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What You Need to Know
What Is a P-Mount (T4P) Cartridge?
A P-Mount cartridge — also called a T4P (Technics 4-Pin) — is a plug-in cartridge format that attaches directly into a compatible tonearm slot without any separate mounting hardware or alignment procedure. Instead of two screws through a headshell, the P-Mount body has a rectangular plug that inserts straight into a T4P-compatible tonearm socket. The four electrical pins on the body make contact automatically when you slide the cartridge in.
P-Mount tonearms were popularized by Technics in the 1980s and can be found on many linear-tracking and mid-market turntables from that era, as well as a number of more recent models. The format offers one key practical advantage: installation and cartridge swapping requires no tools, no alignment, and no protractor. If your turntable has a P-Mount tonearm, the Red4 P-Mount is designed specifically for it.
Important: The P-Mount Red4 is not compatible with standard half-inch mount tonearms. If you are unsure which mounting format your turntable uses, check your turntable’s manual or call us at 800-942-0220 and we can confirm before you order.
The Red4 — Grado Prestige Series
Grado Labs has been making phono cartridges in Brooklyn, New York since 1953. The company is still family-owned, now in its third generation. Their Prestige Series is the foundation of the Grado cartridge lineup — plastic-bodied, high-output moving iron cartridges designed for broad system compatibility, easy installation, and long-term reliability.
The Red4 is the mid-tier entry in the Prestige Series, sitting above the Green4 and below the Gold4. It uses a bonded elliptical diamond stylus on an aluminum cantilever, the same moving iron flux-bridger generator as every Grado cartridge, and OCC (Ohno Continuous Casting) copper in the internal signal path. The Red4 P-Mount provides the same core performance as the standard-mount Red4 in a T4P plug-in format.
What Is a Moving Iron Cartridge?
Grado uses a moving iron (MI) design in all their cartridges, based on their patented flux-bridger generator system. In this design, the coils are stationary and a tiny iron element attached to the cantilever moves within a magnetic field. This keeps the moving mass extremely low — similar to a moving coil design in that respect — while delivering the output level and easy phono stage compatibility of a moving magnet cartridge.
The flux-bridger system uses four separate magnetic gaps, which increases efficiency and allows for fewer coil turns. Fewer turns means lower inductance and less sensitivity to tonearm cable capacitance — a practical advantage for system matching. The result is a cartridge that works with any standard MM phono input (47kΩ) and does not require a step-up transformer or specialized loading.
Bonded Elliptical Diamond — Better Groove Contact Than Spherical
The Red4 P-Mount uses a bonded elliptical diamond stylus on an aluminum cantilever. An elliptical diamond profile is longer and narrower in the direction of groove travel than a spherical (conical) stylus, allowing it to make better contact with the groove walls at higher frequencies. This translates to more accurate high-frequency tracking, lower distortion at the top end, and better retrieval of recorded detail compared to a basic spherical stylus.
“Bonded” means the diamond tip is fixed to the cantilever shank with an adhesive bond — reliable and appropriate for this level of the Prestige range. The stylus assembly is user-replaceable: it pulls straight off the front of the cartridge body and snaps back on without tools. This means you can restore the cartridge to like-new condition by simply fitting a new Red4 stylus when the existing one wears out.
User-Replaceable Stylus — And Interchangeable Across the Prestige Range
One of the most practical features of all Grado Prestige Series cartridges is the user-replaceable stylus system. The stylus assembly slides off the front of the cartridge body and snaps back on without tools — most users can do it in under a minute. You do not need a technician or a return to the factory to replace the stylus.
Additionally, all Prestige Series styli are cross-compatible across the entire Prestige line. This means you can fit a higher-level stylus — say, a Gold4 or Silver4 stylus — onto the Red4 body for a cost-effective performance upgrade without replacing the entire cartridge. It also works in reverse: the Red4 stylus fits any other Prestige body. This interchangeability is a deliberate design choice that Grado has maintained throughout the Prestige Series.
OCC Copper Internal Signal Path
The Red4 uses OCC (Ohno Continuous Casting) copper in its internal signal path. OCC copper is produced in a continuous casting process that eliminates grain boundaries along the length of the wire, resulting in a more uniform conductor with lower resistance variation. Grado uses OCC copper across the 2026 Prestige Series update as part of their coil composition improvements for better signal transmission and channel balance.
