Grado Master4 Phono Cartridge

The Grado Master4 sits just below the Reference4 in Grado's Timbre Series, sharing the same machined boron cantilever and American Osage wood housing in a cartridge that balances performance and value. Built around Grado's patented flux-bridger moving iron generator with OCC copper coils, the Master4 is available in four configurations to match any phono stage and listening preference.

Key Features of the Grado Master4

• Elliptical Diamond Stylus: Dual-radius profile for accurate tracking and balanced tonal presentation.
• Machined Boron Cantilever: Five-piece OTL design with 5% lower tip mass than the four-piece cantilevers used in the Sonata4 and Platinum4.
• Flux-Bridger Moving Iron Generator: Grado's patented low-mass generator for moving coil speed without the loading complexity.
• OCC Copper Coils: Oxygen-free continuous-cast copper for improved signal clarity.
• American Osage Wood Housing: Dense domestic hardwood with natural vibration damping, new to the /4 generation.
• Four Output Configurations: High-output (4.0mV) and low-output (1.0mV) in stereo and mono.
• Hand-Built in Brooklyn, NY: Assembled and voiced at Grado's Sunset Park facility.

About Grado Labs

Grado Labs has been building phono cartridges and headphones by hand in Brooklyn, New York since 1953. Four generations of the Grado family have refined the company's patented flux-bridger moving iron generator system, which delivers the speed and detail retrieval associated with moving coil designs while maintaining the higher output and simpler loading requirements of moving magnet cartridges. Every Grado cartridge is hand-assembled in the same Sunset Park facility where Joseph Grado first began his work over seven decades ago, then tested and voiced before it ships.

Boron Cantilever and OTL Technology

The Master4 shares the Reference4's five-piece OTL cantilever assembly with a machined boron rod. This construction reduces effective tip mass by approximately 5% compared to the four-piece OTL design in the Sonata4 and Platinum4, allowing the stylus to follow groove modulations more precisely. Boron's high stiffness-to-weight ratio means vibrations travel from the stylus tip to the generator with minimal delay or energy loss. The distinction between the Master4 and Reference4 is in component selection and quality grading, not architecture.

Machined boron is the same cantilever material used in many cost-no-object moving coil cartridges. Grado specifies it on the Master4 and Reference4 because the flux-bridger generator's transient response is fast enough to expose any energy storage in the cantilever, and boron's stiffness-per-gram is the highest of any material in widespread cartridge use short of single-crystal diamond. The trade-off is fragility: boron cantilevers are stiffer but more brittle than aluminum, which is one reason Grado retains aluminum on the lower-tier Opus4 through Sonata4 models where price-to-replacement-risk balance favors the more forgiving material.

American Osage Wood Housing

New to the /4 generation, the Master4 and Reference4 are housed in American Osage, one of the densest and hardest domestic hardwoods. The wood provides natural vibration damping without the added mass of synthetic materials, and its resonant properties complement the flux-bridger generator's output characteristics. Grado has refined the housing geometry for the /4 series, improving cartridge stability during playback and simplifying alignment during installation.

Osage's density (around 0.8 g/cm³ at typical moisture content) is what gives the Master4 its housing character. The wood damps cartridge body resonances broadband rather than at any single peak, and its hardness allows for tight mounting tolerances at the threaded inserts. For installers, that means cartridge screws torque to a consistent stop without the housing creeping under load, which keeps azimuth from drifting between setup and final adjustment.

Explore the Full Grado Timbre Series

The Master4 is the second-highest model in Grado's Timbre Series, positioned between the Reference4 and the Sonata4:

• Grado Reference4 - The Timbre flagship, with the tightest component selection in the series.
• Grado Sonata4 - Aluminum cantilever in Mediterranean Olive wood, offering Timbre performance at a lower price point.
• Grado Platinum4 - Aluminum cantilever in Mediterranean Olive wood, second-step in the line.
• Grado Opus4 - Aluminum cantilever in North American Maple, the Timbre entry point.

Above the Timbre Series, Grado's flagship Lineage Series introduces nude Shibata diamonds and sapphire or boron cantilevers.

