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4ohm 40mm Diameter 3W Full-Range Audio Speaker

Specification	Details
Impedance	4 Ohms (Ω)
Power Rating	3 Watts (W)
Diameter	40 mm
Speaker Type	Full-Range
Magnet Type	High-Strength Neodymium/Ferrite
Frequency Response	100Hz - 20kHz (Approx.)

Price

🚚 Ships within 24 Hours
📦 Pan India Delivery

₹ 67.80

(Tax included)

Barcode: 012020

Product Description

The 4Ω 40mm 3W Full-Range Audio Speaker is a compact, high-fidelity driver engineered for portable audio applications and DIY electronic projects. Despite its small 40mm footprint, this speaker delivers a surprisingly rich and clear sound profile across the audible spectrum. The 4-ohm impedance is specifically optimized for low-voltage battery-powered amplifiers, allowing for maximum volume output from standard 3.7V or 5V power sources. Whether you are building a custom Bluetooth speaker, a talking robotic head, or a miniature arcade cabinet, this full-range driver provides the perfect balance of size, power efficiency, and acoustic performance.

Key Features

Full-Range Acoustic Clarity: Designed to handle both low-mid frequencies and crisp highs, eliminating the need for separate woofers and tweeters in small builds.
4-Ohm High Efficiency: Optimized for Class-D mini amplifiers (like the PAM8403), drawing more power at lower voltages compared to 8-ohm alternatives.
Compact 40mm Profile: Slim and lightweight design allows for easy integration into handheld devices and tight enclosure spaces.
Durable Cone Construction: Features a resilient treated paper or composite cone with a flexible rubber/foam surround for extended linear excursion and bass response.
Versatile Mounting: Typically includes a mounting flange or a slim rim that can be secured with adhesive or custom 3D-printed brackets.

Technical Details

Voice Coil Diameter: ~13mm to 16mm.
Resonant Frequency ($F_s$): ~150Hz.
Sensitivity: ~82dB ± 3dB.

Prototyping and Engineering Tips from Robogears

Enclosure is Essential: CRITICAL: A speaker without a box (baffle) will sound thin and "tinny" because the sound waves from the back of the cone cancel out the waves from the front (phase cancellation). For the best bass response, mount this speaker in a sealed or ported enclosure with a volume of approximately 0.2 to 0.5 liters.
Amplifier Matching: This speaker is a perfect match for the PAM8403 (3W+3W) or PAM8302 (single channel) amplifier modules. Ensure your amplifier gain is not set so high that it "clips," as continuous clipping can overheat the small voice coil and cause permanent distortion.
Polarity Matters: Always check the $(+)$ and $(-)$ markings on the solder tabs. If you are using two speakers for stereo sound and one is wired backward, the bass will disappear because the two speakers will be "pushing" and "pulling" against each other (out of phase).
Soldering Caution: Use a fine-tip soldering iron and be quick when attaching wires to the tabs. Excessive heat can melt the plastic housing or damage the delicate "tinsel leads" that connect the tabs to the moving voice coil.
Preventing Rattles: When mounting in a plastic or wooden box, use a thin gasket of foam tape or hot glue around the rim. This prevents air leaks and "buzzing" noises when the speaker plays at high volumes.

Package Includes

1 x 4Ω 40mm Diameter 3W Full-Range Audio Speaker

Disclaimer: Do not exceed the 3W power rating for extended periods as it may cause the voice coil to burn out. Keep the speaker away from metal shavings or iron dust, which can be sucked into the magnetic gap and cause scratchy audio. Avoid pushing the center dust cap or the cone with your fingers, as dents can affect the acoustic symmetry.