PS Audio HCA2 Power Amp

Description:

PS Audio HCA 2 Hi Fi Power Amp
Brand New and boxed these cost around £1500 normally
We can post nation wide and accept paypal or visa

Review below


The introduction of PS Audio’s Power Plant line of AC power regenerators turned the audiophile community on its ear, and PS Audio has obviously been hard at work developing new audio components since. The $1695-USD HCA-2 digital switching amplifier is one of the company's latest creations. I was excited to hear for myself what the PS Audio team has wrought with the HCA-2, but the term "digital" used to describe this amplifier caused me some concern -- I'm an analog kind of guy. So it was with guarded enthusiasm that I installed the HCA-2 into my humble system and began listening.

A little explanation of this HCA-2’s hybrid class-A digital output stage is necessary, but I strongly suggest you visit PS Audio's website for a much more comprehensive discussion. The folks at PS Audio believe that if you treat each of the two independent sections of a power amplifier -- the input and output stages -- as separate and unrelated, and then optimize each without regard to the other, it doesn’t really matter what technology you use to achieve the highest performance.

So the HCA-2 has two distinct parts with unique topologies: the voltage-gain input stage and digital output stage. The voltage-gain stage is a zero-feedback, JFET input stage -- a simple discrete analog circuit with, according to PS Audio, "astounding common-mode rejection, low distortion, fully differential balanced inputs" and is, "in short, a perfect voltage-gain stage." A digital output stage is not the same as a digital-to-analog converter, which is used in the digital front-end of an audio system. Basically, instead of the output devices moving current up and down to match the musical signal at the input to the amplifier, a digital power amp like the HCA-2 has only on or off states at its output.

It is for this reason that this current-gain stage runs with virtually no heat. It is a digital output stage known as SDAT (Super Digital Amplification Technology) and unaffected by the loudspeaker load it is driving because it does not have the problem of varying impedances affecting the amplifier’s performance. According to PS Audio, problems common to other digital amplifiers, such as a hard, bright, or sterile sound, or problems sounding right on different speakers, are eliminated when using SDAT technology.

PS Audio claims that the HCA-2 is nearly 95% efficient (also why it generates almost no heat). This means that almost everything the amplifier’s power supply delivers to the amp is used to produce music. Traditionally, a smaller power supply is used when requirements for power are lower due to the efficiency of the design. But PS Audio uses a large, custom-wound toroidal transformer that was designed for a typical class-A/B 150Wpc amplifier. PS Audio claims that this is one of the reasons why the HCA-2 sounds "so big, so alive."

The HCA-2 can communicate with any other piece of PS Audio equipment via the included PS bus. This bus can be linked to other PS Audio equipment through a standard CAT-5 communication link (which looks very similar to a standard telephone cord). It can turn all connected equipment off or on, among other features. The HCA-2 also has a DC trigger for A/V use.

PS Audio put great emphasis on HCA-2's chassis. The company worked with designer Alex Rasmussen to create a sleek-looking cabinet that was reportedly inspired by classic architecture and, believe it or not, the Audi TT. The car, according to Rasmussen, "was most inspirational in the HCA-2’s front-panel power/standby button detail" and will also appear on some of PS Audio’s future products. The only other feature on the front panel that is visible once the power is turned on is a lighted PS Audio logo, whose brightness can be adjusted with a bottom-mounted control. The rear panel sports an IEC AC receptacle and both single-ended RCA and balanced XLR inputs. The speaker outputs are WBT five-way binding posts. A nice feature is that AC input is via a built-in high-current Ultimate Outlet, which PS Audio sells separately for $399.

The HCA-2 delivers 150Wpc into 8 ohms, 225Wpc into 4 ohms, and 275Wpc into 2 ohms. It measures 17"W x 4"H x 15"D and weighs 30 pounds. The HCA-2 ships with a 14-gauge shielded power cord, but PS Audio recommends their own Mini Lab or Lab Cable "to further enhance the performance" of the amp. I used the stock cord, but I was able to plug it into a PS Audio P-600 Power Plant.

Expectations and sound

In their literature, PS Audio states that the sound of the HCA-2 combines the best of both tubes and solid-state. If I had a nickel for every time I’ve read this about a piece of audio gear I could have bought a house with the cash by now. Even so, my first impressions of this amplifier, even before it was fully broken in, were very positive. It had tight, tuneful bass, a lush midrange, and sparkling and grainless treble. It wasn’t quite a combination of tubes and solid state; it just sounded like a very good solid-state amp.

One of the first LPs that I spin when just about any new piece of equipment graces my system is Miles Davis’ Kind of Blue [Columbia/Classic Records CS-8163]. I know this choice of music seems like an audiophile cliché, but everyone should have a reference for setting up and testing, and this album is as good as any -- and better than most. Indisputable talent occupies the midrange, namely Miles Davis on trumpet and John Coltrane on tenor saxophone. These instruments had very natural presence with very few aberrant peaks or dips in frequency via the HCA-2, or any other artificial flotsam that I could discern. When it came to midrange reproduction, this amp just got out of the way, and endowed the signal with pure gain, so the speakers could then do their job.

After some extended listening, I noticed a slight increase in the amount of upper-midrange energy, but it was hardly a huge defect. Yet this ever so slightly bumped-up region may have been reason for a characteristic that did sound somewhat tube-like. The upper mids ended up sounding bouncy; that is, they displayed a slightly rounded transient response. This made certain instruments, especially percussion or others that veered toward the treble, had a rather animated timbre. The horns on Kind of Blue were affected by this character, but in a good way. I felt as if somehow this enhanced the sense of the musicians being connected to their music. When playing Kind of Blue, the sound was what high-end audio is all about -- that the pursuit of being aurally transported back in time was somehow closer to fruition.

But I don't want to give the impression that this amp leans toward euphonic sound. It doesn’t. It’s just that this slight anomaly in a narrow band in the upper midrange added to the amp's positive characteristics. In fact, in my listening notes I wrote that other than this quirk, the amp sounded exceptionally fast, and quick transient response was noticeable throughout the frequency range. Tautness was also heard in the images, which were notably stable. The resulting soundstage wasn’t as wide as I’ve come to expect (especially with more expensive amps), but it was good nonetheless.

Fans of female vocals ought to check out Eva Cassidy. All of her CDs are good listening, but my favorite is Live at Blues Alley [Blix 10046], the only CD that was released during her all-too-short life. Even though the recording was most likely executed on a shoestring budget, it is excellent. Only a touch of reverb is added to Cassidy's voice on these standards; the rest of her five-piece band is recorded as they played. Through the HCA-2, the entire CD sounded very good, but very noticeable was the highest treble, which sounded simply fantastic