The Flux-Bridger Moving Iron Generator

Every Timbre Series cartridge runs on Grado's flux-bridger moving iron generator, a patented design that sits between conventional moving magnet and moving coil topologies. In a moving iron generator, the coils and magnets stay fixed while a small, low-mass iron armature on the cantilever responds to groove modulations. Because the moving element is just iron, not a magnet or a coil pack, the system carries less moving mass than a standard MM and roughly comparable mass to many MC designs, which is what gives Grado cartridges their characteristic speed and transient detail.

The practical advantage is loading simplicity. Both high-output and low-output Timbre cartridges present an inductive load that any moving magnet phono stage can drive (high-output versions) or that any MC-capable stage can handle (low-output versions). There is no compromise on cartridge loading, no need for step-up transformers on the high-output models, and no exotic phono stage requirement. The flux-bridger architecture also makes Grado cartridges relatively tolerant of capacitance variation in the tonearm cable, which simplifies setup compared to some MM designs that depend on precise capacitive loading to flatten their response.

OCC Copper Coil Wire

The Timbre Series uses oxygen-free continuous-cast copper for the generator coil wire, the same OCC copper specification used across the entire /4 generation. Continuous-cast copper is drawn through a heated mold in a single, unbroken process, producing long crystal grains aligned with the wire's length. The result is a wire with fewer grain boundaries per inch than conventional oxygen-free copper, which translates into more consistent electrical behavior across the audio band and improved channel-to-channel matching when paired coils are wound from the same batch.

Coil wire matters more in moving iron designs than it does in many MM cartridges because the generator's output is directly tied to the coil's electrical characteristics. Grado specifies OCC across every Timbre model precisely because consistency at the coil is one of the cleanest ways to lock in repeatable performance unit to unit.

High-Output, Low-Output, Stereo, Mono

Every Timbre cartridge ships in four configurations: high-output stereo (4.0mV), low-output stereo (1.0mV), high-output mono, and low-output mono. The high-output 4.0mV version pairs with any standard MM phono input, the same input that handles the vast majority of installed phono stages. The 1.0mV low-output version is intended for MC-capable phono stages or step-up transformers; the lower output trades some absolute gain for a potentially quieter noise floor and (depending on the phono stage's MC topology) more headroom on dynamic passages.

The mono configurations are true mono generators with the coils summed at the cartridge, not a stereo cartridge with a mono switch in the preamp. For collectors with significant pre-1958 mono LPs, a true mono cartridge eliminates vertical groove noise that a stereo pickup will reproduce as rumble or surface hash, and it improves apparent resolution on the playback of mono pressings. The mono variants are marked Special Order and No Returns, consistent with how most cartridge manufacturers handle true-mono SKUs.

Tracking Force and Compliance

All five Timbre models share the same tracking-force window of 1.6 to 1.9 grams, with most installations dialing in at 1.75 grams as a starting point. Compliance is specified at 20 µm/mN, which places the Timbre Series squarely in the medium-compliance range that pairs comfortably with most modern tonearms. Effective mass between 9 and 14 grams at the headshell is the sweet spot. Cartridge weight runs 9 grams across the aluminum-cantilever models (Opus4 through Sonata4) and steps up to 10 grams on the Master4 and Reference4, so headshell weight is the main variable to balance during arm matching.

For VTA, start parallel to the record surface and adjust by ear once break-in is past the first 20 to 30 hours. Cartridges in this category typically need that early use time before the suspension settles into its working stiffness.

The Listening Room Difference

We're a third-generation family business with a brick-and-mortar showroom in Chestertown, Maryland, and a reputation built on exceptional service and relentless passion for hifi. Whether you're visiting in person or ordering online, we bring decades of experience, personalized service, and honest guidance to every interaction. We don't just ship boxes. We help build systems, answer your questions like real humans, and make sure every detail of your setup is right, from the cables to the final connection. Our passion is helping you get the most out of your gear, with support that lasts well beyond the sale.

Grado Master4 Specifications