Fostex TH-1100RP Mk2

The TH-1100RP Mk2 is part of Fostex’s RP range and uses planar magnetic technology that the Japanese manufacturer has been developing for over fifty years. This open-back, circumaural headphone is hand-assembled in Japan. It features solid maple earcups dyed using the traditional Awa Aizome technique and a new-generation Premium RP driver with air damping control. The Mk2 version brings refinements to the original 2024 model, optimizing diaphragm movement and improving comfort for long listening sessions.

The most advanced planar diaphragm in the range

The RP mk2 driver is built around the largest planar diaphragm ever used in the series. This fully driven membrane is distinguished by an air damping control system that precisely manages diaphragm movement. Damping materials adjust the internal airflow of the driver, while the optimized magnetic circuit suppresses unwanted resonances. This technical architecture delivers fast transient response and maintains a constant amplitude, particularly in the low frequencies. The 96 dB/mW sensitivity with 32 Ω impedance makes pairing with different amplification sources easier. The frequency response extends from 10 to 40,000 Hz.

An open design tuned for soundstage

The open configuration of the TH1100RPmk2 relies on double-layer etched aluminum grilles positioned at the back of the earcups. Every internal component and the open-area ratio have been carefully tuned to achieve an expansive soundstage and precise imaging. This architecture aims to reproduce a natural acoustic field while limiting listening fatigue during extended use. The hard maple housing contributes density and acoustic neutrality: bass benefits from depth, mids retain their clarity, and highs unfold without excessive coloration.

The craftsmanship of Awa-Aizome dyeing

Each maple cup goes through a manual dyeing process that spans several days. Awa artisans apply natural indigo (Hon-ai) in successive layers, alternating applications and drying periods. Variations in temperature and humidity influence how the pigments penetrate the wood fibers, creating grain patterns that differ from one unit to another. This “Hon-ai” method uses exclusively plant-based indigo derived from Persicaria tinctoria, a plant grown in Tokushima. The result combines the characteristic deep blue with the natural texture of maple, giving the headphone an aesthetic that shifts with the viewing angle and lighting.

mk2 dual-structure earpads

The new earpads adopt an angled shape at the contact area with the face, optimizing pressure distribution. Their internal structure combines two foam densities: a soft outer layer and a highly elastic inner layer that gradually conforms to the contours of the head. The protein leather covering based on silk proteins offers three times the durability of the previous model according to the manufacturer. This combination is designed to maintain comfort even after several hours of continuous listening.

7N OFC copper wiring and detachable connectors

The 3.5 mm 2-pole connector makes cable replacement easy and broadens customization options. The standard asymmetric cable is 2 meters long and uses 7N-grade OFC (Oxygen-Free Copper), offering 99.99999% purity. This level of refinement limits impurities and promotes faithful signal transmission. The gold-plated 6.3 mm stereo jack termination ensures a stable connection. A 4.4 mm balanced cable is available separately (reference ET-TH4.4BL2Y) for those who want to use balanced amplification.

Magnesium alloy and genuine leather headband

The main mechanical parts use a magnesium alloy that reduces weight by 20% compared to aluminum. This lighter construction results in a total mass of around 420 grams without the cable. Rubber joints integrated into the swivel mechanism absorb unwanted vibrations and improve the mechanical quietness of the assembly. The headband and strap are made from genuine lambskin leather that develops a patina over time while retaining its suppleness. This material combination balances long-term structural robustness and comfort.

Technical specifications

Acoustic specifications

• Type: open-back dynamic headphones
• Transducer: RP planar magnetic, full-size diaphragm
• Impedance: 32 Ω
• Sensitivity: 96 dB/mW
• Maximum input power: 3000 mW
• Frequency response: 10 – 40000 Hz
• Weight: ≈ 420 g (without cable)

RP mk2 transducer

• Large-surface planar magnetic diaphragm with optimized mk2 technology
  • Pneumatic damping for controlled movement
  • Magnetic flux adjustment using specific damping materials
  • Active suppression of parasitic resonances
• Acoustic performance
  • Fast, precise transient response
  • High sensitivity for easier driveability
  • Deep, well-controlled bass reproduction
  • Clear, natural sound reproduction
  • Excellent soundstage and stereo imaging

Construction and materials

• Housing in hard maple dyed with Awa indigo
  • Awa Aizome artisanal dye from Tokushima
  • Natural Hon-ai indigo applied using traditional Japanese methods
  • Dense wood with optimal acoustic neutrality
  • Deep indigo-blue color enhancing the natural grain
  • Unique texture and shades for each unit
  • Sound signature: robust, deep bass, clear mids, precise and resonant highs
• Mechanical parts in magnesium alloy
  • Fork and headband in lightweight magnesium
  • 20% weight reduction compared with aluminum
  • Rubber joint on rotating mechanism for vibration damping
  • Improved durability and comfort

Comfort and ergonomics

• mk2 angled ear pads
  • Ergonomic design for optimal fit to different morphologies
  • Dual-density structure: soft outer foam, highly elastic inner foam
  • Protein leather covering made with silk
  • Triple the durability of the previous version
  • Sustained comfort during long listening sessions
• Headband and support band
  • Natural lambskin band
  • Flexible, comfortable adjustment
  • Optimal pressure distribution

Connectivity and cabling

• Connector: 2-pole 3.5 mm mini-jack
  • Connection system allowing easy cable replacement
• Supplied cable
  • Length: 2 m
  • Configuration: asymmetric Y-type
  • Conductor: oxygen-free copper 7N-OFC (99.99999% purity)
  • Output connector: 6.3 mm gold-plated stereo jack
• Optional balanced cable
  • Reference ET-TH4.4BL2Y with 4.4 mm connector (available separately)

Accessories

• Leather carrying pouch
• Safety and user guide