Cary Audio Design CAD-805 monoblock power amplifier Sam Tellig 1/02

Sam Tellig wrote again about the CAD-805 in January 2002 (Vol.24 No.1):

When Dennis Had, of Cary Audio Design, heard that I was listening to the JMlab Micro Utopia speakers, he offered to send me a pair of Cary CAD-805C tube amplifiers.

"Should be a great combination. Besides, I'd like to visit and listen to the Micro Utopia. And you've got one of the only pairs in North America at the moment."

"I've already reviewed the 805s," I told him.

"You haven't heard the latest version."

The Cary CAD-805C has become a classic. First introduced in 1991 as the Cary CAD-805, this single-ended triode (SET) monoblock amplifier looked and sounded completely different from any other high-end tube amplifier available at the time.

That was almost 10 years ago, when few people (including me) were familiar with SET amps. Some of those audio writers who were saw SETs as anachronisms. Or threats—to their own sanity, perhaps?

I remember when I first set eyes on this amp. I truly believed that Had was mad—especially when I heard his contagious laugh. Why, I wondered, would anyone produce such a thing? Who would be crazy enough to buy it? Why didn't Had produce "me-too" amplifiers like everyone else, instead of using antiquated technology—weird tubes first developed in the 1930s?

But I hadn't really heard the amplifier, so I did what a good reviewer should do: I reserved judgment. Maybe Had wasn't so crazy after all. Perhaps there was something in this single-ended triode stuff, for him to make the CAD-805 the flagship of his company. (While Had also produces push-pull tube amps, a SET amp remains his flagship: the $40,000/pair CAD-1610, which was reviewed in the December 2000 Stereophile by Jonathan Scull.)

The original Cary CAD-805 was named after its output tube: the 805. The amp had a 6SL7 input tube (which has remained constant through various design changes) and an EL34 driver tube. The 805 output tube was soon switched to a 211. Dick Olsher reviewed that version in January 1994 (Vol.17 No.1), and it inspired John Atkinson to write his most famous cover line with respect to the Cary and a solid-state Krell: "If either of these amplifiers is RIGHT...the other is WRONG."

As they say in show biz, the CAD-805 has legs.

In January 1994, just as DO's review appeared, Had revamped the amp as the CAD-805B, changing the driver tube from an EL34 to a 300B—a breath of fresh air if there ever was one. This change did much for the amp's transparency. And, in 1997, with the 805C, the output tube became an 845, which RCA introduced in 1931 as the UV845. (The tube was designed as a modulating tube in radio transmitters.) This is the model I reviewed in March 1998 (Vol.21 No.3), subsequently bought, and kept as a reference for more than a year.

In April 1999, sans fanfare, Had introduced the new version without announcing a model change and without raising the price, which remains $8995/pair. The tube complement is the same, with a Czech-made KR300B now substituting for the Western Electric 300B. The 6SL7 input tube is a JAN (Joint Army Navy) Philips, made in the US, while the 845 output tube is produced in China. What a tube! Its plate is a big hunk of carbonized graphite steel and its thoriated tungsten filament emits a brilliant white light—especially dramatic in an otherwise darkened room.

There are just three tubes in the signal path. The distinctive "cat's eye" tube (a 1629/6U5) is set inside the faceplate, where it beats to the music—a characteristic bit of Had madness. When the iris of the eye turns fully dark, the amp is operating at full power: a rated 50Wpc into 16, 8, or 4 ohms. This 50Wpc power rating is what makes the CAD-805C a standout among single-ended triode amps, many of which output a mere 10, 5, or 3Wpc.

Of course, even 50Wpc doesn't seem like much, especially for $9k/pair. But 50W of single-ended triode tube power is not like 50W from a small solid-state integrated amp—or even a small push-pull tube amplifier. The CAD-805C sounds more like a 100W or even a 200W tube amp. Big!

