Feature Articles & Reviews
Chasing Bruno Putzeys Down the Rabbit Hole of Audio and Discovering the Channel Islands Audio E•200S Stereo Amplifier
“Hey, Wes, I want you to look up the new Bruno Putzeys speaker. Giant killer.”
Thus spake Jeff Fritz, Commanding Officer of our enterprise. We’d been e-mailing about another speaker, and this recommendation came as a pleasant surprise. Jeff’s ears regularly experience the best, most expensive loudspeakers made, so when he uses even mild hyperbole, my ears prick up. I looked up Putzeys and the speakers and found only Grimm Audio’s LS1 speaker with LS1s subwoofer. It was obviously a great speaker, but too rich for my blood at $39,895 USD per pair.
But I also learned that Putzeys is considered something of a genius for his class-D amplifier designs. Class-D operation allows amps to run cool and use less electricity, but as nice as those benefits are, they’re side benefits -- there was a time when it was easy to believe that the D in class-D stood for dreadful, as in sound quality. Putzeys cured that dreadful sound. He’s all about absolute noiseless clarity -- no euphony for him. He likes pure sound; i.e., the straight-wire-with-gain approach. He also strongly believes that if it’s there, he can measure it.
Nor is Putzeys a fan of critics who use purple prose to prop up faulty reasoning. In a 2011 white paper describing the implementation of his class-D amplifiers, he wrote:
Not so long ago a reviewer, having to test “yet another Hypex UcD based amplifier” [based on Putzeys’ designs], yammered that it really was no fun writing about these things as “they just sound clean and neutral and do what they’re asked to do.”
Shouldn’t that be the point of high fidelity? I understand that one of the joys of audio writing is generating baroque prose to describe the sonic vagaries (or pleasancies) of products designed expressly so that reviewers can have something interesting to write about them, but as an engineer I can’t help preferring doing a good job.
Ouch! At least, Putzeys assured me that he wasn’t referring to me.
Putzeys designed the amp modules that are manufactured by Hypex in two principal lines. Their Universal class-D (UcD) line, now about ten years old, is available in multiple output levels. Despite the age of the UcDs, enthusiasts will tell you that they still outshine many tube or solid-state class-A amplifiers. Over the years, Hypex has refined and improved the UcD modules, which continue to be used in several of the top active monitor speakers made for recording and mastering engineers.
The most recent line of Hypex class-D amps designed by Putzeys are the Ncore models, of which the principal module is the NC400. Its stereo configuration is specified to output 200Wpc into 8 ohms, 400Wpc into 4 ohms, or 580Wpc into 2 ohms. If that’s not enough, the NC1200 offers 400Wpc into 8 ohms, 700Wpc into 4 ohms, or a whopping 1200Wpc into 2 ohms. Putzeys’s own manufacturing company, Mola-Mola, uses the NC1200 in their Kaluga monoblock. (Bruno’s partner at Mola-Mola is Jan-Peter van Amerongen, who runs Hypex.) Putzeys spends an inordinate amount of time perfecting the input, using separate gain stages, no integrated circuits, and higher-quality capacitors. The Kaluga has vanishing levels of anything bad, from various distortions to noise. It also has a beautiful case. But the NC1200 modules are still quite expensive. By the time it’s all added up, the Kaluga costs $9000 each.
The rabbit hole was getting more complicated. The deeper I delved, the more I discovered about Putzeys’s remarkable accomplishments. Besides his work in an area of amplification most people had given up on decades ago, he began to believe that marrying his amplifier models to speakers, creatively applied digital signal processing (DSP), and carefully controlled directivity, would allow him to make the giant-killer speaker Jeff had mentioned. But it turns out that Jeff wasn’t talking about the Grimm. He meant the Kii Audio Three. (Kii Audio is jointly owned by Putzeys and Bart van der Laan.)
The Kii Three looks quite similar in concept to the professional speakers made by Barefoot Sound, which uses Putzeys’s Hypex UcD amps in their active speakers. Probably few of you have heard of Barefoot, who make some of the speakers most prized by recording and mastering engineers. Hypex not only sells their modules to other manufacturers; they also offer them to the DIY market. But despite the fact that no one can claim to make a better cold-solder joint than I, I demurred. Still, I’m told that it’s quite easy to make a phenomenal amplifier based on these modules. In fact, an entire cottage industry has popped up around these great-sounding modules.
Enter Channel Islands Audio . . .
One of the best examples of a company using the UcD module to make great sound is the California company Channel Islands Audio. Next year, CIA (cute!) will be 20 years old. In fact, the first SoundStage! review of a CIA product was published way back in 1997: of the v3.0 upgrade of Audio Alchemy’s DDE DAC. Audio Alchemy made great-sounding, affordable equipment. The primary player in CIA had worked for AA, and knew exactly what would yield better sound, so they started business doing modifications of AA’s DDE.
CIA now makes two monoblocks, two stereo amps, a headphone amplifier, an asynchronous USB converter, a 24-bit DAC, two passive stereo preamps, and three power supplies. All products are designed in-house, and CIA seeks the best parts -- for instance, all CIA amps include Hypex amp modules -- and then assemble the final product. Every unit of every production run is tested to ensure that it operates at peak ability; it is then packaged and shipped, usually directly to the end user. While CIA does have a few dealers, most people purchase directly from their website. CIA offers free shipping and a 30-day money-back guarantee, less a 10% restocking fee. The warranty is for five years.
The CIA E•200S stereo amplifier ($2500) arrives well protected in a secure box. Its machined-aluminum case, clean and utilitarian, offers enough heat dissipation for the power supply and audio circuitry. It measures 14.0”W x 2.75”H x 10.0”D and weighs just 8.5 pounds. I’m used to hulking amps with knife-sharp heatsinks and power supplies big enough to drive a Tesla S P90D in Ludicrous mode. The E•200S offers 200Wpc into 8 ohms or 400Wpc into 4 ohms, either output at vanishingly low claimed levels of THD and noise.
