ADC Super XLM MKII (1976–1978)
A quadraphonic cartridge from the late '70s, built for a format that never took off.
Overview
The ADC Super XLM MKII was made by Audio Dynamics Corporation in New Milford, CT, between 1976 and 1978. It was one of the last gasps of quadraphonic vinyl, a format the industry was already abandoning by the time this cartridge hit the market. It is a moving iron phono cartridge with a hyper-elliptical Shibata stylus, built for channel separation and fine groove tracing. It was the quad version of the already-respected XLM MKII, aimed at a tiny audience chasing four-channel sound through two speakers and a matrix decoder.
The XLM line had already earned its reputation before this variant showed up. Owners from the era remember it as a cartridge that punched above its weight. Some even claimed it outperformed the Shure V15 Type III, which was practically gospel back then. The Super XLM MKII inherited that design but was engineered for discrete 4-channel playback, so it had to track four modulated walls in the groove with precision few cartridges of the era could match. You need a compatible turntable, a decoder, and the right records, and the records are hard to find. Users who've compared it to modern cartridges like the Audio-Technica VM95ML say it trades a bit of ultimate detail for a richer, more cohesive soundstage and deeper bass. They describe a solidity in the lower mids that feels almost physical.
This is not a plug-and-play cartridge. It needs a light tonearm - think SME Series III, Infinity Black Widow, or Mission 774 - because the design philosophy here was minimal moving mass. The original XLM II had suspension issues, and early runs of the series were known to collapse under improper setup or mishandling. So it's technically strong in its engineering and fragile in practice. Put it on a heavy SME 3012 and it won't work well. It needs careful balance and a system that respects its low tracking force of 1.25 grams. Set up right, owners say it opens up - "more open and musical than anything I tried prior," as one put it. Set up wrong, and you're looking at a dead coil or a bent stylus stem.
Specifications
| Manufacturer | Audio Dynamics Corporation (ADC); New Milford, CT |
| Production year | 1976–1978 |
| Product type | MM phono cartridge / 4-channel pickup |
| Frequency response | from 15 Hz to 50 kHz |
| Stylus tip type | hyper-elliptical Shibata type |
| Output | 6mV |
| Technology | Induced Magnet / Moving Iron |
| Compliance | 33cu |
| Tracking force | 1.25g |
Key Features
The Omni-Pivot Induced-Magnet System
The heart of the ADC Super XLM MKII is the "Omni-Pivot Induced-Magnet" system, a design ADC patented to reduce moving mass in the cartridge's generator. In traditional moving magnet designs the magnets move. Here the magnet is fixed, and the iron pieces move within a magnetic field, inducing current in stationary coils. This allows a lighter, more responsive stylus assembly, which in theory means better high-frequency response and lower record wear. Less mass means faster transient response and less groove drag. The frequency response stretches to 50 kHz, which was likely aimed at preserving ultrasonic cues used in matrixed quadraphonic decoding.
Hyper-Elliptical Shibata for Quad Tracking
The stylus is where this cartridge earns its keep. A hyper-elliptical Shibata tip is engineered to trace the high-frequency, high-modulation walls of a quadraphonic groove with minimal distortion. These grooves are more complex than standard stereo, with additional phase-encoded information riding in the ultrasonic range. The Shibata profile has a long, narrow contact line, and it follows those walls more accurately than a standard elliptical tip. That's why users report a "solid thundering bottom, middle and highs." With an output of 6mV, it's hot enough to drive most MM stages without strain, though it still benefits from a clean, low-noise preamp to preserve the wide bandwidth.
Built for a Dying Format
By 1976 the ADC Super XLM MKII was a solution in search of a problem. Quadraphonic vinyl had already peaked, and the industry was pulling back. The reason to build it was probably that ADC had the tech, the reputation, and a loyal following among audiophiles who refused to let the dream die. The cartridge body even shows signs of adaptation, with what appears to be an add-on providing threaded holes for headshell attachment, suggesting it was retrofitted or modified from an existing design. It's not sleek. For the few who owned it, it was "very well liked in its day."
Historical Context
The ADC Super XLM MKII arrived just as the industry was walking away from quadraphonic vinyl. Released between 1976 and 1978, it was one of the final high-end attempts to salvage a format that had collapsed under competing standards, poor consumer adoption, and a lack of compatible hardware. ADC pushed forward anyway, releasing this rare 4-channel pickup as a niche offering for die-hard enthusiasts. It stood alongside the standard XLM MKII, with the aim of extracting every spatial cue from discrete and matrixed quad records. At the time, the XLM line was already considered a top-tier alternative to the Shure V15 Type III, with some users claiming the ADCs were better. That reputation gave the Super XLM MKII credibility, even as its format faded.
Collectibility & Value
Today the ADC Super XLM MKII turns up on European secondhand markets, Japanese auction platforms, and niche forums. Prices are all over the map. Listings show examples ranging from ¥905 (~$6) on Yahoo Auctions in 2024 to €222 for a new-old-stock unit in Germany. More typical prices hover between €50 and €125, or ¥12,000 to ¥15,000 in Japan. Many of these listings may not be complete, tested, or even original. The suspension issues that plagued early XLM models mean a working unit is a minor miracle. Stylus compatibility is also a problem. JICO and Tonar make replacements, but they may not fit the original XLM or Super XLM MKII without modification. One user warned that a stylus for an XLM MKIII won't work in the original XLM, and the same likely applies here.
If you're buying, assume the stylus is worn unless proven otherwise. A replacement stylus from LP Gear is said to deliver "finer detail and harmonically complete sound quality," but originals are scarce and expensive - one listing showed an original ADC XLM stylus at €149. The cartridge itself might go for under $100, but pairing it with the right tonearm (light, rigid, well-balanced) could cost more than the cartridge.
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