ADC RQ-40 ()

A replacement stylus that promises cleaner groove tracking and better tonal balance - if you can track down what cartridge it belongs to.

Overview

The ADC RQ-40 isn't a cartridge. It's the stylus, the part that rides in the groove. It's listed under the ADC brand, a name tied mostly to moving magnet cartridges and the Sound Shaper equalizers. The RQ-40 itself is poorly documented.

All we know for sure is that it's a stylus, sometimes spelled RQ 40 or RQ40. A current replacement version, sold by LP Gear under part number ADC178, has a polished diamond tip. Some budget replacements use sintered diamond or even ceramic, so polished diamond suggests ADC was aiming above entry-level. The listing claims it delivers "better musical accuracy, improved tonal balance and higher sound quality." That sounds like boilerplate, but a worn or poorly shaped stylus can strangle detail and add harshness.

But here’s the rub: we don’t know what cartridge body the RQ-40 was designed for. We don’t know the tracking force, compliance, or tip shape — elliptical? conical? — and there’s zero documentation on what turntable or tonearm it was meant to ride on. Was it part of a high-output MM cartridge from the late ’70s? A budget offering from the early ’80s? The VTA Brand Index lists the RQ-40 among 68 ADC models, so the brand had range, but this particular model vanishes into the fog. No production years, no original pricing, no schematics, no user manuals. Just a part number and a promise.

Most people only notice a stylus when it's gone, when the sound turns muddy, when sibilance gets spiky, or when records start sounding like they're playing through a screen door. That's when you start hunting for a replacement, and that's where the ADC178 from LP Gear comes in. At $28.95, it's not cheap for a stylus, but it's not outrageous either - about what you'd pay for a decent factory replacement on a classic Shure or Audio-Technica model. Whether it's a faithful recreation or just a functional stand-in, the fact sheet doesn't say.