What Tracking Force and Phono Stage Do I Need?
The Red4 P-Mount is a standard MM-compatible cartridge. Any phono stage with a MM input at 47kΩ input impedance will work. Recommended tracking force is 1.6–1.9g. Set the tracking force using the adjustment mechanism on your T4P tonearm — most P-Mount tonearms have a simple dial or sliding scale for this purpose. If your tonearm does not allow for tracking force adjustment, confirm the fixed tracking force with your turntable’s manual and check it is within the Red4’s 1.6–1.9g range before purchase.
Hand-Built in Brooklyn, New York
Every Red4 P-Mount is assembled by hand at Grado’s facility in Brooklyn, New York. Grado Labs has been making cartridges there since 1953. This is not mass-produced audio — each cartridge passes through individual assembly and inspection before it ships.
What the Experts Say
ecoustics confirmed the Red4’s full specification set and described the Prestige Series overall as the “accessible, user-friendly foundation” of Grado’s cartridge lineup. They noted the Red4 uses a bonded elliptical diamond on an aluminum cantilever, with the stylus assembly user-replaceable and Prestige Series styli interchangeable across models — calling it a high output moving iron cartridge designed for compatibility with a wide range of phono stages.
Grado describes the Red4 as delivering “a balanced and controlled presentation, with clear detail and a smooth, natural top end. The midrange carries presence and body, while low frequencies remain defined and composed.” They highlight the cartridge as offering “broad system compatibility” and note that the die-injection molded housing “supports consistent construction and dependable performance.” The Red4 is explicitly offered in both standard mount and P-mount configurations.
The Absolute Sound confirmed the 2026 Prestige Series improvements, noting that Grado has built the range around “elliptical diamond stylus profiles, aluminum cantilevers, and OCC copper coil composition” to provide “strong tracking integrity, a full and balanced sound, and a presentation that remains true to the original recording.” The Prestige Series is described as “both an introduction to Grado cartridges and a long-term reference for dependable analog playback.”
Pairing the Red4 P-Mount
- T4P-Compatible Turntable. The Red4 P-Mount is designed for turntables with a T4P (P-Mount) tonearm. Common compatible models include various Technics, Sony, Hitachi, Kenwood, and other 1980s-era turntables, as well as some more recent models. Confirm your turntable’s tonearm type before ordering. Not sure? Call us at 800-942-0220.
- Phono Preamplifier. The Red4 P-Mount is a standard MM cartridge at 4.0mV and 47kΩ. If your amplifier or receiver does not have a built-in PHONO input, you will need a separate phono preamplifier. Browse our Phono Preamplifiers.
- Stylus Upgrade Path. Because all Prestige Series styli are interchangeable, you can fit a higher-level stylus on the Red4 body for improved performance without replacing the full cartridge. Ask us which stylus upgrades are available and compatible.
- Red4 Replacement Stylus. When your stylus wears out, a replacement Red4 stylus snaps straight on without tools. Browse phono accessories.
- Record Cleaning. A clean record protects your stylus and extends its life. Browse Record Cleaning Machines.
Features & Specifications
P-Mount (T4P) Format — No Tools, No Alignment Required
The P-Mount body plugs directly into a compatible T4P tonearm socket. Four electrical pins make contact automatically on insertion. No mounting screws, no headshell, no alignment protractor. Installation or cartridge replacement takes seconds. Compatible with any T4P (P-Mount) tonearm.
Bonded Elliptical Diamond on Aluminum Cantilever
The elliptical profile makes better groove contact than a spherical stylus, tracking more accurately at high frequencies and extracting more musical detail at the same tracking force. The aluminum cantilever transmits stylus movement to the generator with good rigidity and controlled mass.
User-Replaceable Stylus — Cross-Compatible Across Prestige Series
The stylus assembly pulls off and snaps on without tools. Replace a worn stylus in under a minute without returning the cartridge to a dealer or factory. All Prestige Series styli are interchangeable, enabling stylus replacement and upgrade without replacing the cartridge body.
