Solid State Preamp Reviews

As I write these words in January 1991, we're right in the midst of an annual media feeding frenzy: the "Best of the Year" follies. This usually takes the form of lists compiled in groups of ten for reasons that must hearken back to some obscure Druidic practice. You know the routine: "Ten Best Books of the Year," "Ten Best Films of the Year," "Ten Top Personalities of the Year," "Ten Best Sports Plays of the Year." Every corner of the media seems eager to get into the act. Special-interest magazines are hardly immune. Car enthusiasts can get their fill of "Cars of the Year." Computer literates find their favorite rags full of the "Ten Best Computers/Computer Accessories/Computer Programs." And music magazines regale us with the "Ten Best Recordings of the Year." Everyone with access to a transmitter or printing press has got, it seems, a little list.

"Desperation is the Mother of Invention." Isn't that how the proverb goes? Certainly it applied ten years ago in the case of the Philips engineers working on the development of the Compact Disc system. Given a specification that had included a 14-bit data word length, they had duly developed a 14-bit DAC chip, the TDA1540, only then to be informed that the CD standard decided upon after Sony joined forces with the Dutch company would involve 16-bit data words. (Thank goodness!)

In recent years, Adcom has carved an enviable niche for themselves in the entry-level category of high-end audio. Their excellent GTP-400 tuner/preamplifier, which I reviewed in September 1989 (Vol.12 No.9), has further enhanced their reputation for musically satisfying sound at affordable prices. The GFP-565 is Adcom's newest preamplifier and their most expensive to date. The GFP-565 was designed to offer more than simply excellent performance for the price asked. This new arrival is Adcom's attempt at manufacturing a preamplifier which can compare favorably to the most expensive state-of-the-art products offered by other high-end manufacturers. As such, its $798 price tag is still reasonable, especially when the 565 is compared with other preamps in the under-$1000 price range.

There are some standing jokes in the audio industry about the qualities a piece of equipment must have in order to be truly "high-end." One definition is that it must be unavailable, unreliable, and dangerous. Another is that it will sound great, break, and its manufacturer go out of business. By meeting at least half of these variables, the Spatial Coherence TVA-1 preamplifier qualifies as a classic audiophile product.

Introduced at the 1988 Summer CES, this preamplifier from San Francisco-based Parasound costs $395 and is manufactured in Taiwan. It does away with mechanical switching for source select and tape functions, replacing it with CMOS integrated-circuit switches similar to those used in the British Linn LK1 and Quad 34 and 44 models. Construction is to a good standard and the circuit is carried on two main pcbs and three small ones. Following a signal from the phono inputs, the MM-only RIAA amplifier is based on discrete FETs, its output joining the line-level signals at the switching ICs, these controlled by DC voltages controlled by front-panel pushbuttons.

A few issues back, in my review of the Mark Levinson No.26 and No.20 (May 1988, Vol.11 No.5), I mused on the fact that the preamplifier, being the heart of a system, had a more significant effect on sound quality in the long term than, say, the loudspeakers. It was worth spending more on a preamplifier, therefore, than on loudspeakers. Needless to say, this viewpoint was regarded by many readers as dangerously heretical. I decided, therefore, to investigate the sonic possibilities of budget-priced preamps in this issue, even the most expensive being less than one-tenth the price of the Mark Levinson.

Choosing a moderately priced preamp has traditionally presented the audiophile with a host of serious problems. Most attempt to be all things to all listeners, expending resources on bells and whistles which would have been better expended on basic performance. Few have anything resembling a decent moving-coil stage. But there have always been a few designers (and companies) willing to expend much of their effort at the "low end of the high end." PS Audio has been such a company. Their new 4.6 preamp, an update and cosmetic clone of the earlier, well-received 4.5, is not at the top of their preamp range—that honor belongs to the 5.5—but it is clearly designed to be more than a price-point product.