Cary Audio Design CAD-805 monoblock power amplifier Dick Olsher 2/94

Dick Olsher wrote again about the CAD-805 in February 1994 (Vol.17 No.2):

Something that really sets Toob Man's heart aglow is the igniting of the 805's mighty 211 power triode tube. When I dim the room lights and throw the filament power switch, the thoriated tungsten filament—at 3 amps and 10V—illuminates like a 30W light bulb. Both the 211's "furnace" and its grid structure are clearly visible through the top of the glass envelope—man, what a sight.

The 211 first came on the scene in 1919 as a radio transmitting tube, courtesy of the folks at the great Western Electric Company. In 1924, the 211's oxide-coated filament was replaced with thoriated tungsten. In 1935, Western Electric introduced the 300A, which was updated three years later to the 300B. The 300B was developed for a new generation of movie-theater power amps and did yeoman service in the likes of the WE 86A and WE 91A.

Now it's possible to view these two greats side by side on the 805's chassis, which has been modified—the triode-connected EL34 driver tube has been replaced by a Cetron 300B. AT&T stopped production of the 300B in 1988. However, it's still manufactured in the US by Cetron, and of course in China (which also continues to manufacture the 211). According to Cary Audio's Dennis Had, the introduction of the 300B was intended to increase the sweetness of the midrange. I can certainly appreciate the strategy—the 300B is probably the sweetest-sounding medium-power triode ever produced. One other "change" worth noting about my new samples is that the GE 211s were substituted for the Chinese tubes—I assume these are NOS (New Old Stock) tubes that Cary happened upon.

I agree with Dennis that the amps sound rather wooden right out of the box, but they begin to bloom after a good break-in. It is very important to break the 805 in for at least 20 hours before attempting any critical listening. And as far as I'm concerned, they begin to walk on water after about 50 hours.

The mids did indeed sound sweeter and more liquid. But even more importantly, the harmonic compass swung from what I previously described as "yellow mellow" soundstage lighting to a fully sunny disposition. The 300B was able to flesh out the full intensity of the upper registers. The upper mids and lower treble took on proper sheen and brilliance. Female voice and violin overtones sounded timbrally right on. The 805's talismanic power of dissolving me in the music's ebb and flow was brought into sharper focus. Better not settle down to a listening session with this amp if you have any pressing engagements on your calendar. The 805'll pull you into the music's heart and soul, as if it had latched on to you with the tractor beam disguised as the tuning eye on the amplifier's front panel!

I found myself making do with less and less feedback, until after 20 hours or so, I turned the feedback pot to the 0dB setting. That's how the amp sounds best now—unadulterated by feedback.

The 805's bass performance was still relatively weak. Bass definition did improve with the 300B in tow, but the 805's ability to delineate bass lines was not even as good as Cary's own 300SE—though, of course, the 300SE lacks the 805's bass drive. Single-ended tube amps aren't known for their bass extension and impact, so don't expect killer bass if you buy one.

The 805's major asset is its pure, pristine midrange—without a doubt, Class A quality. Factor in its palpable portrayal of image outlines, soundstage transparency, and a stunning harmonic tapestry, and the 805 is a major musical experience. Anyone who remains deaf to its Siren call must have a heart of stone.—Dick Olsher