Grado Moving Iron Flux-Bridger Generator
Stationary coils, moving iron element. Low moving mass, high efficiency, insensitive to tonearm cable capacitance. Compatible with any standard MM phono input at 47kΩ. No step-up transformer or special loading required.
OCC Copper Internal Signal Path
Ohno Continuous Casting copper with continuous grain structure for improved signal transmission, lower resistance variation, and better channel balance.
Die-Injection Molded Housing
Consistent, precisely formed housing for uniform acoustic behavior and reliable performance over time.
Specifications
- Mounting format: P-Mount (T4P plug-in)
- Type: Moving iron (high output), flux-bridger generator
- Stylus: Bonded elliptical diamond
- Cantilever: Aluminum
- Output voltage: 4.0mV @ 5 CMV (45 degrees)
- Frequency response: 10 Hz–55 kHz
- Channel separation: Average 25 dB (10–30 kHz)
- Input load: 10k–47kΩ
- Inductance: 50mH
- DC resistance: 660Ω
- Compliance: 20 μm/mN
- Tracking force: 1.6–1.9g recommended
- Cartridge weight: 6g
- Stylus: User-replaceable; cross-compatible with all Grado Prestige Series styli
- Internal signal path: OCC copper
- Housing: Die-injection molded plastic
- Made in USA (Brooklyn, NY)
- MSRP: Verify with Audio Advisor
Frequently Asked Questions
How do I know if my turntable uses P-Mount?
Check your tonearm. A P-Mount tonearm has a rectangular slot at the headshell end into which the cartridge plugs directly — there are no separate screws or a removable headshell. If your tonearm has a detachable headshell with two visible screws, you need the standard half-inch mount Red4 instead. Your turntable’s manual will also specify the tonearm type. Not sure? Call us at 800-942-0220 and we can confirm from your model number.
Does the P-Mount version sound the same as the standard Red4?
Yes — the cartridge internals, stylus, cantilever, and generator are the same. The only difference is the mounting format. Both use a bonded elliptical diamond, aluminum cantilever, and Grado’s flux-bridger MI generator at 4.0mV output. The acoustic performance should be essentially identical, provided the tracking force is set correctly on the P-Mount tonearm.
Can I adjust tracking force on a P-Mount tonearm?
It depends on the tonearm. Many P-Mount tonearms include a tracking force adjustment dial or setting, while some older models have a fixed tracking force. Check your turntable’s manual to determine whether tracking force is adjustable and what range it supports. The Red4 P-Mount requires 1.6–1.9g — if your tonearm has a fixed tracking force outside this range, the Red4 P-Mount may not be suitable. Call us if you’re not sure.
Can I use a half-inch mount headshell adapter with this cartridge?
P-Mount to half-inch adapters do exist, but their use introduces additional mechanical complexity and may affect performance. The Red4 P-Mount is designed and optimized for use in a true T4P tonearm socket. If you need a half-inch mount cartridge, the standard Red4 is the right choice.
When should I replace the stylus?
Most styli last approximately 500–1,000 hours under normal conditions. Signs of wear include harsh or distorted high frequencies, reduced stereo separation, or any mistracking on clean records. When it’s time, a replacement Red4 stylus snaps on without tools in under a minute.
Can I upgrade to a better stylus on this body?
Yes — all Grado Prestige Series styli are cross-compatible. You can fit a higher-level Prestige stylus onto the Red4 P-Mount body for a performance upgrade without purchasing a new cartridge body. Ask us which stylus options are compatible and currently available.
What phono stage do I need?
Any standard MM phono input at 47kΩ will work. The Red4 P-Mount outputs 4.0mV — well within the range of any MM-capable phono stage. If your amplifier or receiver has a PHONO input labeled “MM” or simply “PHONO,” the Red4 P-Mount will be compatible. If you need a separate phono preamplifier, we can recommend options at your budget.
Where is it made?
By hand, in Brooklyn, New York. Grado Labs has assembled phono cartridges at their Brooklyn facility since 1953.
What’s in the Box
- Grado Prestige Red4 P-Mount phono cartridge ×1 (stylus installed)
- Stylus guard
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Not sure if your turntable is P-Mount compatible, or looking for guidance on cartridge setup and phono stage matching? Visit our Audio Advisor Learning Center for guides on turntable cartridges, mounting formats, and getting the most from your vinyl setup.
