Nearly 21 years ago, Dennis Had showed up at the 1989 CES with an unpretentious integrated tube amp that he built at his dining room table. That little amp, a David amidst a show filled with solid-state Goliaths, can perhaps be credited with the rebirth of Single-Ended Triode (SET) amplification in America. But that was several decades after Dennis’ FIRST award-winning amplifier: an amp entered into a seventh grade science fair earned him a blue ribbon. That's right, Dennis was already designing amplifiers at the ripe old age of 12.
These days, Denny’s company, Cary Audio Design, is a thriving business with a full range of products ranging from monster HT amps to high-res digital. But “flea amps” (so-called because of their miniscule power outputs) still hold a special position in Cary's line up, and in the hearts of many audiophiles.
The soul of the 300sei is the 300B power triode output tube, designed by Western Electric over 60 years ago, and still made in many variations and brands. “Single-ended” refers to the simple circuit topology, dating back to the dawn of radio, in which a single output device passes the entire waveform, as opposed to “push-pull” amps in which one device passes the positive half of the waveform, and another passes the negative half. The CAD-300sei has undergone very few changes over the decades, remaining a very simple circuit executed in very close quarters. The result is music as you have never heard it before, and for those who have never heard single-ended at all, it can be a rather shocking revelation. SET veterans will recognize its 300B characteristics, only this little amp presents the sound with more cojones than one would ever guess possible, based upon its size and appearance. Cary rates the current model at 15 watts a side, perhaps slightly optimistic for _classic_ 300B's, but plausible with the newer production tubes supplied by the factory.
So why on earth would anyone want to pay thousands of dollars per WATT of stereo power? The average hi-fi speaker these days is 87 db efficient, meaning ONE watt gets you about 87 DECIBELS of sound. Blow that watt through some horns, and you've got as much as 110 Decibels! So producing adequate volume is NOT an issue for most listeners. Often, the more components there are in a circuit (such as double the outputs for push pull, and multiple pairs for higher power) the more things get lost while traveling through the amplifier. The purity and directness of a good SET amp can be very like real, live music.
Certainly, SET is not for everybody: care must be taken in selecting speakers, and a bad match can be, well, BAD. But we would argue that one can NOT make that decision until AFTER dating a pair of 300B's. The clarity and life of a directly-heated SET can be intoxicating, and this particularly well-endowed specimen of a pure-pedigree species could be a perfect introduction to the genre. A first date, that could lead to a lifelong love affair.