Without question, the 50Wpc CAD-805C is more versatile than, say, a 3?W amplifier using a single 2A3 output tube. But I found that I lost something with greater SET power—some of that special low-powered SET immediacy and stunning resolution.

Nonetheless, the CAD-805C has always had, for me, a special set of virtues. In all of its incarnations, the amp has produced a deep, wide, astonishingly spacious soundstage. It has been dynamic in a way that smaller SET amps couldn't be—able to convey more of the drama and weight of large orchestral works. The 805C has always had a big, warm, rich, spacious sound.

But compared to the tinier triodes, the 805C, until now, had not offered me the last word in low-level resolution and hear-through transparency. Moreover, when I pushed the amp toward the limit of its 50W output, I heard the sound turn slightly grainy, and some of the soundstage magic disappeared.

The new version improved on the earlier 805C in a number of important ways. It sounded more powerful: more dynamic, with deeper, better-defined bass. (Dennis Had says it is more powerful: now with about 55Wpc into 16, 8, or 4 ohms.) There was more of the stunning immediacy I love with low-powered SET amps, a more pristine sound with a purer harmonic presentation. And the new version sounded less strained when I played loud.

Using the Micro Utopia speakers, I put on an out-of-print EMI CD of Beethoven's Violin Concerto, with Yehudi Menuhin as soloist and the New Philharmonia Orchestra conducted by Otto Klemperer (CDM 7 69001 2). I could tell this was an early stereo recording—the orchestral sound, even on the 805Cs, was a tad thin. But it was far more warm, rich, and full than what I heard with other amplifiers.

The late Yehudi Menuhin came to life—standing right there in my living room between the two speakers, playing in his prime. I could hear every detail of his playing, and the tone of his violin was so pure and sweet it really was close to listening live. This is the glory of SETs at their best: they get me closer to live than other types of power amplifier.

I turned to Michael Tilson Thomas conducting Tchaikovsky's Symphony 1 ("Winter Dreams") with the Boston Symphony Orchestra on DG Originals (289 463 615-2). (The recording is available from the BMG Classical Music Service, if you want to get it cheap.) This is the finest reading of the work that I've encountered on record—a beautifully played, tenderly shaped performance. I reveled in the ripe sound of the woodwinds, the burnished glow of the BSO brass, and the just-right acoustics of Symphony Hall.

Later I turned to Louis Armstrong. Like Yehudi Menuhin, Satch came back from the Great Beyond to entertain me, on Satch Plays Fats (Columbia/Legacy CK 64927).

I used a Musical Fidelity A3 CD player and A3CR preamp. (The CAD-805C needed an active preamp, I found.) Speaker cables were the aforementioned XLO Ultra 6. Power cords all around were the silver-coated copper Xtreme from Audio Magic, which retail for a relatively modest $69 each. Yes, I did hear an improvement over the stock Belden cords I had on hand: more detail, less grunge, cleaner sound.

When Dennis Had came to visit, I asked him what was new about the latest CAD-805C.

"For the new version, we replaced the electrolytic capacitors that are associated with the bias of the 805 output tube and the bias of the 6SL7 input tube. These have now been changed to film and foil capacitors. The difference is a dramatic removal of grain from the midrange.

"There is now a separate power supply and an additional transformer for the filaments of the 6SL7 and the 300B. These used to share the power supply that ran the filament of the 845 tube. Once again, this added purity to the midrange.

"To top it off, we have an improved interstage driving transformer that now is flat down to 9Hz. The result is that the CAD-805C now plays deeper bass than before."

I butted in. "That interstage driving transformer is what allows you to get 50W out of the 845 output tube, is it not?"

"Yes. The 805C uses a combination of capacitive coupling and interstage-transformer coupling. Up to approximately 28W, the capacitor is coupling from the plate of the 300B to the grid of the 845. The interstage transformer acts as a parallel choke on the 300B driver tube. At about 28W, the impedance of the grid of the 845 drops dramatically. You need current to drive the 845 tube further, into the A2 mode. That's where the interstage transformer takes over, providing the additional current.

