120×49mm Rectangular Passive Radiator Diaphragm | DIY Speaker
120×49mm Rectangular Passive Radiator Diaphragm | DIY Speaker
120×49mm Rectangular Subwoofer Passive Radiator Diaphragm with Iron Frame
Upgrade your DIY Bluetooth speaker build with this precision-engineered rectangular passive radiator diaphragm. Designed as a low-frequency bass radiator, it works alongside active drivers to enhance bass response in compact enclosures — no additional amplifier channel needed. Compatible with 3–4 inch speaker builds and a perfect fit for Harman Kardon Racetrack-style Bluetooth speaker enclosures.
Key Specifications
- Overall Dimensions: 121 × 48 mm
- Speaker Opening: 107 × 46 mm
- Corner Design: Rounded (R-corner) at all four corners for a clean, flush fit
- Mounting: Includes iron bracket — screw-mount installation, no glue required
- Compatible With: 3–4 inch DIY Bluetooth speaker enclosures
- Package Contents: 1 × Passive Radiator Diaphragm with Frame
Why Choose This Passive Radiator?
- Long-Stroke Design: Specially engineered for deep, accurate low-frequency reproduction
- Custom Rubber Surround: High-elasticity rubber edge for smooth, controlled excursion
- Iron Plate Weight: Centrally positioned mass weight fine-tunes the resonant frequency for optimal bass output
- Premium Craftsmanship: Tightly manufactured tolerances ensure consistent performance and a professional finish
- Easy Installation: Rigid iron bracket allows secure screw-in mounting without messy adhesives
Ideal For
DIY audio enthusiasts, speaker repair technicians, and hobbyists building or restoring compact Bluetooth speakers who want powerful, clear bass from a small enclosure.
Note: This is a passive radiator diaphragm assembly — it is not an active driver or horn. It must be used in conjunction with an active speaker driver.
Made in Mainland China.
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Frequently Asked Questions
Q: What is a passive radiator diaphragm and how does it work in a DIY speaker build?
A: A passive radiator is an unpowered speaker cone or diaphragm that is acoustically coupled to an active driver inside a sealed or ported enclosure. When the active driver moves air, it also excites the passive radiator, which then moves in and out to reinforce low-frequency bass output. This allows compact enclosures to reproduce deeper bass than a similarly sized ported box, without requiring extra amplification or a large port tube.
Q: Is this passive radiator compatible with my Harman Kardon Racetrack Bluetooth speaker?
A: Yes — this 120×49mm rectangular passive radiator is specifically designed to be compatible with Harman Kardon Racetrack-style Bluetooth speaker enclosures. The overall dimensions are 121 × 48 mm with a speaker opening of 107 × 46 mm and rounded corners, making it a well-suited replacement or upgrade diaphragm for those speaker builds.
Q: Does installation require glue or adhesive?
A: No. This passive radiator comes with an included iron bracket that allows you to secure it in place using screws. This screw-mount method provides a more stable and removable installation compared to adhesive-only solutions, making it ideal for DIY builds and repairs.