Art Dudley Listening

Stereo imaging was disappointing, making it easy to understand why serious audiophiles of the late 1970s and early '80s were so impressed with the spatially more precise (and, one could argue, timbrally more neutral) tube amplifiers being brought to market by Audio Research, Conrad-Johnson, Counterpoint, Quicksilver, and others. Although it produced an unusually large soundfield overall, the 8B, for its part, gave poor presence to such soloists as tenor Peter Pears, in the nice recording he made of Britten's Serenade for Tenor, Horns, and Strings (LP, Angel S-36788). That said, and for whatever reason, I found it distinctly easy to enjoy music through the Marantz when listening considerably off center. Which I enjoy doing more and more these days.

It was fascinating to spend a day with a 50-year-old Marantz amplifier, not just because it's good—and it is good—but because it allowed me to hear the origins of the gear of today that I love the best. Indeed, many of the latter—even the Shindos, Fis, and other anachro-amps of my experience—sound very refined compared to the chunky, coarsely textured Marantz 8B. I guess we really have come a long way, even as the products of yesteryear remain valid in their own right. A Marantz 8B may not be an everyday amp, in the same sense that a 40-year-old Noval port is not an everyday beverage. But if I had a collector's budget, I'd buy an old 8B anyway and keep it for those cold summer nights when I wanted to listen to the Brahms Clarinet Quintet and contemplate autumn.

Postscript: The Marantz Model 8B that I borrowed for this piece recently sold on eBay for precisely 10.6 times its original retail price.

To Infinity and Beyond
If the Marantz Model 8B is where we came from, one might wonder if the Z40 amplifier from Z-Infinity, a newish company in the Pacific Northwest, is where we're headed. Established by a Hungarian engineer named Zsolt Mathe, Z-Infinity specializes in tubed electronics; their first components are four power amps, ranging from the 20Wpc Z40 ($2999) to the 60Wpc Z120 ($3299, footnote 1).

The Z40 is a parallel single-ended amp, with two EL34 tubes per channel in a fixed-bias circuit (1 ohm resistors lift the output-tube cathodes just far enough above ground to facilitate bias measurement; those points are connected to banana sockets on the top panel, allowing the use of a multitester or dedicated bias meter). Each EL34's cathode is tied to its suppression grid, and each anode is coupled to its screen grid through a 150 ohm resistor. The anodes of both EL34s per channel are tied together and connected to one end of an output-transformer primary, the other end being tied to a B+ rail of approximately 360V. Because the resistor between each anode and screen grid is so low in value, the output tubes operate in pure triode mode; because the Z40 is a single-ended amplifier, it is, of necessity, a class-A design.

The input circuit is as simple as they come: In each channel, the line-level signal appears on the signal grid of one half of a 12AU7A dual-triode; the anode of that half is capacitively coupled to the signal grid of the other half, and that anode is capacitively coupled to the signal grids of both output pentodes. And there you have it.

But that didn't explain the appearance, on the amp's top panel, of two more small-signal tubes: one 12AX7A per channel, glowing right along with the other tubes. A close look showed that only the heaters of those 12AX7As were connected: All their other terminals remained unused. I asked designer Mathe about the extra tubes, and he offered two reasons: 1) they load the heater voltage, which goes from the power supply to the EL34s, then to the 12AX7As, then to the 12AU7As; and 2) Mathe uses a common chassis design for all of his products, some of which need that extra pair of dual triodes. (I know I've made the point before, but the similarities between this sort of chassis and the standard Carvel Ice Cream cake mold bear repeating: The Santa Claus cake is really nothing more than the Fudgie the Whale cake, rotated 90° and frosted differently.)

Miscellany: The signal capacitors are all AuriCap polypropylene-film types. The Z40's input and output sections are hand-wired, point-to-point, with only minimal use of terminal strips. The power supply is built onto a PCB of moderate size. All of the heater voltages are AC—surprising, given that the Z40 was commendably hum-free when I used it in my system.

The Z40's circuit design gets high marks, but the construction quality was disappointing, with a number of gloppy, overlarge solder joints, and with haphazard bits of electrician's tape used to insulate unused transformer terminals from other parts. Most serious of all, when the amp first arrived, I heard the sound of loose parts inside. I removed the bottom cover and discovered that two very large reservoir capacitors had broken free of their glue joints (they were still connected electrically). Clearly, parts that big should have been clamped into place, probably to the inner sides of the chassis.

Yet for all that, my review sample worked—and worked quite well.

The Z-Infinity Z40, which provided even more gain than my Shindo Corton-Charlemagne monoblocks, also offered a generous measure of the more expensive amps' good tone and texture, with a deep, tight foundation in the lowermost octaves. Alan Spenner's electric bass in "My Only Love," from Roxy Music's Flesh and Blood (LP, Atco SD 32-102), was solid and tuneful, while Andy Mackay's saxophone was perfectly reedy and colorful. Great texture and tone endured throughout other recordings. Strings, woodwinds, and harp were appropriately sweet through the Z-Infinity with Rafael Kubelik and the Vienna Philharmonic's recording of Smetana's Má vlast (LP, Decca/Speakers Corner SXL-2064/5), as were the various acoustic instruments used throughout Andrew Bird's Noble Beast (AIFF rip from CD, Fat Possum FP1124).

The Z40's spatial performance was uniformly excellent. It didn't quite have the sense of scale offered by the best Shindos, yet its stage was large and deep enough to suit me, and offered consistently fine specificity of image placement.

The Z-Infinity was acceptably good at communicating musical touch and force, though not in the first rank. The snare-drum downbeat in Slim Harpo's "I'm a King Bee," from the collection The Original King Bee (LP, Rhino RNLP 106), caught my attention in the first measure and drove the song well enough through the Z-Infinity, although other amps bring that quality even farther to the fore. Similarly, the plucked strings in the Scherzo of Tchaikovsky's Symphony 4, recorded by Pierre Monteux and the Boston Symphony Orchestra (LP, RCA LSC-2369), bounced along well, with good if not superb snap. Yet the battery of percussion in Britten's great recording of his War Requiem, with the London Symphony and soloists (LP, London OSA 1255), thundered appropriately. Of no less import, the melodies were allowed perfect shape and flow and freedom from pitchlessness—in particular Peter Pears' last full solo, the setting of Wilfred Owens' "Strange Meeting."

For those to whom such a thing is important, the Z-Infinity Z40 is an excellent-sounding American amp costing scarcely more than one would pay for a Chinese amp of similar musical worth. While I wasn't bowled over by the wiring and soldering, that would not be a deal-breaker for me—although I would need to know that Zsolt Mathe has cured the problem of the peripatetic reservoir caps. A high-value product from a US firm worth watching.

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Footnote 1: Z-Infinity Audio. Web: zinfinityaudio.com.