"All transformers and all capacitors have a slight phase shift. The trick was to get the capacitor and the transformer to run together so that everything stays in phase. By the way, the amplifier now actually produces 55W into 16, 8, or 4 ohms, and about 30W into 2 ohms, off the 4-ohm tap."

"What if the owner of an original CAD-805C wants to upgrade to the latest version?"

"He can call us or have his dealer phone. The charge is $250 per chassis—that's $500 per pair—plus shipping both ways."

If you're not sure which version of the 805C you have, you can call the factory and read off your serial numbers. Versions of the amp earlier than "C" can't be updated.

"Maybe you should call this version the C-plus," I suggested.

"Like Porsche with the 911, we want to keep the model number the same. Unlike Porsche, though, we haven't raised the price!"

In my 1998 writeup, I called this amp a "soundstage champ." It still is. No other amplifier I have had in my system has produced so wide and deep a soundstage, such a superb rendition of the space of each recording environment.

With the latest version, I heard greater low-level resolution, more clarity, deeper bass, and improved dynamics. Even more successfully than in the past, the CAD-805C took the sound coming from the 300B driver tube and, well, amplified it to provide a far more practical output of power.

I do have some concern, though, about firing up these amps in the presence of toddlers and pets. The tubes are not caged, and that 845 output tube runs extremely hot. Moreover, there is very high voltage running into the tube. If you're thinking about putting them atop a table, the amps are quite large—each is 24" deep by 12" wide, and weighs 80 lbs.

I asked Had to expatiate, briefly, on the joy of SETs.

"Some people think the sound is too good to be true, that the listener is bathed in an excess of second-order harmonic distortion, that the audiophile is meant to suffer, not enjoy."

(I enjoy winding him up.)

"What people forget is that, as you cancel out the even-order harmonic distortion in a push-pull configuration, especially second-order, you're leaving behind the odd-order distortion that the human ear is very sensitive to, especially the higher orders such as the fifth and the seventh. What you leave behind, as you take away the second-order harmonic distortion, really becomes quite nasty to the human ear.

"I get a kick out of those who accuse Cary of designing in or adding second-order harmonic distortion to a single-ended amplifier. We don't add it; it comes right along with the design. Now there's a way of eliminating it. All one has to do is listen to a Cary CAD-805C and turn up the feedback control. The amp becomes a real champ on the test bench with the feedback turned up. But what you find is that you've lost the richness, the foundation of the music, the width of the soundstage. Now it sounds like you're listening to a push-pull amplifier."

"But," I asked, "the bass tightens up a little when you dial in the feedback?"

"It does a little, but at the expense of shrinking everything. The objective should be to reproduce sound as life-size as possible. Feedback just spoils that."

"Why do you even have the optional feedback?"

"Back in 1991, the rationale for including the feedback control was to prove the point, to demonstrate how feedback affects the sound."

The feedback control is not entirely frivolous, however. With no feedback dialed in, the amplifier's output impedance is slightly less than 2 ohms, which is relatively high. If your speaker's impedance is all over the place, you could hear some frequency-response anomalies that feedback might correct—but at a price.

As with any SET amp, you might look for a speaker whose nominal impedance stays fairly flat—that is, close to its nominal 4 or 8 ohm impedance. the Cary CAD-805C neutral?

I'm not sure I care. Every amp has its sonic signature, whether or not its designer admits it (usually he doesn't). I found that the CAD-805C didn't intrude itself on the sound to the extent that all recordings sounded the same. The main thing was the pleasure I got from listening to the CAD-805C—there's really no amp that I've heard that's quite like it, unless it's the $40,000/pair Cary CAD-1610.

Comparatively, then, the CAD-805C is a bargain—rather like the JMlab Micro Utopia when compared to the Utopia or Grand Utopia. And Dennis Had was right about his hunch: The speaker and the amp made beautiful music together.—Sam Tellig