Grado Reference4 Phono Cartridge

The Grado Reference4 is the flagship of Grado's Timbre Series of wood-bodied moving iron phono cartridges, pairing an elliptical diamond stylus with a machined boron cantilever in an American Osage housing. Available in four configurations (high-output and low-output, stereo and mono), the Reference4 uses Grado's patented flux-bridger generator with OCC copper coils to deliver the series' most detailed and controlled performance.

Key Features of the Grado Reference4

• Elliptical Diamond Stylus: Dual-radius contact profile for accurate tracking and natural tonal balance across the frequency range.
• Machined Boron Cantilever: Five-piece OTL cantilever design achieving additional tip mass reduction over the Sonata4 and Platinum4 models.
• Flux-Bridger Moving Iron Generator: Grado's patented system combines moving coil transient speed with moving magnet output and loading simplicity.
• OCC Copper Coils: Oxygen-free continuous-cast copper for improved signal purity and channel balance.
• American Osage Wood Housing: Dense domestic hardwood with natural resonance damping properties.
• Four Output Configurations: High-output (4.0mV) and low-output (1.0mV) in both stereo and mono, matching any phono stage and record collection.
• 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.

Machined Boron Cantilever with OTL Technology

The Reference4 and Master4 both use Grado's five-piece OTL (Optimized Tip-to-Link) cantilever technology, achieving an additional 5% tip mass reduction compared to the four-piece design used in the Sonata4 and Platinum4. The machined boron cantilever provides exceptional stiffness relative to its weight, transmitting stylus vibrations to the generator efficiently without the energy storage that softer materials introduce. The difference between the Reference4 and Master4 comes down to component selection and tolerancing, with the Reference4 receiving the tightest grading in the Timbre Series.

At the Reference4 level, component grading is the lever. The cantilever assembly, generator coils, magnet pole pieces, and stylus profile inspection all receive the line's strictest tolerances. The flagship status means a unit failing any of the Reference4 inspection thresholds drops down to Master4 inventory, not back into a Reference4 box. That is how Grado maintains the consistency that lets the Reference4 sit at the top of the Timbre line without resorting to a separate generator design.

American Osage Wood Housing

New to the /4 generation, the Reference4 and Master4 are housed in American Osage wood, replacing the Australian Jarrah used in previous Timbre models. Osage is among the densest and hardest domestic hardwoods available, with natural damping properties that help isolate the generator from airborne and mechanical vibrations. The updated housing geometry in the /4 series also improves installation stability, making cartridge alignment easier during setup.

Osage is not a common cartridge housing material outside of Grado. The species is native to the central United States and was historically prized for bow staves and tool handles because of how hard and dense it stays at typical moisture content. The wood also holds its dimensions under humidity swings, which makes it a strong housing material for a cartridge generator: it does not move the way some hardwoods do, and its damping behavior holds up across the cartridge's working temperature range.

High-Output and Low-Output Options

The Reference4 is available in both 4.0mV (high-output) and 1.0mV (low-output) versions. The high-output version works with any standard moving magnet phono input, while the low-output version pairs with MC-capable phono stages for potentially wider dynamic range and lower noise floor. Both output levels are available in stereo and mono configurations, giving the Reference4 the broadest compatibility of any Grado cartridge.

Explore the Full Grado Timbre Series

The Reference4 is the flagship of Grado's Timbre Series. All five Timbre models share the flux-bridger generator and elliptical diamond stylus, with differences in cantilever technology, housing material, and component grading:

• Grado Master4 - Machined boron cantilever in American Osage, the Reference4's closest companion.
• Grado Sonata4 - Aluminum cantilever in Mediterranean Olive wood, the mid-point of the Timbre lineup.
• Grado Platinum4 - Aluminum cantilever in Mediterranean Olive wood, sharing the Sonata4's architecture with looser grading tolerances.
• Grado Opus4 - Aluminum cantilever in North American Maple, the Timbre entry point.

Listeners ready to move beyond the Timbre Series step up to the Grado Statement4, the entry to the flagship Lineage Series with its nude Shibata diamond stylus.

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

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Grado Reference4 Specifications