ADC QLM30mkII

The needle that kept a thousand department-store changers spinning - and the one you'll be hunting for when the left channel goes quiet.

Overview

The ADC QLM30 MkII is sold as a phono cartridge, but in practice it's a replacement stylus for the ADC QLM 30, II, and III cartridge series. It's the part that rides the groove. If the sound off a vintage turntable has gone dull, or one channel has dropped out, this is very likely the part you're swapping, not the whole cartridge body. It's a wear part, not a trophy.

ADC built it in the USA, and the same cartridge turned up under a stack of other names: FIDELITY QLM 30MKII, SCHNEIDER QLM30 III, ZENITH 942-100, RADIOSHACK REALISTIC QLM 30 MK III, and SIEMENS QLM 30 MK III. ADC supplied OEM cartridges to a spread of consumer electronics brands during the stereo era, and the QLM30 MkII was one of them. So a stylus hunt for a Realistic-branded changer and a Schneider-branded changer can land on the same part number. For period-correct restoration, that cross-reference list is the useful part.

The record doesn't show when this thing was made or what it cost. The source documentation states that there's no data on original pricing or production years, so there's no honest way to say whether it launched as a budget part or a mid-tier one. Its widespread rebranding and its life in consumer-grade changers suggest it was never positioned as a high-end product. That's an inference, not a spec.

Key Features

Highly Polished Special Elliptical Diamond Stylus

The replacement stylus for the QLM30 MkII is a highly polished special elliptical diamond. An elliptical tip traces the modulations in a record's groove more precisely than a conical tip, particularly in the high frequencies. The "special" designation in ADC's own language suggests the profile was tuned rather than off-the-shelf, though no further geometry is documented. The replacement stylus for the MkII and the original stylus for the related QLM30 MKIII are not the same thing. The MKIII originally shipped with a 0.7mil conical tip. Restorers chasing period-correct playback on a MKIII should not assume the MkII's elliptical replacement is a like-for-like substitute.

Tracking Force Around 3 to 5 Grams

The only tracking force figure attached to this model is 3 to 5 grams, and it comes from a single source - the HTML meta description of the research page, not the visible body copy. That makes it a weak spec. If accurate, 3 to 5 grams is a heavy tracking range by modern audiophile standards, which fits a cartridge designed for mass-market changers. Owners setting up a QLM30 MkII today should verify against their own documentation, because a single meta-tag value is not a manufacturer's spec sheet.

Made in the USA

The cartridge carries a "MADE IN USA" designation. That places the QLM30 MkII on the American side of the manufacturing line, before the offshoring wave that reshaped so much of the consumer audio industry. It doesn't say which factory or which year.

Cross-Brand Compatibility

The QLM30 MkII's real feature is its reach. It fits the ADC QLM 30, II, and III cartridge series, and it appeared in OEM turntables from Radioshack, Zenith, and others. For anyone maintaining a vintage changer, a known-good replacement stylus for a cartridge that shipped under half a dozen brand names means parts are still findable. The Pfanstiehl 111-D7C Diamond Stylus is one documented aftermarket replacement, listed as replacing the ADC RSQ30 and RSQ31 designations and fitting the QLM30/MK III.

Historical Context

ADC supplied OEM cartridges to a range of consumer electronics brands during the stereo era, and the QLM30 MkII was used widely enough that replacement parts still circulate today. It was not a flagship and not a review darling. There's no data on original pricing or production years, so the launch story is a blank. What's documented is the OEM trail - Radioshack, Zenith, and others - and the rebranding list that followed from it.

Collectibility & Value

Nobody collects the QLM30 MkII for prestige. They buy it because a vintage turntable needs a stylus, and this one fits. Market activity across the QLM30 series shows styli and cartridges selling between approximately €15 and €100, with complete cartridges at the higher end of that range. Two specific listings anchor it: a new original stylus for the QLM30 MKIII listed for €53 on Hifishark (May 14, 2024), and an LP Gear replacement stylus (RSQ30, for the ADC QLM30 MKIII) priced at $32.94. Both are MKIII-referenced listings, so they set the neighborhood rather than the exact MkII price.

Complete units surface in estate sales and bulk audio lots, usually sold "as-is" or "tested." Before committing to a complete cartridge, test both channels. There's at least one documented case of a JVC record changer using the same cartridge as the ADC QLM 30 MK III that developed a dead left channel. The cause isn't specified, whether worn coils, loose wiring, or stylus misalignment. A cartridge that's been sitting unused for years is the most likely candidate for channel failure, so a quick continuity test or channel balance check before setup is cheap insurance.

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