The E•200S is not only lightweight; in use, it barely got warm even at its full rated power. On the front panel are only the on/off switch and, in subtle, lightly colored type, the make and model names. The rear panel is almost as empty, with balanced (XLR) and single-ended (RCA) input jacks, insulated five-way speaker binding posts, a trigger jack, and an IEC power inlet for CIA’s detachable power cord, which I used. (Power cords rank very low in my hierarchy of what makes great sound. If everything else in your system is perfect, then go for a $1000+ cord, and let me know what you think about the improvements in the E•200S’s sound.)
I used a 27” iMac Retina 5K computer running OS X El Capitan controlling music from CDs, and streamed music from a Synology NAS or from Naxos, Tidal, or Spotify. The signal was fed to an Oppo HA-1 DAC-preamp-headphone amp via USB, and then to the E•200S via balanced cables.
Unlike some massive class-A solid-state or tubed amps, the E•200S sounded good almost straight out of the box. I didn’t do any kind of special break-in; I just let it stream some quiet kora music for maybe an hour. But no matter what type of circuits an amplifier has, I leave it on all the time. That definitely raises my electric bill, but it generally gives me the highest quality of sound. Something like the Boulder Amplifiers 3050 draws 300W at rest, and that’s from 240VAC outlets -- but the CIA amp is so efficient that it draws less than 0.5W at rest! No surprise that it barely got warm even when worked hardest.
I used two very different speakers with the E•200S: Eclipse’s TD508MK3 ($1499/pair) and ATC’s SCM19 v2 ($4299/pair, review pending). Neither is very efficient, but that’s where the similarities end. The Eclipse has an integral stand, an egg-shaped cabinet, and a single 3.5” driver with no crossover. The ATC has a box enclosure and, basically, 2.5 drivers (the bass driver has an integral soft-dome midrange) and a two-way crossover. Both sound great, but in very different ways. The Eclipse is the world champion at “disappearing” into a soundstage. The ATCs also do a great job of throwing a soundstage, but produce more bass and play quite a bit louder than the Eclipses.
I also had on hand Luxman’s M-200 amplifier, a 25Wpc model that retails for $2790. So I had plenty of time with the CIA and Luxman amps driving speakers I knew well. Despite the fact that these amps are at polar ends of the design spectrum, I listened to both at fairly low levels to get an idea of what each manufacturer was trying to do. Bruno Putzeys’s design goal for the UcD and Ncore amplifier modules is a quality of sound that outclasses both tubes and solid state.
I casually listened to music while preparing to write this review. The Eclipse speakers were attached to the E•200S, and “I Want to Sing a Song,” from Anita O’Day’s All the Sad Young Men, began to play (16-bit/44.1kHz, Verve/Tidal/Roon). The arrangements for this 1961 album were written and conducted by a genius (a term I don’t use lightly) named Gary McFarland, and I found myself concentrating on his work rather than on O’Day’s singing. For the first 44 seconds, it’s just the band playing. When O’Day finally entered, the timbre of her voice had a sexy burr I’d never heard before, as if for years she’d been recorded with a Shure SM57 mike, but for this album sang into a Neumann U 87. The soundstage was well integrated, and even a tad more open than with the Luxman. Given Luxman’s reputation for coherent sound, this was a surprise.
Next up was orchestral music. Both speakers and amplifier make congested music sound congested -- in a word, awful. Sadly, a lot of classical music, especially that recorded at the beginning of the digital era, was recorded that way -- but then, if that’s how it was recorded, that’s how it should sound through genuinely neutral gear. If that bothers you, you might want to stick with more colored components. But with minimally miked recordings that have preserved and present a coherent soundstage, these combinations all sang. One of the finest classical recordings I own is of William Mathias’s Dance Overture, with David Atherton conducting the London Symphony (CD, Lyrita SRCD328). The entire soundstage, from front to back, side to side, and top to bottom, was completely comprehensible.
I’ve lately been very interested in music played on the kora, a 21-stringed African instrument. The sweet sound of the lute-like kora and the virtuosity of some of its players can make for experiences of silvery sound. Toumani Diabate and Ballake Sissoko’s New Ancient Strings (16/44.1 FLAC, Hannibal) presents the gorgeous sound of their koras, well recorded in a decent room. Again the E•200S offered a liquid sound that was just as the signal should sound. As that reviewer complained to Bruno Putzeys, it’s so hard to describe the sound of an amplifier that sounds clear and neutral. Indeed, it’s hard to describe the sound of something that has been designed to have no sound. Once you hear it, though, it’s very easy to comprehend. Soundstage freaks will adore the clarity, the just-opened-a-window sound that we all search for.
What makes the CIA E•200S different from any other amp that uses UcD or Ncore amp modules? The magic occurs in the input stages and power supplies. Imagine the mating of an incredibly quiet tube-amp dad and a very powerful, solid-state, class-A mom. Their child might sound like the CIA E•200S. I can’t wait to hear Channel Islands Audio’s Ncore-based E•125S. This company knows how to design an amplifier that achieves truly exceptional sound for a reasonable price.
And how about this Bruno Putzeys guy? Does he interest you? He does me. I feel he’s really on to something in amplifier design. Interestingly, he feels he’s brought the power amplifier up to the most it can currently achieve, and has decided to devote the next part of his career to designing and making loudspeakers. One thing I liked about interviewing him was that he did a beautiful job of describing what he’s doing with a minimum of engineeringspeak. He was also willing to name names and tell us what he does that makes his designs sound so good. Check out this space next month for my full interview with the man himself.
. . . Wes Marshall