310/2m) and interconnect cables ($465/1m) may be trip-wire thin, but don’t be fooled. They pass along a full-blooded signal to the lively little Two Bs, neither crimping their extension nor squeezing down their dynamics. This was the kind of system that not only reflected the space-saving nature of the C-100 but also embodied the systemmatching synergy that audiophiles of every stripe seek out.