ADC RSZ

A vintage ADC ZLM cartridge gets its "Aliptic" diamond back, and it plays the way it was meant to.

Overview

The ADC RSZ isn't a cartridge. It's not even a full assembly. It's the original stylus for the ADC ZLM, and it gave the ZLM its reputation. The tip is a precision-cut, non-bonded natural diamond shaped into what ADC called an "Aliptic" - their proprietary name for a semi-Shibata profile. It was the top stylus option for ADC's flagship cartridge, designed to pull more high-frequency detail and inner groove clarity than the standard ellipticals of its day. The ZLM replaced the XLM as ADC's premium offering, and the RSZ stylus was the key difference.

An original NOS (new old stock) RSZ is hard to find. These were never mass-market items, and original production years remain unconfirmed. The tip radii are just .0002 x .0015 inch, which lets it trace high-frequency modulations that lesser styli smear. It was intended for 33 and 45 rpm vinyl only, not 78s. It was engineered for stereo, though it's noted as quad-compatible, which dates it to the brief era of four-channel phono.

ADC no longer produces the RSZ, so the aftermarket has stepped in. The most notable replacement is from LP Gear. It uses a ViVid Line Contact Shibata-profile diamond with slightly different radii (.0002 x .0030 inch), bonded to a thin-wall Zualum tube cantilever. It's not the original, but owners report it comes remarkably close, detailed and musical, and that it works on aging cartridges.

Specifications

Manufacturer	ADC
Product type	Replacement stylus (phono cartridge stylus) for ADC ZLM and compatible cartridges
Stylus tip shape (original ADC RSZ)	Semi-Shibata diamond tip, designated "Aliptic" by ADC
Stylus tip shape (aftermarket replacement)	Shibata diamond
Stylus tip radii (original ADC RSZ)	.0002 x .0015 inch
Stylus tip radii (LP Gear replacement)	.0002 x .0030 inch (6/75 µm)
Cantilever material (LP Gear replacement)	Thin-wall Zualum tube
Tracking force range	1.0 - 1.5 g
Compatible playback speeds	33 and 45 rpm
Not for 78 rpm speed	Yes
Stylus construction (original)	Not bonded, natural diamond
Channel configuration	Stereo (Quad compatible)

Key Features

The "Aliptic" Advantage

The "Aliptic" tip was a real engineering choice, not just a fancy name. A semi-Shibata profile means the diamond is polished to a longer, flatter contact surface than a standard elliptical. That lets it ride deeper into the groove wall with more consistent contact, which gives better high-frequency retrieval and less distortion in complex passages. The original RSZ used a non-bonded, natural diamond. That means the stone wasn't glued or mounted in a sleeve but machined directly onto the cantilever tip, a method some believe improves rigidity and signal transmission. Collectors and audiophiles still debate the difference.

Aftermarket Revival: LP Gear’s Take

When the original supply dried up, LP Gear stepped in with a replica. Their version uses a bonded Shibata diamond, labeled "ViVid Line Contact," with a larger upper radius (.0030 inch vs .0015 inch). That may affect ultimate micro-detail retrieval, but user feedback suggests it's still a big step up from elliptical styli. It's mounted on a thin-wall Zualum (aluminum alloy) tube, so the cantilever is lightweight and stiff, which helps tracking without overloading delicate tonearms. One user noted that after swapping from OEM to the LP Gear RSZ replacement, tracking remained perfect without any adjustments.

Compatibility & Use

The RSZ was made for the ADC ZLM, the company's top-of-the-line cartridge at the time, and it can also upgrade other ADC cartridges in the same family. It's explicitly not for 78 rpm records, because the groove geometry and tracking demands are entirely different. For 33 and 45 rpm stereo (and quad) vinyl, it's a precision tool. Owners note it works especially well with lightweight tonearms, where its low tracking force requirement (1.0 to 1.5 grams) is a real advantage. A worn stylus can scar records permanently, so it pays to know when to replace it, or to keep a spare on hand.

Collectibility & Value

An original ADC RSZ in NOS condition is a coup. Historical seller notes suggest prices once ranged between $250 and $400, though current availability is spotty and often depends on estate sales or vintage audio liquidations. Replacement styli for older cartridges like this are routinely discontinued, and once the OEM supply vanishes, collectors are left scavenging. Many owners follow a simple rule: if you're running a ZLM, buy at least two replacement styli while you can. The LP Gear version, priced at $184.47, is a reliable alternative - not vintage-correct, but sonically close and consistently available. One eBay listing notes a "trending price" based on the last 90 days for a Pfanstiehl-made high-quality RSZ replica, indicating ongoing demand. User reviews consistently praise the replacement's sound quality, high-frequency extension, and ability to revive older cartridges. As one put it: "Both are very detailed and musical… easy listening for a wide range of music."