ADC XLM MK III (1978–1984)
Forty pounds bought you a cartridge that could make a familiar record sound like a room you'd never been in.
Overview
The XLM MK III sat at the upper end of what a serious listener would pay for a moving magnet cartridge in the late seventies - £40.00 when new, built from 1978 to 1984. Not exotic money, but not pocket change either, and ADC spent it on the parts that matter rather than on chrome. The design brief was low mass and high compliance, taken far enough that owners describe the XLM family as sitting "on the extreme side of low mass, high compliance." That wants a light, well-damped arm, and it rewards one with agility at the groove wall.
Owners keep coming back to the spatial effect. One put it plainly: with the XLM MK III "you will be exposed to new spatial dimensions from the records you are familiar with." The tonal character gets described as smooth, detailed, full, and musical, never clinical, never harsh. Credit might go to the tapered cantilever, the nude elliptical tip, or a well-sorted generator.
It also behaves better than its spec sheet suggests it should. One user ran it on a stock Lenco L75 tonearm - a relatively high-mass arm paired with an extreme low-mass, high-compliance cartridge, a combination that on paper shouldn't work - and reported it sang.
Key Features
Tapered "OmniPivot Improved" Cantilever with Rectangular Diamond Shank
The cantilever is the heart of the MK III. ADC used a tapered "OmniPivot Improved" tube with a rectangular diamond shank, and claimed the combination improved rigidity while reducing resonance. The original U.S.-made MkIII styli paired that square diamond shank with a true tapered tube. That's worth checking, because later Japan-made versions reportedly used a straight cantilever despite retaining the square shank. So you get a cost-reduced interpretation instead of the design ADC engineered.
0.2 x 0.7 mil Nude Elliptical Diamond
The tip is a nude elliptical diamond, 0.2 x 0.7 mil (also given as .0002 x .0007 inch). Nude means the diamond itself is the tip rather than a chip bonded onto a metal shank. The elliptical profile traces the groove wall more accurately than a conical tip, and ADC's own claim was excellent high-frequency extension with reduced wear compared to conical designs. The recommended tracking force is 0.75 to 1.5 grams. Stay inside that window and it will look after your records.
Loading: 47,000 Ohms and 275 pF
Recommended load resistance is 47,000 Ohms, standard moving magnet territory, with a recommended load capacitance of 275 pF. That capacitance figure is on the high side, so a phono stage with adjustable loading is the sensible partner. Too much capacitance dulls the top. Too little can make it edgy. The MK III is transparent enough that you'll hear the difference either way.
Setup Tolerances: 0.5mm Clearance and ~15° VTA
Two numbers govern the setup and both are fussy. The distance between the record surface and the cartridge body runs approximately 0.5mm, a tight clearance that demands careful tonearm height adjustment. The vertical tracking angle is estimated at roughly 15°, which should inform your VTA setting. Cantilever length can vary between production runs, particularly between U.S. and later Japanese styli, so recheck alignment after any stylus swap. Even a small deviation can introduce tracking trouble on a high-compliance design.
Identification: The Engraving That Doesn't Match the Name
The original stylus housing is engraved "XLM improved MK II" at the bottom, along with "made in USA." That holdover marking has confused buyers for decades. Later replacement styli are marked "ADC MK III," and their packaging may carry the designation "RSX impr." The magnet assembly has a square-shaped nut, the suspension is green, and the needle protector is a front-flap style. Those are the tells that separate an original from a later replacement.
Historical Context
ADC built the XLM MK III from 1978 to 1984, and the company's reputation in that stretch was for thoughtful engineering rather than flash. It was never as showy as some Japanese rivals, but it had a devoted following among listeners who cared about compliance and cantilever geometry. Martin Colloms, writing in the Hi-Fi Choice Cartridges manual around 1979, called it a "best buy" and "a front rank contender." Contemporary advertising in Audio (January 1979, p.59) likewise pitched the XLM MK III on its ultra-linear 10Hz to 20kHz ±1dB frequency response and its record-saving tracking force. The MK III sits alongside the XLM mkI and XLM mkII as separate models in the line. The VLM MK III, QLM30 MK III, and QLM 34 III are related but distinctly different cartridges, and their specs should not be merged with the XLM's.
Collectibility & Value
The XLM MK III is long discontinued and no longer available new. Original units came with a serially numbered calibration card as part of the guarantee - the performance of each individual cartridge was guaranteed by that card - which makes complete, documented examples more desirable than loose bodies. Working units currently trade somewhere between roughly €137 and $299 depending on condition and stylus provenance. A recent listing for an XLM MKIII Improved example sat at $202. Read the market carefully: listings at $48.99 (VLM MK III), $49.85 (QLM30 MK III), and $59.99 (an Omni Pivot Improved cartridge bundled with a QLM 30 MK) are different products entirely, not bargains on an XLM.
Stylus supply is the real constraint. The replacement model is the 108-DEX, historically priced between $98 and $229 around 2011, and availability now is spotty at best. Some Japan-made replacement styli are reported to be less compliant than the original U.S.-made versions, which can bring tracking issues. One forum suggestion is to nudge tracking force upward within the 0.75-1.5 g window when running a later stylus. There are no service manuals in circulation, and given the precision involved, maintenance, especially swapping styli from different eras, is best left to specialists.
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