Pickering U-38/AT
A moving-magnet cartridge built for the first wave of automatic turntables - and the ancestor of a whole family of V-Guard "floating stylus" pickups.
Overview
The U-38/AT arrived when automatic record changers were becoming the centerpiece of the American living-room hi-fi system. Those machines created a problem, and Pickering built this cartridge to solve it. A changer needed a stylus that could survive mechanical shock without giving up the compliance good playback requires. Pickering described the U-38/AT as a "STANTON Stereo Fluxvalve" - a moving-magnet design with a white body and a black V-Guard stylus assembly. It marketed the cartridge in the pages of Audio (August 1962, p.19) and High Fidelity (June 1962, p.4) as "a cartridge designed especially for the new generation of automatic turntables."
The pitch had numbers behind it. Pickering combined complete mu-metal shielding with high output to get what the company called an "unequalled signal-to-noise ratio." Output was rated at 10 mV per channel (the same literature also lists a 2 mV per recorded velocity figure, depending on how the spec was quoted). Channel separation was 35 dB, and frequency response was ±2 dB from 20 to 20,000 cycles (some literature lists 20 to 17,000 cps). Impedance was specified between 47,000 and 100,000 ohms, wide enough to sit comfortably in the front ends of the era's tube preamps. The cartridge weighed 14 grams (some literature lists 15 gms) and mounted on standard 7/16" to 1/2" centers, supplied with universal mounting hardware. Tracking force ran from 2 to 5 grams. That is a high tracking force by modern standards, and it was intentional, because automatic changers of the period needed that much downforce to trip reliably.
Collectors tend to forget that the U-38/AT was not a single product but the head of a small family. By early 1963 Pickering was selling two versions, the AT and the ATG, differentiated by the tracking force at which the stylus would retract into its soft-plastic V-Guard. The logic was simple. A changer that could track reliably at lower forces could use the ATG and gain extra record protection. A changer that needed 4 grams or more nominal force was better served by the AT. Both were sold pre-mounted in plug-in heads for the Garrard Type A and AT6 automatic turntables - the GA/38AT and G6/38AT for the standard version, GA/38ATG and G6/38ATG for the ATG - at list prices of $51.50 and $52.50 respectively. The bare cartridge was priced at $46.50, described in Pickering's copy as the "Audiophile Net."
The safety mechanism needs a careful explanation, because "V-Guard" gets thrown around loosely. Happily, the review concluded it didn't. The ATG version, tested in an automatic changer, was found to perform optimally at just over two grams. Its low-frequency response was judged noticeably smoother and richer than the standard U-38/AT that the magazine had reported on previously. That is a meaningful endorsement from a period source, and it is the closest thing to an independent verdict on the family that survives in the record.
The "floating stylus" language in Pickering's advertising is advertising, not engineering fact. The company claimed the stylus assembly had so little mass that it "actually floats on water" and would "float" over the record surface, protecting both diamond and disc. Whether or not one takes the water demonstration literally, the underlying design is real: a low-mass stylus in a retractable V-Guard mount. The hermetically sealed Fluxvalve generator was warranted for a lifetime, covered under U.S. Patent 2,917,590 among others. In practice the ones that survive tend to survive because the stylus, not the body, is the wear item.
For modern users the practical picture is straightforward. The U-38/AT is a high-output moving-magnet cartridge that will work into almost any MM phono stage. Its 2-to-5-gram tracking range means it is happiest on a heavier arm: a period changer, a vintage transcription arm, or a modern arm with enough mass and adjustable counterweight to sit in that window. The 14-gram body (15 gms per some literature) is on the heavy side by today's standards, which suits those same arms. The real constraint is styli. The V-Guard assemblies are model-specific, and the AT and ATG use different retraction thresholds, so a replacement stylus must match the version. Buyers should confirm which version they are getting. The ATG commands a slight premium in the period literature and is the more desirable of the two for anyone tracking below 4 grams. Original boxes, mounting hardware, and the Garrard plug-in heads are all worth having, since the heads in particular are increasingly hard to find separately.
The U-38/AT is not a collector's trophy the way some later Pickering and Stanton moving-coil designs became. It is a working cartridge from the period when changers went from furniture to serious playback, engineered around the automatic turntable's specific weaknesses. It suits a Garrard Type A or AT6, or any period changer that needs a compliant, well-shielded, high-output pickup, provided the stylus is fresh.
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