ADC Super XLM Mk. II (1976–1978)
A fleeting glimpse into quadraphonic sound, this rare 4-channel pickup from ADC dared to hear beyond stereo—just as the dream of surround vinyl was collapsing.
Overview
The ADC Super XLM Mk. II isn't just obscure—it's a time capsule from the final gasp of a failed revolution. Between 1976 and 1978, ADC released this 4-channel pickup at the exact moment the industry was walking away from quadraphonic vinyl. It wasn't trying to be flashy or affordable; it was built for a niche that barely existed, chasing a future that never arrived. You don’t find these lying around. When you do, it’s usually someone cleaning out an attic full of unplayed records and gear that looked cool in a 1975 stereo catalog.
It’s not a stereo cartridge. It’s not even pretending to be. The XLM Mk. II is a true 4-channel pickup, designed to extract four discrete audio signals from a single groove—yes, really. That means if you had a compatible decoder, a properly cut SQ or QS record, and a receiver with four amps, you could get something close to surround sound from a turntable spinning in 1977. The principle? Induced Magnet, which ADC implemented as a moving iron design but wired to connect like a standard MM (moving magnet) cartridge. That small detail meant you didn’t need a special preamp—just the right decoder and a lot of patience.
And patience was in short supply back then. By the time the XLM Mk. II hit the market, quadraphonic records were already retreating into cutout bins. The format war between SQ, QS, and discrete systems had confused consumers, and most dealers didn’t know how to set up four speakers, let alone sell them. So this cartridge didn’t fail—it was orphaned. It arrived late to a party where the lights were already on and the host was looking for the last guest to leave.
Still, there’s something quietly audacious about it. That frequency response—15 to 50,000 Hz—was insane for the late '70s. Most high-end stereo cartridges of the era topped out around 20,000 Hz, if they were lucky. ADC claimed +2/-5dB across that entire range, which, whether you believe the numbers or not, shows they weren’t playing it safe. This wasn’t about warmth or musicality in the usual audiophile sense. It was about bandwidth, extension, and the ability to capture everything the groove could hold—even if almost no records used it.
But here’s the trade-off: we don’t know much else. No tracking force specs. No output voltage. No channel separation figures. No weight, no dimensions, no stylus shape. That silence speaks volumes. It suggests this was a specialist product, sold in low volume, with minimal documentation. If you owned one, you probably knew what you were doing—or you were in over your head.
There’s no evidence of how many were made, whether they were reliable, or what typically went wrong. No anecdotes about brilliant sound or frustrating setup. No magazine reviews praising its imaging or condemning its price. It just… existed. For two years. Then vanished.
Specifications
| Type | 4-channel pickup |
| Principle | Induced Magnet (Moving Iron, connection as MM) |
| Frequency response | 15 - 50,000 Hz +2/-5dB |
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